I've been doing HPDE events at local race tracks for the past 10 months in my 05 ZCP, and have been pretty happy with how the car felt at higher speeds. Prior to this past week, I've had the following modifications to the car:
<ul> <li>GC Coilovers (Single Adjustable Konis, 440f / 550r) <li>GC Camber plates <li>Front end: Camber: -2.6 deg, zero toe <li>Rear end: Camber: -2.0 deg (the minimum for the ride height), 1/16 toe in <li>Motul RBF-600 brake fluid <li>Stoptech SS braided teflon lines <li>PF-01 pads on the front (Axxis Ultimate for Auto-X) </ul> Autocrossing on this setup left a bit to be desired. The safety-biased handling that works well for my intermediate level skills at higher speeds just turns piggish at autocross speeds.
At last month's autocross, my first practice run was my best time for the day. That's pathetic. It showed me that I was trying to drive WAY to fast, and just overdriving the understeering balance of the car.
I recently managed to put together a set of four 18x9 OEM wheels, and did one track day with those, running a 10mm spacer on the rear. Better handling in the slow sections (e.g. turn 11 at Thunderhill), still very controllable and safe feeling.
Yesterday was the first autocross event I did with the "square" wheel and tire setup. I decided not to run the spacer in the rear for autocross, since the rear end isn't hurting for grip.
Prior to the event I maxxed out the negative camber in the front of the car to approximately -3.25 degrees (very approximately). Driving the hour down to the Marina airport was a handful -- additional negative camber also adds toe-out to the front tires. That combined with the big tires up front made the car want to follow any dip, crack, or micrometer-measurable imperfection in the road. Luckily, I made it without incident.
In autocross conditions, the car is now (finally!) in its element. Gone is the necessity to have absurdly low corner entrance speeds to compensate for the low-speed understeer. The car is neutral feeling throughout the corner, and the tail is very (too?) easily coaxed out with a little gas or a strong lift.
<div style='float:right; text-align:center;'> <a href='/video/watch.php?20060520-autox.mov'> <img src='/video/video.thenobot.org/20060520-autox.mov.jpg' width='120'><br> Watch one run.</a></div> Yesterday, I started out taking it pretty easy, and made a conscious effort to build from there, going as far as to not use full throttle anywhere until the third run. But based on how the car felt, it was VERY difficult to hold back. It just felt too good, entering and exiting turns with an eagerness I hadn't felt from it before.
I had two much more experienced drivers ride along with me, and they were both taken aback by this E46 M3's ability to get around the corners.
So it was a great day out there. I have a new found enthusiasm for doing autocross in this car.
Prior to coming home, I set the front camber back to my street/track setting, and had a nice relaxing drive back north, with a big smile on my face...