Oversteer / Understeer Corrections
07-16-2007, 11:52 AM
#1
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Oversteer / Understeer Corrections
OVERSTEER / UNDERSTEER CORRECTIONS
Understeer Corrections
Push, plowing, front tires slide out first.
Usually slight understeer is safer.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage. .
High Speed. Increase front wing downforce.
Too much front brake.
Vehicle is TWITCHY at limit and hard to keep
Lower front and rear tire pressures slightly.
Suspension may be too stiff.
Shocks may be set too firm.
Tires may be old or hard.
Vehicle may not have enough suspension travel.
Vehicle may have a toe problem front or rear.
Increase negative camber front and rear if
possible.
Oversteer Corrections.
Loose, rear tires slide out first.
Oversteer can be dangerous, especially at high
speeds.
Lower front tire pressure.
Raise rear tire pressure.
Stiffen front shocks.
Soften rear shocks.
Raise front end.
Lower rear end.
Reduce rear track.
Install taller front tires.
Install shorter rear tires.
Install narrower front tires.
Install wider rear tires.
Stiffen front sway bar.
Soften rear sway bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Reduce positive caster.
Stiffen front springs.
Soften rear springs.
May need more rear suspension travel.
Install wider rear wheels.
Use harder front compound if possible.
Use softer rear compound if possible.
Add weight to front of vehicle.
Remove weight from rear of vehicle.
Driver may be going in too deep.
Driver may be getting on the throttle to early.
High Speed. Increase rear wing downforce.
Too much rear brake.
Vehicle slides and is easy to drive at limit but
ahead of in the steering department. does not corner to full potential.
. Raise front and rear tire pressures slightly.
Suspension may be too soft.
Shocks may be too soft.
Roll centers may be too high.
Lower vehicle.
Tires may be too hard.
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
Understeer Corrections
Push, plowing, front tires slide out first.
Usually slight understeer is safer.
Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks. Stiffen Bump.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.
Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.
Increase positive caster.
Soften front springs.
Stiffen rear springs.
May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
Drive a different line.
Use weight transfer to your advantage. .
High Speed. Increase front wing downforce.
Too much front brake.
Vehicle is TWITCHY at limit and hard to keep
Lower front and rear tire pressures slightly.
Suspension may be too stiff.
Shocks may be set too firm.
Tires may be old or hard.
Vehicle may not have enough suspension travel.
Vehicle may have a toe problem front or rear.
Increase negative camber front and rear if
possible.
Oversteer Corrections.
Loose, rear tires slide out first.
Oversteer can be dangerous, especially at high
speeds.
Lower front tire pressure.
Raise rear tire pressure.
Stiffen front shocks.
Soften rear shocks.
Raise front end.
Lower rear end.
Reduce rear track.
Install taller front tires.
Install shorter rear tires.
Install narrower front tires.
Install wider rear tires.
Stiffen front sway bar.
Soften rear sway bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Reduce positive caster.
Stiffen front springs.
Soften rear springs.
May need more rear suspension travel.
Install wider rear wheels.
Use harder front compound if possible.
Use softer rear compound if possible.
Add weight to front of vehicle.
Remove weight from rear of vehicle.
Driver may be going in too deep.
Driver may be getting on the throttle to early.
High Speed. Increase rear wing downforce.
Too much rear brake.
Vehicle slides and is easy to drive at limit but
ahead of in the steering department. does not corner to full potential.
. Raise front and rear tire pressures slightly.
Suspension may be too soft.
Shocks may be too soft.
Roll centers may be too high.
Lower vehicle.
Tires may be too hard.
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
Last edited by AU N EGL; 07-16-2007 at 12:05 PM.
07-16-2007, 01:16 PM
#3
Melting Slicks
Your tire pressure recommendations may or may not be accurate depending on what tire it is. For most of the street tires I've used, you are correct. Adding pressure will help keep the tire from rolling over so much so it has more grip. However, for many of the racing tires, dropping the pressure actually adds grip. The sidewalls are already so stiff that lowering the pressure gives a better contact patch and "softens" the tire giving it more grip.
The only way to know for sure is to try it and see.
The only way to know for sure is to try it and see.
