Highway vibration (yep, another one)

MrBClark

MrBClark

TJ Enthusiast
Joined
Mar 30, 2019
Messages
300
Location
Montoursville Pennsylvania
My 01 TJ has developed a fairly bad vibration at and above 65 mph. It is kinda of a rhythmic vibration. Comes for a few seconds, then fades. I've heard removing the front driveshaft and driving it may help diagnose it. My questions are:

Could it be upper ball joints? The inspection station said mine are worn a good bit. What about axle u joints?

How expensive would it be to have my front driveshaft rebuilt? I may just go ahead and replace those u joints while I'm at it.
 
Cyclical vibrations are usually a U joint going bad or bad angles on the ds.
I would remove the front ds to either confirm or rule out that component.
Rebuilding the ds can be $200+ depending upon where you go and what the rates are in PA.
Usually U joints going bad can be confirmed by squeaking while moving, the U joint cup moving in the ear and not on the trunion and rusty dust coming from inside the U joint cup.
 
pagrey said:
Why not just start here? Seems like a good idea to start with the worn out parts and go from there.
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CharlesHS said:
Cyclical vibrations are usually a U joint going bad or bad angles on the ds.
I would remove the front ds to either confirm or rule out that component.
Rebuilding the ds can be $200+ depending upon where you go and what the rates are in PA.
Usually U joints going bad can be confirmed by squeaking while moving, the U joint cup moving in the ear and not on the trunion and rusty dust coming from inside the U joint cup.
Click to expand...
Does the front driveshaft come out like the rear? Just remove the 4 bolts and pull out the part that goes into the TC? Is there anything I need to do to be able to drive it safely without the driveshaft?
 
MrBClark said:
Does the front driveshaft come out like the rear? Just remove the 4 bolts and pull out the part that goes into the TC? Is there anything I need to do to be able to drive it safely without the driveshaft?
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There are 8 bolts. 4 at the differential, and 4 at the transfer case. Other than making sure there is no loose hardware, there is nothing else you need to do to make it drivable. Just don't shift between 2WD and 4WD while in motion.

You can do the same test with the rear driveshaft as well. After reinstalling the front, you can remove the rear and drive around in 4WD, or essentially front wheel drive. That will rule out any problem with the rear driveshaft as well. Just make sure you use the parking brake while underneath, as the transmission won't hold the car in place without a driveshaft to stop the wheels from turning.
 
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Steel City 06 said:
There are 8 bolts. 4 at the differential, and 4 at the transfer case. Other than making sure there is no loose hardware, there is nothing else you need to do to make it drivable. Just don't shift between 2WD and 4WD while in motion.

You can do the same test with the rear driveshaft as well. After reinstalling the front, you can remove the rear and drive around in 4WD, or essentially front wheel drive. That will rule out any problem with the rear driveshaft as well. Just make sure you use the parking brake while underneath, as the transmission won't hold the car in place without a driveshaft to stop the wheels from turning.
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Well crap. How hard are the bolts at the transfer case? I already replaced the u joints in the rear driveshaft.
 
MrBClark said:
Well crap. How hard are the bolts at the transfer case? I already replaced the u joints in the rear driveshaft.
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I believe they are 8mm heads as well. They're not too difficult to reach, but you'll have to reach over the skid plate. They face the same direction as the joints on the differential, so you'll have to reach back and find them. They're immediately behind the u-joint closest to the transfer case.
 
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