Suspension Settings

[Mopar Boy]

After reading a coupls of threads here and looking threw ACR adjustment specs, I have come many terms I do not fully understand.

Some of these are toe, bump, rebound, camber, damper, etc.

Would someone be able to give me a quick description on common suspension terms and what they mean?

Thanks!

Robert

 

[RTTTTed]

I'll start off with a couple,

Toe = as in "toe-in" meaning the wheel alignemnt front of the tires pointing towards each other. Toe-in meaning tires pointed towards each other and toe-out meaning tires pointing away from each other. The toe controls darting, tire wear, some vibrations, and steering quickness etc.

Camber is the wheel rebounding (travelling upwards over a bump) on an angle. The center of the wheel moves either forward of backwards as it moves up. When the wheel/tire moves too far back the steering stability is great for high speed but adds to the 'weight' of the turning ability.

If the camber is straight up and down then low speed turning feels very light and responsive, but causes stability problems at higher speeds.

Ted

 

[Ratical2]

To add to Ted's comments,
Bump damper and Rebound are in reference to the shock setup.
Damper = rate of shock compression
Rebound = rate of shock extension

There are alot of resources to choose from on the web.
Here are some links from a quick google search that might help you.

Toe, Camber, Caster
Caster, Camber, Toe

Suspension types
Car Bibles : The Car Suspension Bible page 1 of 2

Race car setup
RACELINE CENTRAL: Ultimate Racing Car Chassis Setup Guide and Tutorial

Hope this helps!

Ken Ratica

 

[TexasPettey]

Here's what I've learned from talking with folks and reading about what the settings do for you. This is in the light of road course, not drag strip. Keep in mind, I'm no expert.

TOE: Toe out will make the car more responsive to steering inputs. The car will be 'easier' to turn at speed. The downside is that it will 'wander' through ruts and grooves in the pavement.

CAMBER: More negative camber will give you better cornering traction. As the car and tire roll during cornering, the tire will be flatter. The downside is that you'll wear the tire unevenly on straights and you'll have less traction for braking and accceleration.

COMPRESSION: Stiffer compression on the shocks will keep the car & tire more upright and 'connected' during quick action. It will help the springs not oscillate as much when you enter a corner. The downside is that you'll feel everything and bumps/uneven areas will have more impact on the car's stability. The suspension won't be able to 'absorb' those little impacts.

REBOUND: Stiffer rebound will keep the car from oscillating when exiting a turn. The car needs to adjust back to upright from a roll quickly, but not without going past centerline. Rebound is a bit tricky, because you want to balance it with compression. I have heard that it is best to have a little less rebound than compression to get the car upright as fast as possible without oscillation in the springs.

 

[Mopar Boy]

Thanks guys! That is awesome! I can see I have ALOT of learning to do before I ever even think about touching my suspension adjusting tool that is in my glove box!

Thanks!

Robert

 

[mjorgensen Woodhouse]

Quote: COMPRESSION: Stiffer compression on the shocks will keep the car & tire more upright and 'connected' during quick action. It will help the springs not oscillate as much when you enter a corner. The downside is that you'll feel everything and bumps/uneven areas will have more impact on the car's stability. The suspension won't be able to 'absorb' those little impacts.

Compression should never be used to replace lack of spring rate though. The over use of this setting will overload the tire sooner and induce "loss" of traction. The spring rate is better equipped to apply downward forces. Rebound stiffness is the same it needs to be well mated to the springs chosen rather than the shock doing more than the spring.

 

[99 R/T 10]

Anybody have a recommended setting for the alignment and shock compression/rebound rate for the track? Also, could you use the same settings on the street without too much additional wear on the tires?

 

[TexasPettey]

Compression should never be used to replace lack of spring rate though. The over use of this setting will overload the tire sooner and induce "loss" of traction. The spring rate is better equipped to apply downward forces. Rebound stiffness is the same it needs to be well mated to the springs chosen rather than the shock doing more than the spring.

Thanks. Would you say that the general rule is that a stiffer spring allows for a stiffer setting on comp/rebound? That is, the job of the shock is to get the car to a 'settled' position on the spring as quickly as possible. With a softer spring, more travel is required, thus the shock has to move more to get to the settled position. Suspension settings are complex, and I'm always looking for simple mental pictures.

 

[TexasPettey]

Also, could you use the same settings on the street without too much additional wear on the tires?

I wouldn't expect that the compression/rebound would have much effect on tire wear. There would be more impact felt in the structure, so maybe more bushing wear. However, the tires should be unaffected. Toe & Camber would be the major contributors.

 

[mjorgensen Woodhouse]

Thanks. Would you say that the general rule is that a stiffer spring allows for a stiffer setting on comp/rebound? That is, the job of the shock is to get the car to a 'settled' position on the spring as quickly as possible. With a softer spring, more travel is required, thus the shock has to move more to get to the settled position. Suspension settings are complex, and I'm always looking for simple mental pictures.

The shock settings should be just enough to "control" the rate of the springs. From there you can make "small" adjustments to change the turn in or corner exit. You should always try to not over use the settings for the wrong rates but if you do not have a choice it is better to compromise some body roll etc... before over tuning compression and rebound settings. This will also help the valving in the shock last a little longer.

If you use the shock instead of the spring the movement can not react to the surface as good as the spring and you will loose traction at a less linear rate, the car will be more random handling and give you less confidence.