SCCA STX E30 Build/Introduction

[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!!

[Jean]

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

[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?

[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.

[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

[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.

[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.

[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.

[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 ;)

[Hellabad]

Hay Jay will your SP plates work with some Ohlins hmr's I think is what I have.

Yes, if you have a Bilstein upper perch (aka any inverted strut). If not, we can just make them work.

[JeremyE30autox]

Hey race2win. We need to talk more about car setup and development. PM me your email so we can swap some ideas on what we have done and what may/ may not work in the future.

Looking forward to the 2012 season already even though my 2011 season isnt done yet. I have a ton of plans this winter for next year.

[bmwguy325is]

Make sure you are using the Ground Control "Street Prepared" camber/caster plates. They were designed with y'all in mind. If not, we can convert them.


Jay GC

Hay Jay will your SP plates work with some Ohlins hmr's I think is what I have.

[race2win]

I've seen people swear up and down on the internet that early, base RX-8s are closer to 2500 lbs. from the factory. Was STX weighed at Nationals this year? That would give you a good idea on how you stack up. Can you really get the E30 to 2500+ lbs. in STX? (I really need to ask Alex what he got his DSP E30 down to.)

The top STX prepped RX8s ARE the early models & they are in the 27xx range...no RX8 was ever 2500 lbs stock, thats NC MX-5 Miata territory which is a much smaller car.

As some have said, 2500 for an E30 might be ambitious, but 25xx should be no problem. Doug Hitchcock told me his car is close to 2600, & still has a lot of heavy items that can be legally removed in the class. Even at 2600, the E30 is 200 lbs lighter than any E36, & at least 100 lbs lighter than the RX8 with more torque. That may not sound like much, but when you combine lighter weight with a much more narrow car, I promise it will get through transitions quicker if set-up correctly.

The way I see it is the E30 will be somewhat course dependant, tighter courses with slaloms & offests will be it's strength, so I intend to set the car up to take advantage of that strength.

Also, the internet swears up and down that the construction of the 195 Toyos that the Civics run is different from the other sizes. :?

Correct, all the top ST & STX Civics were on the 195 Toyo. The difference between the 195 & other sizes is that the compound is the same as it wears down. All other sizes apparently have a harder compound as the tire wears.

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??

I understand what some of you are saying regarding the potential competitiveness of the E30 325 in STX, but no offense to those who have tried, throwing some springs/shocks/tires/wheels etc. at one of them for a season or two of regional racing to me isn't a fair comparison of what is possible. Someone mentioned the Vorshlag 318is build, & although there is some great info there, how can they draw the conclusion the car has no hope after one year of developement & one sub-par Nationals result?

I guess ive come to the realization that the e30 cant win STX.
Its impossible.

I should probably not dump a shit ton of money into it and just buy an rx8.

I'm sorry you feel that way, I hope to prove you wrong someday ;) One thing is for sure though, I will have my car built, including the cost of the car, for what it would take to just BUY a nice RX8!

[freeride53]

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

[Hellabad]

Ground control coilovers with GC camber plates over Bilstein Sport struts.

Make sure you are using the Ground Control "Street Prepared" camber/caster plates. They were designed with y'all in mind. If not, we can convert them.


Jay GC