Ok so I my Miata is generating a lot of interest in the classifieds so I figured I would start a thread to anyone that is interested about my build ideas for my 2005 Crossfire. It is a base coupe with 6-speed transmission. I borrowed DaveOH32's race tires a couple weeks ago and am hooked on building the car for stock class autocross. To stay legal for stock class I am limited to only K&N air filters, a custom cat-back exhaust to drop weight and clear my trailer hitch for the tire trailer, along with stock size wheels with an allowance of +-0.25" offset for the wheels. So I can run a 24mm offset on the front wheels to allow slightly more tire to fit instead of the stock 30 mm. The final piece of the puzzle will be Koni adjustable shocks and the 30mm H&R front sway bar. Here is a picture of the car as it looked at the autocross with the race tires which were not on stock class legal wheels.

Crossfire_racing001-1.jpg

Here is a picture of my old autocross car that is now for sale.
6-11-06_autox.jpg

I have spoken with www.ccwheel.com about making a custom rear wheel for the Crossfire that is lightweight and still stock size. They can make a wheel that will weigh just under 20 lbs which is a substantial drop in weight from stock. The front wheels I found will drop 4 lbs from stock and cost under $200 a piece. I could have front wheels custom made as well but will start with more budget wheels till I decide if it is worth getting custom fronts done. I can't find a single stock size rear wheel that weighs less than stock so I will be going the custom route with those.

For tires I am in search of a 245/35/18 Kuhmo V710 that is ready to go in the trash just so I can test fit it. With the extra 6mm of offset I am allowed I think they might not rub the a-arm but we will see. If not I am going to be getting the Hoosier 225/40/18 for the front. In order to get the traction I want on the back, I will either be going with a 265/30/19 or a 305/30/19 Michelin Pilot Cup. By running a harder compound rear tire the natural tendency to understeer will be minimized. I am hoping the fat rear tires will give excellent traction for acceleration out of corners, which will be an advantage over the BMW 3 series which is the only other significant RWD car in the class. I believe the 305 will fit because from the dimensions I have received they are only an inch wider than the 275 Kuhmos I ran a couple weeks back and there was plenty of room to spare and the 305 will give me an extra couple of mph in 2nd gear because they are slightly taller than stock. This is important because on an autocross course a car can be made or broken since most courses stay under 60 mph and if you run out of gear too early and need a shift to 3rd you lose about 0.1 of a second for each additional shift.

That is all for now I will update more in weeks to come as I start getting parts in and prepping the car. Hopefully 2007 will be a successful year.

~Keith