suspension
Burning Brakes
Joined: Nov 2004
Posts: 988
Likes: 4
From: Livermore CA
It's Scrub Steer
Scrub steer is the amount of offset from your steering axis to your wheel center. With zero scrub steer the steering axis will intersect the wheel center at the ground interface. Zero scrub steer will feel very neutral and unaffected by bumbs, dips, rocks on the road, uneven surfaces, low traction conditions. You want zero scrub steer on a Bus. A corvette has a lot of positive scrub steer, the steering axis intersects the ground surface several inches before (inside) the wheel center. Basically the wheel center is cantelevered out from the steering axis. What positive scrub steer produces is a tactile feedback system vital to controlling a sports car. It sends a force back through the steering wheel when either front wheel runs into something irregular (as described above). This feedback enables the driver to know what each front wheel is doing traction, bump and road angle wise. With this information the driver can react properly controlling the car in difficult situations. The negative side of positive scrub steer is the reaction of the car to dips, irregular raod surfaces, ect. This is what you are feeling on your car. If you are not actively hanging on to your wheel the feedback force can cause the car to veer. Tire selection can increase or decrease some of the feedback but not eliminate it. Goodyear Supercars are amplifiers of scrub steer, hence autocrossers like them. Michelin Pilot Sport IIs decrease scrub steer endearing them to more relaxing highway and daily driving. A ZO6 Corvette demands some driver interaction and sacrifice but always pays dividends.
6th Gear
Joined: Dec 2005
Posts: 6
Likes: 0
Bumb Steer
I got rid of the monoleaf by putting in the G-Force Suspension coil-over kit. I lowered the overall height by an inch. The handling is better and there is less body roll. But the reason I got the kit in the first place was to eliminate this problem. I am very pleased with the kit.
Big-T
Big-T
Race Director
Joined: Jul 2005
Posts: 11,308
Likes: 1
From: The Beautiful Greater Bay Area California
Originally Posted by Techfan
Correct. This kit is to correct the geometry. Tires hopping across the pavement is another. And by the way I agree the real problem that we feel is the tires hopping across the pavement. The tire will absorb most of the Geometry induced bump steer until you lower the car and change its geometry. This is why a good front end shop will make sure the car is at proper ride height before adjusting anything. I adjust bump steer on Race cars all the time and even use it to tune the suspension to some degree.
http://www.ioportracing.com/instructions/bumpsteer.htm
http://www.irvansmith.com/tech9.htm
http://www.ioportracing.com/instructions/bumpsteer.htm
http://www.irvansmith.com/tech9.htm
Great links. Thanks for sharing, guys! 
Melting Slicks
Joined: Jul 2004
Posts: 2,340
Likes: 35
From: Folsom Lake CA
Originally Posted by Big-T
I got rid of the monoleaf by putting in the G-Force Suspension coil-over kit. I lowered the overall height by an inch. The handling is better and there is less body roll. But the reason I got the kit in the first place was to eliminate this problem. I am very pleased with the kit.
Big-T
Big-T
