[mellow]

I am campaigning my 2011 335D (with sport package) in SCCA Solo and would like input from experienced owners regarding optimizing vehicle response. I am running stock other than JR 2.8 tune with turbo-back exhaust, EGR and swirl flap delete, all-square 18 inch Apex wheels, M-front control arms and a Drexler clutch-type LSD.

Question #1: Which Mode of Traction/Stability control (DSC light or yellow triangle) should be selected to optimize LSD potential?

Even with the square wheel setup the car understeers significantly especially in tight uphill turns.

Question #2: Will front and / or rear camber changes while keeping the stock springs and dampers allow the car to rotate more easily. I have 60k miles on the OEM suspension.

[Hoooper]

Originally Posted by mellow

Question #2: Will front and / or rear camber changes while keeping the stock springs and dampers allow the c[/SIZE]ar to rotate more easily. I have 60k miles on the OEM suspension.

You certainly can induce oversteer by messing with the camber settings. Getting the front spot on and the rear set nearer to 0 I would think would be the preference. To be honest though, you may just need more mid corner throttle input, I have no understeer on my car when maintaining corner throttle and my f/r is 235/275 so if there was going to be understeer I would certainly see it.

[OmahaDZL]

Originally Posted by mellow

[SIZE="2"]

Question #1: Which Mode of Traction/Stability control (DSC light or yellow triangle) should be selected to optimize LSD potential?

.

So you already have an LSD installed and your ediff turned off through coding?

[floydarogers]

From my understanding and experience, DTC mode is what you want.

You might also consider a stiffer/bigger REAR anti-roll bar to help with understeer (I know, it's counter intuitive.)

[mellow]

Thanks for your responses. The LSD is installed but I have done nothing to disable any electronics. Is that something that needs to be done? Sorry if that's a stupid question. I have been defeating DTC (momentary actuation) for timed runs. Tires are 255-35 R18 Potenza RE71R. I had a recent autocross focused alignment when I installed the M-control arms.
So far I'm hearing a larger rear sway bar will help more than negative camber. My 13 mm rear unit is so small I had to look twice to see I had one.

[charlie fairmont]

http://www.e90post.com/forums/showth...&highlight=Lsd

This thread is worth a read.

[OmahaDZL]

Originally Posted by mellow

Thanks for your responses. The LSD is installed but I have done nothing to disable any electronics. Is that something that needs to be done? Sorry if that's a stupid question. I have been defeating DTC (momentary actuation) for timed runs. Tires are 255-35 R18 Potenza RE71R. I had a recent autocross focused alignment when I installed the M-control arms.
So far I'm hearing a larger rear sway bar will help more than negative camber. My 13 mm rear unit is so small I had to look twice to see I had one.

Yes you should definitely read the thread posted above and get it turned off.

As for the rear swaybar....yes the stock is a joke.... replacing it is no fun at all...gotta drop the whole rear subframe as its mounted on the top side of it...

[m3driver999]

Have also run 2~3 ax w 335d.

I have no LSD,
Also at first had the sport susp w/ 235f 265r
Then installed the BMW PS w/ 255 35 18 RE71 which came w 26.5 front sway (seems same sway as sport but they say wall thickness different - weight was same - outer bends geometry differed)

One thing that is low cost, is wheel offset,
When using the RE-71s I used the Style 189 rims that have 34 offset front 8" rim and 37 rear 8.5",

(I am now finding - expectedly- that changing track/offset can induce understeer or oversteer, in other platform)
(effectively depending on the square set up offset it may alter the contact patch location..front scrub radius..versus stock)
(what rim width and offset?)

Also tire pressures setting, to counteract the understeer,
The M3 LCA probably added more neg camber, then could add too much neg camber under load - it may effectively loose front grip from geometry..

Car does roll and pitch but is decently quick; and the RE-71s are pretty good.

Also, when I went to the PS suspension, first did rear shocks and springs and mounts, that had good benefit in reducing weight transfer to front...just that change improved car a lot..then later did front..but front improvement gain was not that large...

If it understeers into uphill turn, too much braking or weight transfer to front and overwhelming front tires?, or LSD is now very effective into providing forward thrust with power applied mid-turn, effectively plowing..

I had found that car did best by turning early and settle car before turn and keeping momentum and constant radius and speed thru the turn.

Wonder what tire temps would say? all 4 tires get worked?

(also ran all DTC and DSC off 10sec push - as the power was being cut all time otherwise - but caution as all that torque has the ability to get sideways easily)

Maybe do changes up front that have similar effect as changing rear sway, but less work..

..also if it now has more front neg camber, maybe needs more rear neg camber to match?...just some ideas..