128i in STX Autocross

[murph1379]

ok, so why hasn't anyone built one yet?

When I did my initial thinking on the subject, the key limitations that I saw were:
- can't get enough tire up front
- can't get nearly enough camber up front

otherwise, it seems to be close dimensionally, better geometry-wise, better power-wise, and better gearing-wise relative to the 330i I've been campaigning successfully in STX. (please don't look at national results, I'm an awful driver under pressure...)

Since then, I've seen reports that people are getting 265mm tires up front on 9" wide wheels, and I have thoughts on how to get enough camber.

Take a look at this image of the new AST 5220-GA struts:
http://vorshlag.smugmug.com/Product-...24_56F6B-L.jpg

Notice anything interesting? The remote resevoir hose mounts UNDERNEATH the camber plate. So the only thing sitting on top of the camber plate is the strut top nut. What this means is that one could totally make a custom camber plate that locates the strut tower nut under the strut tower, for as much camber and caster as you want!

Food for thought, someone get out there and build this thing! (I would, but I don't have that much money, and I'm busy building my new ZHP...)

[MarkR171]

Isn't STX a new class for this season? That's probably why not many have built one for STX. Not too many people with a 128i doing performance driving either (relative to a 135.) It should do relatively well though.

[Amalfitano]

STR was new, STX has been around a long long time.

One thing i haven't heard consistently about getting 265 up front is whether or not they are swapping the M3 control arms as well as the Camber Plates. If they did both, we can't in ST trim to duplicate it.

Also, with the re-org it's hard to tell what car is going where in the end, and if SCCA deems to give Bimmers a good fighting shot at some championships in new trims, maybe they put the 135i in STX or some new category between STU and STX. Doesn't change the specific camber concerns though...

[MarkR171]

In '08, the DS-Ladies champ ran a 135i with 275 wide hoosier up front with no problems on 7.5 wheels. An stx prepped car should have no problem getting 285s with camber plates.

[Amalfitano]

I sincerely doubt the no problems part, though I never saw the car in person. Through photos and some commentary on this forums, we have a guy showing that 245 hoosiers can fit on the stock size wheels with basically no clearance in any direction and rubbing on the shock. Plus, in stock form its the camber that's an issue and the right offset of wheel. In STX trim, we also have to contend with an optimally lowered car as well.

If more than 265 could be done, i'd think the Berk Time Attack car would've done it, but they didn't go wider until they flared the fenders (not STX legal).

Just in theory, a 275 on a 7.5 just sounds like too much as well. Intriguing for sure though.

[verlumpt]

I agree with Murph... somone should do this, having run in Street Touring classes since 2001 and spending most my time in STX... I think the car has merit and could be a contender.

Originally Posted by Amalfitano

One thing i haven't heard consistently about getting 265 up front is whether or not they are swapping the M3 control arms as well as the Camber Plates. If they did both, we can't in ST trim to duplicate it.

18x9 - 255/35 front, 18x9.5 - 275/35 rear will fit just fine. I setup a friends 135i this way, no reason it wouldn't work on a 128i with proper suspension.

I would actually de-stagger the setup if you can for STX... 9" wide wheels and 255's all around, tweak the suspension to suit, and have a blast! You don't need more than 255s to be competitive.

Originally Posted by Amalfitano

Also, with the re-org it's hard to tell what car is going where in the end, and if SCCA deems to give Bimmers a good fighting shot at some championships in new trims, maybe they put the 135i in STX or some new category between STU and STX. Doesn't change the specific camber concerns though...

The Reorg shows no signs up affecting STX other than keeping the '89 Civic Si out. Which is a good thing.

Thanks - Jon

[axoid]

I've been running my mostly stock 128 in STX for the last year and a half because currently running 225/255 star specs. Before I changed tires I ran in ST.

I'm doing OK in STX, finish 2nd in the last event. That put me less than a tenth off the winner of ST.

I think ST might be the sweet spot for the 128. On 225s all around with the car's RWD power, balance and the E-diff it might be enough to scare the Civics. But I'm going to do anything radical until the ST re-classing settles out.

[verlumpt]

No way a 128 can be competitive in ST. '89 Civic Si will crush it in short order. It's way to heavy for 225s all around and you have to stay with the stock open rear diff.

I think this thread is geared towards those running on a national level, not just local stuff.

[axoid]

I don't think the 128 has a real chance in STX ether, competing with more powerful cars.

Besides, next year the civics will be out of ST.

[verlumpt]

Originally Posted by axoid

I don't think the 128 has a real chance in STX ether, competing with more powerful cars.

What car in STX has you concerned about 'more power' other than the WRX. Power isn't everything and having competed in both... AWD isn't the end all be all, especially when tire sizes aren't equal.

Originally Posted by axoid

Besides, next year the civics will be out of ST.

Nothing is set in stone yet. I think with the new structure of ST as proposed, there is still going to be some heavy hitters that would give the 128 w/ open rear diff a run for their money. w/o an LSD, rwd is going to be tough to make work in the 'new st'.

[axoid]

Originally Posted by verlumpt

What car in STX has you concerned about.

I think anyone would be a fool to dismiss the Mustangs in STX. Specially the 07/08 Shelby's. They can easily turn ESP times in Stock class form. And they only came from the factory running 235 tires.
Power isn't everything, but have enough straightaways it can be a major advantage. And the national level events that I have attended tend to be big and long.

Originally Posted by verlumpt

w/o an LSD, rwd is going to be tough to make work in the 'new st'.

The 128's e-diff is definitely a far cry from a real LSD, but it is way better than a completely open diff. In autocrossing my 128 in both the wet and dry I haven't noticed a serious problems with the car peg-legging under power.

[verlumpt]

most any powerful mustang is going to be a handful on 265mm wide street touring tires. They will struggle to put down power no matter what tire they choose to use. If the 06/07 mustang was such a good package, I think someone would have tried one by now.

stock class = race tires & street prepared = race tires... much easier to put down power. There are tons of cars that work very well in stock class that would struggle in street touring.

Terry Fair and his project '11 Mustang GT will tell us this year if they can be competitive or not. I know he'll setup a top level car. I'm remaining optimistic about it's chances honestly though. I think it will 'fair' better than a certain '69 Camaro that is being prepped for STX though.

I'll know more when I see his car in action at spring nationals. I still think an E36 325/328, 128i, and WRX are faster and better choices for STX, '89 civic Si aside .