Transmission input shaft bearing

[bob in CT]

BIG HOSS:

That looks like a LOT of wear in that shaft. There is no groove like that in a good shaft.

George said the shaft needs to be ground down to .787 for the sealed bearing. The surface of the shaft should be RC58 for the bearing surface, but that looks like it worn into the softer core. That looks like it is half the depth of the splines. A new shaft is $95 from TM. That is the best deal I have seen, but a used one would be OK it you were not worried about the shaft surface as a bearing race if you intend to use the replacement bearing..

[BIGHOSS]

Local machine shop is going to build up groove and machine to fit ID of sealed bearing. I guess now with all of the slack out of the shaft (I'm talking big time slack), it will be harder to slide back through clutch, when it is installed back on tractor. I plan to use the long 1/2" bolts as guides.

[Donny M]

Hoss,

That shaft looks like it may have come out of a tractor that the PTO was used quite a bit with the tractor stationary. In that application not much splash lubracation is getting to the bearing. This is where a sealed bearing would be needed most.

[George Willer]

I just uploaded some pics of the teardown of transmission. The pic of the rear end of the main shaft shows a groove that the bearing wore. My question is this, was there a groove there when shaft was brand new? Or did the bearing wear that much of a groove over a 60 year period?

http://s222.photobucket.com/albums/dd21 ... all%20Cub/

Hoss,

Your pictures show clearly what happens when the galleries become plugged. The groove you show is the wear... it was originally smooth. Now I see why welding may be necessary. That groove looks like it's past the diameter to fit the replacement bearing.

[BIGHOSS]

Actually, as this was my dad' Cub, he never used the pto. The only implement was a cultivator. I think it was just wear and tear and neglect over all the years. The tranny was really noisy. With new front and a custom fitted rear bearing, don't you think it will be quieter?

[George Willer]

Actually, as this was my dad' Cub, he never used the pto. The only implement was a cultivator. I think it was just wear and tear and neglect over all the years. The tranny was really noisy. With new front and a custom fitted rear bearing, don't you think it will be quieter?

It's reasonable to expect quieter but it may not be. It depends on how much the geometry of the gear teeth has been altered by wear while the gears are running a little too far apart. Let's hope for the best!

BTW, you didn't ask but I think you should replace the busted 1/R shifter fork rather than welding it.

[VinceD]

Jack up one rear wheel, put the tranny in gear, any gear then take the shifter off the transmission, now with your face near the top of the transmission start the tractor. Oh, I should mention; bring a towel.

I did this (once) when attempting to find the source of a noise in my transmission. Seemed like a good idea at the time. With the help of a stethoscope, I did find the source of the noise. However, it took more than one towel to clean me and the tractor. At least Annie got a good laugh out of it

[Bigdog]

Another point concerning lube level is that since this is a splash lube system, overfilling it can decrease the effectiveness of the spinning gears to throw the lube inside the case. The fact that so many of them have survived 40 - 50 years with original bearings is a testimony to the design. Add to that the relatively few of them that received proper maintenance over that time frame and it gets even more impressive.

[Gary Dotson]

While I'm not real impressed with the design of that bearing set-up, I certainly can't argue about it's durability. Mine was 55 yrs. old when the failure occured, with all the usual muck from years of neglect.

I always try to keep several bearings around the shop, so I started scrounging through them, to find a replacement and got lucky. The rest is history. Had my shaft not been damaged, I would have replaced the bearing with the original style.

I have no concern with lube escaping the sealed bearing. Everyone of us owns countless items with similar setups, many of them seeing more abuse than the Cub trans. The motor on your air compressor is a good example, you'll expect it to run for many years, without issue.

[Boss Hog]

I just uploaded some pics of the teardown of transmission. The pic of the rear end of the main shaft shows a groove that the bearing wore. My question is this, was there a groove there when shaft was brand new? Or did the bearing wear that much of a groove over a 60 year period?

http://s222.photobucket.com/albums/dd21 ... all%20Cub/

With all that water I think I would at liest check the lower bearings if not replace them
David

[BigBill]

Bill, I just talked to Kit yesterday and he tells me what a great guy you are... I know he is right, and I appreciate the assistance you sent me on Gilles Cadet. I have also met and conversed with both GW and Donny on many occasions, I hold them in the highest regard both personally and especially regarding Cubs.

Neither was trying to offend you, that is not their style.

That transmission was used in well over 300,000 tractors (same one in originals, 100's etc Cadets) and I am sure carelessly (not) maintained by a decent sized group of owners. I consider it bullet-proof and certainly time tested. One of the most reliable pieces of machinery I have ever touched. I am pretty sure the 'problems' with it are due to an operator ignoring the obvious sounds of a bearing problem until the fixes mentioned are required.

I believe that is along the lines of the point they were trying make.

I have pretty limited mechanical experience, but I did try synthetic gear lube in a snomobile chain case (transmission) before it was common and the stuff would come out the seals. Not sure why that happened, but I changed the synthetic out and it quit doing it. The lesson I took from that (right or wrong) is not to use synthetic in an 'older' application. I figured it was the seals. Looked to me like a leak since it was 'leaving' the case. Went back to dino lube and problem solved. Ever since then I am a bit leery of deviation from the 'factory recommended' lubrication.

No problem I get over exceited sometimes and working in the real world then working for engineers i tend to look at things a different way. You guru's have the fixes. Sorry if i offended anyone, if i ever get over exceited again please feel free to slap me again ok. I have to realize my 52 cub is very old and its been really abused to the max too. I'm sure all our tractors have seen lack of maintenace too.

