Official 135i/128i SCCA FS/STU/STX Chat thread

[RyanDavies]

Hit up Dan at Diffsonline. Do what he tells you. Wavetracs are not remotely on the same level.

[jvb6806]

Thanks for the suggestion. That is who I going to order the diff though, I just haven't called over there.

Have any of you had issues with the diffs getting super hot at an autoX? I know some folks with 350z's run the 75/140 gear oil for autoX, but I'm curious if it's necessary with our cars if you aren't road racing.

[RyanDavies]

Tell him I sent you!

Running 75/90 in mine. Would go with the 140 if road racing, not needed for street or Autocross applications.

[Kgolf31]

Originally Posted by RyanDavies

Tell him I sent you!

Running 75/90 in mine. Would go with the 140 if road racing, not needed for street or Autocross applications.

No, me!

I'm the one that runs stickers on my car :P

[The Wind Breezes]

Originally Posted by jvb6806

Thanks for the suggestion. That is who I going to order the diff though, I just haven't called over there.

Have any of you had issues with the diffs getting super hot at an autoX? I know some folks with 350z's run the 75/140 gear oil for autoX, but I'm curious if it's necessary with our cars if you aren't road racing.

Auto-x isn't going to overheat your diff, full stop.

[Bimmer-Bob]

Performance Gearing makes good units, too. I'm running a 30/60 with about 80 ft-lbs of static lock. No push at all and corner exits feel telepathic.

I do have a 20mm rear bar and about -3 of camber up front and 0 toe - all of which should help with turn in (otherwise the lock on decel might push a little, not sure).

[jvb6806]

Thanks for everyone's input. I ordered the diff and gear oil about 20 mins ago. I'll keep you posted.

Originally Posted by Bimmer-Bob

I do have a 20mm rear bar and about -3 of camber up front and 0 toe - all of which should help with turn in (otherwise the lock on decel might push a little, not sure).

It sounds like we have a fairly similar set up. I too have a 20mm rear bar, -3.5* of camber, and 0 toe in the front. My major issue now is going to be my shocks/spring rate and lack of adjustment. For now I am still on the Bilstein B12 kit. I will go to something more aggressive once this is a dedicated autoX car. But for now I like driving it to work most days. Oh and I think I just blew my parts budget for the season.

I have been autoxing for quite a while but this is the 1st car I have owned that was competitive in class and I really enjoy driving. It was frustrating back in DS (a few years ago) so STX was definitely the right move. I never even considered replacing either of the diffs in my BSP EVO9 so this is uncharted territory for me.

[YarkoDrives]

Originally Posted by The Wind Breezes

The reason for your car pushing is more camber than tire pressure unless you're way off. You have a lot more negative camber in the rear than the front which they do from the factory to increase the car's stability (push / understeer / lack of rotation). At least another degree of neg camber up front will see you huge benefits.

unfortunately with F-Street only allows manufacturer specified suspension adjustments. So I cannot get anymore camber. I've pulled the strut mount installation guide pins to get almost -0.7. originally with the pins in the car was around -0.45.

I'm upgrading to Koni SA's for more damping and later a 32mm Hotchkiss bar will help as well.

A lot of the discussion in the forum is for "Street Touring" classes which allow camber plates or alternate arms, so more camber can be had. STU is tough competition for the 135i, STX has a lot of excitement and builds going on and the 128 is proven competitive there.

[YarkoDrives]

SCCA Fastracks is out and the SAC (Street Class Autocross Committee) is seeking member input on moving 6cyl normally aspirated and 4cyl turbo cars from F-Street to D-Street.


This means the 128i would be in D-Street for 2017 if the classing is changed. and leave the 135i in F-Street with the V8 and boosted-6 pony cars.



With the street class wheel width restriction to oem, 7"F and 7.5" rear the 128i just doesn't have enough tire for F- Street.

The 128 may be competitive in D-Street against these below and other smaller engine cars moved from F-Street:

Acura Integra Type R
Audi

A3 (2.0T; FWD and RWD) (2015-16)
A3 quattro (3.2L V6, AWD)(2006-09)
A5 (2008-16)
S4 (2000-03)
TT (1.8T, non-quattro/FWD)(2000-06)
TT (2.0T, non-quattro/FWD)(2008-09)
TT quattro (AWD) (2000-06)

Chevrolet Cobalt SS (2.0L Turbo) (2008-10)
Eagle Talon Turbo (AWD)
Lexus SC 400 (1992-2000)
Mazda Mazdaspeed6
MINI

Clubman JCW (2009-14)
Clubman S (2008-14)
Cooper Coupe JCW (2013-15)
Cooper Coupe S (2013-15)
Cooper JCW Hardtop (2006-16)
Cooper Roadster JCW (2012-15)
Cooper Roadster S (2012-15)
Cooper S Hardtop (2002-16)

Mitsubishi Eclipse Turbo (AWD)
Lancer Ralliart (2009-15)
Saab 9-2X Aero (2.0L Turbo) (2005-06)
Subaru

Forester 2.5XT (2004-13)
Legacy 2.5GT (2005-12)
WRX (non-STI) (2001-16)

Volkswagen

Golf R (2012-13)
R32 (Golf chassis) (2004, 2008)

Any SCCA members that think it's a good idea and might run the 128 in DStreet should send a comment to the SEB/ SAC in support.

