Weird vibration?

[Palmer7]

Just recently I have been getting an interesting vibration it starts around 15 mph and its worst is at 20 mph and stops at about 25mph. The vibration is only noticeable when not pressing the gas and sounds like its mostly in my rear end because my back hatch is rattling. Any guesses? I just rebuilt the rear end and put in new u-joints on rear drive shaft. Also sorry to add this in at the end but its most noticeable around 20 in first gear like pushing about 3000 rpms but still is noticeable in 2nd don't know if that changes anything.

Thank you for any responses.

 

[littlebro294]

did you double check everything make sure there is no weird wear on it after a bit of driving?

 

[Palmer7]

I did the 500 mile fluid swap check and everything looked pretty normal. I mean if I can't figure out if its something else ill take off the cover and look again.

 

[Palmer7]

Seems it might be getting worse now anywhere up to like 30 mph pretty bad shaking. I have a spartan locker in my rear end also and it made a prett violent pop yesterday coming into my neighborhood I don't know if my rear end is the problem yet but I'm hoping its not.

Edit: just anther reminder it's only on deceleration around these speeds there is a slight vibration while driving but nothing worse than normal (at least to me)

 

[littlebro294]

if its popping and making noises then it sounds like its time to take it apart and check it all, especially if its getting worse.

 

[Palmer7]

Alright I'll tear it down this weekend and get an update.

 

[4x4junkie]

Noise on decel is often loose pinion bearings (which very often results in destruction of the ring & pinion gears too).

If you just had the rearend rebuilt, it sounds like they may not have tightened the pinion nut correctly (or they reused an old pinion nut w/o also using Loctite)

 

[Palmer7]

Well I rebuilt it myself so I know I got it tight.

Also there isn't really much noise it's all vibration.

 

[FR-425]

Ok, here's my guess; Slip yoke binding or drive-shaft out of balance.

Double check your u-joints. May have lost a snap ring.

The drive-shafts on these are "clocked" the front and rear flanges must be maintained in the same orientation or the factory balance is lost.

If you pulled the slip yoke apart and did not mark it, and everything else checks out, you may need to take it to be re-balanced.

 

[Palmer7]

Well I guess I kinda forgot on my rear driveshaft while I was replacing the u-joints I could literally remove the t-case side one with my hands because the holder is so worn. So.... That could be my problem?

 

[FR-425]

Yup

 

[Bobmbx]

Ok, here's my guess; Slip yoke binding or drive-shaft out of balance.

Double check your u-joints. May have lost a snap ring.

The drive-shafts on these are "clocked" the front and rear flanges must be maintained in the same orientation or the factory balance is lost.

If you pulled the slip yoke apart and did not mark it, and everything else checks out, you may need to take it to be re-balanced.

Ditto on the balance. You might even find weights glued to your drive shaft that were installed at the factory. The first time I saw them on one of my cars I thought..."must've been one them tire monkeys screwing around".

 

[Palmer7]

Where could I get them balanced?

 

[Maniak]

Just call the driveshaft shops in town and ask if they can do a spin balance of your drive shaft..

From my quick googling...

Driveline Service

9041 NE Vancouver Way
Portland, OR 97211
503-289-2264

seems to have a good reputation..

~Mark

 

[4x4junkie]

Well I guess I kinda forgot on my rear driveshaft while I was replacing the u-joints I could literally remove the t-case side one with my hands because the holder is so worn. So.... That could be my problem?

Very possible. I'm not quite as confident an actual driveshaft imbalance would present itself only on decel, but certainly loose parts can (which the looseness can indirectly throw it's balance off under certain conditions).

 

[Palmer7]

My driveshaft bolts are almost completely backed out on the trans side I'm thinking due to the looseness of the u-joint and the vibration it's causing. They were lock tight in before I'm thinking by the previous owner for this specific reason