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Damper Tuning Over/Under Steer

General Car Setup Discussion

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Hello everyone, dampers don't particularly fall into alignment, however are often easily adjusted and can play a major part in setting up your car for a race.

Dampers are incredibly complex, but for this discussion it should be possible to keep things simple.

Dampers are velocity resistance. They control the speed at which body roll, or pitch occurs.

Springs are displacement resistance. They control the amount of body roll, or pitch.

The primary difference is that dampers will be doing things during transient conditions; corner entry and exit, while springs the entire duration of the corner. If for an example, we have a car that is perfectly setup for neutral steer, and set the front dampers comically stiff, they will resist body roll at the front. The car chassis will transfer however much force is necessary to move the dampers at the same speed, say 900 lbs for 1 in/s in the front, and 100 lbs for 1 in/s in the rear.

The result of this, is a understeering car on corner entry, once the dampers allow body roll to happen, a neutral steering car. The inverse is possible on the rear giving entry oversteer. Both front and rear stiffer will benefit things like slalom, with rapidly changing directions.

The downside of this is having notably higher transmissibility, how much a bump will move the body of the car and a large reason why higher end dampers are 4 way adjustable.

Most people I discuss this with seem resistant to changing dampers to control transient conditions. For reference, my car is a mr2 that's setup to have equally loaded outside tires at 1.3g ~950 lbs once in steady state. The interest is keeping the tires closer to equally loaded prior to the full weight transfer, and lateral load. Is there a component of this that I'm missing? Has anyone here spent a bit of time experimenting with this and willing to share their experiences?

Most of this is in regards to autocross, changes like this can be very detrimental to a street cars handling, and I change them back if driving to and from an event.

Basically, yes. You can also soften the front for less underteer, etc.

A little more work, but biasing the alignment for a little more toe-in on the front and toe-out on the rear will also aid direction change, for the tighter courses, but it will be more nervous on the road. If you can access the tie-rods you can do it at the track - mark them first, with a paint line or similar so you can get it accurately returned to the correct position and just keep a note of the turns you made from that in adjusting it.

50-50 balance is good for the same tyre size, etc, front and back, but if you're running wider rears, you may gain some benefit if you can more it rearwards, so the tread is more equally loaded?

Wider rear tires would certainly help, as I'd no longer be reliant on roll stiffness to equally load tires (if we were looking at weight*contact patch size) but would likely put me into a different class.

Toe changes could help with the initial turn in, but won't do much in regards to rate of weight transfer. The alternative options I can think of is a combination of stiffer rebound damping and some amount of anti dive, allowing trail braking to handle the longitudinal weight transfer, but that's far from a consistent method.

Another possibility is changing the leverage curve of the entire setup, so that the stiffness of the front is initially significantly stiffer than the rear, but decays, or progresses slower, keeping the 50/50 distribution on outside tires at/near the limit. This would absolutely put me in a different class.

With all that being said, toe and damper settings don't require a budget to adjust and test, so there's no reason not to try out a couple of different setups.

Is there any reason why I wouldn't just reach for the damper adjustment to handle transient weight transfer if I'm not concerned about surface conditions I'm running on?

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