76 Muskeg differential rebuild- how much bushing play is acceptable?

[Chip]

Greetings- Just found the forum a few days ago and have really enjoyed poking through the archives. There's a pile of good info here. Several other piles too. Very helpful, entertaining and encouraging as I wallow deeper and deeper into grease and grime. I keep thinking there's not much further I can go, but there always seems to be more.

I'm looking at replacing the crown and pinion set, so I'll have the differential all apart, and there is a fair amount of play in the brake drum bushings; the edges of the drums will move about 1/16" when twisted side to side. Is there a standard method to measure the play (feeler gauge slid in the bushing?) and an allowable tolerance, or is it more a case of "that doesn't look like quite $40 worth of new bushing yet". Not having seen how tight new bushings are, I haven't a clue. I do know my wallet is tighter than the bushings, but I intend to work this machine in the woods for a while and I don't want to have to pull it all apart again in six months.

On a related note, has anyone found the large pinion gear bearing seat in a differential carrier to be out of round? I've seated (and reseated) a new race in it and the new bearing doesn't ride right. The rolls don't roll all the way around, just on opposite sides. I thought the race might be skewed, but it is fully seated and the individual rollers skip rolling in the same areas both times I set the race. There was very bad asymmetric race wear on the bearings I removed, and I suspect this might be the root cause of that.

Thanks

 

[MNoutdoors RIP]

Greetings- Just found the forum a few days ago and have really enjoyed poking through the archives. There's a pile of good info here. Several other piles too. Very helpful, entertaining and encouraging as I wallow deeper and deeper into grease and grime. I keep thinking there's not much further I can go, but there always seems to be more.

I'm looking at replacing the crown and pinion set, so I'll have the differential all apart, and there is a fair amount of play in the brake drum bushings; the edges of the drums will move about 1/16" when twisted side to side. Is there a standard method to measure the play (feeler gauge slid in the bushing?) and an allowable tolerance, or is it more a case of "that doesn't look like quite $40 worth of new bushing yet". Not having seen how tight new bushings are, I haven't a clue. I do know my wallet is tighter than the bushings, but I intend to work this machine in the woods for a while and I don't want to have to pull it all apart again in six months.

On a related note, has anyone found the large pinion gear bearing seat in a differential carrier to be out of round? I've seated (and reseated) a new race in it and the new bearing doesn't ride right. The rolls don't roll all the way around, just on opposite sides. I thought the race might be skewed, but it is fully seated and the individual rollers skip rolling in the same areas both times I set the race. There was very bad asymmetric race wear on the bearings I removed, and I suspect this might be the root cause of that.

Thanks

we have been repairing differentials for over twenty years and what you are describing is acceptable on that differential. anymore than that then replace.
there is a timing procedure on those internal pinions ( the long straight cut gears in the differential ) there should be a punch mark on the ends make sure they all point the same typically toward the center or it with rotate several times and lock up. here is a link to your differential for repair

http://www.mn-outdoors.com/documents/T-16ControlledDifferential.swf?

 

[snowbird]

Welcome to the forum! Glad to see another Bombardier "user". I think you'll find that "Boggie" and others are a super help with most any problem you'll face in your restoration. I've got a Bombardier SkiDozer and enjoyed restoring it and driving it (although we're going to need some snow).

 

[Chip]

Hey, thanks for the quick replies!

I've got a Bombardier SkiDozer and enjoyed restoring it and driving it (although we're going to need some snow).

Snowbird, thanks, but I can wait a bit for snow, my machine is in pieces strewn around the driveway.

Boggie- I appreciate your expertise and the link. Two Questions:

Is there a way to pull the end bearings without the handy-dandy puller; and
do you have any thoughts on my pinion bearing seat?

 

[DynatracGuy]

Boggie,
Thanks for posting the differential repair. As a Muskeg tractor owner it may be a real life saver sometime in the future.

 

[MNoutdoors RIP]

Hey, thanks for the quick replies!

Snowbird, thanks, but I can wait a bit for snow, my machine is in pieces strewn around the driveway.

Boggie- I appreciate your expertise and the link. Two Questions:

Is there a way to pull the end bearings without the handy-dandy puller; and
do you have any thoughts on my pinion bearing seat?

It is very hard to get a ordinary puller under those bearings about the only thing that work which means you will destroy the bearing is to cut the outter cage take the rollers out and then very carefully cut into the bearing with a thin cutoff wheel at an angle DO NOT OVER DO IT. then give it a hit with a chisel and it should crack then it will come right off. sometimes after you cut the cage and remove the rollers you can get a two piece bearing puller to grab it. we use the factory puller

with the bearing race out have you checked for out of round on the the seat where the race goes? somebody may have used heat in the past and caused it to warp.

 

[MNoutdoors RIP]

Boggie,
Thanks for posting the differential repair. As a Muskeg tractor owner it may be a real life saver sometime in the future.

