Setting up a race/rally Cerbera

[Omerta]

I am building a race/rally (tarmac, not gravel) Cerbera here in NZ using a salvaged donor that I brought back from the UK a few years back now. The project brief is for it to be road legal, 70/30 biased for competition/road use. It will be used for the Targa of New Zealand ( www.targa.co.nz) which is run under rally rules with 5 days of closed stages of 10-50km each on rural tarmac roads - think twisty b-roads in Wales with plenty of bumpy bits but no gravel. Will also get onto a racetrack occasionally, but that's not the main point of it.

Modifications either planned for or already done are:
- LS6 (450hp), TKO-600 5-speed trans, standard diff (which I'm pretty sure is a Hydratrak unit )
- Roll cage
- Race seats and harnesses, removing rear seats
- Floor mounted pedal box (from a T350)
- Superflex bushes all round
- Gaz gold shocks (budget option which I will upgrade when $$$ permit)
- Heavier springs (can't recall the exact weights now)

What else would you do to lighten / improve suspension / upgrade brakes (has standard 4.2 Cerb AP Racing setup)? Should I worry about snapping driveshafts with the extra torque of the LS6?

Cheers
Don

Edited by Omerta on Wednesday 9th July 05:42

[teamHOLDENracing]

Hollow/ rifle barrelled driveshafts would be a good idea as the additional torque could cause you issues. Even then it would be best to avoid very violent starts and definitely no wheel spinning to put heat in tyres. The rear stub axles could also be vulnerable

I think you will definitely need an oil cooler on the diff (and possibly the gearbox).

Good luck!!

[Obiwonkeyblokey]

I would email Mike Saunders ( itsallyellow) he seems to get more speed from his yellow racing cerb than scotty managed from the USS enterprise.



O

[trackcar]

There's a few things that spring to mind, but obviously your safety is foremost so I'm assuming your major budget will go into your cage and seats and harnesses? Sadly for performnce you've already decided to cut costs on the one thing you should be spending your money on : suspension. For a road rally with bumps you should really have factored that early into your build rather than later. However seeing as this is what you've got to work with then first thing is to check what driveshafts you've got : if they have two circlips per CV joint you'll probably end up snapping them. If they have just an outer circlip groove and a raised hump to locate the inner CV point you'll be ok. Uprated shafts are available off the shelf so no issues there anyway.

Brake upgrades are ten a penny now for Cerberas : just like suspension everyone seems to be doing their own versions. Im still a big AP fan on Cerbies because they've been proven over the last 10 years and still look vaguely OE fit. Indeed both our T350 race car and Mike's cerbie 4.5 use a straightforward AP conversion onto Cerbera 4.5 hubs although larger conversions involving bigger discs/calipers are available of course. For a road going car you'll not want ultra low profile tyres (potholes / kerbs etc) so hopefully you're sticking with a sensible 17inch wheel which means the 330mm disc option like we're all racing with would be perfect.

Have you thought what you're going to be doing with the engine yet? rebuild? remap? new exhaust? I think it'll be a flyer with an LS6 in anyway lol! I'm assuming you'll have to have something reasonably quiet on the exhaust side for a road rally car that you'll also use for non competition? Plus it means you can hear pace notes and any bits falling off the car better. A quiet car can mean catching a potential problem early and maybe saving your car / engine / rally.

Other than that get rid of some weight from teh beastie and go have fun I think

Edited by trackcar on Wednesday 9th July 09:40

[teamHOLDENracing]

Have you checked your gear ratios? With the LS6 revving a lot lower than the AJP and depending on the gearbox, the diff ratio may be wrong. You could change the hydradtrak for a BTR cone diff - which should be readily and cheaply available in your neck of the woods or across the water in Oz.

[Omerta]

Some great advice already - thanks guys

I bought the Gaz shocks when I thought I was building a road car, then the plan changed. I might be able to get a set of Ohlin 3-ways that were bought for a Chim race car and never fitted, would they go on the Cerb OK?

Driveshafts - pretty sure they're one circlip with a lump. Do the race ones come any cheaper than £378 each from Clever Trevor - I'd have thought I can get them custom-made here for less than that!

