Here We Toe Again

Setting the toe was a bit of an ordeal. First I had to master setting up a home made string alignment system, Then I had to actually properly set the toe. However, given that I had 4mm of front toe-in, either I do it myself, or pay someone to do it.

The string alignment system I used is detailed on Lotus Talk, but I deviated slightly. First off, I cheaped-out, and bought one $9 length of 1/16th inch aluminum U channel instead of 2 1x1x1/8 aluminum angle ($21 each). I saved $30 this way, but I'm not sure it was worth it. The flimsier channel flexed a little, requiring a little extra re-measurement and fiddling around to make sure everything was straight.

So once I got the strings set up, and figured out which way to turn things, I removed all front toe-in. The car drove somewhat more nicely on the street and I did well at my first event. However in putting the tires on for my second event I noticed a rub mark on the frame. Honestly I'm not sure if it's been there all along, but there seemed to be some corresponding signs of rubbing on on of the front tires, so I made a quick in the field adjustment to add 4mm of toe back in with the gracious help of my competitor Matt (lent wrenches), and PJ (lent jack stands). I ran the race, but it felt a little bit tail happy, and even more tail happy back on a faster course at Devens for the third race.

The (possible) rubbing was on the inside rear of the front left tire. The initial theory I had was that the wheel had rubbed when I was cornering hard left around a pin cone in the first part of the course, and accelerating, thereby unweighting the front left corner and allowing the wheel to droop. Liberally applied crayon to the rubbing area so I could tell if it rubbed again. It did not, and I was relieved, since I REALLY don't want to rub a weak spot in the frame. That would be dangerous, and even if I didn't experience a direct failure, it would force me to total the entire car.

However, after the third race I spent some careful time looking at the rub marks and the wheel, and I noticed a few things. The wheel had little strings of what looked like peeling off in the rubbed area, and the wheel weights had an odd-safety orange color to them. I pulled at the strings and noticed that they appeared to come off, and appeared to be added on to the surface of the rubber, not part of the rubber itself. Also the stringy bits didn't seem to stretch much at all, not what I would expect from bits of tire rubber, more like plastic. Hmm... what's orange, and plastic at an autocross... hmm... sounds familiar... hmm... CONES! I distinctly remember having a cone caught under the left front wheel on one of my runs in the first race.

So now I believe that the rubbing on the wheel and maybe the marks on the frame came from a trapped cone, not wheel contact. However, I'm cautious about leaping to conclusions here, so now I've dialed back out half the toe-in (giving me about 2mm front toe-in), and also stiffened the front shocks 2 clicks to (hopefully) help with the over-steer.

The NCR Porsche club event on 6/2 was a soaker, so I never put the race tires on, and never got a good test of the new settings. I'm hoping for better this weekend with Renegade Miata... right now the weather man is saying it will be dry, which probably means it will rain....