Vibration Issues

[jwburrow]

Hey all,
I have a 1991 78 series that has recently developed what I think is a vibration issue. When I am driving at interstate speeds and hit any kind of slight bump it will cause the vehicle to violently shake pretty uncontrollably until I pull over and slow down to about 20 mph. Then I can safety speed back up to speed but happens every time Im doing interstate speeds. Anyone have a similar issue or have an idea of what the problem is?

 

[FJBen]

Hey all,
I have a 1991 78 series that has recently developed what I think is a vibration issue. When I am driving at interstate speeds and hit any kind of slight bump it will cause the vehicle to violently shake pretty uncontrollably until I pull over and slow down to about 20 mph. Then I can safety speed back up to speed but happens every time Im doing interstate speeds. Anyone have a similar issue or have an idea of what the problem is?

Thats a pretty classic case of death wobble.

Caused by any of the following or combination:

too little caster
loose u-bolts on springs
worn/loose knuckle bearings, trunion bearings being a big culprit.
loose/bad tie-rod ends
Looses wheel bearing pre-lload

 

[jwburrow]

Thats a pretty classic case of death wobble.

Caused by any of the following or combination:

too little caster
loose u-bolts on springs
worn/loose knuckle bearings, trunion bearings being a big culprit.
loose/bad tie-rod ends
Looses wheel bearing pre-lload

Thanks! Ill have to check these out this weekend

 

[FJBen]

Thanks! Ill have to check these out this weekend

No problem. Yep just google "death wobble" or search it on here. You will find a ton of info on it and sometimes it's an easy fix, others it's multiple factors.

 

[LDowney]

If you have leaf spring suspension on the front end, I would advise checking/replacing your spring bushings at the pivot (opposite end of the spring from the shackle) on the front axle.

My BJ70 will start displaying limited death wobble once the bushings are sufficiently worn. My 40s never display this sensitivity to bushing wear, so it might be unique to my 70 or other 70s too.

Good luck. Also if you can get access to a vehicle lift, all of the items identified for you to check will go faster on a lift