Expert: Dan Liddy - 10/8/2008

Question
QUESTION: we have a 1983 mustang dirt car it is pushing bad in the cornor on the front we have LS spring 850# RS 950# on the rear on LR 200# AND RR  175# we run hoosier tires RC-4 with air presure of RF 18# RR 16# LR 14# LF !2#

ANSWER: I think you have the front way too heavily sprung- - -but you don't tell me anything about sway bars. Type of front suspension, whether it's adjustable , coil over - - -what ??  You also haven't mentioned camber and caster settings. Tell me your corner weights too.

Here are a few things to start with.

RF camber neg. 4 to 5 deg.
LF camber pos. 2 deg.

Front toe out about 1/8" total to as much as 1/4"

If you are not using a sway bar, or are using the stock one , you should change to about a 1" diameter adjustable.  Look for Ground Control Suspensions on the web. Also a company named Afco I believe.

The real key to this is to make ONE change at a time and record the results.  Both lap times, and driver comments, plus any visual input from experienced observers.  Be sure and write EVERYthing down.  One full page for each change, include the date, track conditions, air temp and so forth.

Finally get the book:  "Hot To Make Your Car Handle" by Fred Puhn.  Bookstores have it or can order in a few days, it's about $16.00 and has a goldmine of info within.

Be sure and write back both with more info, and any success stories you'd like to share.

Good Luck

Dan Liddy
Sarasota, Florida   



---------- FOLLOW-UP ----------

QUESTION: sir you have been a great help to us just one more ? where would you start off with the ride height we have adjusters cups on all 4 springs mesuring from the frame to the floor what would you set the height rf on frame rr on frame Lf ON FRAME LR ON FRAME  thank you so much

Answer
OK  for this one you need to check your local rules- - - the answer is just as low as you are allowed, frequently it's 5" - - -sometimes something a little different.

The important thing is to get it as close to what the rules allow as you can. And corner weights and percentage of weight bias is just as important as ride height.  Both make a difference.

Your rules will probably allow you about a 55% weight bias to the left, and perhaps a 5" ride height.  Work HARD on getting the weight bias right, the ride heighth should be easy enough with your adjustable arraangement.

One last note , I just noticed you asked for a 'frame to floor' measurement. Almost universally in racing sedans, ride height is measured from the bottom of the rocker panel at the door, and does not include the seam between the rocker panel and the floor (of the car)  Do check your local rules for clarification, and final measurements and weight bias allowances.

If you don't have a front sway bar- - -get one !


Dan Liddy