ES2K

Update 3-9-21
After installing all 8 collars, the NVH that occurred at over 55 mph was unbearable. The drone and buzz did not justify the minor performance improvement provided by the collars. I took the collars off and I am not looking back.

Has anybody had good results by leaving the inboard collars off when installing the diff mount collars?
I began removing the rear mounts by unbolting the sway bar, unbolting the mounts then carefully lowering the diff so I could pull off the mounts. Because I have the OEM exhaust, I could not move the sway bar far enough out of the way to remove the rear mounts. It looks like I need to remove the cat back portion of the exhaust in order to drop or remove the sway bar in order to remove the mount.
The bolts on my cat are well rusted and will need a liberal soaking with liquid wrench. I don't want to risk snapping one of the cat bolts because I don't have any replacements on hand.
I'm tempted to NOT install the inboard collars for the rear mounts. But that seems real bush league and I am concerned that I may put too much stress on the un-collared inboard side of the mount.
Suggestions?

afzan

I think what I did was unhook the exhaust from the hangers and lower it slightly without disconnecting

alternative suggestion: drill the mounts and drain the fluid out, rinse them out and fill them with urethane

ES2K

My next plan is to disconnect the hanger donuts.

ES2K

This may be more of a rant than a response. I have evolved to be a conservative, cautious back yard mechanic. The differential collar install should be a no big deal. But...installation instructions note that the rear sway bar is to be disconnected to provide room the remove the rear mounts. I have the OEM exhaust which prevented moving the sway bar far enough to provide clearance. On reviewing the instructions, I see that the vendor's car had a single exit, aftermarket exhaust that left ample room for accessing the differential mounts. OK, I'll just remove the sway bar. However, to do so requires that I remove my cat back exhaust. Next hurdle; my cat has very rusty mounting studs. The cat studs are pressed in bolts with button heads. Some of the bolt heads are behind heat shield tabs. I am aware of people snapping the old cat studs. Since I do not care to fight with knocking broken studs out of an old cat, the exhaust stays on. As afzan suggested, my next option was to remove the muffler hanger donuts and allow the exhaust to drop a little. The rear donuts are not pushed over spear headed studs as are most exhaust hanger brackets. The top hanger is a u shaped hook that opens to the back, while the muffler bracket is u shaped and opens to the front. After removing tension on the donuts by jacking up the muffler, I could not push or pull the top of the donut far enough to clear the top u hook because the bottom was be held by the opposing u hook bracket. If this is confusing, just crawl under your car and take a look. It appeared to me that these donuts are installed before the exhaust is attached to the cat so the exhaust can be pushed for and aft while installing the donuts. If I had to remove the donuts without disconnecting the exhaust, I reached to point that I would have cut them off.
I am determined to not created problems for myself when playing with my car. So, I installed the differential collars without the outer collars on the rear mounts. I ended up installing 6 of the 8 collars. I can notice the torsen doing it's job in tight turns, not yet sure if shifting has been improved or a placebo effect is influencing me. If I ever remove or replace my cat back, I will take that opportunity to install the remaining collars.

Slowcrash_101

Any movement you take out of the drivetrain will improve shifting precision. Remember that the shifter is physically connected to a rod that goes into the transmission(solid linkages). The less the drivetrain moves(Engine, transmission, differential, drive shaft) the more precise shifting becomes.

ES2K

"The less the drivetrain moves... the more precise shifting becomes"
I understand the physics. My first impression is based on a short drive thru the neighborhood with a cold transmission. It was meh with respect to shifting improvement. By leaving off 2 of the collars I may be missing some of the goodness. I'm withholding judgement until I get on an open road and can run thru some red lined shifts. The 2 to 3 shift is the one that counts for me. Down shifts have never been a problem.

ES2K

I decided that I was not going to let this little install beat me. I ordered the cat to cat back exhaust gasket, broke out the liquid wrench and installed the two front collars for the rear differential mounts. After I disconnected the exhaust from the cat, I was able to remove the rubber (?) hangers by supporting the mufflers with the scissors jack and pushing, pulling and tugging with channel lock pliers. With the exhaust hanging down nice and low, I could swing the sway bar down far enough to remove the mounts. I used my scissors jack to support the differential while I removed the two rear mounts. I was able to adjust the scissors jack by hand while on my back, under the car; which was much easier than using a hydraulic floor jack. I never felt comfortable leaving out the two collars. So, now I have the complete set of collars installed and look forward to the added differential support.

fernando.

Lets hear about the driving impressions.

B serious

How come you didn't just disconnect the cat at the spring bolts?

ES2K

"How come you didn't just disconnect the cat at the spring bolts?"
I didn't want to mess with the O2 sensor wiring. I have too much experience in causing problems while trying to fix or change things. So, I never considered disconnecting at the spring bolts. At least, I didn't have the weight of the cat hanging on the exhaust.