Rotec Cycles

Sponsor of BRISCA F1 Stockcar # 92

Last Car Build

 3rd April 2012

Chassis had it's first top coat of paint and it needs moving to another location for the next so we had to mount the axles temporarily:






















Axles,wheels,suspension bars, etc still to be painted but chassis is ready to be moved for the next coat of paint........




















21st March 2012


With the chassis out of the garage for painting it's time to get everything sorted for the final build up so a few pics to show whats going on:



  LD back axle having a final sort out - caliper mountings being installed.

















 View of the inside birdcage. I have used 5/8" coarse threaded studs from the states which are a direct replacement for the fine threaded Transit studs.














 On the right is the 'standard' sliding suspension bracket we are using. This is made for 1 1/2" box so first thing is they need opening up for 40mm box.

Si wanted clamping bolts at the front  and this was needed anyway to suit the additional plating for the 2013 rules as plate goes behind the rear mountings so we had to do the mod anyway. On the left is the modified bracket which meant tapping for larger diameter bolts. Its tight for locating the rodend bearing but works using cap head bolts.




Power steering pump is on the top and alternator bottom right both have belts running from the crank and the water pump - the alternator belt is tensioned from  a bracket on the chassis so thats still loose.

Fuel hoses are being installed you can see supply from pump to pressure regulator







Here you can see the fuel hoses from the regulator via quick release fittings to the carb - we have this arrangement on both engines so we can easily swap carbs without spilling fuel.












19th March 2012



 Out of the garage and off for painting

















13th March


A few more pics - looks like the car will be off for painting this weekend. Si wanted to change some of the body panels and I have been busy making spare suspension bits, making flexi hoses, etc. I also plated the sides of the floor below chassis level for the new 2013 regs.


Additional plating to sides of floor to meet 2013 regs. It made the change a bit interesting around our sliding suspension mounts but it's all sorted













A few spare suspension bits ready for fence testing!























Mk 11 side panels cut out ready for bending 
















 A wingy thing........



















 Side panel after bending






















1st December 2011


A few pics I had forgotten to add...



 A message from my wife.........She loves me really!




















 Part way through making the radiator cowl




















View of ongoing work on the bonnet 


















6th September 2011


Time to catch up with a few pics to show some of the details.



 This is a view of the fire wall with the throttle linkage installed.

Carb is a Demon Oval Race model. 





















A closer view of the throttle linkage. The cross bar is mounted on two rod end bearings mounted on the fire wall. Springs still to be added.




















 Screw on canister fuel filter. I have still to make all the fuel, pwer steering and oil filter hoses.




















 These are the Alcon brake and clutch master cylinders which have spherical bearing mounts at the roll cage end. This means that the master cylinders pivot and keep a straight push on the shafts.


 The brake bias pivot system is also different than the normal system and I still have a few mods  to complete the job. These are all s/h rebuilt ex Nascar parts.















 You should be able to make out the master cylinder pivot points. We still have to do a final fit for the pedals
























 Power steering header tank.





















 Another view of the brake and clutch master cyclinders






















 The secondhand Dart block does not have a mounting pad for the oll filter so this is the remote mounted filter which will have hose connections to the block. Block oil connections are at the back of the engine close to the filter mounting although I could move the filter to the front of the radiator if we need additional oil cooling.






















This is a 3 section brake fluid reservoir for the clutch and and the 2 brake master cylinders 













 I have the instrument panel and fire extinguisher mounting ready for the ally welder and am left with mounting MSD units and clips for cables brakes + completing bodywork and wing mounts. Only 10hours spent since the last report so thats 428 hours to date.








27th July 2011

A couple of trips home spent on the old car and with other commitments and limited time at home, progress on the new car has been a tad on the slow side! Nether the less I am getting there............Throttle linkage completed, clutch pedal / slave cylinder mounting completed, brake pedal/bias adjuster completed, mountings completed for the remote oil filter/fuel filter/ power steering pump/alternator/ fuel valve/ starter switch/ electric isolator etc.

I have just been working on the instrument panel and the instrument mounting plate has been hole sawed for the gauges and next chance I get, I will complete the ally panel for welding + needed some ally welding for the fire extinguisher mount. Only other bit to complete before I strip the car will be a radiator fan shroud and with the car stripped, I have an hours welding on the chassis and engine mounts...............I also expect to have modify a couple of pedals when Si has a final "fitting"!

Body panels  will need a bit more work before  painting and the back axle will need caliper mounts welding on + I need to make spare suspension bars and on the rebuild after painting brake pipes, fuel lines and wiring will have to be installed. 

 I have spent a further 16 hours so thats a total of 418 hours



23rd April 2011

Well the car is back together and I have been completing things as I go along. Been working on pedals - just have to fit grease nipples for the clutch and accelerator pedals so I can finally position the pedals then get onto the throttle linkage. I am also ready to complete the brake pedal/bias adjustment/master cylinder installation. Completed protection tubes for the front coilovers and am progressing with installing the power steering pump and alternator and we have been  looking at the best locations for MSD control/rev limiter, coil, remote oil filter, fuel filter, power steering header tank, etc,etc.........the good part is that these are the final details but rushed or bad decisions result in unreliability. A Brisca F1 Stock Car has to take all the punishment out on track and if you mess things up,  the result is you spend a lot of time retiring from races for stupid reasons.

Consumed another 6 hours in the garage (total 402 hours) . RAM goes in for it's test in a couple of weeks and it should not be too long before I can strip the new car for painting and tidy up the old car - doesn't time fly when you are having fun!! I will attempt to take some pics of some of the details next time which will probably be the last pics until painting is completed.


29th March 2011

 So finally back to where there is decent Broadband where I can update things easily! So I managed 6 hours in the garage (total 396 hours) and completed fitting the 5mm thick roof plate followed by the front cage mesh. Still a few brackets to go and I might drop the engine in +fit the axles to sort out the last bits before painting.


 Full frontal with roof and front mesh fitted.







































24th March 2011,

Wow finally found a computer where I can modify the website - trouble is I cannot upload any more pics, I will have to do that from home. So the chassis has been up on both sides so I could complete the welding, all that took a box of welding electrodes so had to buy another box - better hide the electricity bill!! Well the chassis is back the right way up and I am part way through welding on the roof plate - next time home I will complete that and weld in the front cage mesh and a couple more brackets and have a good old grind. I will then hand over the chassis to the boys for painting and I will sort out the old car. Hours wise I would say we are upto 390 hours. Not decided on a race date yet, we will see how the painting + my time works out


Plan at the moment is to race the old car on whatever surface Si feels like but as it's a new engine we might make that a tar meeting to start off. As yet I will not speculate on the date but we have the makings of a plan.........mind you I did'nt expect to have 2x 2 week trips to KL & Dubai.........




 A couple of pics of the chassis on it's side but from this pic you can get an idea of how much welding was required as most joints were only tacked. A few bits needed tidying + a few plates added in right places to try and control underside damage.

























































18th January 2011


OK backtracking a bit with photos and as usual adding photos away from home and proper internet access is a bit random so they are of course in the wrong order and need resizing..... Anyway, I have covered most  of the stuff in the pics so will add comments as we go.





