Sprint/Track car build

[DoctorDrift]

Hey Guys,

Just finished a local sprint season in the road going class with my standard 318is. Over the winter i have a lot of work i want to do to get the ol girl up to scratch. I have therefore got some questions for you all.... Please bear in mind this is a road car and i want to remain in the road going class...

1. Suspension wise coilovers or challenge spec Bilstiens? ive heard great things about the Billstiens and i have heard people say coilovers are no better unless you spend some serious money on them but the adjustablility is appealing? Can you guys recommend a decent brand which dont break the bank eg over £800

2. Naturally i need to replace all the worn suspension bushes so am thinking of going down the eccentric m3 bushes route. I remember reading somewhere that the m3 wishbone is not compatible with the ARB drop links on a 318is as the mount points are different. Is this true?


Any help is most appreciated.

[MrBenn]

In answer to q.2 The m3 front control arm is compatible, they were also used on some standard e30's , 325 tourings iirc, the m3 has the drop link mounted to the strut but the control arms have the hole in them to bolt the drop link bracket onto. Your other option is to modify the strut to take the m3 drop links, have a look at 'Martin's second attempt at a rally car build' thread on this page, he has just done this.
Alex

[Jhonno]

Wishbones are the same fit..

Your only choice for coilovers at that budget are Gaz Golds, or DIY with billy inserts..

[UweM3]

what are the rules in your class? what in NOT allowed?

[DoctorDrift]

Hello guys thanks for all your replies helps greatly.

Having just looked a bit more closely in the regs for the road going class it seems the suspension must remain as per the orignal type eg. macpherson strut must remain macpherson strut. The actual strut is free so i can run coilover or normal strut.

I have seen the Gaz Gold coilover kits but they seem to be custom order and in the region of 800-1000. Is spending the extra 300-500 on Gaz coilovers worth it over the Bilstien B12 kit which seems to be around 530? Given that the car is for road use and sprint/hillclimbs?

Thanks again

[Brian28]

Have a look at the DIY coilovers on Martins rally car build. It's the same idea whatever the inserts, so you could have adjustable Spax, Avo, Koni or whatever. If you want to experiment with different spring rates etc, the easiest way is probably to forget rear coilovers. Use matching shocks to the front fitted as they normally are, and 2.25 race springs in the usual rear spring position. If the regs allow, you can add a threaded platform for rear height adjustability.

[Demlotcrew]

Have a look at the DIY coilovers on Martins rally car build. It's the same idea whatever the inserts, so you could have adjustable Spax, Avo, Koni or whatever. If you want to experiment with different spring rates etc, the easiest way is probably to forget rear coilovers. Use matching shocks to the front fitted as they normally are, and 2.25 race springs in the usual rear spring position. If the regs allow, you can add a threaded platform for rear height adjustability.

Diy Coilovers for the E30 without custom dampers are not something i would recommend, there is simply not enough travel in the damper before they hit the bump stops. You can with very small profile top mounts and cut down bump stops get away with it, but its far from a good solution in my opinion.

Depending on how low you need to go, the Bilstein dampers will be much much better than the twin tube oil as fitted to Gaz kits.

Andrew

[DoctorDrift]

Thanks for the reply Andrew.

I dont need to go very low because the sprints down my way are pretty rough almost like gravel stage rallys plus dont want to be samshing my sump on every speedbump.

So all things considered the bilstien b12 shocks are probably the best option for my requirements then?

I was also thinking to cut out my rusty arches and fit some wider rally style arches. Then i can run a nice wide tyre but with a bit of depth something like 215/60 R15. Thus by fiddling with my tyre pressures i will have a nice bit of "tyre suspension adjustability" - dont know the correct term for this but hey

[pistonbroke]

Dr. Ben, after your performance in yesterday's AutoSolo and previous performances at sprints this season I'd say the driver has talent (from a mere spectator/ observer's viewpoint) and the car has balance. Stiffer/ lower springs, Bilstein inserts up front and adjustables out the back, polybushes, adjustable a/roll bars, M3 w/bone bushes will sort you out. Then List 1B tyres on 8" rims, 215/ 50 etc. depending on what sizing is available. Keep it simple and within budget, ie. coilovers while nice aren't altogether necessary. I saw your mate's Diamond Black 318is whizzing up the A30 afterwards and it was going alright so maybe you'd not need to spend a fortune underbonnet......P & B[/b]

[DoctorDrift]

Ha ha only just seen this post. Who are you Pistonbroke? You will be delighted to know i have just ordered a pair of Bilstein front inserts so with decents springs and everything polybushes the front will be fairly well sorted. On the rear im thinking of going for AVO adjustable shocks at 80 a pop? any good or should i get bilstiens for the rear too at 120 a pop?

Thanks again guys

[pistonbroke]

AVO adjustables should be OK for your chosen motorsport disciplines with the bonus of adjustability. If stage rallying then you'd choose Bilsteins without question. Only the thoughts of a rank amateur though - you should await the input of the pros. P & B

[rix313]

everything polybushes the front will be fairly well sorted.

I'd say there is a reason the Bilsteins are 50% more expensive than the AVO's. I'd say have a matched set of dampers then you know where you stand.

[DoctorDrift]

ok guys thanks again for all your input. i think on balance i will go for the bilsteins then