New STX car

[cledbetter]

Hello all,

I have been watching so many BMW race the last couple years, I thought I would join in on the fun. I recently purchased a 1997 BMW 328is without a sunroof to turn into a STX car. My first RWD car. I think I am going to like it much more than my SVT Focus I have been driving in GS the last couple of years. I think i am going to get the AST4200 for the car and am wondering why kind of spring rates I should run.

Does anyone know what offsets or spacers are needed for some 17x8 wheels and 245/40R17 tires? I have been looking at the Enkei NT03-M with 38mm offset at 17.5lbs.

Thanks,

Christopher Ledbetter

[John in Houston]

Re: New STX car

600# front, 700# rear with the 4200s assuming you aren't going to daily-drive this car (that's what is on my 98M3 setup for STU).

Spacers for the wheels will be based on 1) wheel offset 2) height of front spring perch & 3) length of front springs. A 38mm offset in the rear should be just fine.

[cledbetter]

Re: New STX car

I was planning on driving it on the street. I don't mine it being stiff though.

On the bushing, I was going to replace the lower control arm bushing and rear control arm bushings. Is there any benefit to use polyurethane bushings for any of these? What other bushings should be replaced? The front lower control arms worth replacing?

Does the front of the car have any rubbing issues with tires or is it mainly in the rear? Is the front ok with this wheel/tire combo?

Thanks,

Christopher

[John in Houston]

Re: New STX car

Stock style bushings tend to last the longest. You can install urethane, but I'm not a big fan of them. If you replace the rear trailing arm bushings (RTABs) with stock-style, also install some limiters (UHMW Polyethyln) to help control dynamic toe changes.

Those wheels will fit fine with absolutely no rubbing. If you do an adjustable front coil-over setup, you may need to run a spacer to move the fronts out some if the offset is too low (higher number) and you have clearance issues with the spring or spring perch. With 17x8s, this really shouldn't be an issue unless you have some really whack offset.

[Redwood]

Re: New STX car

I'm not sure if the E36 goes through control arms like my E46 does, so maybe one of those people can answer that. I'm sure the RTABs need replacing. The general recommendation is to not go with poly. However, you should get the RTAB limiters from Vorshlag to install with the new RTABs.

As somebody with a very similar engine, you will eventually want to go with a cold air intake and software update. I really like my Conforti intake and software update. Very noticeable difference. I would focus on the suspension first though, if you can't afford to buy everything at once. I also like my B&M street short shifter, but there are other ones that are probably good as well. I don't know if it's a competitive advantage at all, but it makes driving a lot more pleasurable.

You'll want to update your motor mount and transmission bushings so you don't have a "money shift" I just installed poly motor mounts to go with my UUC race tranny bushings. There's a LOT more vibration at idle (due to the motor mounts), but it's not bad while drivng. I'm still trying to convince myself that it was the right move since I mostly street drive my car with some autocrossing in STX. The throttle response is very nice though!

[cledbetter]

Re: New STX car

Did you have the race trany mounts in before the poly engine bushings and it want very bad on roughness?

If I am replacing the front control arm bushings, should I go with the offset M3 style for more caster? How important is it to change the other bushing in the rear that dont wear out as fast but are still 10 years old?

Thanks,

Christopher

[Redwood]

Re: New STX car

Did you have the race trany mounts in before the poly engine bushings and it want very bad on roughness?

If I am replacing the front control arm bushings, should I go with the offset M3 style for more caster? How important is it to change the other bushing in the rear that dont wear out as fast but are still 10 years old?

Thanks,

Christopher

The vibration wasn't nearly as bad, though it was rougher than it should have been from what I'm told. It turned out that one of my motor mounts was completely collapsed. At a couple of highway speeds, it's smoother with the poly motor mounts now (better than metal on metal). It's just rough below 1000rpm. I'll defer to the E36 experts on the RTABs/control arms.

[Fair!]

Re: New STX car

Did you have the race trany mounts in before the poly engine bushings and it want very bad on roughness?

If I am replacing the front control arm bushings, should I go with the offset M3 style for more caster? How important is it to change the other bushing in the rear that dont wear out as fast but are still 10 years old?

Thanks,

Christopher

The "roughness" Redwood refers to with his poly motor and race poly trans mounts is barely noticeable by many. Some folks are just "very sensitive". Its completely nonexistent above 1000 rpm. The nylon motor mounts are a bit more noticeable, but we still have a lot of street car E36/46 owners using them happily.

As for the control arm bushings, well, DON'T use the offset '95 LCA bushings unless you use the '95 M3 lower control arms (its also not legal to swap control arms in STX if you use camber plates - which you should!). People still do use the offset LCA bushings with the wrong control arms, but its still not a good idea. Your tires will rub the front of the fender opening.

Being a non-M car I can't tell you which bushings to use... just stay away from the poly and Delrin nonsense. Maybe Teucci can chime in on the LCA bushing to use for non-M E36 cars? He ran in STX in a '95 325is before it became a DSP car...