Originally Posted by klammer
When you guys talk about breaking below the 1:30 barrier, what are you guys thinking makes the biggest difference? Tires, suspension, or both. Never thought I'd say this, but actually thinking about "upgrading" from the AD08's... but maybe not and think I'll try and make it that weekend.
The component that gives you grip are the tires. If your tires are crappy even if you have the best suspension set up in the world you will not be able to find grip.
Without getting into r-comps (which usually require a second set of wheels specifically for track duty) I don't know what tires would be better than AD08's.
The suspension set up comes next. I don't believe the M3's sways are adjustable from factory. The stock suspension should hold up good enough depending on experience.
Once you find your preferable tires, what comes next is the alignment. Despite the fact that I've been a member here for just above a week I've seen people post camber numbers above -3 degrees, which to me sounds a little crazy. I don't know what alignment M3's come with from factory or the set up on the people's cars that posted such numbers, but it seems excessive for street cars.
I don't have much experience with the M3, but I do have track experience with Porsches. In my old GT3 with stock suspension and rose joints (rubber eliminated), which should be stiffer than M3's stock suspension, I still was running -2.6F and -2.3R of camber with r-compound tires.
With softer suspension you have more flex, meaning the chances of lifting the inside tires is less likely. So I see no reason to run such excess camber numbers. The stiffer the tires and the suspension the more camber you will need.
The best way to find the alignment that works for you is to first find the optimum running temperature for the tires, then measure the tire wear. If the inside tread depth and the outside tread depth is about the same after 2-3 DE days then your camber is good. I cannot say much for toe and caster. I'm sure people with more experience with these cars can jump in.
If you get into adjustable coilovers and sway bars you will be lost unless you can find an experienced race shop that run BMW's. I don't know how to dial in the suspension in terms of compression and rebound. And will have to learn how do adjust sway bars all over again because it's the opposite of the RR platform which I'm used to.
Hope this helps a bit.