SCCA STX E30 Build/Introduction

[JeremyE30autox]

Solid mounts on the transmission are not allowed in stx

[race2win]

Solid mounts on the transmission are not allowed in stx

Correct...I did not install solid mounts, they are OEM rubber replacements ;) The lighting in that picture does make them appear metallic, here is a pic of them next to the old ones...

[JeremyE30autox]

Then your good!

[McCall]

Hey, it's great to hear from you! Yes, I followed that build closely, before my current E30 I had a 91 318i 4-door that I was considering an ST build with. It's great to hear the car is still in competition, even if it's been an up-hill battle. No question the lack of LSD hurt the car's chances, it's too bad the ST rules only allow Viscous LSDs.

From what I remember, Terry was saying the car was in the mid-2300 lb range at one point...does it have a different tire/wheel package now or something? Still, 2400 lbs is very light, I wish I could get my 325i that low.

Put a 4.10 LSD in your car & come play with us in STX!! I seriously considered doing that with my 318i because it had a factory LSD. It would definitely be down on power, but the tire-to-weight ratio would be by far the best in STX. I wouldn't try 245s though...you would have to run 17" wheels, & even IF you could get them to fit, they would hurt gearing & carry too much of a weight penalty over 15s.

For that car I would carry 2 sets of wheels/tires...a set of 15x8s with 225/45-15 Hankook RS3s (like I am running), & a set of 15x7.5s with the 195 Toyo R1Rs (which you may already use). On heavier cars, the 195 Toyos just don't work very well, but on the lighter cars (like yours & the Civics) they have proven to be very fast...plus they are a great tire in the wet, unlike the RS3s.

The only issue with running your car in STX is that you will have to request to the STAC & SEB for it to be included in STX. The way the new rule-set works is that the cars listed are the ONLY cars eligible for National events. Locally you could run it just fine, but if you decide to compete nationally you would need to send a letter & request it be included...which I'm sure they would do.

Here's the car in action at a National Tour-




Yes, the no LSD in ST really ended up being the downfall of the car. Regarding the viscous diff, remember it had to be factory installed in that model of car. I'd thought about dropping a 325ix viscous diff in the car but that was a non-starter with the rules makers. ;)

Regarding the weight, you are right. I forgot the last time I weighed the car I had added a 60lb 4-point roll bar for track days. So she could be down to sub 2340 easy if I put it back to full autox trim. Again, if I were to take the extra time, I’m sure I could get the car close to 2300lbs.

As far as tires, I’ve run 225 R1Rs, 215 Yokos, and finally the 225 RS3 on my 15x7.5 Rota Slipstreams. The RS3s were by far my favorite, followed by the Yoko. I'm just not a fan of the Toyos and it probably is because of the weight of the car. Also, you are probably right about the 245s not fitting. With some 8" wide wheels and some aggressive ST-legal rolling I could probably squeeze 235s but it would be tight with my ride height. 225s on 8's is probably the best combination.

Regarding class hopping, I believe I can. Here's what FasTrack just said-

Street Touring Xtreme (STX)
BMW 3-series (E30 chassis, including M3)


Of course there was this earlier this year from the Feb 2011 FasTrack-

Limited Slip Differentials – Option #1:
Status quo, no change to 14.10.K.
Note: Maintains parity by limiting the advantage of higher horsepower cars in
both ST and STS. If cars need to be down-classed in the future, then
competitors may have to remove LSDs.

Limited Slip Differentials – Option #2:
Modify 14.10.K to apply the existing STR/STX/STU LSD allowance to all ST
classes.
Note: This would minimize the LSD-removal impact of any future downclassing
of cars, at the expense of an immediate upgrade for most
current ST/STS competitors. Street Touring is premised as a bolt on
category and aftermarket diff installation is not generally bolt on. LSDs
are not available for many of the newer target ST cars which may hurt
diversity. May require moving some cars to different classes than those
listed in the above proposal to compensate for the addition of an LSD


I believe as of the Oct issue, Option #2 has been choosen but I'm just not sure yet. So if the LSD option #2 is good, I could actually get a LSD (hello OS Giken!) and heck that alone might make it worth it to go after God's Chariots (ST Civics) again. A Metric Mechanic ST-legal refreshed motor would go a long way as well. Who ever said autoxing at a National level was cheap!?! :D

Good luck with your build and I'll be following your progress.

