H55F pitting on output shaft journal - replace or re-use? (1 Viewer)

[Eurasiaoverland]

Hi All

I'm rebuilding a circa 1988 H55F from a BJ60. Where I live, it's not as simple as buying a new H55F and swapping the input shaft, so I have to do a piecemeal overhaul. I was hoping to re-use the output shaft, the rear splines are perfect (and it's -60071 with the longer splines than the currently available -60072) but on the journal for 1st gear there is some minor pitting. I think the vehicle was sat for a long time and the previous owner seems not to have been keen on changing transmission oil. See the photo below.

I've cleaned the area with some 1500 grit wet-and-dry. The black marks are negative features (i.e. holes in the surface). In my mind the long needle rollers won't really feel these imperfections as they do not extend far across the journal. Also, the bearing is only moving when the gear is idling - it is never moving under any load (though as first gear it will be spinning almost continually during use, often at relatively high speeds assuming the box is in 5th).

I don't mind replacing with a new shaft, but I'm not keen to spend several hundred dollars on something which would be fine. What do you think?

For those that are interested, the transmission had badly worn gear teeth on the input shaft, rounded shift teeth on 3rd and 2nd gears, some corrosion on the inner race of first gear, rounded splines ends on the 1st - 2nd synchro ring assembly and worn splines on the 3rd - 4th shift hub (splines on the output shaft look and feel fine). All these items, as well as all bearings and synchro rings will be replaced. The counter shaft, 5th and counter 5th gears are fine, even though the box was not running an oiler cup (can't see the point of them anyway, but will add one when I rebuild).

Thanks

EO

 

[ChaserFJ60]

Of course there's only one right way and thats to replace.

But if its only spinning in neutral and its already a salvage type transmission it mayyy be okay? I only have the experience of rebuilding 1 h55f

 

[Spook50]

Hi All

I'm rebuilding a circa 1988 H55F from a BJ60. Where I live, it's not as simple as buying a new H55F and swapping the input shaft, so I have to do a piecemeal overhaul. I was hoping to re-use the output shaft, the rear splines are perfect (and it's -60071 with the longer splines than the currently available -60072) but on the journal for 1st gear there is some minor pitting. I think the vehicle was sat for a long time and the previous owner seems not to have been keen on changing transmission oil. See the photo below.

View attachment 3056923

I've cleaned the area with some 1500 grit wet-and-dry. The black marks are negative features (i.e. holes in the surface). In my mind the long needle rollers won't really feel these imperfections as they do not extend far across the journal. Also, the bearing is only moving when the gear is idling - it is never moving under any load (though as first gear it will be spinning almost continually during use, often at relatively high speeds assuming the box is in 5th).

I don't mind replacing with a new shaft, but I'm not keen to spend several hundred dollars on something which would be fine. What do you think?

For those that are interested, the transmission had badly worn gear teeth on the input shaft, rounded shift teeth on 3rd and 2nd gears, some corrosion on the inner race of first gear, rounded splines ends on the 1st - 2nd synchro ring assembly and worn splines on the 3rd - 4th shift hub (splines on the output shaft look and feel fine). All these items, as well as all bearings and synchro rings will be replaced. The counter shaft, 5th and counter 5th gears are fine, even though the box was not running an oiler cup (can't see the point of them anyway, but will add one when I rebuild).

Thanks

EO

If you've got it down to where you can't feel the marks at all with a fingernail, I say run it. Keeping oil in the tranny will keep them from getting worse, and as long as there's no burrs or anything sticking up from the shaft, you won't damage the bearing. Though this is the most we would consider serviceable (because hey, aircraft), we would continue using landing gear trucks with markings like this on the bearing races when I worked on the KC-135s in my active duty days.

 

[Eurasiaoverland]

If you've got it down to where you can't feel the marks at all with a fingernail, I say run it. Keeping oil in the tranny will keep them from getting worse, and as long as there's no burrs or anything sticking up from the shaft, you won't damage the bearing. Though this is the most we would consider serviceable (because hey, aircraft), we would continue using landing gear trucks with markings like this on the bearing races when I worked on the KC-135s in my active duty days.

Great reply, thanks. I can catch the marks with a fingernail, but there is certainly nothing sticking up to catch on a bearing roller. The worry would be that the rollers start to erode the journal more, but there was no visible damage to the old bearing and I feel like they will just trundle over it, given the bearing is stationary when drive is put through the gear.

Thanks

EO

 

[Spook50]

Great reply, thanks. I can catch the marks with a fingernail, but there is certainly nothing sticking up to catch on a bearing roller. The worry would be that the rollers start to erode the journal more, but there was no visible damage to the old bearing and I feel like they will just trundle over it, given the bearing is stationary when drive is put through the gear.

Thanks

EO

Nothing sticking up is a good thing. I should've worded that to say that as long as there's nothing sticking up that'll catch a fingernail you should be good. The pitting looks to be from minor corrosion likely from sitting stationary (and likely dry) for as long as it may have. Best of luck on the rest of the rebuild. Are you installing new synchro assemblies too?

 

[Eurasiaoverland]

Nothing sticking up is a good thing. I should've worded that to say that as long as there's nothing sticking up that'll catch a fingernail you should be good. The pitting looks to be from minor corrosion likely from sitting stationary (and likely dry) for as long as it may have. Best of luck on the rest of the rebuild. Are you installing new synchro assemblies too?

I just cleaned the shaft in petrol (gasoline), along with the old needle roller bearings that ran on the 2nd and 3rd gear journals (they are identical) and cannot detect the corrosion while running the bearing over it, no matter how slowly I rotate them or how firmly I press them against the journal, so I am happy to run with it.

But cleaning the output shaft and counter shaft have revealed some additional wear (light spline wear on the output shaft and wear on the counter 4th (or counter input) gear teeth... I wish I could have just bought a new H55F....

Yes, all synchros and most of the gears will be replaced... in fact pretty much anything that moves by the looks of things...

Thanks again for your help,

EO