Supergoat Garage

Continuing my quest to solve my rear end noise issue, I set my sights on the rear differential mounts thinking they may be the issue given the 140k on them. They seemed fine overall actually, but a little soft from age. I felt it was still a worthwhile endeavor even if they do not turn out to be the issue. Here is how it all went down.

The rear differential bushings do get worn over time and it’s not uncommon for them to need replacing on these cars. I was convinced that the clang noise I was hearing when starting off from a stop was related to the driveline in some way and figured that reinforcing these mounts would be the answer.

My day started with jacking up the passenger side rear of the vehicle to do the wheel bearing. Initially I wasn’t able to break the axle nut loose on that side so I figured I’d save it for another day. However I didn’t want this day to go to waste so I decided to take a look at the rear differential mounts and see if I could at least do the inserts. At first glance, and based on a video I watched, it seemed doable. So I placed a jack stand under the car and went to work, still with just the passenger side rear in the air.

I went under mainly for an exploratory look but even with just one side in the air I had plenty of room. Having an aftermarket exhaust also helped with access to some of the bolts. I crawled back out and grabbed a scissor jack I have and placed it under the diff housing for support before undoing the two bolts that mount it to the subframe. They required a little effort but came apart easy enough. Once the bolts were pulled out I was able to use the scissor jack to lower the diff as far as I could, basically having it rest on the subframe, but still supporting it with the jack as well.

Lowering the diff down gave me access to the four nuts on top that needed to be removed to separate it from the mount. I could reach up and feel them easily enough but getting a socket on them was going to be near impossible. Not wanting to be defeated, I grabbed my ratcheting 17mm box wrench and was able to position it on one of them. My thinking being if I can get it on one then I should be able to get it on the rest of them. That logic doesn’t really work when working on cars usually, but this time it did! Thankfully. It was tough though. I had to find a different approach and angle for each bolt. Having a ratcheting wrench was an absolute blessing for this job as there is little room up there but having a swivel head would have been even better. Also having an aftermarket exhaust which had a smaller muffler than stock helped too. The stock muffler seems like it would have gotten in the way when trying to reach the two bolts closest to the rear of the car.

Finally the last nut was free. I was able to remove the mount from the body of the differential and move it out of the way enough to where I had enough room on either side of one of the factory bushings to slide in the polyurethane inserts. They went in easy enough with a little force. They were tight enough to feel like they would take up the slack but not so much that it was hard to get them in. I did the passenger side first, and then had to try and move the mount over to the other side. With a little bit of fiddling with it, I was able to find a position where I could just get the inserts lined up and pushed in.

With both factory bushings now better supported with poly inserts it was ready to put back together. It took a few attempts but I got the mount to sit back on the four studs mounted on the top of the differential and loosely installed all 4 nuts. Once they were all hand tight, I finished them off with the wrench. Getting a torque wrench in there was not going to happen so I used the method of “That’ll do” and tightened them as much as I could. Once all four nuts were tight, I used the jack to raise the assembly back into position, slid the mounting bolts back in and tightened them all down. I was able to use a torque wrench on these.

I put the rear wheel back on, lowered it down and took it for a drive. I didn’t really feel much of a difference in the car itself. Shifting feel may have slightly better engagement overall but that was about it. Noise and vibration seemed to be about the same. Speaking of noise, the rear end clang I had been chasing was still there. I drove back to the house feeling a little disappointed that I had not solved my noise issue. I did feel good that the rear bushings were actually in good shape though, and now that they were reinforced, I probably wouldn’t have to think about them ever again. I did end up buying a swivel head ratcheting wrench by the way so I could get a better angle on the nuts that mount the differential. I went back under with the new wrench just to make sure they were tight. They were, they would not budge or get any tighter by hand so while I didn’t need to check them again, I feel better having done so.

In part six I will go over what finally fixed my rear end clang. It makes so much sense that I am mad at myself for taking so long to properly diagnose it.