 Not a great photo but this is a view into the cab with seat, belts and steering installed. Not easy to make out but the ratchet lap strap is on the drivers left




















 So fuel tank and battery holder are almost in position but will both move a bit towards the front of the car.

We are using a fully sealed aircraft auxiliary battery (like a pucka race battery but obtained for a tad less.....) and this is installed flat so the holder is a bit different. I will put on a pic with the battery installed next time.










 This is a view of the shoulder belt mountings tacked in position
















 The other belt mounts tacked in position - on the drivers left are parallel plates for fixing the ratchet lap strap and on the drivers right a clip in mounting for the other lap strap. I have modified the front seat support to take a piece of tube for the crutch strap mounting.  














 I had to drop the steering shaft and from memory, this is the final location. We now have semi formal almost but never definite confimation that the belt and steering position might be acceptable to the driver.....














 See below for the details but the engine mounts are bolted in position

















 Regardless what we have done in the past, we find that the engine mounting bolts end up distorting the holes in the chassis so this time I have drilled 1" holes in the chassis and made some 1" OD 13mm ID spacers for welding into the chassis.
















 A quick rest from trying to break my wrist using a hand drill with 1" drill bit with 1/2" shank..... needs must and I didn't have clearance to use a magnetic drill stand on the chassis.

















4th January 2011


Well the plan was to have a mega weekend session on the car in December as Elly was away for the weekend but snow intervened and I was stuck in Rotterdam, admittedly not the worst place to be stuck but a few miles away from my garage! Bummer!! In the end I did manage about 15 hours work in the last month (total 370hrs). A few of those hours were spent on 3 goes attempting to locate the steering column where the driver wanted it........I think we are there now and whilst I had him in his "office" I located seat belt mounts and agreed (until he changes them!) the of location brake byas adjuster, battery isolator, etc..

I had the car outside to remove the engine, gearbox, etc and sorted the engine mounting holes - I drilled 1" holes and made 1" dia spacers with 13mm holes and welded these in place to strengthen the chassis holes. I also completed a fair amount of general chassis welding with the engine mountings in place to keep things fixed . I tacked in the seat belt mounts and left steering, seat and belts in position to make sure sir gives approval. Following on from my last report, I also made the mounts for the alcan brake master cylinders and clutch cylinder. Also mounted the Tilton multi compartment brake/clutch fluid reservoir. 


2nd December 2010


Hard work trying to get the photos on here and they are all in the wrong order but sometimes you can't win! Spent another 15 hours (total of 355 hrs). All slowly coming together- I spent a fair bit of time on the lathe making all the bits for the brakes so next time I will mount the master cylinders and finish the steering.








This view is looking down on the pedal shaft which runs across the car and is supported at each end with bearings. The shafts located to get the correct pedal ratio and allow the brake pedal to give potential of full stroke of the master cylinders. Si aquired some pucka alcan master cyclinders which are the bees knees - these pivot on a bearing at one end so the cylinder shaft is always parallel to the cylinder.








This pic shows the gear linkage connected to the box and shows the gear change gate - this still needs a good tidy up but you can get the idea.


















This is a better view of rods connecting the linkage to the box. You can also see the front supports for the floor which are welded to the engine mounting plate. 


















Not sure if Si will use it yet but but there are right and left foot brake pedals. These are welded directly to the cross bar and the pedals are shaped to give the best driver position and they  give the maximum possible stroke to the fire wall. Also shown is the throttle pedal that rune on a bearing bush(with needle roller bearings) thats free to rotate on the cross shaft. The similar bush for the clutch pedal is on the left of the cross shaft but pedal is not yet mounted. I have machined some washers to locate the throttle and clutch pedals.







 Bit better view of one of the cross shaft bearings and the brake pedals welded to the shaft. I will mount the pivot for the brake master cylinder at the left pedal and the extra alcan master cylinder I found for the clutch will mount close to the brake master cylinders.

You can also get a decent view of the floor installed.










2nd November 2010

I did'nt get chance to download the next pics but will catch up with those later. I have made a cover for the gear change linkage which includes a gear change gate and also completed paneling of the floor. I addition,  I have paneled the sides between the rool cage and front fire wall using 3mm plate (really an extension of the cab side) - this is not required but it does give additional protection to the drivers feet/ankles. The ally welder did a great job with the floor and after a few minor mods this is now fitted. I installed fixings for the bonnet and boot and finally made a start on installing the pedals. Plan will be to complete the pedals then the steering, seat belt mountinds and finally fit the roof plate. There are a few other bits and pieces to do before I put the car on the scales prior to strip down, final welding/ grinding then painting. We also have to decided on location of gauges, etc and I need to fit brackets for brakes, fuel ines and wiring. I spent about 15 hours (total 340 hours)  


6th October 2010

Catch up with some photos and some more progress. I have completed the ally body panels with just a few details to complete - you will have to wait for photos of the paneled car......I have completed the gear change mechanism as requested and completed the installation of the firewall.  I spent about 13 hours (total of 325 hours).


 Second cross member added so the floor will not be affected by the remote gear change mechanism. Pic shows the completed gear change mechanism and just the rods to the selectors to be installed - the bolt used for the gear lever is temporary!!

The outer tube is made from 3/4" steering tube running in rod ends (used for overall mounting) and a 12mm inner bar is used running in needle roller bearings. I chose the bearing OD so that I needed to machine the tube ID for a good fit. The gear lever mounts in a 12mm female rod end so a total of 5 bearings used. I will be making an ally cover for the mechanism and the plan is to make a gear change gate,  Ferrari style (although we have more power!!)







 You can see the sealing strip I added to the rear engine mount and the mounting brackets for the firewall. I welded all the mounting nuts so they are captive.

I can now install the throttle linkage, etc on the firewall.














 Not giving much away showing the rear panel! I have welded fillet plates to finish off the body line between the front roll cage and sides - you can just see the inside one.















 Part of the floor 'kit' before welding. There are also sides but I wanted to show the cover over the gearbox which also encloses the gear selector rods. I could have made the floor slightly deeper but this stops above the clutch fork which I preferred.















Still a couple of small end plates to weld to the tank frame to prevent sideways movement of the tank + some tidying up before I finally weld in the frame. Still not finally decided on the tank orientation so position may change.











22nd September 2010

Afraid no photos this time and not much available time, spent about 12 hours (total 312 hours). Completed the fuel tank mounting, modified the rear engine mounting to tie in with the floor and made all the pieces for the ally floor ready for the welder to do his stuff. Front bulk head is sorted including a sealing strip to the rear engine mounting - looks tidy but all takes time....... Bonnet is ongoing, cut to size and all marked out - I mensioned previously that as the air filter is almost inset in the down bars, I will be making a scoop into the bonnet rather than a scoop on top of the bonnet so that means a cutout around the air filter so took a bit of time sorting the best way to do it. Made the steering drop arm and have sorted most of the bits for the pedals, gear linkage , etc. Whilst making the floor, I added another cross member just infront of the seat as the seat would be in the way of lifting the floor - this leaves a nice gap for installing the gear linkage. The driver was winging about  the movement in the linkage of the old car so this ones being built with bearings in both the inner and outer sections of the offset remote linkage - this has used up far too many brain cells but should be acceptable to himself! Not happy with yer normal brake master cylinders said driver aquired some of the latest bearing mounted master cylinders for a good price including a pucka balance bar but failed to aquire the pedal assembly to go with it . Still a few more wasted brain cells and I think we have the technology and bits to sort it - looks like will install the pedals and gear linkage next time as well as completing the bonnet and other ally body bits.  Just working out all the bits for the throttle linkage, clutch linkage and with a few more E Bay purchases we will be there.


