I'm planning to try a few more autocross adventures this year. I did one last year and I was sliding all over the place. Had fun but want a bit more control. I have a bone stock '05 Z4 roadster with the 2.5L motor, 5 speed manual transmission, and 16" wheels. It's a fun, reasonably fast (easy to hit 120mph) and quite economical (30mpg) everyday commuting car. I'm planning to get rid of the runflats and go with conventional Michelin Pilots due to past experience. I'm contemplating 18" wheels but the roads here in the Dallas/Ft Worth area are awful. Has anyone installed aftermarket sway bars, stress bars, or cold air intakes? I'd appreciate your input and experiences. Thanks, Myron M. Ft Worth, TX
Autocross options Tires make a huge difference. If you're thinking of Michelin Pilot Sport 2s, however, I'd wait two months for the Pilot Super Sports: better grip wet and dry, plus a wear number of 300---at the same price as the PS2. (Yes, it's magic.) Before investing in too much suspension, I'd look into a limited-slip differential (Dinan and elsewhere).
WHY would you want 18" wheels? If anything, they will degrade your autocross performance. More of the weight of an 18" wheel is farther from the center of the wheel, so there's inertial loss both accelerating and braking. It's doubtful that a wider tire would even make up for this with better cornering. Hell; who hasn't? None of those are the solution to your problem, though. As Satch says, the very first thing you need, if you don't have it, is a LSD. After that, I'd look into better tires on stock size wheels. OTOH, if you haven't done so, there's a good chance that the car's better than you are. The solution to that is to take an autocross school or at least a 'CCA-type car control school. Most rookie autocrossers simply overcook the course and then blame the car.
I put 18" non RFT's on my previous Z4- world of difference in ride and handling. It was definitely worth the expense.
Yeah, they're all correct... As CR says, the car is a handlin' fool to begin with; maybe it would save a lot of grief if you spent some time finding its limits before you think about expanding those limits. (It would be easier if we would allow it at a BMW CCA driving school. . . but oh well.) Meanwhile, the mention of run-flat tires has a kinda-sorta component: While the RF tires we get in Homer-ica are "all-weather" POS rock-hard abysmals, in reality, the Other World has caught up. I just spent a day driving on Dunlop SP Sport Maxx GT run-flats, and they were just like the Sport Maxximoids I had last year on the roadster, and I loved those tires! I put Michelin Pilot Sport 2s on the roadster last summer. When I grind them into artgum crumbs, I will replace them with up-to-date run-flats---if they are importing the damn things.
Well, there's the grain of a new idea. I wonder if we can start up a 'grey market' for tires. I've never devoted any thought to it or whether there are any insurmountable regulatory obstacles to it. Hmmm .................................................
I did have an instructor with me for my first few runs of my last auto-x. Too many years had passed since my last one at Bridgehampton in the '80's. Lots of helpful hints on technique from a veteran. My next auto-x is about five weeks away. That will let me squirrel some coins away into the Momma Don't Know fund for tires and a proper spare & jack. I did speak with a rep from a local road course. They allow roadsters for their track days and offer instructors for old geezers. Just what I need. Thanks, Myron M, Ft Worth, TX.
