Auto Racing: Rear wheel chatter?, drive wheels, sarasota florida

Question
QUESTION: I have a 94 Ford Escort 4dr, auto, set up for oval dirt. My question is, how do I stop "wheel hop" in the rear end? The car is all over the track. Also we are not allowed any spoilers. Thanks I have enjoyed many of your answers. Shane

ANSWER: Hi Shane :

I guess I'm going to need a bit more info- - - your description of wheel hop is a bit confusing.  Wheel hop is uaually caused by poor control of the drive wheels, and is due to a wrapping of the leaf springs in the rear . Since your car is a FWD, and has a coil spring rear, I'm not sure what symptom you're talking about .  Also "all over the track"  is a bit vague.  Try to tell me more precisely what happens.  Does the rear slide out when you enter a turn, or when you exit ?  or does it happpen in in the middle of the corner ?  Or is it simply bouncing around and losing traction as a result ?

Finally, tell me what's been done to the suspension so far, and your set up numbers, RF camber and caster, LF camber and caster, toe in or out ? and how much, als o any rear toe.

With that I should be able to help you settle in down some, for  an old road racer, I've had some surprising success helping you circle track guys.  GEt me the info and please write back !\

Thanks

Dan Liddy
Sarasota, Florida

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

QUESTION: Thanks Dan, The rear end is bouncing around like it needs more weight. When I go into corners the car wants to keep going straight even if I have the wheels cranked, eventually the wheels will grab, the car will dive hard into the corner and then straighten out violently. The rear end doesn't slide around at all only when it jerks around in the corner. My original question states that my car is "set-up" for dirt. That is not the case, we need to know how to set it up for dirt. The car has bone-stock suspension and I belive all of the numbers are to factory specs. Any and all help will be greatly appreciated. Thanks so much Shane

ANSWER: OK  Here are some numbers to start with.


FRONT END
LF positive camber 2 degrees
RF NEGATIVE camber 5 degrees

Front toe OUT 3/16" to 1/4"

REAR END
LR camber positive 1 degree
RR Negative 2 degrees
If the rear end is independent, it will be easy to adjust. If not, you'll have to bend the axle, a front end shop or frame shop can help you with this

Rear toe should be about 1/16" toe in if it's independent, and 1/32" if it's a solid axle.

It sounds like you need a set of adjustable shocks for the rear, you simply can NOT spend too much money on shocks these days. Adjust the rears for maximum rebound, and the fronts for maximum bump.

Finally replace the front sway bar with a larger one, about 1" diameter is about right. Then eithier find or fabricate a sway bar fro the rear I use a 3/4" OD chrome moly tube 1/8" wall with long end links which are drilled at 1 inch intervals.  This way I can adjust the tension of the bar, and add preload or assymetrical preload for specific tracks.

Talk to compeitiors about tire pressures, I have only very limited experience with dirt, and it's related to Outlaw Modifieds.

Hope this gets you started !

Dan Liddy
Sarasota, Florida

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

QUESTION: Thanks for all of the info, I will be getting to work on this right away. Do you have any secrets for the engine? It is a 1.9 liter 4cyl and auto tranny. I am looking for some things I can do that are simple adjustments or just plain cheap. I can't spend to much money as it is a "claimer" class and I could lose the car if it seems too fast. This class is designed with the novice racer in mind and my 13 year old son has been driving the car. I drove it Sat. nite to see how it handled and it was horrible. Thanks for the info on the "set-up". Any help with cheap engine work would be great.  Thanks again, Shane

Answer
Hi again:

You can advance the timing so that at 2500 RPM you have a total advance of 34 degrees. Then run 10 hot laps and look at your plugs CAREFULLY.  The insulators (white center) should be very light tan- -If they're pure white with little specks on them , the specks are bits of piston!! that's too much advance, back it off 2 degrees.

There are tricks you can do with fuel injection that will lean it out a bit.  One is to bypass the cylinder head temp sensor and replace it with a good potentiometer (volumn control) but go to a real electronics parts store NOT Radio Shack, and ask for a very GOOD one. Should be $20 or so.  Splice it into the circuit and adjust your mixture with a CO meter. You may need to enlist the aid of a real mechanic for this.  Try to find one that has an interest in racing.

Again , hot laps, and read your plugs. Run HARD, and shut the ignition off at the end of the straight, coast into the pits in neutral and do the plug cut. They should still be a very light tan- - -almost white, no spots !

I know some other stuff that will help in a big way- - -none of it is cheap !

Keep writing

Dan