Have to say that it's so much easier to sort all the bits these days and not have to spend my valuable time trawling round local shops for all the bits - to give you an idea of what was waiting at home for me (ordered on E Bay or internet) this time:


rod end and needle bearings for gear linkage

rod end lock nuts and inserts for bars

head restraint net

seat belt eye bolt plates

carb spacer

mutli reservoir for brake/clutch fluid (3 sections)

tubing for reservoirs to master cylinders

hose fittings for the non standard master cylinders (reservoir connections)

bias brake pedal assembly ( to be machined to take sirs special bias bar)

clutch pedal assembly

clutch master cylinder

fan spacer


Just working out the next shopping list of bits and pieces.............


26th August 2010

 Another 17 hours along (total 300 hours) and I reckon about  50 hours to go + painting.  I have completed the under bracing on the side nerf bars which includes tieing in the exhaust silencer supports, installed the rear bumper hoop, welded up the exhaust system, put on the gearbox and am almost there on making the frame for the cylindrical fuel tank. Prop shaft hoop is on but we still need a few bits for the prop shaft . Theres still quite a list of bits to do including making the bonnet and side pods, floor, firewall, pedals, steering, etc.


Unfortunately not enough time at home to complete the car and it looks like we may get out to test it this year but will have to wait to race it until next year 






 This a view under the offside nerf bar showing the down bracing to the sump guard/ exhaust support frame and the silencer mountings 








 Exhaust silencers and system welded up, just needs a bit of grinding to tidy up. These bolt directly to the flange I have welded on the exhaust manifolds. The pic above shows the mounting brackets which are the clamp frames for the U bolts welded to the supports and then the silencers are fixed with the U bolts.








 The car has been a couple of feet in the air whilst I have been working on underside stuff - this is what a few drivers will see before being punted!














Gearbox in so I can make the floor, firewall, gear linkage, pedals, etc and made a final measure for the prop shaft + made the prop hoop. Bit of plate still required under the gearbox but we have a decent sump guard.













 Still need to put on a carb spacer so carb will be about 1" higher but all well protected by the down bars. Bonnet will feature a lower scoop infront of the carb rather than a convention intake scoop on top of the bonnet. Will also carry that forward to a scoop for the radiator and I think it's going to look a bit  'aggressive'






8th August 2010

 As well as installing the engine (see pics from 1st Aug), I also installed the radiator, completed sump guard, installed steering box, set/ tacked the exhaust systems and made  the frame for the front firewall. Managed to get in 25 hours (total 283hrs). Probably anothere 20hrs or so and I will have a reweigh to compare the overall weight with my weight programme, then remove engine, axles and all the bits for a final chassis weld and tidy before painting. I have already cut the roof plate but this will be the last to go on as it's easier to work inside the cab without banging my head! 



Frame for front firewall 


















Flowmaster silencer in place - I carried these back on a business trip to the USA. Theory is that they are designed to "scavenge" the exhaust gasses so you don't loose power due to exhaust back pressure - we will see!  













View of exhaust manifold and sump guard 


















Matching flowmaster silencer. The frames the silencers are mounted on will be tied into the side nerf bars + additional stiffeners added from the the sump guard to the side nerf bars. 













 Bit dark but view of radiator and steering box installation.
















 Ist August 2010

Quick update. A few years ago with the help of a mate at work, we modified a weight control programme for offshore platforms to a weight control programme for cars - you put in the wheelbase and wheel positions relative to a datum then all weights and positions of all components. The programme gives weights on each wheel, inside weight, rear weight, etc. Trouble is you need accurate weights of all the bits, the engine being the one I did'nt have accurate weights for.

So I had produced a weight estimate of the overall car and I decided to have a check weigh now to see where we stood with the rolling chassis, then add the engine. So a change to the programme got me the estimated weight of the rolling chassis



As I wanted to put the engine in after the initial weighing I pushed the car onto the drive and put it on the scales.


Estimated weight: 769kg


Actual weight: 781kg.


Now I had based the estimate on weight I had (shortened axles) and we used full uncut axles + bumpers to match so 12 kg extra was not too bad as I was still showing that the overall car would be slightly under weight. 





So drop the engine in - was easy cos I'd already modded the engine mounts.


Estimated weight: 1058kg


Actual weight: 1037kg


Now the engine was bare with just mountings + exhaust  manifolds + bellhousing but that was still a nice result.

So with mounts and manifolds + bellhousing the engine weight is 256kg




When I remove the engine to painting the chassis, I will check the weight of mounts, exhaust manifolds and  bellhousing but the engine is in the region of 225kg bare.


At present the engine is positioned with the back of the engine on the centre line of the car. This gives a rear weight %slightly over my estimate so I will check the rest of the weights and may move the engine a tad forward. Out of interest, with talk of offset engines, we are allowed to move the engine upto 40mm sideways, I checked this on the programe and with our small block with gearbox and all the bits this only makes a difference of 0.6% on inside weight. Whilst there are still bits to add which go on both inside and outside, we already stand on 52.7% actual weighed so the engine would only be moved to front (in our case) or back in the chassis. I have put our offsets in the overall car. 



 8th July 2010

For a change my plans changed and I only had a short trip home. However still managed to get 14 hours on the car (258 total hours).

Completed most of the steel work on the front end (over rider hoop, etc) sorted out the coil overs so the chassis was ready for the engine.

Had a few mods to do on the engine mountings (time consuming but necessary) and managed to get engine ready to drop in. I will explain on the pics.


 Chassis all ready for the engine and all ready to roll!













 View underneath the front end with overrider bar in place













Modified engine mounts installed and exhaust manifolds fitted. I bought these in the states as a complete set instead of using a manifold kit but it was touch and go if there was enough chassis clearance to use them. Turned out they were made for the job.








Quartermaster bell housing installed. Plan for exhaust is to mount the Flowmaster silencers  outside the chassis with protection under the nerf bars. This allows a lower floor and prevents toasty feet!

Engine is ready to drop in, I just ran out of time!







8th June 2010


Shorter time away at work but also a shorter time home plus Si needed some help sorting the shop...... A bit more work on completing nerf bars, etc changed out all the wheel studs for coarse thread American ones, tidied up suspension mountings on rear axle, completed suspension mounting on the front axle, sorted front panhard bar and tie rod to make car a complete roller. New engine mounts have been collected but I did'nt get chance to pick up the engine and box, etc from the unit and install. I did manage to have a good clean up and clear out of my garage to make it an easy task to drop in the engine and drive train next time home - I should be home for end of June and may have a bit longer at home to get this puppy together. Overall I only spent 10 hrs in the garage (total 244 hrs).


