Saturday, December 13, 2008

developing the aero package

We raised enough scratch to buy the ugliest, cheapest, universal wing on ebay (Did you mean: bomb wing?). Here's a shot of the wing after install:

Yes, that's 2 layers of awesome wing that you see. $50 of china's finest heaviest aluminum. It must be the latest high tech aluminum and lead alloy, because the wing really does weigh at least 10lbs.

So with the new wing installed I towed the LeMon up to ThunderHill for a Friday with TEAM Racing. I was instructing, so I got a white wristband: my ticket to drive like an ass exemplary instructor in any session. The plan was to drive as much as possible and break anything on the car that was going to break.

And break it did.

First session of the day, lap #2 as we're entering the front straight (just after pit exit), I felt some moisture on my cheek. Then I looked at the temp gauge and saw it in the middle of a seizure. I pulled the car into the paddock, popped the hood using the BMW special hood opening tool, and spotted the belt that drives the alternator and water pump dangling from the engine compartment. It was a bit mangled, and clearly was not where it was supposed to be. Luckily I had the belt we took off the car when we replaced it with a brand new one. Yeah, that belt should be just right here back at home in a box. Luckily, another Spec E30 racer was there, and he supplied me with his spare alternator belt. I put a new belt on the car, and fired up the motor. Mike S, another Spec E30 racer, noticed the crank pulley wobbling like mad. I took it all apart again, couldn't figure it out, so I put it back together and drove it, wobbles and all.

Out of sight, out of mind.

Next up I noticed horrible understeer into turn 1 and turn 8 at Thunderhill. Both turns are taken at 80mph+ To my surprise, the wing was actually being effective and creating downforce on the rear of the car!

That's great, but without any aero on the front of the car all it did was produce understeer. Ridiculous "slide the car into high speed turns" understeer. I managed to trail brake to get the car to turn in a little better, but it got hairier and hairier as I pushed harder. After one session, a driver who followed me through turn 8 found me in the paddock and remarked "wow, your car was all balled up and twisted with a front wheel up in the air"

That convinced me that it was time to stop driving around the problem and to try to remedy it. So I pulled off the top wing. Less surface area has to have less downforce, right?

It worked, and the car went back to a more normal level of understeer. Hopefully in the actual 24Hrs of LeMons race, due to the track configuration, we'll be going a little slower and the wing won't need further tuning. If not, at that point, we'll be tuning using another special tool.

The rest of the day was fairly uneventful.

There are some pics from the day up at Check out that suspension compression! Used KYB shocks and Vogtland springs are about the lamest E30 suspension kit on the market, but it's the cheapest ... so here we are.


  1. Mad body roll, yo! Are you sure your front sway bar is connected? Our car looked like that at the local autocross, where we later learned we were driving with the front sway bar disconnected!

    Team Porcubimmer

  2. um, I believe the front sway bar is actually disconnected. Laz, did we ever replace that bolt we broke? I really think it's still hanging loose.

  3. o ye of little faith: the front swaybar is connected. The broken bolt was replaced before the first shakedown weekend.

    We really need more spring, or more sway, or both.