Crazy ass vibration in rearend...

[Johnny Bravo]

I recently (just over a week ago) got the tranny in my GVR-4 rebuilt. Now before I got it rebuilt this noise in the rear was already there so I know it's not likely tranny related. Initially I thought it was related to the carrier bearing as I did get the loud "thumping" in the rear under WOT. Now the noise seems to have progressed into an almost constant loud vibration/buzzing. It is not gear dependent in that when I shift gears the RPM of the vibration does not drop in relation. When I let off the throttle the noise disappears immediately, but then reapplying throttle the noise immediately returns. When I get back on the throttle it sounds as if there is some kind of "slack" in there as well...kinda "bounces" a few times before the noise goes constant. Could it possibly be a rear axel or wheel bearing? I wouldn't think it's the carrier bearing/lobro joint as I would imagine the RPM of the driveshaft varies depending on gear. I can't think of anything that would stand out immediately as a problem, but who knows. If anybody has any clue as to what to look ingo I'd appreciate it. TIA!!!

 

[blackgsxrcst]

well, having slack in it when you accelerate could possibly be something gone wrong in the rear differential. but it could also be just a broken axle in the rear. there are little bearings in the cv joint and one could possibly be broken or worn wrong thus making the thumping, vibaration sound you are getting. does the rear end make any noises like a whinning noise or anything?

 

[Johnny Bravo]

No there is no whining in the rear at all either on or off throttle. When no throttle is applied at all, but still in gear, there is no noise whatsoever. It's only when in gear & under throttle that the noise appears. Now since the tranny rebuild there is a very very light, muted thumping in the tranny area (barely audible), but I'm attributing it to the tranny only having like maybe 20mi. on it since the rebuild & still being tight.

Oh FWIW, one thing that I do recall now is that a shop I recently took it to said that it "might" be one of the rear axels. They weren't sure if that's what it even was & didn't know which side it would even be.

 

[zac83]

improper backlash in your rear end <-- makes noise when the ring/pinion pull the car instead of vice versa - the problem is the trailing side of your ring has some wear in it thats causing noise. could be catastrophic, would recomend pulling atleast the pan off the rear dif and checking for contamination and burned oil.

 

[Johnny Bravo]

Well, when I got my tranny rebuilt they also changed out the rear diff fluid as well. They said it was dirty & had a slight metallic quality to it (probably some gear wear in there)...or something to that effect. I actually just got word from the garage I had it at over the weekend (like a block from my house, but they're good) and another mechanic there said it appears the passengers side driveshave cv joint is bad & the other is going bad....also that the carrier bearing does appear to be going bad too as I had imagined.


Yeah, it does sound like some kind of backlash in the rear. I suppose this would mean swapping in a new rear end. If so then of course it's time for a 4-bolt LSD rear