The Bushing That Everyone is Afraid of.

[Jack B]

I did a post several years ago about how bad the pinion arm bushings are on the Gen 2. At that time I replaced them with poly bushings, but, did not document the process. I just changed out another rear end and have the info for this change.

THE PROBLEM

1. What can this extremely loose bushing cause:

A. A clicking sound when accelerating, turning corners or backing up.

B. A car that is not level in the rear.

C. When a car accelerates the rear chassis rises in the rear and as the torque diminishes the chassis settles. In this case the same happens, however the pinion arms are loose so they tend to float and that leaves the rear wheels unloaded. That is a bit of an over exaggeration, but, there is some truth in that statement.

D. Why aren't these fixed when a rear end is changed - It take a lot of work and time to change this bushing. In most cases it is not noticed till the rear end is pulled and the shop does not have the time to fix the bad bushing.

E. The problem - it is not the rubber bushing that is the issue, but, it is the steel bushing inside the rubber bushing. It is not even a true bushing in that it is a piece of soft rolled steel.

F. I do not know if the shop or CC supplied the bolt for the 998 recall, however, the recall bolt in mine had a .050 smaller diameter than the orginal bolt. Tha is not a lot, however, it just creates more play.


THE FIX

1. The bushing kit is listed below in a picture - it comes from a C5 Vette.

2. There is a puller made specifically made for pulling the old bushings. I use a punch to knock out mine. It only comes out one way.

3. The oem busing is asymmetrical, it projects more to the front than the rear. You will have to remove about 1/8" of the poly on the rear and add a washer/shim on the front.

4. When you insert the new split bushing into the pinion arm it has about .005 play. I have some ,007" brass shim stock that I used to make a tight fit.

5. A new bolt - the new bushing cannot use the the old bolt, you need a 1/2" X 4.5" bolt. A Gen 2 head bolt works perfectly.

Here are the pictures


The POS Bushing

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The Steel Bushing, Bolt and Rubber

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[Camfab]

Thanks Jack, I do remember reading your old post on this matter. The new bolt pictured is quite a bit shorter, is it sufficiently long enough? Did you replace the bushings on the outer ears of the diff cover as well? I'm just wondering if that would be a good idea as well, so that no single part of the cover gets more stress transferred to it, due to different durometer bushings.

 

[GTS Dean]

Jack,

That is the same style bolt that the Gen 1 & 2 shocks were mounted to the frame and wishbones with. IMO, the diameter difference between the holes and the ACR 2812 Koni shock (1/2" dia bolts) is why they were referred to as "rattlers" .

Thanks as always for your very informative posts!

 

[Jack B]

The longer bolt is the recall bolt, the shorter bolt was the oem bolt from pre-recall. The corvette poly bushing has a .505 inside diameter, that is why the the 4-1/2 X 1/2" Gen 2 head bolt works so well. The Gen 2 head bolt is very close to the length of the bolt from the recall. Again, I do not know if CC or the dealer supplied the recall bolt. It had to be longer because the recall added a support bracket at the pinion bushing that forced the change to the longer bolt.

Thanks Jack, I do remember reading your old post on this matter. The new bolt pictured is quite a bit shorter, is it sufficiently long enough? Did you replace the bushings on the outer ears of the diff cover as well? I'm just wondering if that would be a good idea as well, so that no single part of the cover gets more stress transferred to it, due to different durometer bushings.