Mechanics

CHEVY REAR END MAKES LOUD "THUNK"

1999 Chevrolet Suburban

Drive Train Axles Bearings problem
1999 Chevy Suburban V8 Two Wheel Drive Automatic 124000 miles

I have a 1999 2wd (limited slip) Chevy Suburban 1500 with 126,000 miles.
My issue is with the rear end. In Deccember of 2007 the rear end went out and I had it completely rebuilt. In May of 2008 the transmission failed and I had the dealership repace it with a brand new unit (not remanufactered).
Since all of this work has been completed I have a very noticeable thunk in the rear of the vehicle that can be both heard and felt, which gets progressively louder and more consistant the longer you drive the vehicle and apply the brakes. The noise becomes more pronounced as the truck warms up and occurs when stopping as well as when releasing the brake to move forward.
In everyday driving it is noticeable but in hour + of stop and go traffic on the LA freeway it is almost scary.

I have had the brakes pulled and re-done, I have had the stabilizer and spring bushings replaced all to no avail. The only thing that we have found is a slight leak in the axle seal on the rear passenger side.

At this piont I am completely at a loss and am not sure where to go next.
Avatar
Kevinpf
January 2, 2010.



Have you had the universal joints checked? Also, I will tell you that if you get gear lube on the brake shoes, they will grab and stick. If u-joints are good, gear lube on the brakes isn't the problem, with the vehicle in neutral, the park brake on and a helper holding his foot on the brakes, craw under the truck and grab where the rear u-joint goes into the differential. See if there is any play in the pinion bearing. Do the same on the front trans output bearing. IF they are both tight, I feel the differential cover needs removed and backlash need checked. IT may need reset and allowing excessive play in the differential.

Let me know what you find.
Joe

Thanks for the quick feedback.
There isn't any lube on the brakes. I will check the u-joints and pinoin and let you know the result.

As a side note, not long after I bought the car new I complained about a clunk noise in the rear end and the dealer had this to say
" Cause: Pressure build up in yoke. F1280 propeller shaft assy (btwn trans & rear Diff) normal wear & tear. R& R lubed yoke.

Any thought s on this? Could it be the same issue only worse?

Tiny
Kevinpf
Jan 2, 2010.
That is where I am telling you to check. THat is what the driveshaft connects to before going into the differential or the transmission. I checked for recalls regarding this part, but came up with nothing. Something tells me that you are going to find play there and either the splines are going to be worn or the pinion bearing is going to be bad. As far as what they did when it was new, that would have been standard procedure.

Let me know what you find.

Joe