[mmurray]

For some background, I've been getting into autocross this year and find myself struggling to properly rotate the car into turns. Admittedly I'm still getting used to AWD and have had the chance to experiment with trailing braking to help turn-in but am looking for something to help scrub off some of the understeer which I feel pushing me though some sweeping sections (especially in the wet).

I've been told that a rear swaybar upgrade may help - to stay in the stock class, I can only replace one of my sway bars and I'm eyeing an OEM M3 replacement for the rear. Not really sure what I should be looking for in terms of bar spec or real gains so any insight/advice would be hugely appreciated - thanks

[vasillalov]

1. M3 lower control arms and M3 tension rods.
2. Max out the camber on the front. You should be able to get -1.5 negative camber (with the pin removed) on the front (not sure for X-drive)
3. Wider tires and stickier tires
4. Dinan camber plates add -0.7 negative camber on top of the the stock adjustment

[benjlv]

based on your signature you are running a staggered tire setup. probably a 225 in front and a 255 in the rear. If the rules allow it, i would attack the issue in this order. More camber negative camber in the front. Then wider tire in the front. The rear sway bar might also help by stiffening the rear roll resistance and taking some of the load off of the front. From my understanding this will affect your steady state balance more than your dynamic turn in issue though. I suggest the first 2 options first because they add grip to the front end of the car, which will allow you to load the front and rear further which would provide more total overall grip than a rear sway bar. The rear sway bar will just move load from the front of the car to the rear axle. This can increase total overall grip, but it would not do it as much as if you added grip to the front so that it had a grip capability that matches the rear.

[kaede]

+1 for m3 control arms upgrade with Max camber possible. Usually these mods goes unnoticed for staying in stock class. Run a square tire setup instead of stagger (if you are staggered that is). use more aggressive weigh transfer depending on what corner. Honestly the Understeer is not AS BAD as you think, i used to autox with a stock mk v VW GTI. Understeers and weighs a ton haha. Have fun!!

[CJ421]

Camber + bigger tires will help you as noted.

A bigger sway bar up front will improve turn in responsiveness by reducing body roll but ultimately not solve your current problem. I would not recommend upgrading the rear sway bar; the rear of the car needs to roll a bit to keep the tires in contact with the ground. I believe even with xDrive, there's a power bias towards the rear.

[RimasRS]

OP read this it is very good info http://www.1addicts.com/forums/showthread.php?t=510253

[mmurray]

For some reason, my notifications went haywire and I missed these - thank you!!

Sounds like control arms are the obvious (but not SCCA stock class legal) fix. The short term may be for me to wrap 255s over the stock front (again, factory spacing and wheel sizes are limited but tires have some wiggle room).

Early Xdrive is a rear bias (a tad over 60/40 IIRC) so I guess front bars would be the first jump - and legal (can only have one). I know I could swing plenty without getting re-classed but I'm doing well enough bone stock so would like to play fair.

That 1addicts post was awesome too, I may have to start a similar one myself... Getting absolutely hooked on Auto-X and headed to my first BMWCCA track day next month - very excited!