Seized Pilot Bearing

[FMS88]

I've pulled the engine in my Ram 50 4x4 to replace the clutch, main seal and fix some other oil leaks. After removing the clutch I found the pilot bearing was seized and that it wore a .375 x .012 groove in the spline end of the main drive gear assembly (input shaft). Since even a new pilot bearing won't properly support the shaft end, what options do I have other than a trans tear down and replacement of the main drive gear assembly - something I'd really like to avoid.

Thanks

[FMS88]

I may have found a solution that doesn’t require replacing the input shaft, but does anyone have an idea or comment concerning a fix?

[geezer101]

Might need one machined up. We're lucky - Mitsubishis have pilot bearings. Things like Nissans don't (glaring example is Pulsar GTiR - these piles of junk eat gearboxes, especially the minute you wind up the boost on them past 10% extra horsepower output) Could also get the end of the shaft welded and milled but that is the hard way to fix this issue.

[FMS88]

Welding and turning the shaft would require a tranny tear down, wouldn’t it? I’m trying to avoid that since I’d have to have a shop do it. A solution I’m investigating is to use a wider bearing that can span the groove. A National bearing, PN 63202LLB, is wide enough to do this and leave about .120” on each end that would contact and support the shaft end. The inner bore is correct, but the OD is 2mm greater so boring the flywheel is required.

This isn’t ideal but seems workable, hopefully for another 20-30k miles. The current tranny is a rebuild with 50k so I’d like to get a few more miles out of it before considering another rebuild or replacing the truck. Incidentally, the pilot bearing cut a groove in the shaft of the original tranny that had other internal bearing failures at 100k. The tranny shop replaced the original unit with a rebuilt they had in stock. Seems very odd that this has happened with two different units. I never saw the first failed pilot bearing, but the current one had lost lubricant and was rusty. Any ideas what could be causing such pilot bearing failures?

Thanks for your reply and comments.

[geezer101]

I haven't got an answer on why the pilot bearing has failed but one way or another something will have to be disassembled, welded and machined to correct the problem before it causes a gear failure. :shrug:

[FMS88]

So you don’t think the a bearing that’s wider than the groove is an option?

[claych]

Just a thought,
How about a bronze/oilite bushing instead of a bearing?
There are so many, and so common You could get all size parameters
needed by machining the bushing only!

[FMS88]

Just a thought,
How about a bronze/oilite bushing instead of a bearing?
There are so many, and so common You could get all size parameters
needed by machining the bushing only!

Thanks for the suggestion.it has merit but machining would definitely be required. None of the manufacturers I researched offered a bushing with the pilot bearings ID and OD. Have to start with bar stock.