3rd May 2010


This time home I installed the side nerf bars and completed the bumpers - from the pics it looks a lot of progress but thats just because theres been a lot of steel installed! Still not too bad for 18hrs spent (total of 234 hrs).


 View of the car with front bumper installed. All the bracing consists of 2 pieces of 40x40 box but you can only do this for the bumper ends if you use a similar sort of internal bracing otherwise its the chassis that suffers.






















As I meansioned previously, the main chassis stops at the bumper end support cross bracing and then the bumper "clip" is more like an F2 but fully welded (and a tad stronger!). I thought that I would go this way for a couple of reasons, the first being that bumper end bracing can be stronger without risking chassis damage. The second is that this design allows the front end to be adjusted with regard to the strength of the bumper bracing so it can be used to absorb more force to lessen loads on the driver. Whilst potentially I could make this stronger than a "normal" chassis, I think it's the way forward in giving F1's a shock absoption zone at the front of the car.


You can clearly see that all the bumper loads go to two "nodes" where these loads are distributed to the main rail, cross bracing, down bracing from roll cage and partially to the sump guard (not fully completed yet).  Again it should be emphasised that the roll cage down bracing can only really be included in this if it is adequately tied into the main chassis (see other pics of this). The use of unbraced down bars from the roll cage really do little for the strength of the chassis (but they do protect the engine) - they are too long on our cars if unbraced and will bow rather than transfer load. My view is that you don't "waste" weight - it should all be put to structural use.


Also, triangulation is obviously used in all this approach



































Rear bumper outside bracing - again all bracing is 2 pieces of 40x40 box (x2 !!) don't try this at home if you are using a conventional chassis.







































































From my point earlier about bracing of the roll cage down bars - you can see here the triangular bracing of both the down bars and sump guard to the main rails which structurally tie the chassis together and allow them to add to the overall strength of the chassis.


I have still to add the diagonal bracings from the sump guard to the side nerf bars and maybe at the front a diagonal bracing from the roll cage down bar to the front of the side nerf bars.


When I drop in the engine for a trial fit, I will also complete the sump guard which at the moment is only an outer frame.


Overall, what I am going to do is complete the car as far as tacking in all steel work, mounting steering box, radiator, etc, (at this stage I will just cut out the roof plate but not weld it) and put the car on the scales with water in radiator, temporary body panels, exhaust, etc , then I will put the car on the scales to finally locate the engine. In theory I should have a bit of weight to play with (under weight limit) and I have a number of structural additions to gainfully use the weight. Having achieved the optimum weight distribution I will remove the engine and bolt on bits, raise the car and complete all the welding / tidy up grinding, complete body panels and paint the chassis.



































































































16th March 2010


Well back in Heathrow again on my way back to work, just for a change not a lot of time spent on the new car ( 15hrs, total of 216hrs) but still did OK. Tidied up a fair few bits and pieces but most of the time spent on bumpers - made a new front bumper as the one I had made previously was a bit short (will do for the old car) and plated the bumpers/ sorted out bumper ends, etc. Installed the rear bumper and temporarily mounted the front bumper so I could but the puller between them to bend the ends. Sorted most of the bits and pieces for the small block and next time home I will complete bumpers and hope to get the engine in.


As Si had not managed much time to sort the old car, I left that with him cos he was working on a few different things. Anyway while I was home he installed the 496 BBC - he had to modify the sump guard, engine mounts and exhaust. He will not be ready for the start of the season and has major shop rework going on over Easter

but still looks like he will have things together to start racing in mid April


19th January 2010


Things have progressed but the snow did'nt actually help with the masterplan! Spent about

14 hrs on the car (total 201hrs), completed all the coilover mounts on the chassis so I could have the car rolling. More or less sorted the seat belt mountings - just a bit different as we are using a Hooker harness with ratchet. Picked up the new 434 SBC - even though it's built using mainly S/H bits it's a corker! Also made a couple of engine lifting plates and sorted some parts we needed for the 496 BBC going in the old car. Some of the pics are a bit dark but hope you can still see whats going on!



Bolt on rear coilover mounting - took some making but it looks the part, keeps the coilover unit vertical but every thing is pretty well protected by the wheel. Local strengthening plate added on the inside welded to the 3mm side plate. Will be maing a spare later.....


















Looking back at the rear outside coilover mounting - a couple of holes still to drill but someone needed my drill bits at the shop + my Landy!!


















Front inside coilover mounting, will be adding protection tubing later. I used 1" bar and drilled it 1/2" on the lathe to make the bolt on section. The support is made from 60x40x3 HT box the inside one is set at 15 degrees (shown) and ouside one at 25 degrees. I made templates at the sides of both of the box sections to mark out the tube cutout - the tube goes down and bends in towards the centre of the chassis at this point.


















New 434 SBC in the back of the Landy having just picked it up. This the part exchange deal we did with Peter Knight to swap with bits of our original BBC- the block, heads are second hand Dart parts but after the man has done his work I doubt if we will notice but it was the only way we were going to afford this little beauty. Thats our original Demon Oval Race Carb which had only been used a couple of times on the original BBC. Out of interest even turned sideways we had to pack the engine for transport - the BBC would not fit sideways!!















Closer view of the Demon carb on top of the Dart intake manifold






















25th November 2009


As usual, a busy trip home again - never enough time to do what you want! Managed to spend 25 hrs on the car (total 187 hrs) mostly spent on the suspension and sorting out the fuel tank. The small block is ready for the new car but think we need to go for a "fitting" for the engine mounts before coming home. Also heard that the big block for the old car has arrived in the UK so we should have it soon. We will have to see how much time Si has to sort the old car out as he fancies racing in December - I won't be back home till after that so I will have to leave him with it! Based on the normal December at the shop, that sounds like a busy Christmas....


 This is a pic of the bits for the fuel tank. As I've said before this is based on using seemless ally tubing to make a cylindrical tank. It took a fair bit of time to cut ou t the end pieces, baffle (put in position for photo) and I even broke a hole saw.




















The complete tank after a visit to the specialist  welder we use for the shop for welding ally and titanium frames,etc.




















Inside rear coil over mounts. We decided to follow the design from the old car which has bottom axle mountings which keep the coil overs well protected. Top mount is a bolt on arrangement and you can see from the weld heat marks that theres a stiffening plate welded on the inside. The caliper mount has to be relocated - this was on the axle when we bought it.















Pic shows the rear outside coil over mounting on the axle - again this is a bottom mount which keeps the coil over tucked away. It does mean that the coil over is mounted at an angle and not vertically (angled from the side, vertical from the rear) but this really only affects the spring rating we use. I did not take a photo of the top mounting - this too is a bolt on design. You can just see the bent tube which I have used to make this. Again, the caliper mount has to be moved. Subsequent to this photo, I have completed the bolt on top mount.








27th September 2009


As I explained last time, not much time at home with new job schedule but I've just put in another 20 hrs taking the total to 162 hrs. Much of that was spent welding and grinding but continued making suspension bars and a bit more general work on the chassis - easier to describe with photos! I understand engine is just waiting for the dyno so should be available next time I'm home. Also I decided to hang fire installing bumpers, etc until we have some Goodyear tyres on rims so we have the correct dimensions when we decide what rims and offsets to use. We are also looking at using the original car for shale so we are looking for another engine.......................