[YarkoDrives]

midnight server reset - double posted...

[RyanDavies]

Fwiw, the 128 will still be hopelessly uncompetitive in DS. Closer than it was in FS, but zero chance of being competitive. It probably sits somewhere between HS and GS in ultimate pace, but there's little benefit for the SCCA to competitively class it, given how few of the "right" car were made (stripper non-sunroof M-sport), and even more so, how unpopular it is as an autocross car.

[jvb6806]

The diff arrived this morning, and the hardware should be here tomorrow. I have already done 4 events this season and my goal is to have this in for an event Sunday in Rantoul (central illinois).

I am going to do swap the housings, swap the covers & let the RTV set tomorrow, fill Saturday, race Sunday.

Everything looked good when it arrived. I am very happy that is came with the stub shafts and everything ready to go. I ordered new hardware for the axle shafts and the drive shaft. I think those are the only torque to yield bolts back there.

Thanks to Ian S. at TMS and DiffsOnline. I can't wait to put this together.

[Xaeryan]

Originally Posted by jvb6806

I ordered new hardware for the axle shafts and the drive shaft. I think those are the only torque to yield bolts back there.

Having just installed a new diff of my own, what (and where) did you find the torque specs for all of these?

[jvb6806]

Originally Posted by Xaeryan

Having just installed a new diff of my own, what (and where) did you find the torque specs for all of these?

I have access to a couple of aftermarket service information databases.

PM Sent.

Side note... I knew all of those inverted torx bolts were supposed to be replaced but they are not actually toque to yield. They have a ribbed edge on them. That is why BMW recommends replacement. After doing some reading it looks like I should have ordered one of the nuts that holds the diff onto the subframe but I'm pretty sure a bit of locktite will get the job done.

[imported_mega]

I'm running my r53 in d-street in the local club, but I might do an event or two with another club with my 2008 135i Running f-street I'll try to get some re71r's but probably not gonna happen as the mini EATS them

anyone have any alignment tips? I might be able to swing a swaybar but that's it for mods, the car is bone stock right now

I do not daily drive, maybe once a month but we do go out to tail of the dragon so I dont want to go tooo aggressive on the alignment

[Kgolf31]

Originally Posted by imported_mega

I'm running my r53 in d-street in the local club, but I might do an event or two with another club with my 2008 135i Running f-street I'll try to get some re71r's but probably not gonna happen as the mini EATS them

anyone have any alignment tips? I might be able to swing a swaybar but that's it for mods, the car is bone stock right now

I do not daily drive, maybe once a month but we do go out to tail of the dragon so I dont want to go tooo aggressive on the alignment

Well if you're running in street you won't have to worry about an aggressive alignment.

[imported_mega]

I've never looked at what we can do for camber, is there no adjustment like the mini?

[RyanDavies]

You can pull the pins and gain about a half a degree that way by pushing the strut all the way in in the slotted holes.

If I were running the car in FS, I would go to zero toe front, max camber. 1/16 *total* toe in the back, or less. 27 or 28mm front bar, and around 2 degrees of camber in the back ( or one greater than front, whichever is less). Shocks would do a *lot* to help this chassis. Most critical would be the tires. Fit as much RE71R as you can under the fenders up front, and match the size in the rear. I would guess a 245 would fit. Don't stagger the tires, you'll be fighting catastrophic terminal push as is, you do not want more rear grip. The larger front bar is to help control camber loss in roll, so it'll actually help prevent understeer on stock springs. The stock bar is also very, very bound up from the factory (as is the common M3 sway bar upgrade). You should be able to move your bars without endlinks attached with very minimal force (index finger without hand moving), to ensure no preload from bushings.

[imported_mega]

I'm probably stuck with these hancook venus v12 evo things at 225/35/18 and 235/40/18 this year but I think I can get a front bar

[RyanDavies]

I wouldn't worry about it much then, just go out and have fun. Sort the alignment / camber when you get the chance. Those tires are going to hold you back enough, and the setup would be completely different going to better tires, not worth chasing your tail.

[Kgolf31]

For those who are curious.

Local event yesterday on Toledo.

[imported_mega]

I dug into some old posts, looks like 225 is biggest that fits front without rub