Sympathetic front to back bounce

Cracker39

Cracker39

Senior Member
I get what seems like a sympathetic bounce, from front to rear, on smooth roads at around 25 mph - although it's not specific to just 25 mph. The tires are new and properly centered on the rims. The rims appear to be in excellent condition. I was suspicious of a bent driveshaft or stiff universal - but I think that I would be having more noticeable problems if that was the case. Any suggestions?
 
Have a friend follow you around the block and ask them to look for bent rims.
Or put the rear axel up on jack stands and run the car in gear and look at the rear wheels.
Bob
 
I made a "tool" to check if my wheels were round. I found the two front ones were 1/4 to 3/8 out of round. Attached is the pictures of the "tool" I used to check them. The rear tires/wheels seemed to be OK.

I had a similar problem to yours where at 10 - 20 MPH the car would sort of "lope" down the road. That is it would seem like it got lifted up and then let down again. Don't know if that describes your problem or not but it sounds similar to what you are talking about. The car would run OK at higher speeds.

I changed the wheels out with other wheels and tires that seemed rounder and the problem seems to have gone away. I then put the original tire on a rim that seemed round and tried it again and things seem to be better. I am still working on this situation but I think I am making progress and still have one wheel/tire to change around.

Hope this maybe helps your ideas and problems. Also hope I don't get laughed at to much for my crude tool. But it was easer than laying on the floor with the wheel jacked up and seeing how far it moved off the floor.
 

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