Chassis setup

[HalM3]

Our BMW M3 sedan picked up the inside rear tires on the majority of the corner exits at Marina during the Zone7 weekend. What changes would you make to keep the inside tire planted?

[krote6]

more front bar or less rear bar Hal... what is corner exit like? understeer or over steer? do you have a limited slip?

[HalM3]

Corner exit had very slight oversteer with our stock 25% lock up LSD. You can hear the inside excessive tire slipping in the videos from my runs on Saturday. On Sunday, the RS3 street tires were fine with the exact suspension settings. Rear 24mm bar is already full soft but we can stiffen the front 30mm bar two more settings. Just don't want any more corner entry understeer.

[krote6]

its always a compromise isnt it Hal..


can you add about 25 pound stiffer front springs?

[HalM3]

I have a set of 600lb but went with the 550lb to reduce the understeer. I can stiffen the front bar, reduce rear rebound 1/2 turn for quicker shock travel. Stiffen rear compression.

[krote6]

umm looks like the best first try would be the rear shocks .. slightly more compression slightly less rebound ..

[grant]

More front bar is best bet since you have adjustable front. Back off the rear bar and use compression settings on your shocks to add stiffness in rear. What kind of alignment are you running in the rear? If you have too much negative camber you may want to back off a bit so tires so light tire sits a little flatter. What do you run for tire pressures on your streets?

[HalM3]

Our rear is toed in 1/8" and camber is set at -2.2. If I can't soften the rear bar I can stiffen the front bar one more position. Tire pressure: We run 39/37lb lbs hot in the street tires. We had 35psi all the way around on the r-comps but the track we run 40psi hot. I'm taken Olivia to the shop today to switch pads for Thunderhill and will check bars and the diff as well. We should see about 60lbs before the lifted tire moves (other tire on the ground and transmission in neutral), if it's far less then I get a 40% lock up rebuild...

[grant]

Running much toe out in front? I'd run at least an 1/8 of toe out. I run 1/4 on the Z. Tires: Hoosiers I run 34 front and about 32 rear

[HalM3]

Diff was worn out, less than 10%. Having a 40% lock up diff built for the next event. Tow in front is 0 since we track her so often. Will try the lower tire pressurs hot. Comment: The Hankook V214 with C51 are a pretty good track tire but not as good as the BFG R1 were...