Reducing Understeer - RC Handling Guides

Understeer, also known as push, occurs when you turn the car's front wheels, but the car doesn't follow -- the front wheels slip and the car just continues going in the same direction, usually forcing you to slow down to put weight on the front wheels in order to help them grip. Understeer, naturally, is the opposite of oversteer.

In this video watch the leader in the green car as their car pushes in the last turn before the straight, letting the 2nd place car make up some time. You can see the front wheels turned to the right while the car continues to go straight:

‍

How to Reduce Understeer / Push

Reducing understeer generally

Most impact

1. Anti-roll bar: thinner in front
2. Ride height: lower in front than in rear
3. Tires: softer compound in front / more additive / more additive time
4. Weight distribution: more in front
5. Shock springs: softer in front, harder in rear
6. Shock damping: less damping in front, more in rear. Pan car: less damping in side shocks/tubes.
7. F1: more downforce in front wing

Medium impact

1. Camber: more
2. Diff fluid: thicker in rear
3. Roll center: higher rear, lower front
4. Droop: more in rear
5. Toe: less rear toe-in
6. Steering throw: more

Less impact

1. Bump steer: links more level
2. Chassis flex: more
3. Camber gain: more
4. Track width: narrow in front

‍

During corner entry / off-power

Most impact

• Anti-roll bar: lighter front / stiffer rear
• Weight distribution: more weight in front
• Tires: softer front compound / harder rear
• Diff fluid (4WD): lighter front & center, heavier rear
• Roll center: lower front / higher rear
• Camber link: inner stud lower
• Shock springs: lighter front / stiffer rear
• Shock damping: lighter front / heavier rear
• Ackermann: increase
• Reactive caster (pan car): more

Medium impact

• Shock angle: outward at front tower / inward at rear tower
• Droop (R): more
• Ackermann: more
• Rear axle: use differential instead of solid axle (on-road)
• Front axle: use one-way or differential instead of solid axle (on-road)
• Caster (F): less
• Ride height: lower front / higher rear
• Toe: more front toe-out, less rear toe-in
• Wheelbase: shorter

Less impact

• Camber: more front / less rear
• Anti-squat: more
• Kick-up: less

Mid-corner

Most impact

• Anti-roll bar: lighter front / stiffer rear
• Tires: softer front compound / harder rear
• Roll center: lower front / higher rear
• Shock springs: lighter front / stiffer rear

Medium impact

• Shock damping: lighter front / heavier rear
• Shock angle: inward at front tower / outward at rear tower
• Reactive caster (pan car): less
• Side links (pan car): inward at front
• Droop (rear): more
• Rear axle: use differential instead of solid axle (on-road)
• Front axle: use solid axle instead of one-way or differential (on-road)
• Caster (front): more
• Ride height: lower front / higher rear
• Wheelbase: shorter

Less impact

• Toe: more front toe-out, less rear toe-in
• Camber: more front / less rear
• Anti-squat: more
• Kick-up: less

During corner exit

Most impact

• Anti-roll bar: lighter front / stiffer rear
• Tires: harder rear compound / softer front
• Roll center: lower front / higher rear
• Shock damping: heavier rear / lighter front
• Caster (F): more
• Diff fluid (4WD): heavier front & center, lighter rear
• Transmission layout (2WD off-road): laydown or layback / 3-gear
• Droop (pan car): more
• Ackermann: more
• Toe: less front toe-out
• Center shock angle (pan car): flatter

Medium impact

• Shock springs: lighter front / stiffer rear
• Shock angle: outward at rear tower / inward at front tower
• Toe: less rear toe-in
• Rear axle: use solid axle instead of differential (on-road)
• Front axle: use one-way or differential instead of solid axle (on-road)
• Ride height: lower front / higher rear
• Wheelbase: shorter

Less impact

• Camber: less rear / more front
• Anti-squat: more
• Kick-up: more

At high speed

• Body / body mounting (on-road): reduce rear downforce, increase front
• Rear wing: less downforce (reduce angle / move forward / move down)
• Front wing (off-road): use front wing

‍