Bump Steer

[coralcoupe1993]

What is it? How doest it work? When would one need it?

[wick]

I am supposed to need it with all my front end stuff done. I dont see where it would do any good though. I have not noticed any problems yet with the way it steers.

[One Sweet Day]

:D

Bump Steer

A. Definition
Bump Steer is when your wheels steer themselves without input from the steering wheel. The undesirable steering is caused by bumps in the track interacting with improper length or angle of your suspension and steering linkages.
Most car builders design their cars so that the effects of bump steer are minimal. However, you must still take care to bolt on your suspension carefully so as not to create unwanted bump steer. Make sure that you are always using the correct components for a particular car. Bump steer must be designed into the car and cannot be adjusted out if improper parts are used or if pivot points are moved without considering bump steer design principles.
In order to accomplish zero bump the tie rod must fall between an imaginary line that runs from the upper ball joint through the lower ball joint and an imaginary line that runs through the upper a-arm pivot and the lower control arm pivot. In addition, the centerline of the tie rod must intersect with the instant center created by the upper a-arm and the lower control arm (See diagram below).
The instant center is an imaginary point that is created by drawing a line from the upper a-arm ball joint through the a-arm pivot where it is intersected by an imaginary line that extends from the lower ball joint through the inner control arm pivot. Where the two imaginary lines intersect is the instant center.
Sounds complicated? Really it is very simple. To achieve zero bump the front end must be designed correctly. The tie rod must travel on the same arc as the suspension when the car goes through travel. Simply matching lengths and arcs to prevent any unwanted steering of the front tires.
To exaggerate, if the tie rod were only 10" long and the suspension were 20" long then when the suspension traveled the tie rod angle would shorten much quicker than the suspension arc. In this scenario the tie rod would shorten much quicker through travel than the suspension and the car would toe in drastically over bumps. The shorter arc of the tie rod would pull on the spindle and toe it in through travel.
Bump Simplified - When designing a car, if the centerline of the outer tie rod lines up with the centerline of the lower ball joint, and the inter tie rod lines up with the lower pivot point then the length and angle of the tie rod and suspension will be the same resulting in zero bump. Most car builders design their cars in this fashion.

$355.50 160-045 Comptech Front Bumb Steer Kit For 91-03 NSX

[coralcoupe1993]

I am supposed to need it with all my front end stuff done. I dont see where it would do any good though. I have not noticed any problems yet with the way it steers.

I dont have them in the notch (front SLAMMED) but TA383 just told me about them.....Makes sense.

[One Sweet Day]

I dont have them in the notch (front SLAMMED) but TA383 just told me about them.....Makes sense.

383taman?:o

[wick]

I would not worry about it.

[383taman]

:D

Bump Steer

A. Definition
Bump Steer is when your wheels steer themselves without input from the steering wheel. The undesirable steering is caused by bumps in the track interacting with improper length or angle of your suspension and steering linkages.
Most car builders design their cars so that the effects of bump steer are minimal. However, you must still take care to bolt on your suspension carefully so as not to create unwanted bump steer. Make sure that you are always using the correct components for a particular car. Bump steer must be designed into the car and cannot be adjusted out if improper parts are used or if pivot points are moved without considering bump steer design principles.
In order to accomplish zero bump the tie rod must fall between an imaginary line that runs from the upper ball joint through the lower ball joint and an imaginary line that runs through the upper a-arm pivot and the lower control arm pivot. In addition, the centerline of the tie rod must intersect with the instant center created by the upper a-arm and the lower control arm (See diagram below).
The instant center is an imaginary point that is created by drawing a line from the upper a-arm ball joint through the a-arm pivot where it is intersected by an imaginary line that extends from the lower ball joint through the inner control arm pivot. Where the two imaginary lines intersect is the instant center.
Sounds complicated? Really it is very simple. To achieve zero bump the front end must be designed correctly. The tie rod must travel on the same arc as the suspension when the car goes through travel. Simply matching lengths and arcs to prevent any unwanted steering of the front tires.
To exaggerate, if the tie rod were only 10" long and the suspension were 20" long then when the suspension traveled the tie rod angle would shorten much quicker than the suspension arc. In this scenario the tie rod would shorten much quicker through travel than the suspension and the car would toe in drastically over bumps. The shorter arc of the tie rod would pull on the spindle and toe it in through travel.
Bump Simplified - When designing a car, if the centerline of the outer tie rod lines up with the centerline of the lower ball joint, and the inter tie rod lines up with the lower pivot point then the length and angle of the tie rod and suspension will be the same resulting in zero bump. Most car builders design their cars in this fashion.

http://addictiveracing.com/catalog/p...pg&w=184&h=120 $355.50 160-045 Comptech Front Bumb Steer Kit For 91-03 NSX

Good Job

[One Sweet Day]

Good Job

I didn't write it, just found it! lol ;) :D

[coralcoupe1993]

I would not worry about it.

Maybe I should sell my 2" lowering springs and get 1.5". The bottom of the fender is like 4" from the damn top of the tire though.

[Pure Stock]

Maybe I should sell my 2" lowering springs and get 1.5". The bottom of the fender is like 4" from the damn top of the tire though.

I remember my 94 GT. That thing had a lift kit installed from Ford in it. Hell, they didn't charge me for it though.

[DING]

A bump steer kit will improve your times in the quarter. You will notice improved steering response and your car will not "walk around" in the groove.

You will not pick up tenths, but you should feel a difference.

[coralcoupe1993]

I remember my 94 GT. That thing had a lift kit installed from Ford in it. Hell, they didn't charge me for it though.

Yea, it is really high.