[rvguy]

allison hd4060  transmission output shaft seal leaking.  Looks like a pretty straight forward job. Has anyone done this repair on there own ?

[Richard]

Adam,

I have not, but my input is related. I had a catastrophic incident pulling into a campground when the input yoke to the tranny came loose, fell out of the tranny, and took half the driveshaft with it.. The yoke had been attached to the output shaft with Allen head screws. I suppose someone had done that because it is a difficult place to access with a wrench or a socket.

However, there is not a good way I know of putting a keeper on an Allen head. So I went back with grade 8 hex head bolts. I make a keeper to put under the bolts, and bent up the tabs when I had them tight.

Had the driveshaft fallen out five minutes earlier on the freeway, it would have been much worse.

[Jack Houpe]

Oh Richard I will have nightmares tonight thinking about that.

[rvguy]

Well i guess when I take it apart I will look at that possible issue as well

[rvguy]

Richard you hit the nail on the head.  Pulled my driveshaft assy and both retaining bolts were broke off in the output shaft letting the yoke extend way out past the seal. Suprised we did not loose the driveshaft and cause major damage. was able to extract the broken bolts luckly no damage to the yoke. Replaced the seals, bolts and did what you said locktited them in and made a retaining clip for the 2 bolts.

[Jack Houpe]

Thank God you caught it before it happened.

[Richard]

It’s possible that the yoke wallowing around is the root cause of the seal failure.

[rvguy]

It’s possible that the yoke wallowing around is the root cause of the seal failure.

so all that was left engaged in the trans was about 1" of yoke. Heck I dont think it was even touching the seal.

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FYI, depending on the differential sometimes the yoke torque value is very important to the assembly of the carrier. It often affects the tolerances in the carrier assembly. Just keep this in mind.