SCCA STX E30 Build/Introduction

[race2win]

Oh shit dude you're in San Ramon?
I worked on Alcosta over the summer.. we should all go for a drive sometime...

Yep, been here about 3 years & LOVE it, originally I am from the Sierras. I have seen a couple nice E30s driving around in this area, not sure if they are members here or not. Getting together for a drive would be fun, as long as my car isn't on jackstands ;)

[Gary Horneck]

Can't wait to see how you do in STX, especially next year. I am headed over to FP with my project. I need to be able to do more than ST class will allow, and the prepared classes are wild and crazy.

[nrubenstein]

Honestly, for me, the biggest challenge of an E30 in STX was the steering. Slaloms are painful with the stock rack. (My red car used to be a well built STX car.)

On paper, and in reality, the 325is is going to face a very, very uphill battle. Either way, though, it'll be a damned fun car.

[AsharC]

Civics are around 2000 lbs, 105-ish WHP, 195 tires, not sure what the width is but they are narrow. Yes, they are considerably lighter, but the point is lighter-is-better, & I hope to use that as an advantage with the E30.

I won't need to run ST Civic times to win STX next year (they will no longer be able to run STX starting 2012), I figure I can still be a second slower than an ST Civic & still win STX! :D

Civics are usually swapped with a DOHC. They usually push around ~180-190hp. They usually run 205's.

[bmwguy325is]

Civics are usually swapped with a DOHC. They usually push around ~180-190hp. They usually run 205's.

In STX you can not swap engines. That is street mod

[cenotaph]

However, I must say, do you honestly feel the ST Civics are that fast just because of the tires? Or, just maybe, it has something to do with 8+ years of National developement & collaberation, between literally hundereds of drivers & many, many National Champions??

The only reason? No. But if there wasn't a fairly large advantage to running the 195s, you wouldn't see most (all?) of the competitive ST Civics using them over the 205s. Now, maybe that advantage has more to do with tire size than construction, but the advantage is still there.

[Zac.Autox]

I'm new to BMWs (don't have one yet), but not new to autocross. Currently thinking of building either an e30 or e36 STX car.

Would there be any benefit to running 17x8 wheels? Thinking mostly of the Apex Arc-8. Although not as light as the 15x8. Should help with the gearing slightly. And should provide more options for tires. That's assuming you can fit something wider than a 225. Is it possible to fit a 245 on the e30?

[Jean]

Yes it's possible to fit 245 and 255 and 275 with work :)

[race2win]

I'm new to BMWs (don't have one yet), but not new to autocross. Currently thinking of building either an e30 or e36 STX car.

Would there be any benefit to running 17x8 wheels? Thinking mostly of the Apex Arc-8. Although not as light as the 15x8. Should help with the gearing slightly. And should provide more options for tires. That's assuming you can fit something wider than a 225. Is it possible to fit a 245 on the e30?

I actually have plans to try some 17x8s with 235/40-17 Dunlop Star Specs. You are right, should help with gearing on longer straights, & it will give a better cold/wet condition tire option over the RS3s. However, as long as the temps are more than 60*, it's dry, & as long as the course is the typical SCCA 60 MPH +/- max, the 225 RS3s on 15X8s should be the best choice.

Update on my build...

Although I don't have anything big to report as far as parts installed, I have made some updates to the car & plan to take it out this Sunday for a local SCCA event for some fun. Most of the updates have been centered around preventive maintenance so far to establish a solid foundation.

First off, installed a S3.73 diff...

Keep in mind my car is a standard 325i coupe, which did not come with a limited slip diff. The STX rules allow any limited slip unit that retains the original final drive ratio...so I picked up a pretty tight 3.73 LSD differential from a 325is.

I picked up this unit used for $200, which seems to be about "going rate" for a decent one. However, it came out of a junk yard so who knows what kind of mileage & condition it's in. I did not check the torque of the LSD unit, but it "felt" very tight so I decided to go ahead & install it as-is.

I contemplated a few options initially...First was to completely rebuild it with 2 extra clutches for a heavy lock-up, as well as a 3-clutch set-up which would provide 40% lock. But after talking with a few E30 experts (such as Tony at Edge Motorworks in Dublin CA) we decided those options may provide too much lock up for an autocross application...especially on street tires. With as much "turning" there is, too much lock-up means constantly chasing the back of the car on-throttle...so some slip may be a good thing. The goal is to start with this used unit to establish a baseline, if too much slip is present, then we will rebuild with 2 clutches & evaluate further...

More to come, stay tuned!!

[race2win]

Yes it's possible to fit 245 and 255 and 275 with work :)

All true, however keep in mind that in STX the rules only allow rolling of the inner fender lip...no changes to the outer contour/shape of the fender is allowed. With that in mind, anything larger than 245 isn't possible in an E30...& even 245s are very questionable. I think it may be possible, but the ride height may have to be too high to be beneficial.

[wannaBMthree]

Honestly, for me, the biggest challenge of an E30 in STX was the steering. Slaloms are painful with the stock rack. (My red car used to be a well built STX car.).

So I assume your not allowed to swap to a newer rack? bummer cuz the z3 rack is baaad

[Lof8]

I'll subscribe. Good luck on your quest!

[Jean]

Good luck, let us know how it goes! I went with a 4clutch diff build for my autocross car, works great with dot R tires ;) I do still have the stock rack, it blows.

[325ix]

All true, however keep in mind that in STX the rules only allow rolling of the inner fender lip...no changes to the outer contour/shape of the fender is allowed. With that in mind, anything larger than 245 isn't possible in an E30...& even 245s are very questionable. I think it may be possible, but the ride height may have to be too high to be beneficial.

275's

[Jean]

Can't wait for that ^ SM here we go. but this is offtopic to STX discussion!