> -----Original Message----- > > I'm running 245/40 17s in the front and 285/30 18s in the rear > and the fenders have NOT been flared or crimped and the tires > do NOT rub. These are on the Kinesis Super Cups. The tolerance > is very minimal. > > In addition, the rear control arms have NOT been pinned. What does > that mean w.r.t. handling? I don't feel like I'm having any problems. > Maybe I'm missing even better handling than the go-cart-like feel that > the car has now? > > Can someone explain *exactly* how and where the pin is inserted. > Do you drill a hole somewhere? What holds this "pin" in? A cir-clip? > A cotter pin? Bubblegum and string? > > --Patrick > 79 > 82 > 84 > > > From: C.S. Mo > > > > Anything over 265 in the rear will require pinning, I belive. However, > > Devek's pinning kit is pretty inexpensive. Additionally, anything over > > 265 rear/245? front will require some fender rolling/flaring. I saw John > > Veninger's car w/275/315 and there was very minimal rolling/flaring - > > looked great, actually! > From: Jay Kempf [jkempf@tds.net] Sent: Friday, August 10, 2001 2:58 PM To: 928 Subject: [928] Re: Tire Sizes and control arm pins Patrick, The "pin" is already there. It is the pivot pin in the flexible joint in the front attachment point of the lower control are in the rear. You can see it from underneath the car. In the barrel shaped part of the front of the control arm there are two bosses. One is drilled out and you can see the end of the pin where it is pressed in. This traps the back of the small clevis or rod end that is actually attached to the chassis. In between the two is a rubber tube. With braking load or deceleration (and to a certain extent acceleration) the rubber part compresses and allows the two parts to deflect with respect to one another increasing the toe-in of that rear wheel proportional to the braking force. The pin is located at the back of the rubber tube and rod end so it has quite a bit of leverage to deflect. If you move the location of the pin closer to the chassis attachment point you change the way that it deflects under load basically making it stiffer to compensate for larger tires. Marc Thomas of Devek explained to me (because I was curious) that this was planned for by Porsche and that they tested different tire widths and settings. I understood this "pinning" that many discuss generally on this list to be a procedure that locked the flexible joint by drilling and pinning it so it wouldn't move at all. That is a misnomer and I disagree with (my strong opinion) perpetuating the benefits of defeating the Weissach action unless you know more than the person or persons who designed and tested it. Also, in talking to several race types who run big rubber and don't have their Weissach joints modified it seems that there are varying opinions and results on whether this mod is necessary for big rubber, at least enough to make me wonder. If you want to make a decision for yourself you should have a conversation with Marc Thomas as he is very knowledgeable and experienced with this subject and has a bunch of aggressive race environment experience. You should also talk to people like Mark Kibort, Mark Anderson, Dave Lloyd, Kim Crumb, Rich Andrade, Stan Shaw III and any other people that are known to have track cars. Collect all the opinions and then make an informed decision. Jay Kempf 79 US 5ish speed