07-16-2007, 02:33 PM
#4
Former Vendor
Your tire pressure recommendations may or may not be accurate depending on what tire it is. For most of the street tires I've used, you are correct. Adding pressure will help keep the tire from rolling over so much so it has more grip. However, for many of the racing tires, dropping the pressure actually adds grip. The sidewalls are already so stiff that lowering the pressure gives a better contact patch and "softens" the tire giving it more grip.
The only way to know for sure is to try it and see.
The only way to know for sure is to try it and see.
.Randy
07-17-2007, 10:05 AM
#8
Le Mans Master
Thanks Tom....handy info to us novices! 
I would say my '06 handles fairly neutral, certainly does not understeer (F55 with Z51 bars and tires) but I'm seeing some very wierd tire wear on the fronts....basically there are 5 rows of tread pattern with the 2 widest sections being the outside of the tire on the car, the 3 & 4 rows in are really beat up and wearing in what looks like a V shape when looking down the tire profile. Any comments or suggestions?
I would say my '06 handles fairly neutral, certainly does not understeer (F55 with Z51 bars and tires) but I'm seeing some very wierd tire wear on the fronts....basically there are 5 rows of tread pattern with the 2 widest sections being the outside of the tire on the car, the 3 & 4 rows in are really beat up and wearing in what looks like a V shape when looking down the tire profile. Any comments or suggestions?
07-17-2007, 12:52 PM
#10
Tech Contributor
Member Since: Jun 2004
Location: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
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While most of the suggested changes are sensible corrections (wider tires, wider track, less weight, etc), I'll confess no shortage of bewilderment with some of the remedies. I have never understood the philosophy of trying to induce neutral handling by degrading the half of the car that is working better (i.e.: reducing oversteer by installing smaller front tires, setting tire pressure to non optimal levels, or adding weight to the front of the vehicle). Reducing the size of your tires obviously reduces your traction (assuming same compound, etc). This is not a bright idea when trying to gain position by outbraking your competition, or just trying to avoid a spinning car ahead of you. Non-optimal tire pressure just means you're running on a portion of the tread. Not good for tire wear or traction (remember that spinning car in front of you). Adding weight is always a negative, whether braking, accelerating, or cornering (swerving). I would honestly like to see some testing comparing a lightweight poorly balanced car versus a heavier balanced car. Other than in extreme cases I would put my money on the lighter car.
07-17-2007, 05:28 PM
#12
Burning Brakes
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07-19-2007, 07:44 AM
#15
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Your tire pressure recommendations may or may not be accurate depending on what tire it is. For most of the street tires I've used, you are correct. Adding pressure will help keep the tire from rolling over so much so it has more grip. However, for many of the racing tires, dropping the pressure actually adds grip. The sidewalls are already so stiff that lowering the pressure gives a better contact patch and "softens" the tire giving it more grip.
The only way to know for sure is to try it and see.
The only way to know for sure is to try it and see.
08-01-2007, 12:32 AM
#19
Tech Contributor
AU N EGL,
All good basic info - and thanks!
I would just like to add that more advanced racers go a step further by analyzing the vehicle behavior at various stages IN EACH CORNER. For example,
"Are we getting understeer on corner entry, at the apex, on track-out, during all three?"
"Is this behavior (say understeer on corner entry) the same in high-speed turns as in low-speed corners?"
"Is this behavior always following HEAVY braking?"
Here is the race engineer's "Black Art" - "fixing" the car which generally understeers on corner entry, oversteers on track-out; but does the reverse in very fast sweepers.
A clue? As 69427 so accurately points out, adding weight will NOT help!
Ed LoPresti
All good basic info - and thanks!
I would just like to add that more advanced racers go a step further by analyzing the vehicle behavior at various stages IN EACH CORNER. For example,
"Are we getting understeer on corner entry, at the apex, on track-out, during all three?"
"Is this behavior (say understeer on corner entry) the same in high-speed turns as in low-speed corners?"
"Is this behavior always following HEAVY braking?"
Here is the race engineer's "Black Art" - "fixing" the car which generally understeers on corner entry, oversteers on track-out; but does the reverse in very fast sweepers.
A clue? As 69427 so accurately points out, adding weight will NOT help!
Ed LoPresti
08-01-2007, 06:18 AM
#20
Team Owner
