Differential Bushings (Oh Dr. Adams.....)

While I was parusing (Is that even a werd?) through the topics my good friend Mickrz's posted this.....

Joel found my problem (he's really good)! Lower and upper bushings need to be replaced under the differential. She's not "clunking" anymore. Joel is one smart dude, but everyone already knows that, eh?

Occasionally I hear this clunking sound under the Blacray if I hit a dip in the road or a sharp bump. It's loud and annoying. In an effort to dissmiss it in my mind I usually say something like" Eww I bet that hurt or Poor little feller he won't be gettin up after that..."

I have looked every stinkin place for it but have yet to find the source. Until Mickrz posted this.... So Dr. Adams could you shed some more light on this here subject?

What do I need?
Where do I pick up the bushings?
How much are the little rascals?
What do I need to do?
Is there anything else I need to look at / replace while I am here?
How freakin long will this take?
Did I miss anything?

Oh yeah. Thanks Bro. (here's a Texan size hug fer ya)    

Parts

my7T12009-02-24 07:26:13

Thanks for the offer T.... I already have the Blackray up off of the ground in the garage.... (it stays that way most of the winter).

This should be a quick easy fix for me... (I think).

These bushings don't make noises if you hit a bump(or an armered-dilly) or a dip. The diff nose bushings will usually only "clunk" under acceleration/deceleration, as the nose of the diff moves up/down under load. Mickers would make noise just taking off fwd or backward. The nose of the diff is moving up/down, and the slop in the worn out bushings is creating the cluck as the nose bottoms on the chassis mount for the bushings.
If yer getting a noiez when dipping, or bumping, it's in the suspension, or exhaust, but not likely the diff nose bushings.

darnit.... I was afraid of that! I know it isn't the exhaust. I replace all of it and it is definately not the culprit.

I suspect that it is the passenger rear body mount. I read a post by Mike Bogedain about replacing these in Bob Hsmiltons car. He indicated that prior to this it was making a very similar noise.

I have been putting this off because I know the bolts are NOT going to play nice and come out without being torn up or most likely cut out.

Oh well thanks for the info.... rats

My Ole' Targa Blue 72 makes that "clunk" upon acceleration/decelereation and also when placing the shifter in "D" and "R".  

Hey..."No Huggy, no ansy..."

What do I need?
There is an "upper' and a "lower" bushing...replace both.

Where do I pick up the bushings?
Any of the Corvette parts vendors will have the bushing kit.

How much are the little rascals?
Normally around $30 or so for both.

What do I need to do?
Remove the old ones, install the new ones.

Is there anything else I need to look at / replace while I am here?
Not particularly. Just a general once-over in the area...u-joints/leaks/loose stuff, etc.

How freakin long will this take?
Depends on how freakin slow you are...
You should be able to replace the bushings in a couple of hours...longer if you take potty breaks.

The procedure to replace these bushings is in the service manuals, but basically, on the '68-'80 cars with the iron diff, there is a removable bracket bolted thru the lower nose of the diff. Remove the bolts on that(be sure to note which way they face...it is important that they go back in the same direction). There is a bolt that holds the lower cushion to the bracket. This bolts goes all the way thru to the upper cushion, which happily is situated pretty much directly under the yoke of the diff., which makes it such a pleasure to remove.
Anyway....
With the nut removed from the bolt, and the bracket removed from the diff, you'll need to raise the nose of the diff up with a jack(or similar appliance), and remove the bolt, and the upper cushion. It may be necessary to dis-connect the rear u-joint(driveshaft) from the yoke to get the bolt out. Every car is different. Some will raise the diff nose enough to remove the bolt without taking the driveshaft loose...some won't.
Replace in reverse order.

The '80> cars with the aluminuminum diffs are a little different to change the cushions on, since they do not have the removable bracket on the diff nose. The "bracket" is actually part of the diff housing. You can only raise the nose of the diff so far on those in order to get the bolt out of the cushion(s).


That's it in a nut-shell....see Terry's link above for a visual image of the set-up.
hth

Hey, Joel.......Thanks for the quick response and "easy to understand" info.  Looks like I've got a project!

here is a side view on a dissambled car..  very very simple task.

I think I will go ahead and replace the bushing now anyway. Its a pretty simple task and it sure won't hurt a thing.

Thanks for all of the tips, pics, and links...... !