Bump steer
- Thread starter droptail
- Start date
Azmotorhead
Full Access Member
Yeah these things have wicked bump steer.
Check with Global West Suspension I know they have eliminators for other vehicles.
I'm too poor to even go world wide window shopping anymore.
Check with Global West Suspension I know they have eliminators for other vehicles.
I'm too poor to even go world wide window shopping anymore.
DrPierceMD
Full Access Member
Azmotorhead said:
Pardon the ignorance but what is Bump Steer?
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Didn't you see City Slickers?? :dontknow:DrPierceMD said:
DrPierceMD said:
Here you go.
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.
Here is the site if you want to read more.
http://www.racerpartswholesale.com/longtech3.htm
DrPierceMD
Full Access Member
Silverback said:
Thanks Pop:rock:
DrPierceMD said:
I'm here to serve.
droptail hollar at me saturday and i'll
post pics of mine
its relativly easy to do
i'm above milwaukee riht now but should be home later tonight
post pics of mine
its relativly easy to do
i'm above milwaukee riht now but should be home later tonight
Thanks for the good article/reference Silverback.
This bumpsteer is new to me and I'm trying to learn it. Now that I am runing road coarses, I want my suspension right. Actually, my new arrangement doesn't have me darting like the stock setup did, which I believe was not enough bumper stop clearance. I noticed that my steering link is not parallel to the ground which I thought created bump steer, but I am learning its more complicated than that.
This bumpsteer is new to me and I'm trying to learn it. Now that I am runing road coarses, I want my suspension right. Actually, my new arrangement doesn't have me darting like the stock setup did, which I believe was not enough bumper stop clearance. I noticed that my steering link is not parallel to the ground which I thought created bump steer, but I am learning its more complicated than that.
droptail said:
Suspension geommetry is very complicated. Kind of makes you appreciate those damn engineers a little more doesn't it.
I'll see if I can get yo some pics today
walenator
Full Access Member
I've seen a kit for Chevy's that flips the tie rod thread end up then drill out and install a cone at the spindle mount. This puts the tie rod level.
sorry had an appointment I forgot about with some kids, couldnt miss it, get them tommorrow
Here's some , its real easy , just get a clevis joint, tire rod adjuster, so on.
I took the easy way out, bought a kit for a mustang, rethreaded the sleve to work with our tie rods .
I took the easy way out, bought a kit for a mustang, rethreaded the sleve to work with our tie rods .
walenator
Full Access Member
Looks like that will do the job. The one for Chevy trucks is from DJM. They suffer with the same problem when lowering.
Its been discussed a thousand or more times, I bought a kit for a mustang, remachined the tube and got it to work, I really dont see how most are driving the lowered ones iwthout a bumpsteer kit, even thought about making them myself for yall
silversrt
Full Access Member
Stinker said:
Ill take a set!
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