Back axle located with all bars fitted (not final) and triangulation fitted to down bars, etc





































































21st July 2009


WellI was very busy this time home but unfortunately this was wrecking the kitchen and not building our car! Barney managed a bit of time on the car fitting the remaining down bar and machining threaded inserts for the rear suspension bars - I was limited to temporarily installing both axles usinf existing suspension bars. So we are set up for installing the bumpers and side nerf bars but it's not happened yet! Between us we've spent 12 hrs on the car so thattakes us to 142hrs so far. It looks like I will have to spend longer at work in the UAE so I'm not going to be able to do anything on the car for some time......................










23rd June 2009


As stated previously, the boys have completed the roll cage and this time home, I completed the 3mm plate under the seat, base fixings for the seat and plating the roll cage sides with 3mm plate + I spent some time on suspension mountings. I estimate that between us we have spent 30 hrs on the car so thats a total of 130hrs so far.

We are now at the position where we need to mount the axles then put on bumpers and side nerf bars - bumpers and nerf bars are welded and waiting so we are not in a bad state. However, we still await the engine so it does look like we can get the car ready in time..............






 Roll cage all together












































































The panhard and suspension mounting brackets shown on top of the chassis needed a bit of modification to open them up to use on 40mm box (supplied for 1 1/2" box, 38.1mm). 

























3mm plate tacked in position - these have now been welded top and bottom.


One of the down bars from car to front of car is fitted and we will be having a steepish bonnet line - this is high on the front hoop and there will be curved fillet plate to blend this into the cage side. The cage side is higher at the rear hoop which is not too clear on the pics - also because  I took the pics standing, the cab sides look lower than they really are. Photographer I am not!!! But in the "flesh" it's looking pretty cool.  












































































31st May 2009


I've no photos yet but Si and Barney has been continuing work on the roll cage and from the pics sent to my phone, everything is looking cool. Had a few phone calls from them for guidance on how I want things and it's great to start getting progress when I am away - up to now it wasn't easy for any of them to take over as I had not put everything down on drawings and anyway I change things as I go along! Cage is tacked together so there will be a good welding session but the time is in the fabrication. When I put on the photos I will check and see how many man hours they have put into the car and update the info. 


25th May 2009


Well to say the roll cage has to be built around full containment seats is a fair comment! 20 hours (total100 hours so far) further on, the seat is well and truely located with 20 bolts holding it in and very time consuming bracketry! I also fitted the 3mm plate behind the seat to get all the fiddley bits completed in one go. It's bank holiday but I've got to catch a plane - however Si and some of the team are free to play so I hear they have been working on the roll cage so hopefully there will be some good progress on the car whilst I am away!! I will keep track on the hours they put in to keep things up to date but I was pleased with the progress I made with the tricky bits and things should really start moving now............









This is a view of the bracket on the seat back/shoulder restraint























Rear view with additional cross tube behind the head rest


























This view shows the three fixing locations on the seat, one at the top of the seat "bucket" and two on the head rest.



























3mm plate going in behind the seat



























Still some welding to complete on the rear plate and i've still to install the seat belt mounts and the cross tube for the belts. Think we will go for a new set of ratchet belts which will complement the seat and make for a very secure driver. 
























27th April 2009


Had to make a few mods to accomodate the new back axle - slightly different mountings from our existing axle + I duffed up on the location of the mount for the rear panhard bar, anyway all sorted and axle is temporarily in place to help with seat location.

Started roll cage construction and completed all the main bends. Rules allow front to back or side to side main hoops - most use front to back these days which has some advantages, ie, you can use a smaller roof plate as the front roof cross member can be positioned to suit. Anyway, just to be different, we have gone for a side to side cage design which will give a different look + the cage is wider down to cab height at the front which also means that the down bars from roll cage cab height to front of car start wide of the chassis at the roll cage so with a slight bow this allows engine removal/installation without having to mess about - engine mounts normally get in the way if installed first. At the end of the day, it will give a different look so it will be in the eyes of the beholder.

In all spent  about 20 hours on the car so up to a total of 80 hours. Roll cage bending takes a bit of thought particularly as the front hoop has two bends which each have bends in two planes (easier to see on photos) but theres more brain cells destroyed working out and cutting some of the tube to tube cuts which are a tad more tricky on the side to side design. Anyway, I will attempt to describe whats happening in the photos......


Back axle positioned and on brick to give approximate running height which gives the location of the axle central mounting.
























Rear cage hoop being positioned - this angles back 20 degees so photo is a bit misleading. Thers a 50mm raised section in the top of the hoop. The seat will be installed at the same 20 degree angle.




















Rear cage tacked in position and front cage being set up. Bends at cab side height on the front cage slope backwards and also in to the chassis. From the side, the front legs are at right angles to the chassis although it does not look like it from the photo! - in this photo the bottom of the front cage legs still need to be pulled in a couple of inches.






















Front hoop positioned and tacked + bars from rear hoop to chassis installed.






















Perspective makes this shot look a bit wierd but it does give a different view of the cage. Incidentally, the back axle needs moving about 1" to the inside



























17th April 2009


No more progress on the build - I should be able to update that at the end April. However, a radical change in plans as the new engine will be delayed in completion to June..........Based on status of the build, it looks like the plan will now change to concentrating on completing the new car and forget about installing the engine in the old car - the engine delay should mean that by the time it arrives the new car should be ready for it and instead of spending time on modifications to fit the small block in the old car (new firewall, floor, fixing new engine mounts, exhaust, new bonnet, etc) I will be at the stage where I can do this on the new car. There will be some "cheating" involved as up to date I have done all the work on the new car and to get us out on track asap Si and the team will have to help with stuff like front fire wall, floor, brakes, bodywork, painting, build up after painting, etc. We will be getting some engine mountings off Bruno and he is busy as well so all in all it looks like it may be an interesting few months...........


Incidentally, although it's not available straight away, the old chassis (all sorted with new bumpers, etc)  without axles but with big block engine mounts, exhaust headers, fuel tank, bodywork and probably quite a few other bits will end up on E Bay with a 99p start price and no reserve but the buyer would have to arrange collection, ie trailer and a few guys to help lift it.


30th March 2009


Finally managed to get some spare time at home to work on the car but the majority of the 20 hours (now total of 60 hours) I did get to spend on the build was almost continuous welding. We now have bumpers and side nerf bars ready to go on the car and I completed much of the welding on the chassis - with the 40x40 double box on the X bracing, that was considerably more welding than on a normal chassis.


With the good news that a small block in now going in the new car, I have been looking at how I am going to use the available weight and whilst not really adding to the structural integrity, the roll cage will be lengthened.  Fortunately I had not started bending tube, so this time away I will redesign the cage and hopefully next time home I will start work on the cage. Going back in October 08, I meansioned about reworking the former, however on a few trial bends it showed that the former needed higher sides to control the high tensile pipe I am using - after making the steel side extentions to go on the cast iron former, I borrowed the oven to preheat the former to 200 deg C, welded on the steel side extensions with special rods then put the former back in the oven and switched it off to allow it cool down slowly to prevent cracking. This worked fine but my tube was not playing the game and was flexing the sides of the former, so on went Mk1 attempt to clamp the top of the former - this first attempt was not strong enough so a heavy duty Mk11 design was used and I am finally getting there! I was contemplating aquiring a US type bender which uses double formers to control the pipe and is a better way of doing things but it looks as though we are on a winner.........


