MTFCA Forum

I have the Muncie apart and am looking at replacing some bushings. There is a bronze pilot bushing in the input shaft that the end of the output shaft rides in. As it is now, the bronze pilot bushing is a slip fit in the input shaft. So, the outside of the bushing can turn in the hole in the input shaft and the output shaft can turn in the inside of the bushing. The hole where the bushing goes is ground so it could be that it’s designed to do this, but I have never seen a pilot bushing like this. Should the bushing be fixed in the hole or is this how it was designed?

Hi Morgan,
I have not had a Muncie apart for a while but the one input shaft I have is, not machined smooth in fact it is rather rough machined. As best as I
remember that bushing is pressed into the input gear & turns on the output shaft. This is not a real critical thing as the input & output shafts do
not turn in each other very fast because in direct they don't turn at all & in over & under they only rotate the speed of the difference in the
ratio speed. But if you look close there is a hole for oil in the input shaft to allow oil to pass from the pilot bearing to in front of the input shaft
bearing that will allow oil to travel through the pilot bearing to the coupling that you where concerned about ( sorry I forgot about that ) so if
the bushing is floating in the input shaft it can block that flow of oil through the pilot bushing there for leaving it not adequately lubed. That
gear looks good seems you found a pretty nice Muncie!
Craig.

Thanks Craig, that’s what I was thinking. I can order some bushing material and fit it properly. I am thinking of replacing the bushings in the idler gear as well while I have it all apart. They are a bit worn on the ends so the gear is rubbing on the case instead of the bronze.

This one is in pretty good shape. The nose of the gears show some wear, but it’s not bad. The bearings were bad but I am replacing them.

I have a Jumbo that was rebuilt at one time using brass bushings on the cluster shaft instead of roller bearings. They are all loose to the point of being a drop fit. Because of the oil holes, was thinking of making new bushings and using sleeve lock to hold them in so the oil holes stay lined up.

The bushing should be a press fit in the input shaft. Most likely, if the hole in the shaft is not worn, a standard sized bushing should fit. You may need to resize the bushing ID after press fitting.

Mark Gregush wrote: ↑

Thu Oct 31, 2024 11:38 am

I have a Jumbo that was rebuilt at one time using brass bushings on the cluster shaft instead of roller bearings. They are all loose to the point of being a drop fit. Because of the oil holes, was thinking of making new bushings and using sleeve lock to hold them in so the oil holes stay lined up.

If you're making new bushings, why not just size them for a press fit and forget about the "sleeve lock"?

The old bushing has a spiral oil grove. Put that back in after sizing. Avoid the tightness trap. Leave plenty of clearance for the 600 wt to lubricate.
Absent of other evidence, like a shaft that is a slightly odd undersized to make clearance for a standard reamer size, I would shoot for .005" clearance.
In my limited experience with aux transmissions, feed back on a unit I restored confirmed 600wt grease was the best stuff to use.
Made for a "much quieter" gear box & easier shifting.
Good luck. I find restoring these gear boxes is quite satisfying.

Jerry VanOoteghem wrote: ↑

Thu Oct 31, 2024 12:25 pm

Mark Gregush wrote: ↑

Thu Oct 31, 2024 11:38 am

I have a Jumbo that was rebuilt at one time using brass bushings on the cluster shaft instead of roller bearings. They are all loose to the point of being a drop fit. Because of the oil holes, was thinking of making new bushings and using sleeve lock to hold them in so the oil holes stay lined up.

If you're making new bushings, why not just size them for a press fit and forget about the "sleeve lock"?

The inside of the cluster gear is/was a bearing surface so is maybe too smooth to grab a bushing pressed in and hold it. My lathe skills are good, but my lathe might not be able to keep that close of tolerance.

For what its worth, .001” press per inch of diameter is a respected standard.