walterj
walterj HalfDork
8/26/08 10:06 p.m.

OK, so... I sold my E36 M3 IP car and decided to race an E30 because its light, cheap, small and has inexpensive rotors and tires. I also instruct and a spec E30 is too slow to run in an instructor group ot time trial at many of the tracks I frequent (please, no flaming, the car is fun but I'm used to a car that was 7 to 10sec a lap faster than a spec E30)

This car will be raced in NASA GTS or BMWCCA DMOD with a soon to be built 2.9L stroker, megasquirt and other goodies to make roughly 235-250wHP. It will weigh around 2300lbs or less with driver. I have everything worked out but how to best accomodate the suspension while doing the cage...

-Do I relocate the subframe higher in the chassis to keep the toe change from lowering it at bay?

  • Do I move the springs to a true coilover?

  • Do I fashion camber/toe adjustments and weld them to the subframe?

  • Is the weight of a Z3 5 lug setup worth the weight penalty to gain access to wider wheels and tires/bigger brakes?

  • Do I need to tie the diff carrier into the cage? If so... why not hang some unequal length control arms and links and be done with the trailing arms altogether? I could probably sneak an E36 multi-link subframe into the cage pickups...

  • Is this interesting for anyone but me?

ansonivan
ansonivan New Reader
8/27/08 12:08 a.m.

I think it's an excellent project, particularly the idea of multi-link rear suspension.

I would plug in an s50 engine rather than spending all of the development hours wringing power out of the m20. This will allow you to concentrate on chassis/suspension setup.

I've googled the poo out of every variation of "e36 rear suspension in an e30" and came up with nothing, if you find anything please do share.

walterj
walterj HalfDork
8/27/08 7:31 a.m.
ansonivan wrote: I would plug in an s50 engine rather than spending all of the development hours wringing power out of the m20. This will allow you to concentrate on chassis/suspension setup.

The 2.9L stroker is an M50 block, S50 crank, S50 rods and the M50 pistons with S50 cams. It keeps me in the small bore classes... if I go over 3.0L I have to fight with the 450wHP crowd and there is only so much mass one can remove ;)

z31maniac
z31maniac HalfDork
8/27/08 8:05 a.m.

Go over to e30tech and PM iflytii, he is a mod and also prepping an E30 for BMWCCA CMod (due to the S52) he used to run in Dmod I believe with a turbo'd M20.

I can tell you he is 5 lug running 18s, with Massive Lee's giant brakes all the way around, Tilton master cylinders, etc etc etc

minimac
minimac Dork
8/27/08 8:21 a.m.

We once had an old race car with a 3 pt. rear. What we found was that the longer the lower arms were, the better it worked. We ended up mounting them at the transmission mount.We were running soft coils, with stiff shocks, rather than coil overs(rules). The trailing arms were fabbed out of 1" seamless w/threaded heim ends, to be adjustable. Once we got the lengths sorted, it worked very well and forward bite was excellent. If you were to go to coil overs, it would probably save more weight than what we had. The 5 lug conversion , while adding a bit of weight , would be well worth it if for no other reason than opening up a whole lot of choices with regards to wheels. The E-36 subframe swap would be a good thing, but why not fab up one and save weight.The factory subs are pretty hefty pieces-pipe,angle, and channel could be used to keep the weight to a minimum,without sacrificing strength.Take a look at your local short track and see how the rear hoops on the late models or modifieds are to get an idea. It's really not difficult , just have to figure the suspension mounting points.

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