I am now considering using roll cage tube for the down bars from cab to front of car + more use of 40x40 box in the "sump guard" which is now more of a bottom chassis, all of which will be using the additional available weight to strengthen the chassis.  


5th February 2009 - Second batch of photos


When I completed my play in the garage this trip home, I have spent a total of 40 hrs working on the car - the status so far:


I have fabricated angled bracing to the sump guard to make a 'framed structure' that will also tie in the the front and rear axle radius bar mountings. In this photo, I have only completed one side of the chassis.
























A closer view of the triangulation


























Angled bracing has now been fabricated on both sides of the chassis and this is one of the 4 axle radius arm mountings that use a bolted socket at the top and welded bottom for easy replacement. We will be using the same type of sliding mount as I used for the panhard bars. All 4 axle radius arm mountings have been installed but triangular strengthening plates still require to be installed for the chassis mounted  'sockets'

























5th February 2009


This is status after 27 hours - I will add more photos when I get chance of the progress to date  



The front and back axle panhard bar chassis mountings use 40x 40 box and slider mountings. The chassis mountings are bolted into a fabricated socket on the chassis and welded to the sump guard frame on pads






















This is one of the panhard bar chassis mounting sockets welded to the underside of the chassis - replacement of one of the vertical bars is easy with just easy welding onto the sump guard frame.
























Another view of the panhard bar mounting and slider. Decision has now been made to employ the same system for the front and back axle chassis radius arm mountings.
























View of the rear of the chassis showing panhard bar mounting and sump guard angle bracing to back bumper






















4th February 2009


First of all a bit of a catch up! These are the photos of where I was up to after 22 hrs:



This is where I had finished, main sump guard frame welded in position and plating added for front bumper bracing, front nerf bar bracing and back bumper bracing.





















View at front bumper bracing - plates cover the 'honeycombe' of box sections.






















View of plating for back bumper bracing






















I managed to get a lot more work done this time at home and when I get chance, I will add the photos. 



2nd January 2009


Unfortunately no more photos at present and not much happened since early November due to very limited time spent at home. After the last set of photos I did spend a further 4 hours in the garage making a total of 22hours so far. I welded on strengthening plates for the front/rear bumper supports + front nerf bar supports, fitted the main sumpguard frame with four verticals and marked out the front and rear suspension bar chassis mounts ready for drilling.


3rd November 2008


This is the final set of photos I took during my last "play" at home. At this stage I have spent a total of 18 hours in the garage and a few too many of those were spent fitting the X bracing that was a tad challenging! But effectively I have a full flat chassis which still has to be fully welded. To minimise distortion, I will wait until the sump guard, rollcage and down bar from cage to front bumper cross bracing are installed. I have actually completed more of the build but someone had

grabbed the camera so you will have to wait until I am home again!



The completed X bracing, only tacked but it's in there!























I have now assembled the rear of the chassis which of course is welded onto the back bumper cross bracing. This view is looking at the top of the chassis. This is a fairly conventional layout because you still have cage mountings to consider but the back bumper support cross bracing means that we can use 2 x 40x40x2.5 box for the rear bumper bracing. It's true that this does not (usually!!) get as much hammer as the front bumper but we had to introduce some strengthening on the existing car which had some "issues" even using lighter bracing. The rear section of 80x40 box is flush with the main chassis to make plating the cab sides easier. The lower piece of box on the rear add on section of chassis is 60x40x3 box just to give a greater surface area for rear bumper mounting. 






















This is a view of the underside of the chassis - it's easier to turn over without bumpers on so I will add those later. The temporary bracing is still installed but this will be removed and the correct bracing installed when the roll cage and seat position is finalised. I have sorted out a new Kirkey series 53 full containment seat which was not cheap but is an excellent piece of kit and should help protect Si when he tries to demolish my work! There will be extra roll cage work to install this.  

















1st November 2008



First section of X tacked in position. 40x40x2.5 is used for the X. Bottom opposite diagonal will also be a single piece and others will cut to fit.
























This is a cut out for the end of each X piece. 5 cuts a piece and 8 pieces to make. Actually I made an extra one cos I duffed up with the "handing" of one! Cutting and fiting the X took much more time that I expected but thats how it goes.





















View at front bumper cross bracing. As before it ends up with 20mm above the main rail and wil also be the same below. There are no other bracings going in and the "nodes" at the ends of the front bumper cross bracing will take all the loading - the end of the X bracing support the "nodes" and give extra support area for the bumper bracing. If you look at the "honeycomb" of the connected boxes, this provides substantial strength for bumper bracing. Compare this to a "conventional" chassis with 70x70 box.  




















View at radiator cross bracing. 




























Top section of X tacked in place. It will be a while before I install the front bumper as its not needed until the end but each corner will have 3 bracings to the "nodes" a V to the front on the "nodes" and the bumper bracings to the end. All these will be made from 2 off 40x40x2.5 box.






















31st October 2008


Back bumper cross bracing (2off 60x40x3)

again plated and inserts used in the end

100mm of each box. With chassis the right

way up, the main rail is flush with the top of

the cross bracing.





















Another view of the radiator cross bracing

showing the 20mm deep top and bottom

overhang on the chassis.























View of the front bumper cross bracing.

The 40 deep main rails look a bit "lost"

relative to the depth of the bracing but 

the masterplan should be a bit clearer

when the X bracing is added. I have

said before that we have a similar front

bumper bracing on the existing car but

this is built around the main rails:








































30th October 2008


 First of many.... Remember that the main rails only run between the bumper cross bracings so they are just under 3m long (on a "normal" car with the main rails running between bumpers the main rails are more like 3.65m long).


The bumper bracings are the full chassis width, front is 3 off 40x40x 2.5 and rear is 2 off 60x40x 3. Also shown is the radiator cross bracing and you can just see how the overalpping is going to work at the front of the chassis.


Other cross member you can see is just a temporary one.














This is the front bumper bracing. As well as being plated, it has inserts in the ends of the box to stop crushing. The main rails are vertically central on the cross bracing. 





















This is a view of the radiator cross brace as it overlaps the main rails top and bottom






















22nd October 2008


General Information


Following might be of help:


Materials: I have purchased all box and circular section steel in high tensile grade steel, only exception is 25x25x2.5 which the stockholder could not locate.

I stayed with mild steel for plate as it is more readily available . Note that as my steel stockholder is part of a nationwide group, they do not keep HT box in stock so it took a couple of days to deliver. Point is it probably came from the midlands/ north so it's not a southern thing. Remember to always request a copy of the material certificate for your HT steel, if the stockholder can't supply this don't buy it. I've spoken to some who didn't have a clue about HT steel and would have supplied MS steel telling me it was HT steel.



