in-frame gearbox rebuild

[pisten-bully]

parts arrived, so new bushing with my new brake cylinder hone (thanks Tom!) to size it:

5E09E2AD-47E4-4681-99E4-39A2103A612D.jpeg

new cork washer for the back of the drive sprocket:

8ABD5BB8-C238-4E67-A989-E76E7713CFF6.jpeg

and checked clearance on the countershaft to bushings, .001

74D8BBAE-AD8F-466C-9D4B-CCB0CAF9F2FB.jpeg

Cleaning the case is a bit more difficult with the gearbox in the frame, that's for sure

[pisten-bully]

I also ordered a new generator drive bushing and seal. I couldn't detect any leaking from the drive at all...bushing only with no seal, and it's against my nature to replace things that are working as they're supposed to, so I'm curious if anyone has experience with the shorter bushing and seal...good, bad, or indifferent?

[tfburke3]

Glad it worked for you.
The corks can be to thick and bind so you may want to check the clearance without the cork then sand the cork down to stick out about+. 002 more than the clearance,then soak in oil and flip and install.
If you move the mic over 1/2 inch to the other side of that wear line you can measure for wear where the brass bushing rides on the shaft,then measure the inside of the bushing,subtract shaft dia.and thats the clearance.
The steel bushing and the shaft are stationary so any wear there is pounding. Measure the shaft in the middle where the spacer is and you should get the original shaft diameter with is probably .001 under like the plain end shown.
Tom

[tfburke3]

I also ordered a new generator drive bushing and seal. I couldn't detect any leaking from the drive at all...bushing only with no seal, and it's against my nature to replace things that are working as they're supposed to, so I'm curious if anyone has experience with the shorter bushing and seal...good, bad, or indifferent?

Either way is fine.The original setup gives a little more bushing surface and if it does start to leak you can think of of it as an early warning system for bushing and shaft wear.
At your milealge im suprised the shaft isnt worn.
Keep at it
Tom

[pisten-bully]

Thanks Tom. When I did the gearbox for my 101 Scout I had viewed Kiwi's great video on transmission rebuilds (https://www.youtube.com/watch?v=_HK06bLXYDE ) and it helped a lot. But it would have been a really long video if he were to cover every single detail so I thank you for filling in some of the missing pieces!

Taking a look at the counter shaft cluster gear bushings and shaft wear I find the shaft wear is small, .0003, but the two bushings are tight on the shaft (explains why it took lots of hits to get that shaft out), I can't push the shaft through the bushings by hand, must have used a press to get that shaft in? I only hope the bushings weren't turning inside the cluster gear and wearing the bore of the gear instead of wearing the shaft! Greer's shows a 1" o.d. on their bushings, next step is to measure the bore of the cluster gear and cross my fingers!

Cluster bore where the bushings fits measures up .9975

[tfburke3]

The shaft should slide right in and gear spin free.Only the bushings are pressed in. think bushing clearance is .002-.004but would have to look it up.
The shaft may be bent,the only tapping is the last 3/4" or so into or out of the case.If you had to press the old bushings out your good(plus that measurement looks good).
I would find someone with a sunnen type hone to fit the shaft after both bushings are pressed in and your sure shaft is straight,not the brake cyl. hone.
Tom

[NiteOwl]

Just wanted to say, This is a great thread, thanks for posting it! Very informative.

[pisten-bully]

All I had time for today was installing the new bearings in the case. I used a heat gun to heat the area around the bearing seat, then pressed the bearings in with a screw jig that I put together:

A69A653A-68CD-4495-8CE9-49DBB6ACE060.jpeg

[pisten-bully]

The sprocket side bearing went in easily, but on the clutch side bearing I had to re-heat as the bearing stopped moving halfway in. I also tapped the hole in the case provided for access to the counter shaft and installed a 3/8-16 plug in the hole (just below the sprocket bearing).

And the bearings supplied by Greer's are sealed (both sides) so I'll remove the seals on the bearings sides that face into the gearbox.

[Peter Cooke]

And the bearings supplied by Greer's are sealed (both sides) so I'll remove the seals on the bearings sides that face into the gearbox.

Just curious as to why you would do this given the bearings are pre lubricated for the life of the bearing by the OEM?
If it's a crash box wouldn't you be leaving the bearing at more risk of damage from metal particles?

[pisten-bully]

Just curious as to why you would do this given the bearings are pre lubricated for the life of the bearing by the OEM?
If it's a crash box wouldn't you be leaving the bearing at more risk of damage from metal particles?

Good question! "Lifetime lubrication", I think, leads to a false sense of security. No bearing will last forever ...so which came first (chicken and egg sort of thinking) the bearing fails because the metal wears out, or the bearing fails because the lubrication is gone? At least by removing the inner shield the oil in the gearbox can lube the bearing, but if the shield is in place and the factory installed grease eventually breaks down then the oil in the gearbox can't reach the bearing. It's my opinion of course, and there are lots of sealed bearings that live long lives, so I'll keep using magnetic drain plugs and change gearbox oil every few thousand miles.

[pisten-bully]

Just as an illustration to show you how I came to this bias, here's a picture of a sealed bearing on an axle of one of our machines. Notice the seal is letting lubrication escape, as it ages and works for a while the lubrication breaks down and the seals can't keep it in and the bearing goes dry. Even though the bearings are fully visible (unlike inside a gearbox) many of my customers ignored the early warning signs of oil specks outside the bearing and continued to run them ....resulting in more expensive repairs. The bearings in our transmissions, on the other hand were all open and running in oil (splash) and we had zero failures of our transmission bearings. So that's how I've come to this way of thinking...right or wrong

bearing #2 copy.jpg

[Peter Cooke]

That all makes sense to me and seeing what you're seeing at work would no doubt have me thinking the same way. I like the magnetic drain plug idea.
Everyday's a learning day!

[pisten-bully]

Now I'm in the re-assembly stage, I've replaced the bearings, replaced the bushings in the clutch hub and triple counter shaft gear cluster, checked the drive sprocket driver bushing and the splines and decided they were good.. as were all the gears. (I'm sure I'm forgetting some odds and ends here!).

But first, here's my "work environment" ... nothing fancy just a Chief on its center stand crammed into a shed:

workspace.jpg
One big motivator for me was to stop a persistent oil leak from the primary, and that's why I removed the inner primary (not necessary for this job) so that I could seal up those joints, and I also went with a new generator drive bushing and modern seal...even though I could not detect any leaking from there. I really gobbed on the Hylomar (cleaned up there):

primary.jpg
So most of what I have to do now is install the main shaft and then the clutch and kicker gear... check the main shaft end float once more because for some reason I had to drop .030 on the thrust washers from what was originally in there to get to .007 top down.jpg :

So that's it, skipped over a lot of things but I couldn't really present a step by step. I strongly suggest watching the Kiwi Mike video, it's not step by step either but very, very good. So, if you need some parts you might consider Kiwi Indian as your source to support his efforts.

And now I've got trips to go see family all complicating my schedule... thanks Covid!

[PaulCDF]

Looks GREAT Harry; Thanks for posting. Really nice work and pictures. Enjoy that family time.