Bump steer, causes,fixes?

corvette8n

corvette8n

Well-known member
Noticed a little bump steer on a rougher country road I drove about a week ago. 1941 sedan coupe with 15” radials, rebuilt shocks by Andy, new shock links from C&G. King pins feel ok, although I do have a coupe of king pin kits in my parts stash. Steering box has some play. What do I need to look for and repair/replace thanks.
 
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Pretty sure fixing the sector box would help.
Check the toein/out
Checking/increasing the caster would help too.
Finally, not too sure how your drag link is hung but in the ideal world the relationship with your drag link and outer tie rod ends should be parallel with the earth with the car at ride height. Again, we are talking about the ideal world.
If they aren't when you hit a bump you're gonna change your toe in. If you're tow in goes to toe out, you're gonna be chasing the car.
 
In my experience, bump steer usually involves a car that has been lowered. As the car goes over a bump and the suspension goes up and down the drag link at the spindle end is moving up and down, and at the steering box at the pitman arm it is not very much. This makes the drag link essentially acting shorter or longer in an arc depending on if it going up or down which makes the wheels move as if the steering wheel was being moved. I think with everything in the stock position this kind of movement is vastly reduced due to the original engineering. Bump steer is more prevalent in early cars where the drag link is going forward to the left spindle than in later cars where it is over to the right spindle. My 2 cents.
 
I worked on phone company trucks. We had F-450s with aerial booms mounted to the maximum weight. If there was "any" play in the steering linkage, and you hit a bump the steering would start shaking so bad it would practically rip the steering wheel out of your hands you would have to bring the trucks to a stop to get them to stop. I used to road test them over railroad tracks that crossed the road, that would set it off if there was a steering play, it was violent. We stocked drag links, tie rod ends and shocks for them and that usually cured them.

With the car on the ground have someone turn the wheels back and forth while you look for play in the steering and suspension parts. Check the alignment to. You can try rotating the tires.
 
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Thinks guys, this list will keep me busy over the winter season.

Gene: unfortunately I sold the 8n a few years ago, wish I kept it as I keep coming up with projects I could use it for.
 
Now that you've sold the tractor, you realize you will have to give up your forum name unless you still have a Corvette.
 
tubman said:
Now that you've sold the tractor, you realize you will have to give up your forum name unless you still have a Corvette.
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Unfortunately both Corvettes gone, a ‘78 automatic and ‘95 6-speed, I’ll keep the name for nostalgia purposes. BTW I still running your condenser in my ‘41 no ignition worries.
 
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Gene1949 said:
Pretty sure fixing the sector box would help.
Check the toe-in/out
Checking/increasing the caster would help too.
Finally, not too sure how your drag link is hung but in the ideal world the relationship with your drag link and outer tie rod ends should be parallel with the earth with the car at ride height. Again, we are talking about the ideal world.
If they aren't when you hit a bump you're gonna change your toe in. If you're tow in goes to toe out, you're gonna be chasing the car.
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See page #629 of this link.

https://www.dropbox.com/scl/fi/7tco38kox38mlogrbzrwp/Techno-Source-for-the-1932-thru-1953-Flathead-Ford.pdf?rlkey=uhtpp3w4mpqncxu1p4u1u283w&st=nmxn05bb&dl=0
 
Check your tire pressure - I find running around 27 lbs is ideal - the more pressure, more likelyhood I will have issues. This has been my experience ….
 
Thanks Glen, I did download the PDF to my laptop a while back, one of these days I going to print the whole thing out on a laser printer and keep it in a binder in my garage.
 
corvette8n said:
Thanks Glen, I did download the PDF to my laptop a while back, one of these days I going to print the whole thing out on a laser printer and keep it in a binder in my garage.
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Good. I did quite a few, mostly formatting changes in the engine ID section so suggest you get a new copy.

Glenn
 
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