Steel costs (June 08):


3mm MS Plate: 2m2                                            £39.25+vat


5mm MS Plate: 2m2                                           £65.16 + vat


80x40x4 HT box based on 1off                         £67.01 + vat


60x40x3 HT box based on 3off               each £42.50 + vat


40x40x2.5 HT Box based on 7 off          each £25.85 + vat


25x25x2.5 MS Box based on 5 off         each £10.60 + vat


48.3 dia x4 HT Circ based on 4 off       each £40.00 + vat


42.4dia x 3.2 HT Circ based on 2 off    each £36.00 + vat


Box and circular based on nominal length bars of 7.5m


Fuel Tank

Rules require either minimum 1.5mm thick steel or minimum 3mm thick aluminium for fabricating the tank. Normally these are rectangular which means 12 main welded seams, we had a chat about this and I suggested we could try a tubular tank to reduce seams + also this is the better stronger shape to use in our sport , ie you don't see many fuel tankers with rectangular tanks! In addition our rules state tank capacity of maximum 20.5 litres (approx 4.5 gallons).

Best material I located was 10½" O/D x1/4" thick (approx 6mm thk) seamless Aluminium Tube - we decided to use this even though it is thicker than required but to limit our tank capacity to 3 gallons. I managed to buy an offcut of this + some 6mm plate (both tube & plate are a weldable spec). Tank length will be about 12½". Overall tank will be more secure due to shape and thickness and will have 50% less welded seams than a rectangular tank.





15th October 2008


Selection of Main Rails and Bracings


I've already said that the deal is to get at least equivalent strength for lower weight compared to a conventional car with 70 x70 main rails and framing is the way to go to achieve this. However, you have to look at the overall chassis because whilst you can do a good job to ensure the car is strong with regard to say bending from vertical loads or from compression, with a F1 Stock Car you can never forget bumper bracings. With say a space frame chassis you will often see bumper bracings split and supported on the two main rails but it is not easy without adding weight to have the equivalent strength of a conventional car. Personally, I prefer to use the benefits of framing to achieve the overall strength but not to compromise the most important aspect of bumper bracing.

So I could save weight by using HT 70x70x3.6 box but what are the other alternatives? Well both 60x 60 and 80 x 40 have been used, dropping to

60 x 40 or 50 x 50 leads to a more space frame solution. So for info a comparison of what I considered:


Section                weight(kg/m)     Area(cm2)  Section Mod (Vert/Horiz)(cm3)


70x70x3.6 HT        7.46                 9.56                   20 / 20


60x60x4 HT           6.97                 8.96                 15.7/ 15.7


80x40x4 HT           6.97                 8.96                11.5 / 17.8


As the areas are vary similar, there not much in regarding compression loadings but obviously, the dimensions of the section has the most influence on the section modulus. However, even though 80x40x4 has a relatively low section modulus for vertical loading when used flat, this is easy to rectify using framing.


What made my mind up was not just looking at the numbers but how I could design the bracing. Whilst I am using some of the weight I have saved, using

2 pieces of 40x40x2.5HT box for main bracing means that the chassis internal

bracing can overlap the main rail with 20mm top and bottom of the rail. This appealed to me due to the strength this will give the whole structure + gives

good strong mounting areas for external bracing for bumpers, etc.


Finally, it's you pays your money takes your choice and how this stands up on the track is what matters!


I've already covered tying in the down brace to the main rails to improve the vertical resistance to bending by making a 3D frame. Well providing this is done correctly it has a substantial effect - I checked by calculation and results as follows:


70x70x3.6HT box 1½ down tube not installed or not tied to main rails

                                vertical Section Modulus = 20cm3  (from front

                                of chassis to cage)


80x40x40HT box, 11/2 "  down tube structurally tied to main rails, section modulus

                               is as follows:


                               At bumper bracing:                 34.7cm3 


                               At Front Roll Cage Post:        142cm3


Now that's the difference that structural bracing makes, up to 7X the resistance to bending for minimal weight used. For my calcs I have assume using 42.4 dia x 3.2 HT tube for the down tube, bracings will be 25x25x2.5 box (1.74kg/m) - I will be using about 3m so assuming you are going to use a down tube anyway, thatï 5.22kg to increase the strength 1.7X to 7X. Way to go!  





10th October 2008


Selection of Materials


So the idea is to save some weight in the chassis but have equal if not more strength than a conventional car with 70 x 70 main rails.

First thing is choice of materials - well theres no real choice as far as I am concerned, we need to take advantage of using high tensile steel. I remember in my early offshore days,  if the design was say for Norwegian waters then a lower design temperature was used and so stronger steels were required. At that time the normal mild steel specification for box section was BS 4360 43C, the high tensile steel developed was BS 4360 50C which was designed to give the same strength as 43C but at -20degC or so. Whilst the Specifications have been superceded, the similar steels are still available -  typical specs are:


Mild steel EN 10219:2006 Grade S235JRH


High Tensile steel EN 10219:2006 Grade S355J2H


Many steel stockholders only stock the mild steel but can get hold of the high tensile if you harass them enough. It's not easy to give exact price differences as you pay less per item when you buy multiples + overall discounts, etc. However, this time I ended up with a few requotes because I was quoted the wrong specs, for example for one length (nom 7.5m) 80 x 40 x 4 box I was quoted £58.57 +vat for mild steel and £65.16 + vat for HT steel (as part of a decent size order). Always request copy certificates for all the steel and remember to segregate/ mark which is high tensile!


So what are the differences? Well the grade designation gives the real info,

The 235 and 355 refer to the minimum Ultimate Tensile Strength (UTS) of the steel, the units are actually N/mm2.

The UTS is the limit on the steel deforming elastically in tension, below this number, the steel will return to it's original size, above this it's permanently distorted. So effectively the UTS is a good comparison. If you look at a certificate it will give the actual test UTS for your steel and will normally be more than the grade required minimum strength.


So to demonstrate how the steel selection can affect us I have compared the max loading that can be applied in tension to 70mm x 70mm box of varying thickness & material


Section      Cross Sectional Area    Weight     Material     Max Tensile Load

                                mm2                  kg/m                                      kN


70x70x5                  1300                     10.1     MS (235)             305.5


70x70x3.6               1062                      7.46    HT(355)               377.0


Now as this is a comparison don't have to bother about the units but the bigger the number the better so if you use 3.6mm thk HT instead of 5mm thk MS, you save about 2.5kg/m and in addition its 23% stronger in tension.


OK so we are more concerned about how this equates to compression, well it's the same providing there is sufficient support as the rail gets longer (won't go into it here but this is determined by the slenderness ratio). For us, the normal internal chassis bracing performs this job and the increased strength applies also to compression. I would not back off from using strengthening pads for the likes of bumper bracings but say for a normal chassis, you can save about 19kgs just on the two main rails. Incidentally, the slenderness ratio is also a good reason for using braced down bars from the cab height on the roll cage to front of chassis as the resulting frame ensures the chassis stays where it should and does and not bend like a banana (the affliction of my first car!).


Only other consideration is that technically if you were welding HT steel instead of MS steel to operate at -20 degrees C you would need to use different welding rods (ie winter racing in Iceland!!). However, for our temperatures, good general rods for carbon steel are fine (I buy mine from the BOC stockist and we checked and compared specifications).


So if you are with me so far you should be asking the question -but won't this affect the resistance to bending? Well for the same 70x70 comparison, the section modulus is reduced for the 3.6thk box due to there being less material but the steel strength has increased,  it just comes out in favour of the HT steel.