[SoloSol]

Sorry, not for sale at this time. That's a classic Soundstream 4-channel bridgeable amp with built in crossovers, I used to install those professionally back in the late 80s-early 90s. I think I am going to keep it around for my next street car project, it's a very nice sounding amp.

Too bad. I also appreciate this amp for what it is. Having installed and owned many of them in the past. Enjoy.

On topic
You mention removing the rear bar? In my head thats because you want less inside tire lift = more exit traction

[race2win]

Here's the car in action at a National Tour-

Great looking car! I really miss my old 318i, it felt so much more nimble & light on it's feet than the 325i...just no torque what-so-ever:(

As far as tires, I’ve run 225 R1Rs, 215 Yokos, and finally the 225 RS3 on my 15x7.5 Rota Slipstreams. The RS3s were by far my favorite, followed by the Yoko. I'm just not a fan of the Toyos and it probably is because of the weight of the car. Also, you are probably right about the 245s not fitting. With some 8" wide wheels and some aggressive ST-legal rolling I could probably squeeze 235s but it would be tight with my ride height. 225s on 8's is probably the best combination.

As long as the temps are above 70*, no question the 225 RS3's on 8s will be best. However, if it rains, or is even cold out, they do not work very well at all...they NEED heat to work best. The Toyo R1R's are best when wet and/or cold, & the Yoko's & Dunlop Star Specs are in the middle...pretty much GOOD in all conditions but not the best in any particular area. To run a 235-wide tire, you would need to run a 17...I'm just not sure it would be worth the weight penalty to run those over the 15s. However, my plan is to test some 17x8s wrapped in 235/40-17 Dunlop Star Specs...

You mention the 225 R1R's...have you tried the 195s? That particular tire has a different tread compound than other sizes, this is why all the ST Civics use them. At your car's weight, they just might work, if I had your car I would try them.

Regarding class hopping, I believe I can. Here's what FasTrack just said-

Street Touring Xtreme (STX)
BMW 3-series (E30 chassis, including M3)


Of course there was this earlier this year from the Feb 2011 FasTrack-

Limited Slip Differentials – Option #1:
Status quo, no change to 14.10.K.
Note: Maintains parity by limiting the advantage of higher horsepower cars in
both ST and STS. If cars need to be down-classed in the future, then
competitors may have to remove LSDs.

Limited Slip Differentials – Option #2:
Modify 14.10.K to apply the existing STR/STX/STU LSD allowance to all ST
classes.
Note: This would minimize the LSD-removal impact of any future downclassing
of cars, at the expense of an immediate upgrade for most
current ST/STS competitors. Street Touring is premised as a bolt on
category and aftermarket diff installation is not generally bolt on. LSDs
are not available for many of the newer target ST cars which may hurt
diversity. May require moving some cars to different classes than those
listed in the above proposal to compensate for the addition of an LSD


I believe as of the Oct issue, Option #2 has been choosen but I'm just not sure yet. So if the LSD option #2 is good, I could actually get a LSD (hello OS Giken!) and heck that alone might make it worth it to go after God's Chariots (ST Civics) again. A Metric Mechanic ST-legal refreshed motor would go a long way as well. Who ever said autoxing at a National level was cheap!?! :D

That version of Fastrack is fairly old, they ended up keeping status-quo in regards to differentials. STC, STF & STS are OEM Viscous LSDs only, the rest get any LSD unit. For you (& myself) I honestly do not see the need to go with an aftermarket diff...just bolt in a good rebuilt S4.10 diff & call it good. You would have a hard time convincing me that an OS Giken, KAAZ, etc diff would be a significant improvement on the clock over a good BMW LSD diff...especially on anything with less than 200 WHP.

Most of the proposals in regards to Street Touring are still in the BOD's hands & not 100% official yet. There is one thing for sure though, as of 1-1-2012 class-hopping will be a thing of the past in the Street Touring category. Only cars specifically listed are eligible to compete in each class...so for you, & every other E30 in existence, STX it is :D That being said, I still think a 91 318i/is could be a dark-horse, especially at 2300 lbs !

[Cinnabar325is]

Great thread, thanks for doing this; I'm following closely.

