Many of you know I had a fully prepped 2008 135i, before the 2011 135i DCT, with TC Kline DA coilovers, springs, camber plates, Ht-10 brakes, M3 subframe bushings, etc., so I have some pretty good data on how a 135i can feel in good form on a track.
Well I have been wanting to take the 2011 135i DCT out on the track, so I thought I would see what the "minimum set up" might be to have some fun on track days. I have been driving a 2006 Lotus Elise as a track dedicated car, so the 2011 135i has remained stock and been the daily driver.
Anyway here is the starting minimum set up:
Hotchkis front sway 32mm hollow bar (95% stiffer than stock)
Hankook R-S3 225/255 on stock wheels
Motul RBF 600 brake fluid
M3 wishbones
Here is some video of the 2011 DCT in action (BTW- the DCT is fantastic for the track, like it quite a bit. Use headphones to hear all the action as the wind noise is covering up the DCT shifts):
http://www.youtube.com/watch?v=43yRx9XXwTA
Here is the data:
Stock brakes, of course, have to be driven with care. I was touching 130mph at the end of the straight and being very careful with using too much brake. We all know they will cook if driven hard, but I seem to be able to push into the 6 or 7/10ths range of effort and still maintain them usable. Enough to still have fun. When I pushed beyond that, goodbye brakes. The Motul fluid is the winner here, helps a lot.
Tires, fantastic, absolutely necessary. The R-S3 is better than the Z-1 on the track, and I love the Z-1.
Tire wear on outside front edges, extreme. I thought the M3 wishbones, coupled with the big sway bar might help preserve the R-S3 some, but camber plates are needed if you don't want to chew through tires quickly. I would not even bother with the M3 wishbones and just go straight to an adjustable plate with at least 2.5 - 3.0 degrees negative camber.
Stock springs (linear rates on the 2011, way better, but still softies) and shocks...well, the car moves all over real funny like, BUT, was very grippy overall (thank you R-S3), and once you got used to the unnerving bushing/suspension movements in the turns, it really was quite manageable, surprisingly grippy, and a lot of fun.
Using that data, I will be adding the Ground Control street camber plates this coming week and report back. I think the "minimal suspension setup" will be:
Hotchkis front sway 32mm hollow bar (95% stiffer than stock)
Hankook R-S3 225/255 on stock wheels
Motul RBF 600 brake fluid
Camber plates (you can skip these if your willing to go through tires fast)
Did I mention the DCT rocks!!
Cheers
