Bracket for drive shaft carrier bearing

[71CHEVYSHORTBED402]

Originally Posted by HO455

I'm going to try and clear some misconceptions up. The carrier bearing in question is for the basic coil spring 1/2 ton truck. These trucks did not come with a sliding joint in the rear drive shaft like the 3/4 tons and leaf spring 1/2 ton trucks like 71CHEVYSHORTBED402 shows.

I have seen 3 different styles of carrier bearings for the various 67-72 trucks and there may be more I haven’t seen so it's no wonder as to why there is confusion. Photo #1 shows the basic 1/2 ton driveline with no sliding joint.

When the truck's rear axle moves up and down the drive shaft moves fore and aft. On trucks like 71CHEVYSHORTBED402's the slip joint absorbs this move by collapsing and expanding as needed.

On the basic 1/2 ton the movement is absorbed by the yoke on the end of the transmission moving in and out of the tailshaft. In the 2nd photo the red arrows indicate the fore and aft movement of the driveline. Since the bearing doesn't slide on the driveline the rubber bushing flexs to allow the bearing to move fore and aft. The green arrows point to the rubber bushing that must flex. The rubber will only flex so far so the carrier bearing MUST be installed with no preload on the rubber when the truck is at ride height.

The yellow arrow points to the slots in the bearing mount that allow the carrier to be installed with no preload at ride height.

Things get problematic when the truck is lowered (or raised) too much and the adjustment range provided by the factory isn't enough and the bearing gets installed with a preload either forward or aft. When that happens the rubber cannot flex enough and the bracket then is forced to flex, eventually work hardening the steel and breaking apart.

Another common cause of carrier failure on a stock height truck is installing the carrier with the rear axle hanging and not sitting at ride height. 2 post lifts are nice but.....

As mentioned you can replace the factory style carrier bearing with the billet style but you MUST replace the complete driveline with one that has the sliding joint in the rear half of the driveline as the billet carrier does not flex. Billet style shown in last photo. Green arrow indicates the sliding joint.

I hope this helps. If not just shout out and hopefully I answer the questions.

Nice education, appreciated. Sounds like two general types, one for leaf springs, one for coil springs. For 2wd anyway.