Dumb question here I'm sure, I must be missing something. But, why not run in ST? Just looking at the 2011 rules here (maybe 2012 is different): http://www.scca.com:8090/documents/2...lo%20Rules.pdf

On page 175, it has BMW 3 series (non M) listed under ST and says normally aspirated up to 3.1 liters.

They do have the E30 M3 listed in STX.

[Nsquared97]

Great thread, thanks for doing this; I'm following closely.

Dumb question here I'm sure, I must be missing something. But, why not run in ST? Just looking at the 2011 rules here (maybe 2012 is different): http://www.scca.com:8090/documents/2...lo%20Rules.pdf

On page 175, it has BMW 3 series (non M) listed under ST and says normally aspirated up to 3.1 liters.

They do have the E30 M3 listed in STX.

Not a dumb question at all. Main reason is the only LSD's allowed in ST are OEM viscous type, and the OEM LSD's that BMW used are clutch type. For this reason the 325is isn't allowed in ST.

[race2win]

Not a dumb question at all. Main reason is the only LSD's allowed in ST are OEM viscous type, and the OEM LSD's that BMW used are clutch type. For this reason the 325is isn't allowed in ST.

Exactly, Viscous LSDs only in ST. That being said, a car like mine (325i) could still run ST in the past since it came with an open diff. Technically, right now, my car can run both ST & STX in the same day/event...just swap out the diff.

As I have mentioned before, this will all be changing starting 1-1-2012, class hopping will be eliminated. Only cars specifically listed are able to run that class, & all E30s will be listed in STX regardless of model, diff, options, etc. Now, that doesn't mean you can swap pieces around to build the perfect E30...that would be Street Prepared ;)

Honestly though, you wouldn't want to run ST anyway...I know it doesn't seem like it, but ST is a faster class. That class is dominated by sub-2000 lb EF Civics...on a twisty autocross course, heavier cars such as most BMWs just can't keep up. Check out the STX results from this past Nationals...the top 4 or 5 cars were ST prepped Civics, & the top finishing BMW was well more than 2 seconds back!

STX is going to be a great class in 2012, a lot of top drivers are building a wide range of cars, now that the Civics can't crash the party more people (myself included) are willing to try new ideas. At next year's Nationals the top 10 in STX could include E30s (325i/is & M3), E36s (325 & 328i/is), Mazda RX8, Subaru WRX, Mazdaspeed3, Lexus IS300, Integra Type R, Mustang GT 5.0 (both new & old), & even a 67 Camaro Z28!! I have heard of potential builds being planned & completed on every one of those cars listed, it should be a very entertaining class!

[Nsquared97]

That's some pretty exciting news, can't wait to see how it pans out.

[Cinnabar325is]

That is exciting news about STX. Thanks for the helpful clarification too.

[325ix]

I will be looking back to this thread next summer when I prepare my car for the track and auto-x.

[Wanganstyle]

You would have a hard time convincing me that an OS Giken, KAAZ, etc diff would be a significant improvement on the clock over a good BMW LSD diff...especially on anything with less than 200 WHP.

Agreed. I'm running a KAAZ unit with a close to 200hp high comp M20, still don't have enough torque to really use the LSD to the max

a moderately or aggressively set OEM diff is usually enough for close to stock S52/S54 power for motorsports use with slicks

[McCall]

As long as the temps are above 70*, no question the 225 RS3's on 8s will be best. However, if it rains, or is even cold out, they do not work very well at all...they NEED heat to work best. The Toyo R1R's are best when wet and/or cold, & the Yoko's & Dunlop Star Specs are in the middle...pretty much GOOD in all conditions but not the best in any particular area. To run a 235-wide tire, you would need to run a 17...I'm just not sure it would be worth the weight penalty to run those over the 15s. However, my plan is to test some 17x8s wrapped in 235/40-17 Dunlop Star Specs...
You mention the 225 R1R's...have you tried the 195s? That particular tire has a different tread compound than other sizes, this is why all the ST Civics use them. At your car's weight, they just might work, if I had your car I would try them.

I hear what you are saying about the R1Rs, but even at colder temps, I never liked the overall grip they provided nor did I like the steering response and feel at the limit. Regarding the 195/225, I still think that was more an internet rumor encouraged by a few select Civic drivers and was nothing more than that. I read the whole thread on SCCAforums as well as talked with competitors in the grid and there are just as many who dismiss it as try and substantiate it. Anyway, for STX I agree with staying light with 15's and going 225s on 8" wide wheels. In the end, buying a couple set of wheels and tires, and then testing, testing, testing will really let you know the best set-up.

