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Chassis setup

PostPosted: Sat Jul 30, 2011 7:30 pm
by 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?

Re: Chassis setup

PostPosted: Sat Jul 30, 2011 7:46 pm
by krote6
more front bar or less rear bar Hal... what is corner exit like? understeer or over steer? do you have a limited slip?

Re: Chassis setup

PostPosted: Sat Jul 30, 2011 8:18 pm
by 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.

Re: Chassis setup

PostPosted: Sat Jul 30, 2011 9:31 pm
by krote6
its always a compromise isnt it Hal..


can you add about 25 pound stiffer front springs?

Re: Chassis setup

PostPosted: Sat Jul 30, 2011 10:56 pm
by 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.

Re: Chassis setup

PostPosted: Sun Jul 31, 2011 12:09 am
by krote6
umm looks like the best first try would be the rear shocks .. slightly more compression slightly less rebound ..

Re: Chassis setup

PostPosted: Tue Aug 02, 2011 10:57 pm
by 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?

Re: Chassis setup

PostPosted: Thu Aug 04, 2011 5:46 pm
by 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...

Re: Chassis setup

PostPosted: Mon Aug 08, 2011 6:27 am
by 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

Re: Chassis setup

PostPosted: Mon Aug 22, 2011 9:53 pm
by 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...