Rear Diff Bushing Install - Lessons learned
 

This topic has been covered before, but I thought I would add my :twocents:
Decided to replace my front and rear differential bushings this week. The factory bushings were still in good shape, with no evidence of cracks or loss of silicone fluid ... however, I elected to replace them since they are known to be failure-prone. Decided to go with the Z1 Motorsports polyurethane bushings as replacements. Completed the job over the course of two days. It took several hours from start to finish. Job specifics have been covered already by others. There are also several YouTube videos that are helpful. My lessons learned:

1. I'd recommend that you recruit a friend, relative, colleague, son or daughter or spouse to help out. The diff is heavy and dropping it and re-installing it takes a bit of finesse, even with a jack to support it. My spouse volunteered (pic attached). Having a second person available to position the jack and raise and lower the diff is a big help. I suspect that it would be a bit*h to have to manoeuvre the diff into position on your own.

2. I'd also recommend that you remove the muffler and mid-pipe, sway bar and brace before disconnecting the axles and driveshaft and removing the diff. since it will provide a lot more working space. Some of the YouTube videos show folks struggling to remove the diff with the sway bar, muffler, etc. still in place ... with a lot of strong language needed to encourage the diff to come out. Better to remove the muffler, sway bar, etc. and eliminate the frustration IMHO.

3. I elected to use the Z1 bushing removal tool as opposed to the "drill and saw-z-all" method to remove the factory rear bushing. This proved to be the most anxiety-ridden part of the job. The removal of the inner part of the bushing using the tool proceeded smoothly. However, the removal of the outer sleeve caused a momentary panic attack when the large plate used to force the sleeve out of the sub-frame decided to become twisted and wedged in the opening ... which is not entirely unexpected since the opening is not perfectly circular, but rather is distorted. Trying to "wish" the large plate out of the opening using a hammer and punch didn't work. However, fortunately, the plate was no match for several direct swings with a 3-lb sledge hammer. There was a huge sigh of relief when the plate popped out of the opening. The lesson learned is to consider using a saw-z-all to cut the sleeve out.

4. Installation of the new bushings proceeded smoothly. Just make sure to smooth out the bushing bores with a flapper wheel until "baby butt-smooth" (Rusty's wording) and liberally lubricate the bore and bushings before installing. I used anti-seize. I also placed the bushings in the freezer overnight. I was able to install the bushings (... even the rear bushing) simply by tapping them into the bores with a rubber mallet (... albeit the rear bushing required a little encouragement by way of a couple of firm taps with the 3-lb sledge with a piece of 3/4" oak placed over the end of the bushing before striking). One question I had related to the final resting position of the rear bushing. Input was provided by both Rusty and Z1. The bushing needs to sit such that the rear end of the diff (where the stub is located) is flush with the bushing, with no space between the two mated surfaces. Also, it's advisable to secure the rear end of the diff with the stub nut before tightening up the bolts that run through the front bushings.

5. Final piece of advice: Read the posts from others who have completed the job and watch the YouTube videos. Gather up the necessary tools beforehand and know the torque specs (available in the FSM). Also, safety first. Make sure to follow all safety procedures when jacking and supporting vehicle. Finally, wear vinyl or latex gloves. I've been cleaning "stuff" from under my fingernails for the last 3 days!!!

Trust the above is helpful.

:tiphat:

You ready to do another one? :rofl2:

The bushing hole is not perfectly round. It's kind of egg shaped. When they weld up the sub-frame. The welding distorts the bushing hole.

Explains why the Z1 bushing removal tool plate can become wedged in the hole. Not pretty based on my experience. I was sweating bullets while trying to dislodge it.

I've done 3 diff bushings so far. None of the hole have been round.

Have put on approximately 1000 miles since installing the Z1 polyurethane rear differential bushings. No noticeable difference in noise or vibration. However, on a recent inspection, I noticed that the rear bushing appears to have eased rearward slightly (i.e., less than 1/8") in the subframe. Is this type of movement within normal limits? There is no gap between the mating surfaces of the differential and the rear bushing and all bolts/nuts were torqued to spec when the new bushings were installed. Thanks in advance for any input.

With the bushing up against the diff stud. The poly is finding it's natural resting place.

OK, as always, thanks Rusty!

I am in the middle of this project along with sub-frame collars from Z1.

1. I purchased the removal tool from GK Tech, similar to Z1. This helped in removing the old bushing core and I used it to install the new bushing. However, it was useless in removing the old sleeve. IMO you will need a reciprocating saw to remove.

2. Make sure to have the bushing flush with the front of the frame. Failure to do this will mean the mounting holes for the other two bushings will not align. And you'll need to redo the rear bushing.

3. I agree having a 2nd person will help a lot in finessing the diff into place.