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Bump steer adjustment without a bump steer gauge?

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Bump steer adjustment without a bump steer gauge?

Old 08-21-16, 08:21 PM
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Bump steer adjustment without a bump steer gauge?

Is there a way too measure and adjust bump steer without using a bump steer gauge?

I have three-position adjustable tie rods (currently in the middle position since that's what it originally was set to). I'm wondering if I really need to build/buy a bump steer gauge, or can I drive the car over single-wheel bumps and see which way it goes.

The FD has knuckles that point forward, so lowering the front should cause more toe-in bump steer, mean you need more shim. Or are there too many factors (road surface, tire wear?) that keep you from doing it by feel?

In theory, couldn't you just jack up the front of the car, take the wheels off, lower it to ride height on some blocks, disconnect the sway bar, and then watch the steering wheel move as you jack one corner up and down?

Or is that not precise enough of a measurement for the purpose of bump steer adjustment?]



As for rear bump (roll) steer, I don't suppose it's really worth the cost and effort unless you've slammed the rear?

Last edited by Valkyrie; 08-21-16 at 09:23 PM.
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Old 08-21-16, 09:29 PM
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Your way of watching the wheel won't tell you anything. Bump steer happens in the steering geometry, not in the wheel.

Remove the front springs and use a laser pointer on the hub pointed at the wall in front of the car. Just draw the pattern with a pencil as you cycle the suspension. Adjust as needed from there.

If the tie rod is parallel to the pivot points of the lower control arm you'll be close to zero bump steer.
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Old 08-22-16, 08:36 PM
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You sure?... You're supposed to keep the wheel from moving when using a bump steer gauge. So as long as you're lifting one wheel at a time, anything moving the steering arm should move the wheel if it's not locked in place.
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Old 08-24-16, 09:57 AM
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Originally Posted by Valkyrie View Post
You sure?... You're supposed to keep the wheel from moving when using a bump steer gauge. So as long as you're lifting one wheel at a time, anything moving the steering arm should move the wheel if it's not locked in place.
You do not measure bump steer from the steering wheel. You are measuring toe change through the suspension travel. You don't want the steering wheel to move while setting bump steer for the same reason you don't want it to move when you align the car. The measurements are useless when the steering wheel is not locked and allowed to move around.

When driving the car you feel bump steer as extra steering over a bump or jounce when you have not applied any more steering input.
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Old 08-25-16, 12:34 AM
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Simplified:
Bump steer is extra steering that resulted from compression of the suspension, not turning the steering wheel.
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Old 09-02-16, 10:19 AM
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Put a jack stand under both spindles, so they stay at constant height. Either mount a laser to the spindle, or mount a mirror to the spindle and put the laser shining on the mirror. Make a mark on the wall where the laser beam hits. Now get a floor jack located under your cross member. Raise and lower the jack slowly, and watch the laser beam where it hits the wall. If the beam moves, then you have bump steer. If the beam stays in the same spot as the chassis goes up and down, then you do not have bump steer.
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