Chassis Setup

[ack fia]

Now that the track day bug has bitten, I need some help.
The car is up on the corner scales and the individual wheel weights are available. But what should they be?
Does anyone have (or know of) a basic chassis setup for road racing?? The place where I bought the scales provided a brief set of instructions but they are for a dirt racer looking for bite in the left rear. I need to know the set up (or basic starting point) for a road course.
Can anyone help??
Pat

[Tommy]

Pat -
From my very limited experience as a fellow amatuer car tuner and track driver, there is no easy answer to your question. For road racing, it is generally recommended to balance the cross weights of the car (i.e., front right plus left rear equals front left plus right rear), but there is much more to it. I suggest you check out the transportation section in your favorite book store and look for a book on this subject. One of my favorites is "How to make your car handle" by Fred Puhn. Good luck.

[RACER X #99]

Pat,
I suggest you take your car to an experienced Road Race shop for your initial setup. They can set your car up for the track you plan on running and then you can make minor adjustments after taking tire temps at the track.
Cobra Automotive in CT. can do that for you.

As far as your car being heavy, I disagree. My Contemporary weighs in at 2,800 lbs with the 210 lb. driver and 15 gallons of fuel. That's with a small block w aluminum heads.

Good Luck,

Roger D

[Mike Simard]

Aside from the usual toe and camber settings, you'll want to know that you have no bumpsteer. I apologise if I'm stating the obvious but bumpsteer is when the front wheels toe in or out during wheel travel, most noticable as darting under hard braking. Bumpsteer is adjustable by moving the steering rack or tie rods up or down. It would also be nice to verify that you have a little camber gain with wheel travel while you're checking things. A typical Cobra has relatively short control arms and is therefore sensitive to instant center/roll center point changes from the ride height being unoptimal. It's a good idea to consider the suspension geometry when setting ride height and not just ground clearance. For the rear suspension you want zero toe to toe in, you also want the wheel to toe in under suspension compression if anything and NOT toe out. Another book recommendation is Chassis Engineering (I think) by Herb Adams, it has a cute method of checking bumpsteer using stuff lying around.

[Clois Harlan]

For those in the midwest that want to address this issue consider coming to Run and Gun on Wednesday October 11, 2006. A professional set up team will be at Run and Gun on Wednesday complete with scales and the expertise to help you set up your car. In addition Gateway will be will provide us with track time to test and tune after lunch to test our adjustments. A new Run and Gun webb site will have complete information in a couple of days. In the meantime if you have any questions you can give me a call or Jay Nordstrom.

Jay Nordstrom
11817 Cromwell Dr.
Dallas, TX 75234
972-742-2594


Clois Harlan
8160 S 270th E. Ave.
Broken Arrow, OK 74014
918-633-5336