Need help/information - 11.5 inch rear - pinion/yoke seal.

[DickWells]

Had a weeping pinion seal, behind the rear driveshaft yoke and harmonic balancer. Got the 12 point nut off and pulled the yoke off the pinion splines. This was after I had picked up a new pinion seal, which proved to be the right one --- EXCEPT. The rear extension of the yoke (56mm OD) had a rubber-lined, flanged bushing squeezed onto it(60.5mmOD), to give a good, serviceable surface for the seal to run on, just like the two-piece axle seals. Now, that was the part that was worn, and rough, allowing the seal to leak.

So, the frustrating part. I go back to NAPA and tell them my story, and they say, "Dealer stock item only.", and that they had never seen a driveshaft with a balancer on it! So I go to Bond Auto, and get the same story. Then, on to the Chevy dealer. They trot out a seal that's identical to the one from NAPA. They turn their terminal so that I can see it, and tell me that the bushing that I pulled off the pinion extension is obviously an integral item, and not replaceable! Indeed, the terminal doesn't show a separate bushing. Their solution? Buy a new yoke/balancer for $169 + something for the governor. Why? Is there something that I'm missing here? I went to all the bother to make witness marks on the universal parts and yoke, the nut and threaded shaft and the balance disk, and the pinion housing, so that it would go back together just as was built. I find it hard to believe that GM would put a bushing on that yoke extension, with an internal rubber seal just like the axle seals, if the dang thing wasn't supposed to be replaceable.

What do the experts on TDP say? As always, any and all help will be greatly appreciated.

DW

[More Power]

I don't have any first-hand knowledge of the part you're asking about, but the folks at Randy's Ring & Pinion should be able to help.
http://www.ringpinion.com/TechnicalHelp/TechHelp.aspx

I visited their shop in Everett, WA back a few years ago. Very helpful and knowledgeable folks. They rebuilt a 9-1/2" GM axle for me at that time. While there I photo'ed an AAM 11.5" rear axle being taken apart like that used in your truck. I don't remember the yoke details.... Jim

[DickWells]

Thanks, Jim. I just got off the phone, having talked with Randy's tech people, and, unfortunately, they tell me that the manufacturer considers that bushing an integral part of the yoke! Talk about a throw-away society. The yoke with the damper (apparently) has been discontinued, and the replacement just uses a larger OD extension to run inside the pinion seal, although I suppose that the replacement might also have a sleeve pressed on there, just like the one with the damper.

Regardless, at this time, I'm going to clean up the old sleeve and do some judicious use of some RTV behind it, to mate up with the rear face of the yoke, press it back on and put the thing back into service for the Summer. If things stay dry over the next couple of months, I'll just go about my business. If it leaks, I'll bite the bullet and do whatever I have to.

In the mean-time, if more of the expert DIY'ers on TCP have any advice, or info regarding availability of the bushing in question, I'd really welcome a response to the thread.

Thanks, Y'all.

[More Power]

The damper was originally installed on the driveshaft for the same reason dampers are used on the front of an engine - especially a diesel engine.

The harmonic torque spikes produced by a diesel engine are much larger than those produced by a gasoline engine. These torque spikes rise and fall in amplitude depending on engine speed, load and other factors. With a locked torque converter, some fraction of these torque spikes are passed through to the transmission and the remainder of the driveline. In general, the hollow rear driveline can produce an audible "ring" without a damper, in some applications and situations. GM Powertrain chose to include a driveline damper to reduce the possibility of this ringing and possibly to reduce the potential for long-term damage caused by these torque spikes.

Jim

[Kennedy]

I would think this yoke with damper should be available. I know that I've bought some of these for 1480 joint/shaft conversions so I know that at least that one is available. I could check on the 1410 (stock) setup if you like.

[DickWells]

Thanks, John.
It's back together, now, and dry at this point. Looks like I would have no trouble getting a new yoke, either locally at the dealer's, or from Rock Auto, etc. That's really not the issue with me, though. I can't understand for the life of me, why the manufacturer would not make that obviously easily replaceable item not available. I actually was able to push that rubber-lined bushing back on there with my fingers! And, it runs true, too. It's now glued on with high temp RTV gasket compound and (I think) that the polished OD is clean and smooth enough to do the job. Time will tell. Anyhow, I now have close to $50 tied up in new synthetic 75/90 W, which it needed in any event. Hard to believe that the stuff is costing $12 a quart these days.
Thanks for your effort and info. I'll let you know how it's going after I get some road-time on it.
DW