This is the standard differential for the bombardier's except the little bombi,br100 and the br100plus. it is the same as almost all the others.

to name few sw48,sw54,sw64,j5,br60plus,sv200,sv250,sv252,sv300sv301,sv302 they all use the same diff. with three possible ring and pinions 6/35 is the most common right hand ring left hand pinion. just a few had left hand rings with right hand pinions and some of the muskegs have 9 tooth pinions if the have the final drives from about 1972 on.

 

[Chip]

It is very hard to get a ordinary puller under those bearings about the only thing that work which means you will destroy the bearing is to cut the outter cage take the rollers out and then very carefully cut into the bearing with a thin cutoff wheel at an angle DO NOT OVER DO IT. then give it a hit with a chisel and it should crack then it will come right off. sometimes after you cut the cage and remove the rollers you can get a two piece bearing puller to grab it. we use the factory puller

with the bearing race out have you checked for out of round on the the seat where the race goes? somebody may have used heat in the past and caused it to warp.

Yes, the seat is out of round, min/max dias measured 4.123 and 4.128. The original machining spec I got was .123 - .124, so if I remove any more metal it will be oversized. But, I think before I pull out the diff carrrier to have it machined (is there enough meat to sleeve the seat?) my machinist buddy suggested making a screw jack with a head and foot turned to fit the seat curvature and try to rewarp the seat back to round- I can't help notice this damn smiley next to my typing box here... - I might also try blueing the seat and fitting a series of turned plugs into it to scrape the blue off the high spots and then ease them down by hand. Maybe I can get it round enough and locktite the race in. I really don't want to reinstall a diff carrier 'cause it sounds like a tough job to get the drive axles lined up right- is it difficult to do that? The service manual says to use a set of rods and sleeves, which I don't have.

 

[Chip]

Well, I pulled out the differential carrier after all, which makes it much easier to work on. Tried the screw jack, which improved the diameter variation in the large pinion bearing race seat from .005 to .0015, so the bearing runs pretty evenly now. Sometimes the easiest solution actually works (I think I lucked out).

The end bearings on the differential came off pretty hard- we removed the retainers and rollers, then before trying to cut and crack the races off, we tried grinding a groove under the outer edge of the race on both sides, and we got a two armed puller on it with a clamp to hold it and pulled them off.

Here's the jack. The bottom is tapped for the threaded rod and the top has a smooth hole so that turning the nut spreads the ends. Their radius is a bit smaller than the race seat:

 

[Chip]

Next question: I have to replace a steel sleeve in the differential that the brake drum spins on. The manual says drive it on, but it's pretty tight. Is heating it the way to go? By the color of the new one it looks as if it might have been heat treated. What do you do, Boggy?

 

[Chip]

What do you do, Boggy?

Sorry Boggie, no slight intended. Shouldn't be posting after my bedtime.

 

[MNoutdoors RIP]

Next question: I have to replace a steel sleeve in the differential that the brake drum spins on. The manual says drive it on, but it's pretty tight. Is heating it the way to go? By the color of the new one it looks as if it might have been heat treated. What do you do, Boggy?

Heat is the way we put them on, normally you can get by with just a small propane torch, do not over heat, they are heat treated

 

[Snowtrac Nome]

i don't know about what these bands look like but if it is practical you gan do like i do with bearings on and that would be heat up some oil to over 200 some thing like 215 to 230 just below boiling degrees drop in your metal piece let it warm to thr temp of the oil take it out and prestoyour bearing will slide over your press fit shaft

 

[MNoutdoors RIP]

i don't know about what these bands look like but if it is practical you gan do like i do with bearings on and that would be heat up some oil to over 200 some thing like 215 to 230 just below boiling degrees drop in your metal piece let it warm to thr temp of the oil take it out and prestoyour bearing will slide over your press fit shaft

yes, if you have a old fry daddy , french fry cooker they work great just do not tell your wife and put it back

 

[Chip]

Well, I put them on with the torch so I wouldn't have people or critters wandering into my shop looking for something to eat, although french fry oil would be an improvement over the diesel fuel vapors- I'm soaking my brake bands to try to displace the gear oil which the previous owner put in the diff. case. Not sure how I'd know if they are cleaned out enough to work well. Maybe I should deep fry the brake bands, along with a couple of rubber gaskets for flavor.

 

[MNoutdoors RIP]

Well, I put them on with the torch so I wouldn't have people or critters wandering into my shop looking for something to eat, although french fry oil would be an improvement over the diesel fuel vapors- I'm soaking my brake bands to try to displace the gear oil which the previous owner put in the diff. case. Not sure how I'd know if they are cleaned out enough to work well. Maybe I should deep fry the brake bands, along with a couple of rubber gaskets for flavor.

come on "chip" you should have deep fried them in 10W-30

 

[59muskeg]

Hello Chip,ant those muskeg diffs fun, On those bearings you were trying to get off,remove the cage and rollers, run a bead of weld on the inner part of the bearing where the rollers use to ride,a mig welder is best. After the welding grab the bearing with channell locks,it should come rite off due to the heat from the weld,i have done this many times. How much water was in the was in the diff compartment when you pulled the cover? Make sure your axel seals and top cover are sealed good and that there is no other way for water or muddy water to get inside the diff area.

