Rear Diff Pinion Shaft play

[rick3216]

Well, replacing the notorious rear differential yoke gasket. Upon disassembly and removal of the yoke I find a lot of up-down and side-to-side play (1/8" at least) in the pinion shaft. Knowing that there is a bearing inside of the differential casting, I'm thinking the bearing is toast and needs replaced. I only ask because I did not notice any play of the rear drive shaft prior to disassembly.

My search on the subject has not produced much information. If the bearing needs replaced, any suggestions as to sequence of removal and replacement?

Thanks, Rick

[PoW]

There are three bearings on that shaft. There is no measurable side play in any usable condition.

Long before the time yours is moving that much, I'd say the ring/pinion are shot.

Sorry.

DDG

[w30bob]

Hi Rick,

Diffs have been discussed on here, but using the search function usually just ends in frustration. From what I recall one of the maintenance TMs gives step by step instructions on how to rebuild one, but I believe there are special tools involved that most folks just don't have. I remember Charles at MSeriesRebuild gave us some good info, and he usually chimes in when he sees his name in a post.

Charles, if you see this could you give us summary of what's involved in rebuilding one of these rears..........I'd like to know myself. If he doesn't answer just PM him, as he always seems willing to help people out here on the forum. Sorry I can't be of more help Rick.

regards,
bob

[just me]

There is no magical mystery to building a diff when you have the manual. It will list step by step what to do and what tool you need to do it. Just realize that it doesn't 'fall' together. You need to make accurate measurements, put it together, test, make adjustment, do it again, etc. After you have done a few, it only takes a few hours to do it. The first one, however, can be a weekend project. It really helps to have someone who has done it help you with your first one.

[w30bob]

just me,

Thanks for posting. Seeing as you've rebuilt these diffs, are all the bearings still available? I see the spider gear kits from time to time, so they can be found..........I was just wondering about the bearings.

thanks,
bob

[just me]

Got mine from local axle house. VPW or others may also have them. (Not cheap, but once done should only last another 60 years.)

[Carter]

Before you replace anything Rick and with the pinion seal removed, reinstall the companion flange yoke and torque it down to the required 300 ft.lbs. and then check for movement and you may find that with the flange in place no side to side play is noticeable. The pinion needs to be drawn tight against the bearings in order to get an accurate gauge of free play if the rear was assembled correctly to begin with.

[MSeriesRebuild]

Carter has the right info here. I believe you mentioned there was no noticeable motion before disassembly. While it is absolutely true that 99 out of 100 differentials in these trucks have some undesirable issues going on; you very likely do not have serious issues with yours like you are thinking of.