I asked my neighbor when he changed his oil last in his ford 8n and cub cadets, he said never..... I took the cover off his gearbox on his brushhog and the gear oil looked really bad. My point is i'm sure there are a lot of tractors treated like this too were seeing the results of many years of neglect and abuse. Its really not the tractors fault but you have to wonder why it lasted this long in this condition. I guess there pretty tough.

[Joe Howard]

The pictures aren't as clear to me as they'd need to be for me to thoroughly understand, but I assume you're talking about the upper transmission shaft train.....the one that has the dogdick that goes into the flywheel. I'd like to throw up a flag to those contemplating weld repair to build up that shaft to just over the diameter of a proposed "inner race" bearing application in lieu of a needle bearing arrangement where the needles run on the shaft. Is that correct? That being the case, that has long been an accepted practice, but not to the metalurgists.......weld buildup creates stress risers in the metal because of the high heat associated with weld buildup; kinda crystalizing the metal and making it brittle, and increasing dramatically the probability that that shaft will break sometime in the future, the only thing being up for grabs is when. A better fix, and one that I have seen on pump applications where the shaft-to-bearing inner race fit has been lost is to (1) machine the shaft down until getting to good metal (which will likely be only a few thousandths), chamfering the ends of the undercut a bit, (2) make a bushing whos inner diameter is that of the shaft undercut, (both width and diameter) and whos outer diameter is that of the proposed bearing inner race, then (3) split the bushing (axially) and put the two halfs on the undercut shaft and slip the assembly into the new bearing. Works slick as snot. Just a thought, again I'm not COMPLETELY sure I'm on track with the real problem but I think so. JH

[BIGHOSS]

This is a great thread with a great deal of fresh thoughts, ideas and concerns. This has a great interest with me, because I am right in the middle of the transmission repair. So, I actually know what most of you are talking about, which is rare for me.

Some more points for discussion:

1. Is the shifter fork actually broken? I went to the local IH/Case dealer yesterday for bearings, etc, We neither one could see what was broken. The top of the RH side portion is made from machined bar stock. While the bottom is made from a stamping. The dealer had a new shifter fork and it is made from a completely different design. Remember, this is s/n 9216. Maybe, I need to make some more pics for better clarity.

2. That is a good point that D. Howard made about welding on the shaft. I plan to talk to the machine shop about the possibility of a sleeve or bushing fitted to the shaft to make it fit the ID of the new sealed bearing.

3. How much clearance is needed where the front of pto shaft slides into the input shaft? As you know, there is a brass bushing inside the input shaft. There is quite a bit of loose play now. I don't believe that a new "off the shelf bushing" would be the way to go. Because, the pto tip is pitted and needs to be cleaned up. So, I'm thinking that I will let the machine shop clean up the pto shaft and make a new bushing custom fitted to the input shaft. I just didn't know what the clearance should be, since the main shaft turns free when the pto is not engaged. If the fit is too tight, wouldn't the pto, while dis-engaged, have a tendency to creep?

Your thoughts please>

[George Willer]

This is a great thread with a great deal of fresh thoughts, ideas and concerns. This has a great interest with me, because I am right in the middle of the transmission repair. So, I actually know what most of you are talking about, which is rare for me.

Some more points for discussion:

1. Is the shifter fork actually broken? I went to the local IH/Case dealer yesterday for bearings, etc, We neither one could see what was broken. The top of the RH side portion is made from machined bar stock. While the bottom is made from a stamping. The dealer had a new shifter fork and it is made from a completely different design. Remember, this is s/n 9216. Maybe, I need to make some more pics for better clarity.

2. That is a good point that D. Howard made about welding on the shaft. I plan to talk to the machine shop about the possibility of a sleeve or bushing fitted to the shaft to make it fit the ID of the new sealed bearing.

3. How much clearance is needed where the front of pto shaft slides into the input shaft? As you know, there is a brass bushing inside the input shaft. There is quite a bit of loose play now. I don't believe that a new "off the shelf bushing" would be the way to go. Because, the pto tip is pitted and needs to be cleaned up. So, I'm thinking that I will let the machine shop clean up the pto shaft and make a new bushing custom fitted to the input shaft. I just didn't know what the clearance should be, since the main shaft turns free when the pto is not engaged. If the fit is too tight, wouldn't the pto, while dis-engaged, have a tendency to creep?

Your thoughts please>

Hoss,

1. I can't explain the different appearance of your fork but the usual failure mode is for the upper part to separate from the fork part. This prevents the fork from properly clamping the rail. Clever machinist repair in the past? I'd replace it.

2. J.H. has a point if the shaft is high carbon. Our opinions may differ about the metalurgy of this particular shaft. They aren't particularly hard and not likely high carbon. I would prefer not to weld it but sometimes you do what you have to do. His idea of the split bushing has merit. I've been thinking about assembly (the bearing should go in the case first) and think the bushing halves could be taped to the shaft until they're started into the bearing bore.

3. That wouldn't be the first time for a custom pilot bushing. The PTO pilot can wear on one side if the tractor is used a lot with the PTO in a fixed position. I think John !#$%^& had that problem. I'd say .001" to no more than .002" running fit. (confirmed from Machinery's Handbook)

[Jim Becker]

2. J.H. has a point if the shaft is high carbon. Our opinions may differ about the metalurgy of this particular shaft. They aren't particularly hard and not likely high carbon.

I don't have any hard data (intended) on the metalurgy of the shaft. But IH was pretty big on induction hardening. I wouldn't be surprised if the original bearing surface was induction hardened. If there is much wear, most if not all of the hardened surface could be gone.