Bump steer?
Thread Starter
|
Senior Member
Joined: Oct 2002
Posts: 185
Likes: 0
From: Knoxville, Tn
Bump steer?
I just lowered my 99 with the western chassis lowering control arms and a 1 inch drop coil for a total of about 3 inches.
I think I am getting what is called bump steer but I want to make sure I know exactly what bump steer is.
Now when I go over bumps my steering wheel has some movement in it, it kind of like jiggles in my hands.
I have talked to a few people and some say this is the b.steer because of the angle of the tie rods and when the suspension flexes that the tie rods actually pull the wheels inward giving you the movement in the steering wheel.
Can somebody set me straight about this.
Also I know there aren't any b. steer kits available but is there any fixes at all. Wouls a steering stablizer help out at all.
Thanks
Chris
I think I am getting what is called bump steer but I want to make sure I know exactly what bump steer is.
Now when I go over bumps my steering wheel has some movement in it, it kind of like jiggles in my hands.
I have talked to a few people and some say this is the b.steer because of the angle of the tie rods and when the suspension flexes that the tie rods actually pull the wheels inward giving you the movement in the steering wheel.
Can somebody set me straight about this.
Also I know there aren't any b. steer kits available but is there any fixes at all. Wouls a steering stablizer help out at all.
Thanks
Chris
Senior Member
Joined: May 2002
Posts: 4,928
Likes: 1
From: The People's Republic of Los Angeles
All of the information above is correct. Ayrton is working on a solution now. There are also a couple of companies which claim to be working on a solution. I have no more info.
Senior Member
Joined: Sep 2002
Posts: 1,703
Likes: 0
From: Atlanta
Working out the "kinks" now...
Here is an explanation of bumpsteer from Steeda...
What is Bumpsteer? Is it a mysterious term that racers use to excuse their ill handling racecar? The technical explanation is a change in toe caused by suspension travel or an unwanted steering input caused by such a toe change. If you already understand that explanation you probably have fixed any bumpsteer you may have had. If not, imagine driving through a parking lot. The right side of the axle has a speed bump and you try to go around. You miss, the right front tire hits the speed bump and your car steers itself to the right even though the steering wheel did not move. Now imagine you are going to turn a corner and you choose to go through the corner at a very high speed. As you approach the corner you turn the steering wheel in and the car begins to roll. As you have the steering wheel set in position to carry you through the turn, the car continues as the suspension compresses on the loaded side of the car. The front wheel turns in more than you had originally intended, causing the car to turn more sharply. You correct the steering wheel in the opposite direction pulling the car out of its roll and you miss your intended path through the turn. Both of these examples illustrate bumpsteer and are undesirable when maximizing the handling performance of your Mustang. Two things happened when the vehicle crossed the speed bump or when the vehicle entered the turn. First, there was suspension travel, the wheel, spindle, a-arm and other components moved upward as it crossed over the speed bump or when the vehicle began to roll into the turn. Second, this suspension travel caused the wheel to change direction even though the driver did not turn the steering wheel. This change in wheel direction made the vehicle turn in a direction not intended by the driver.
When the suspension travels up and down, the wheel moves up and down in an arc or half circle around a pivot point. This pivot point is not a physical location or suspension part but is an imaginary point on the chassis, similar to a vehicle's center of gravity. The distance from the pivot point to the wheel and spindle is equal at all points in the wheel's range of vertical movement. The tie rod and steering rack must be positioned so that as the wheel moves up and down, the tie rod follows an arc which is parallel to the arc followed by the spindle. If the steering rack or tie rod is not positioned correctly, the distance between the steering rack and wheel may differ from the distance between the pivot points to the wheel at different suspension heights. When this occurs the steering rack will push or pull the spindle as the suspension moves up or down thereby turning the wheel and causing a change in toe angle.
The direction the front wheels are pointed is called toe angle. When both wheels are pointed parallel there is 0 degrees toe. When the fronts of the wheels are pointed inward, there would be positive degree toe or what is called toe in. When the fronts of the wheels are pointed outward there is negative degree toe or what is called toe out.
Here is an explanation of bumpsteer from Steeda...
What is Bumpsteer? Is it a mysterious term that racers use to excuse their ill handling racecar? The technical explanation is a change in toe caused by suspension travel or an unwanted steering input caused by such a toe change. If you already understand that explanation you probably have fixed any bumpsteer you may have had. If not, imagine driving through a parking lot. The right side of the axle has a speed bump and you try to go around. You miss, the right front tire hits the speed bump and your car steers itself to the right even though the steering wheel did not move. Now imagine you are going to turn a corner and you choose to go through the corner at a very high speed. As you approach the corner you turn the steering wheel in and the car begins to roll. As you have the steering wheel set in position to carry you through the turn, the car continues as the suspension compresses on the loaded side of the car. The front wheel turns in more than you had originally intended, causing the car to turn more sharply. You correct the steering wheel in the opposite direction pulling the car out of its roll and you miss your intended path through the turn. Both of these examples illustrate bumpsteer and are undesirable when maximizing the handling performance of your Mustang. Two things happened when the vehicle crossed the speed bump or when the vehicle entered the turn. First, there was suspension travel, the wheel, spindle, a-arm and other components moved upward as it crossed over the speed bump or when the vehicle began to roll into the turn. Second, this suspension travel caused the wheel to change direction even though the driver did not turn the steering wheel. This change in wheel direction made the vehicle turn in a direction not intended by the driver.
When the suspension travels up and down, the wheel moves up and down in an arc or half circle around a pivot point. This pivot point is not a physical location or suspension part but is an imaginary point on the chassis, similar to a vehicle's center of gravity. The distance from the pivot point to the wheel and spindle is equal at all points in the wheel's range of vertical movement. The tie rod and steering rack must be positioned so that as the wheel moves up and down, the tie rod follows an arc which is parallel to the arc followed by the spindle. If the steering rack or tie rod is not positioned correctly, the distance between the steering rack and wheel may differ from the distance between the pivot points to the wheel at different suspension heights. When this occurs the steering rack will push or pull the spindle as the suspension moves up or down thereby turning the wheel and causing a change in toe angle.
The direction the front wheels are pointed is called toe angle. When both wheels are pointed parallel there is 0 degrees toe. When the fronts of the wheels are pointed inward, there would be positive degree toe or what is called toe in. When the fronts of the wheels are pointed outward there is negative degree toe or what is called toe out.
