Bump Steer, New problem

Phillip Moores

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Caution, long story.
I had a car changed from beam to A-arm. I bent the rack 2nd time out testing this setup. I brought the car back to my friends shop. He changed it from rear steer to front steer & beefed up the rack system. It was set up with dual opposed steering dampers valved 80/20 when it was rear steer, but he didn't put the dampers back on with the front steer setup. The car has awful bump steer now.
Anyone in the Antelope Valley area know what the hell the are doing and willing to take a look at this?? Any recommendations on a steering/suspension shop?
 

partybarge_pilot

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Pictures of the current set-up? The spreader bar on the rack is probably the wrong spread along with the steering arms being off.
 

Phillip Moores

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IMG_20190602_122658.jpg
 

partybarge_pilot

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Ok, first you need different front rims. They have way to much offset making your scrub radius horrible. This just serves to amplify your bumpsteer issues. Second, your rack isn't wide enough. Your inner tie rod should be about where it is in the second pic with the wheel straight. The "steering arm" on the spindle looks a little high also.
 

Phillip Moores

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Soooo, I may be confused. What is bump steer... The problem I am getting, is any bumps the front end hits get translated to the steering wheel. Is this bump steer? And pardon the newb ignorance, but for scrub radius, is there an optimum offset, is there a way to calculate it, or less is simply better??

Thanks for the help!
 

partybarge_pilot

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Bumpsteer is when you cycle the suspension and the tires moves in and out. It should stay in the same position as it cycles or it will make the car handle funny and give you weird feedback.

What you are describing is mainly the offset of the wheel.

Scrub radius, Draw a line through the pivot points on the spindle. Where this imaginary line hits the ground should be about center of your tire. Right now the center of your tire is several inches past this point. This gives it a lot of leverage and makes little bumps feel like large bumps at the steering wheel. All that leverage is also had on your steering components, wheel bearings, suspension.........

That is a light car with a big fat heavy tire up front. Go to a 6" rim and a 33X10.50AT. If you really want to keep those tires, look into an electric PS unit. And shortly after that a bigger rack.
 
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