1972 Differential Snubber Bushing Oddity?

[Owen L.]

My car: 1972 LS-5 automatic

Been cleaning and rejuvenating since Covid began, finally tackling the snubber bushing as the car has had a very hard rear clunk from park to reverse, reverse to drive, and back to park. I've had the car since 1990 and I don't think the bushings were changed from '72 to '90 but I'm not positive. Here's what I found:

IMG_1041.jpg
^ This is the bottom side of each component; from the left: is the bottom nut; (issue #1) there is no lock washer but the bottom nut is one of those squished locking nuts; (issue #2) there is a cupped washer and rubber bushing under the diff bracket; (issue #3) the large bushing between the bracket and frame has no metal component bonded to the bushing or otherwise.

Here's the topside of each component:
IMG_1042.jpg
Are these original components as installed in St. Louis? The AIM doesn't show the bottom-most cupped washer and rubber bushing but does show a large flat washer and locknut.

Lastly, there are no cotter pins in the castellated nuts for the snubber bracket to differential. Is this uncommon?

Thanks all!

[Patrick H.]

Re: 1972 Differential Snubber Bushing Oddity?

These may help:

https://www.flickr.com/photos/124695...7649252735124/

https://www.flickr.com/photos/124695...7649252735124/

[Gary B.]

Re: 1972 Differential Snubber Bushing Oddity?

[ATTACH=CONFIG]122776[/ATTACH]

The lack of a cotter pin and the use of that cupped washer are not uncommon for a previous owner who was a terrible backyard mechanic. Both are bad ideas. You can see where the cupped washer dug into the bushing because the washer OD is smaller than the ID of the rubber. I would bet the farm that GM did not do that.

Gary

[Owen L.]

Re: 1972 Differential Snubber Bushing Oddity?

Thank you Gary.
I found the remnants of the cotter pins, they just didn't have the bent legs on them any longer. I believe the rubber piece has deformed to that shape from the torque on the bolt - a similar thing happened to the top bushing. (Trailing arm bushings deform this way too.)

I agree about the possibility of a backyard mechanic modifying the components, but it takes a bit of intentionality to put on the cupped washer, small rubber bushing, and squished nut instead of the simple large washer, lock washer and regular nut. It all just seems too well done to be a cobbled together Bubba fix but it's always a possibility.

For what it's worth, I put the new bushings in with the standard parts as shown in the AIM.

[Leif A.]

Re: 1972 Differential Snubber Bushing Oddity?

Owen,
Look at the two links that Patrick provided you in post #2. There is NO cotter pin used with the snubber bolt. The snubber bracket...YES but not the snubber bolt itself.

[Owen L.]

Re: 1972 Differential Snubber Bushing Oddity?

Hi Leif,
I wasn't clear. The cotter pins I was referring to are in the bracket to differential. My snubber bolt is just a regular bolt design.