That version of Fastrack is fairly old, they ended up keeping status-quo in regards to differentials. STC, STF & STS are OEM Viscous LSDs only, the rest get any LSD unit. For you (& myself) I honestly do not see the need to go with an aftermarket diff...just bolt in a good rebuilt S4.10 diff & call it good. You would have a hard time convincing me that an OS Giken, KAAZ, etc diff would be a significant improvement on the clock over a good BMW LSD diff...especially on anything with less than 200 WHP.
Most of the proposals in regards to Street Touring are still in the BOD's hands & not 100% official yet. There is one thing for sure though, as of 1-1-2012 class-hopping will be a thing of the past in the Street Touring category. Only cars specifically listed are eligible to compete in each class...so for you, & every other E30 in existence, STX it is That being said, I still think a 91 318i/is could be a dark-horse, especially at 2300 lbs !

Yep, the diff thing was from Feb as I stated but I must have missed where they finally provided an decision. They sometimes sneak those out months later so I missed it. So while it's a bummer, I understand their reasoning about it being a bit more than a bolt-on. Heck, I'm booted to STX anyway so that's a non-issue now.

Regarding a real built LSD vs. a stock unit, having run CSP the last two years I can tell you there are a class full of 180 whp Miata National Champs that will disagree with you. There's more to a built diff than the power it can handle. Its about how it delivers the power and locks up during transitions. OS Giken has a pretty good FAQ that covers this - http://www.osgiken.net/faqs.html#200903_03

As far as a 318is in STX, I'm just not sure. Yes, it will be the lightest and smallest car in class, which is always what you want, but the lack of torque will always be it's Achilles’ heel. A E36 328is is probably the best base car to start with but you 325is developed might have a chance. If I can give you any advice, test, test, test. Buy some cones, a cheap single beam timing system, and find a local site you can rent. Then throw out what you read on the internet and try a bunch of different springs, sway bars, and tons of wheel/tire combos. Don't be a lemming. Be a trail blazer and try new things.

[race2win]

Regarding a real built LSD vs. a stock unit, having run CSP the last two years I can tell you there are a class full of 180 whp Miata National Champs that will disagree with you. There's more to a built diff than the power it can handle. Its about how it delivers the power and locks up during transitions. OS Giken has a pretty good FAQ that covers this - http://www.osgiken.net/faqs.html#200903_03

Sorry, I didn't really clarify what I meant... What I meant was, in a BMW with less than 200WHP on street tires, spending big money on a custom diff wouldn't net a measuarble gain on the watch in autocross. In a sub-2000lb 180WHP Miata on 275/15 Hoosiers, different story ;) You are right however about there being more to a diff than how much power it can handle, there are definite benifits to a good diff in any situation, the question is will all that money make my car measurably faster?

One of my goals with this build is to do it cost effectively, so that others in the E30 community can duplicate it without spending what their car is worth just on a diff or custom shocks. In 2005-2006 I built one of the first Nationally competitive STS Miatas (then it was STS2) in the country. I put it together with basic off-the-shelf parts for a very reasonable budget, & was able to win a National Tour & Pro Solo against a multi-time National Champion who had just about as much money invested in their shocks & springs than I did on the entire build. It's a lofty goal to expect those kind of results with my E30 now, but that is my target anyway :D

As far as a 318is in STX, I'm just not sure. Yes, it will be the lightest and smallest car in class, which is always what you want, but the lack of torque will always be it's Achilles’ heel. A E36 328is is probably the best base car to start with but you 325is developed might have a chance. If I can give you any advice, test, test, test. Buy some cones, a cheap single beam timing system, and find a local site you can rent. Then throw out what you read on the internet and try a bunch of different springs, sway bars, and tons of wheel/tire combos. Don't be a lemming. Be a trail blazer and try new things.

Thanks for the advice! I think I am definitely attempting to be a trailblazer by building an E30 325 for STX...no lemming about that for sure. I will do some testing for sure, but I honestly feel the car will be pretty close right out of the gate...it's already proven to be within striking distance with virtually zero development. I do agree the items that will need some testing will be spring rates & possibly shock valving, & then tires (different brands & sizes). Then, just get it as light as possible