Diff - Andy, why are you saying an oil cooler is necessary? Is it standard fitment on all racing TVRs? Regarding ratio, you're probably right that it will want to be lower, but I think I'll get it on the road with what I've got and swap it out for a Holden one later once I see how it goes. BTW, you probably don't remember but we met at Steve Howard's once, some years ago.

Cage, seats, harnesses are all strictly controlled by motorsport regs and will not be skimped on. Regarding the cage, the major mounting points will be to the outriggers and behind the cubbyhole. To get maximum stiffening benefit should there be any extra bracing from the outrigger mount points to the rest of the chassis?

Brakes: I'd have to import 4.5 hubs as there's only 4 Cerberas in the whole country and as far as I know the others aren't selling theirs! So an aftermarket set, or something based on performance Jap bits (which are cheap and plentiful here) might be a better option.

Engine is from a 2003 Corvette, uprated cam and valve springs done by Lingenfelter to get to an easy 450hp. I'll be running 1 3/4" headers into 2 x 2.5" or 3" pipes, all yet to be made up. Computer will be either the standard GM one remapped, or the home-grown LinkPlus aftermarket solution.

Thanks again - lots to think about!

[rev-erend]

If the tracks are like the UK forests - then ground clearance and width of the Cerbera track will cause issues.. nevermind things like the fuel pump being hit by stones and rocks..

[teamHOLDENracing]

Hi Don - sorry I don't remember meeting!

For sustained hard work on track, with the torque you are putting through it and the overall weight of the car, the diff will be borderline. It will get exceptionally hot and is a failure waiting to happen. You don't need a very big cooler but it does need a decent cold air feed. The cooler on my LS2 Sagaris is mounted at the front of the car for precisely that reason - we also have temp sensors fitted in the diff and gearbox. Use a decent (i.e. not plastic) oil pump or the pump will melt.

Circuit racing will be more extreme than rallying, but if you are doing tarmac stuff then you won't be far off those stresses. You might get away without a cooler on short sprints, but anything longer than 30 mins and the diff will fail fairly quickly.

Regards

Andy

[Omerta]

Rollcage.... I've been advised by the guys I'm working with here to put the new rollcage inside the existing one because the existing one is needed to keep the bodywork in place: "it will go floppy and out of alignment if we cut it out and we might not get doors, glass, etc. lined up again". Are they being too cautious here? Seems to me if it's cut out after the body's bolted down to the chassis it shouldn't be a problem.... or is it? Jonny/Mike - I know you're busy boys getting ready for the next race but any info on this would be much appreciated

[itsallyellow]

Mine was cut out? Didnt have any problems! The only bit that got left in place was the front legs as they hold the doors in place.

Mike

[JonnyW]

Aplogies for taking time, but running three cars on the track at the moment with my son so no spare time!

Adding to Mike's post:

Basically the only sound piece of protection is the bit that covers your feet by all accounts, the rest is pants for racing and the rear bars don't even join up wit the bottom frame, so the rear is not protected.

Mike and I took our cars to Andy Robinson, the European Top Fuel Dragster leader, as you needed to send serious money on a moby steel sytem and it had to be made from scratch, they took the lot out bar the front bits and welded all new moly in. This was a £3000 plus in the UK by someone who had also done one before Mike and I, so he knew his stuff!!

Whatever you do, don't short change yourself on cage!!!!!!!!! I witnessed a very nasty four car, flat out, pit wall crash yesterday with Porsches and Ferraris and it was the cage of these steel and ally cars that protected the drivers, whatever anyone says, at speeds in excess of 100 mph plastic offers little protection, but will absorb shock with a good cage under it!!

For real car cage protection watch the Tarantino movie "Death Proof"!!!

All the best

Jonny

Edited by JonnyW on Monday 21st July 21:27

[Omerta]

Thanks Jonny and Mike - knowing you've both done it without problems, I'll cut it out. There is no question that the cage will be anything but quality - the regs here are strict regarding design, materials, welds, joins, etc. with inspection by the relevant authorities.

Cheers