E-M Understeer questions

[rbray]

Hi Guys,
I have an EM with an 8.8 rear and the custom tubular front end.
I'm running a 351W and adjustable coil overs.
The car has not been to the alignment shop yet, but I'm trying to get in the ballpark before I start shelling out money.
Right now I have the toe-in adjusted to what I think is close to zero. The camber is set by using shims, so it is currently set to whatever the factory shims offer.
The car tracks straight as an arrow, now wheel shake, but it does understeer. I notice the understeer at times on the street, but on an autox course the car just plows like a pig even after using all the weight transfer techniques.
I'm wondering if I should try adding some toe-in by adjusting the tie rod ends.
What do you think?

[strictlypersonl]

To reduce understeer you can do one or more of the following:

Increase negative camber in the front end.

Increase toe-out on the front.

Soften the front damping or stiffen the rear's. That will only change the turn-in, not steady-state, but in an autocross, that may be what you are actually looking for.

Increase the front tire pressure or reduce the rear pressure.

Decrease the ground clearance all around.

Add a rear anti-sway bar (or stiffen the one you have.

Sometimes, if you have excessive roll, adding or stiffening a front anti-sway bar will increase corning power at the front too, but it will still feel like it's pushing.

[rbray]

Thanks for the advice. I had it backwards ( wanting to and toe-in)
as usual.
I'll give it a try

[392cobra]

Rodger,
This is from Roger Kraus Racing.

OVERSTEER / UNDERSTEER CORRECTIONS

Understeer Corrections
Oversteer Corrections.

Push, plowing, front tires slide out first.
Loose, rear tires slide out first.

Usually slight understeer is safer.
Oversteer can be dangerous, especially at high speeds.

Raise front tire pressure.
Lower front tire pressure.

Lower rear tire pressure.
Raise rear tire pressure.

Soften front shocks. Stiffen Bump.
Stiffen front shocks.

Stiffen rear shocks.
Soften rear shocks.

Lower front end.
Raise front end.

Raise rear end.
Lower rear end.

Widen front track.
Reduce rear track.

Install shorter front tires.
Install taller front tires.

Install taller rear tires.
Install shorter rear tires.

Install wider front tires.
Install narrower front tires.

Install narrower rear tires.
Install wider rear tires.

Soften front sway bar.
Stiffen front sway bar.

Stiffen rear sway bar.
Soften rear sway bar.

More front toe out.
More front toe in.

Reduce rear toe in slightly.
Increase rear toe in.

Increase front negative camber.
Reduce front negative camber.

Increase positive caster.
Reduce positive caster.

Soften front springs.
Stiffen front springs.

Stiffen rear springs.
Soften rear springs.

May need more front suspension travel.
May need more rear suspension travel.

Install wider front wheels.
Install wider rear wheels.

Use softer front compound if possible.
Use harder front compound if possible.

Use harder rear compound if possible.
Use softer rear compound if possible.

Remove weight from front of vehicle.
Add weight to front of vehicle.

Add weight to rear of vehicle.
Remove weight from rear of vehicle.

Drive a different line.
Driver may be going in too deep.

Use weight transfer to your advantage.
Driver may be getting on the throttle to early.

High Speed. Increase front wing downforce.
High Speed. Increase rear wing downforce.

Too much front brake.
Too much rear brake.


Lower front and rear tire pressures slightly.
Raise front and rear tire pressures slightly.

Suspension may be too stiff.
Suspension may be too soft.

Shocks may be set too firm.
Shocks may be too soft.

Tires may be old or hard.
Roll centers may be too high.

Vehicle may not have enough suspension travel.
Lower vehicle.

Vehicle may have a toe problem front or rear.
Tires may be too hard.

Increase negative camber front and rear if possible.
Widen track front & rear.



A properly set up vehicle will usually push slightly on corner entry, be fairly neutral at the apex (STEADY STATE) and exhibit slight power oversteer on corner exit. Tight courses may require more oversteer, fast tracks understeer.

Items needed: Accurate tire pyrometer, tire gauge, notebook and tape measure. Suspension information books.

Note: This is a sample of the methods used to correct various handling problems. Books have been written on this subject. Not every correction will always work as expected. Stiffer front sway bars will, in many cases, decrease understeer because of reduced body roll and better camber control. The best rule is to change only one thing at a time and keep notes.

http://rogerkrausracing.com/overundr.html

[rbray]

Thanks for the link Fred. This will help a lot.