Sunday, November 05, 2006

A Show of Restraint

With the guys gone, I settled down to solving the problem of the camber limiter.

The original Grinch had been a "Z-Bar" car. That is it used a Z shaped bar to act as a torsion bar for the rear swing axles and additionally to keep the axles from going in to positive camber.

Mike Schiffer, the Grinch’s first owner after the Dassingers built it, decided he didn’t like that.

At the beginning of his second season with the car, he installed a cable restraint system.

The idea is simple. Cinch up the cable to the point that the rear axles are constantly in negative caber and can not droop any farther even if both wheels are off the ground.. Short, quick, positive.

It can mean however, that you get some very nasty transitions when the cable is at the end of its tether. You don’t get much warning of impending loss of traction. I guess you just have to learn, by unpleasant experience ( like spinning out), when it is going to go…… and not go there.
I could do without that. I wanted something a bit more forgiving.
I knew I was planning to build a "zero roll" system for the back end but I didn’t have time to do it before next weekends race. I also knew that in order to get the zero roll assembly under the rear end bodywork, I would have to drop the whole thing down as low as possible. That, in turn means I have to get a new exhaust system built that will not be in the way of the zero roll gear. Everything on a racecar is give and take. Move this a little bit here and you are in the way of something else. It makes you really appreciate watchmakers.
I finally figured out a system of brackets mounted to the upper coil over shock mounts and connected to the rear axle locating arm with a bar. The bar, in turn feeds through a spring mounted on the top of the bracket. Since the bar is threaded I could then crank down on the spring to adjust the amount of camber. The second spring should provide some slight warning the you are about at the end of your reach and maybe, just maybe, let you know when to back off.
We’ll see next week when we go to the track.


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