7th October 2008


Overall Chassis Design


So far all I've done is advising some of the main materials and some aspects of the design. Whilst I might be going through some of the items already covered in the Structural Design pages, some of you may not have read or understood what I was wittering about!

There are obviously many aspects which have to be assessed in designing a chassis and I will attempt to take you though some of them and then explain why I am going a certain way.


Resistance to bending in the vertical plane is very good on the rear of the car due to the roll cage inc side plating, however, it's a different story at the front of the car. From the roll cage forward, cars used to have to rely on a basically flat chassis with a bit of sump guard to help. It's a good move to use a down tube /box from cab height on the roll cage to the front of the car but this needs to be structurally tied to the chassis to achieve the best benefits. The down tube can be in say 40mm box/ equivalent tube and ideally this should be braced to the chassis using a triangulated design with say 25mm box or similar small dia tube  - this substantially increases the resistance to vertical bending at the front of the chassis and changes a flat chassis to a 3 dimensional frame. If the down tube/box is not tied to the chassis, then on it's own it is only giving a marginal increase in strength as it will easily deform under load (but it at least will help with engine protection).

Triangulation if used correctly can reduce weight for the same strength and I aim to lighten up in some areas to allow additional weight in priority areas.


Probably most damage in our racing is to the front bumper and bracing hence bent front axle and majority of heavy chassis damage is in this same area. We've seen some changes in designs in recent years to overcome this and allow strong bracing without damaging the chassis. Over bracing of the front bumpers has always happened and get a good wack on the bumper end and instead of the bracing giving way, the main chassis rail is distorted then the rail gives way. I covered what we do on Si's existing car in the Structural Design page with photos of the arrangement - this allows better bracing which means we can take a bigger hit and hopefully carry on racing. The same can happen on the rear bumper bracing but it is not as frequent as front end damage.


We've been pleased with the design used on the present car but I decided to go one step on and actually end the main rails at the front and rear bumper chassis cross bracings and take those bracings the full width of the car. This is used a fair bit on F2's and what I have done is made the ends of the front bumper cross bracing "nodes" which take all the chassis loadings. These areas have to be strong so I took quite some time deciding the best approach



4th October 2008


Weight Considerations


We are already on the "back foot" cos of our engine + LD axle. Unless you weigh your engine you have to go on estimates but based on what we are allowed in the rule book, we have to consider (info I have found):


Big/ Small Block full cast iron engine: GM big block           675 lbs (307kg)

                                                            GM small block       575 lbs  (261kg)


From info I have found it looks like you can add about 10lbs (4.5kg) for an aftermarket block as they are strengthened around the cylinders but it also depends how much you bore it out to and light weight cranks, etc!


As above but with Ally heads:             GM big block         606 lbs (275 kg)

                                                            GM  small block     535 lbs (243kg)


All the above will not include starter motors, alternators, etc, and obviously the substantial engine mountings.


A couple of years back, we did weigh the engine but with mountings on + bell housing and starter motor and worked out our complete engine weight (GM big block with Ally heads) without mountings as 300kgs which compares with the above.


Overall we are carrying about 30kg more than an ally headed small block. Note that due to the larger size of big block heads, changing to ally heads saves a bit more weight compared to doing the same thing with small bock heads.


Although ally blocks are not allowed in the rules, I found that changing to ally blocks would save a further 59kg on a big block and 41kg on a small block at 2 to 3 times the cost for the block.


Regarding the back axle, I weighed our LD axle and complete with discs, callipers, hubs and brackets and it came to 144kg I'm not sure if I kept a check on the Transit axles we used to use but I think the saving was about 20kg.


So for example, when we are racing on tar, we will be competing with cars

that can have about 50kgs more weight in their chassis. Which is why the likes of FWJ's (to name but one!) tar car has plenty of additional bracing on the chassis.


So do we stay conventional with a 70mm x 70mm x 5mm chassis and compromise on relatively week bumper bracing and nerf bars or do we look at alternatives? Well I decided to digress from the norm and try and achieve 1350kg + fuel weight (car must be no less than 1350kg prior to and after racing without topping up the fuel tank).

For reference, Si's existing car weighs about 1385kg but that's with our mods to front and rear bumper bracing and a bit of extra weight used to achieve inside & rear weight requirements so if I don't get carried away we should be fine.





2nd October 2008


So the plan is to build a new car based on using our existing big block engine and an LD back axle. To construct a strong car which will be close to the minimum weight limit is not an easy task and normally compromises have to be made which do affect the strength of the car. We are up against cars running competitive small blocks which allows much more weight to be used in the chassis to make the car stronger (at least it should! But some waste it on ballast). We could save some weight running a transit back axle but these are not as strong as the trusted LD and as we want a dual surface car I think it preferable to stick with the LD axle and work around all the extra weight.


At times it is easy to ignore weight concerns vs aesthetic appearance so the design has to be practical. For example, many people seem to prefer the long cab designs that are common these days but whatever weight you add on you have to compromise somewhere else. Whilst we too would prefer to use a longer cab design, it's not practical due to addition weight, ie, and extra 12½ " length in the roll cage costs approximately 13kg due to extra cage tube, 3mm side plate and extra side tubes in the cage. Remember the rules require 3mm plating from front to rear of cage ït's not the same problem with roof plate as minimum size is required but it must be welded to cage on all four sides.

Presently, whilst I know the approximate dimensions of our cage, we have not decided on the final design although it will be governed to some extent by the new seat we intend to use.


With regard to the overall structural design of the car, it is possible to look outside the normal 70mm x 70mm box section chassis by designing a framed structure with equivalent (or greater) strength. I've previously given my views on down tubes which add no real structural integrity to the chassis due to inadequate bracing and often the same goes for the 'engine protection' tube running from roll cage to the front of the chassis - for minimum additional weight this can be structurally tied to the chassis and truly be part of the frame.


With the exception of some details that I will sort as we go along, the design is complete and I will explain things as we go along hopefully with a few pics to help.


The first thing to say is that the chassis will not be conventional as the main rails do not run from bumper to bumper but instead between front and rear bumper support cross bracings and those cross bracings are full outside chassis width. This will be clearer when I have some pics when I have got that far, to date, I have cut all my chassis plates, cut and welded the front and rear cross braces - the front is made up from 3 off 40mm x 40mm x 2.5mm HT box to make 120mm deep x 40mm brace and the rear from 2off 60mm x 40mm x 3 HT box to make 80mm deep x 60mm brace. As these braces have to take main rail loading, to prevent them being crushed they are being plated at the ends + I've added internal stiffeners at the ends of each bracing. I'm just up to the point where I am welding on the plating for these bracings and have also cut the main rails and much of the chassis cross bracing.

The main rails are 80mm x 40mm x 4mm HT box section with 80mm side horizontal and the internal bracing (front X and radiator cross bracing) will be made from 40mm x 40mm x 2.5 HT box section, each cross bracing is made up of 2 pieces of box to make 80mm x 40mm which will overlap and be welded to the main rails. It will make more sense when you see the pics!     

Recent Videos

3035 views - 1 comment
11569 views - 0 comments