 

[Chip]

come on "chip" you should have deep fried them in 10W-30

Dang! I could've had brakon with my muskeggs.

 

[Chip]

Hello Chip,ant those muskeg diffs fun, On those bearings you were trying to get off,remove the cage and rollers, run a bead of weld on the inner part of the bearing where the rollers use to ride,a mig welder is best. After the welding grab the bearing with channell locks,it should come rite off due to the heat from the weld,i have done this many times. How much water was in the was in the diff compartment when you pulled the cover? Make sure your axel seals and top cover are sealed good and that there is no other way for water or muddy water to get inside the diff area.

Hi 59, I'll file the bearing removal trick away for future reference- sounds slick. Not much water, just enough to pit the crown gear badly in spots ($1700 worth of water actually).

So speaking of leaks, on the diff cover, how do the brass seal washers work? I figured they'd have some kind of rubber coating or something to seal around the studs, but no. Do they just keep things from rusting together? And the seal washers on the diff carrier bolts, which did have a rubber coating, are supposedly no longer available. What to do. Grease the gaskets and ?

 

[Chip]

After rebuilding the differential with a new crown gear, bushings, etc, pulling the differential carrier and finally reinstalling the whole shebang, I have a couple of ideas that might be helpful to others, to add to those in earlier posts. Here’s the mess I found when I opened Pandora’s gear box- not too bad, but bad enough:




To remove the differential, you loosen the pinch bolts and back off the bearing collars on either side. Before you turn the collar, clean out any crud in the threads, especially in the gap where the bolt is. Flush or blow out any grit that could work its way into the threads. Someone had adjusted the backlash previously by turning the collars with a punch and bunged up the notches in the collars pretty good. I had to grind the mashed parts down so I could get the collars out. They turned pretty hard until I sprung the gap open a bit and liberally oiled the threads, then I could turn them fairly easily with a square shank screwdriver in the slots.

Before I took out the diff. carrier, I ground a couple of little notches across the top edge (across the gasket) where the carrier is bolted to the flange on the tub on either side to help locate the carrier when reinstalling it. Of course, if you put in a different carrier, this won’t help you a bit, but it allowed me to get the carrier back in very close to where it was originally so the stub axle alignment was pretty good. When you cut the welds, try to cut as close to the side wall of the tub as you can. I had to grind a bit with a dremel tool (very tedious- I don’t have a die grinder) on one side to get clearance for the edge of the carrier to slide up and out, and you don’t want too big a gap to weld up when you reinstall it.

Got the rebuilt differential adjusted in the carrier with .009” backlash (the manual says .007-.011”) and ran a tooth pattern with machinists blue layout dye. I’m posting this photo because the tooth pattern pictures in my photocopied manual are illegible, and I couldn’t find any others. The rubbed spot should be centered on the tooth, but I decided this was close enough to avoid removing the diff., pulling the pinion gear out, driving out the large race and changing the shim pack (I put the same shim pack thickness back that was there originally) and reinstalling the race, pinion bearings, re-shimming the pinion, reinstalling the diff. and adjusting the backlash and running a new tooth pattern and then discovering I took shims out when I should have added more or vice versa and then have to go through the whole exercise again.



Since I was working by myself and have no hoist I had to take the differential out of the carrier again to put the carrier in the tub (the notches got me aligned), and then reinstall the diff. and readjust the backlash, then check the alignment of the stub axles as best I could. I probably just about wore out the threads on the bearing collars; I did wear out my patience; you need to shift them over about an inch and you can only get 1/6 of a turn with each notch. Tedium ad nausium. Once you have the carrier aligned, be sure to use threadlocker on the bolts, then weld the joints and clean up. Keep the diff and final drive bearings covered and clean!


The brake bands have to be sprung over the drums which I found bent them open so that they didn’t lay around the drums quite right. I tried to spring them back, slipping a rod between them and the drum to bend them over, and was moderately successful. One still drags slightly when turning in reverse, but hopefully 80 horsepower moving 8000 pounds won’t notice. Greased the gasket, poured in a bucket or two of trans-hydraulic fluid, bolted down the cover and plopped the engine onto its mounts just before it started to rain.

Well, there. Wish it went as smoothly as it sounds in this description. The next one certainly will be easier.

 

[how610]

Chip: I am looking for a Crown & Pinion set for my 1970 Muskeg Tractor.
Where did you find your parts??