PTO questions

[Daves rusty bits]

I`ve started to tackle the gearbox / back axle seals in my FPM. The oil was leaking from the gearbox through and out past the pto shaft so much I had to keep a drip pan underneath the back end while stopped and pour it back in the gearbox before next use.
I`ve got it almost ready to split in two, but the pto shaft has thrown up a couple of questions.
There is a metal disc loose inside the shaft, I can get hold of it with pliers but it won`t come out through the internal splines, its just a bit too big. Where is it from or is it meant to be there?

Next question, how do I get at the oil seal for the stub shaft, does the seal housing knock off towards the stub end or do I have to start on the inside , take off the large circlip and move everything inwards?

Thanks for your comments Dave

[whirly]

First question - I have no idea but second question I do.

Start at the back side with the circlip and remove the gear then 2 more circlips.

Here is the exploded view:

[AdrianNPMajor]

I'd like to agree with Whirly's comments.
The metal disc captive in the space beyond the splines is a bit of a headscratcher. I can only think that it was created somehow during the machining process, and as it didn't interfere with the meshing of the male and female parts the quality control guys at the factory let it pass. Just a guess, as I can't think of another explanation.
Re getting access to the seal, remove the first circlip that holds the gear in place, then knock the gear off its seat and remove. You can leave the second circlip in place - this acts as a stop for the gear. Now the gear is removed, you can get at the circlip set into the inner circumference of the casting. Remove this circlip, then tap the casting off the bearing. The casting is now in your hands. In the recess you will see the seal. Remove and replace, then reassemble.
The shaft looks rather rusty. I just wonder if it was spinning with very low oil levels in the back end. If so, once you have removed the casting, the bearing will be exposed for inspection. Check that any low oil levels haven't caused it to become worn.
Best, Adrian.

[Brian]

It is a bit of a fiddle but you do not have to remove the gear, at least I do not. You can get at the bearing circlip with a couple of long screwdrivers then just tap the housing off to get at the seal.

Your oil leak could be the PTO/gearbox seal but it could also be the large gear seal at the back of the gearbox.

[Daves rusty bits]

Thanks for the replies, they are most helpful. Whirly your diagram is much clearer than the one I have and it helps to see what is coming.
Adrian I was surprised at the rust, believe it or not I drained just under 75 litres of oily emulsion from the gearbox and backend so it must have been either low on oil in the past or just too high a water content in the bottom of the oil. It doesn`t seem to have attacked the metal very badly, I can rub my hand up and down the shaft and not feel it if that makes sense.
I have a day off on Friday and the plan is to replace the big seal, bolt the tractor back into one piece then take off the PTO gearbox and replace the smaller seal in there. Maybe more questions to come. I`ll try Brians` suggestion on the shaft seal hopefully it will save a bit of time and I do need the old boy back on the sawbench asap. Thanks Dave

[super6954]

Hi Dave
I'm with Brain on the bottom seals for the PTO drive to. Don't ask how I learned that when I started messing around with majors many years ago , as routine if I'm doing them I change both sets of seals, it seems some of them had leather seal material that dissolves rather than rubber compounds like modern seals, by changing them I know 99.9% i'm not going back 3 weeks after somebody uses the tractor and the oil starts mixing. or they don't realize and destroy the top bearings in the gearbox .
I have seen one super that the collar on the top shaft where the seal rides came loose and it by passed oil between the shaft and the inside of the collar to, leading a guy to think it was the top seal, I found that by filling the gearbox(before I took the pto drive from the bottom) and while it was split from the back end, I changed all the seals to be sure while I was there to.

With that plug in the shaft, im wondering if it was either a fixed part of the end of the welded spline insert from machining. Or a plug that was inserted and used to stop the shaft filling with oil. maybe excessive end float from a snap ring being pushed out the rear pto housing, Or a bad bearing allowing the pto to be pushed back onto the male shaft in the pto drive box by a pto driven implement , with to longer shaft to slide properly forcing it in. Then it's punched that piece out the end .
I have seen tractor shafts have considerable end float and found the snap ring or the groove busted out before. Maybe somebody repaired it and didn't notice the "plug " or didn't care .
Regards Robert

[Daves rusty bits]

Hello Robert,
Thanks for your message, yes I planned to do both seals while it was all apart but I see the one I got for the pto gearbox is only about an inch OD so I feel I may have got the wrong one,it looks tiny, time will tell when I get in there unless anyone knows the size needed.I was toying with putting a couple of pints of petrol in the gearbox followed by an airline to see if it shifted any crud.
I had wondered if I could refill the gearbox with oil with the tractor apart after replacing the seals and give it a day or two to see if it was oil tight.

The plug seems quite happy where it is, when I tilt the pto shaft and look down through the end I can see the plug is a perfect fit and doesn`t look damaged at all. If its been in there 50 odd years it can stay a few more.
I had a quick play with the pto shaft today but couldn`t release the circlip by the bearing as Brian suggested so I took the one by the drive gear off and tried to move the gear both by levering and driving it with a piece of wood and a hammer.I stopped when the wooden block disintegrated and it hadn`t moved. I feel a visit to my son`s garage coming on, he has a case full of circlip pliers I can try on the one by the bearing again, failing that I could use his press on the drive gear but I`m a bit reluctant in case I break it .
Thanks Dave

[AdrianNPMajor]

Hello Dave
The water in your oil has introduced rust into the equation, as you described above.
When you get to your son's garage, a little heat on the gear flange should do the trick. Mine tapped off with a minimum of effort.
This is the double lip seal you need for the PTO housing located below the gearbox.
Best, Adrian.

http://www.silverfoxtractorspares.com/f ... 1444-p.asp

[URL=http://s1216.photobucket.com/user/ ... .jpg[/img][/url]

[Daves rusty bits]

Didn`t get far today but I eventually got the drive gear off with heat and a blunt cold chisel, the last resort but with no damage. The old oil seal didn`t give in easily either, the rubber parts were like steel, hard as hell but it came out a piece at a time with a hammer and old screwdriver. Got the new seal in, tapped in with some grease and a seal fitting tool which I didn`t even know existed, borrowed from a friendly garage owner. Had to knock the drive gear back on despite cleaning and oiling the two contact surfaces it was still a bit of a slog and I really didn`t like doing it that way but got it fitted, again with no damage which was a result as far as I`m concerned. Celebrated by drilling and removing a broken bolt out of the seal housing, one of three used for attaching the pto guard.
Every little job seems to take about 3 times longer than I think and I havn`t got to the hard part yet!!.

[AdrianNPMajor]

Hello Dave
With your never-say-die attitude, you'll find that the hard part isn't quite as hard as you think!

Best, Adrian.

[Daves rusty bits]

Made progress over the weekend, the output seal is fitted and the tractor back in one piece. I`ve taken the pto gearbox off today and after reading up on one of Adrian`s old posts, took off the end plate and gave the shaft on the opposite end a bonk with a rubber mallet. This moved the bearings off their seats, but it also partially dislodged the spring clip which keeps the bearing in place. The clip went back on with a push from a screwdriver but I`m a bit uneasy that it came off in the first place.
I can see that the seal has started to disintegrate and perhaps a piece of it dislodged one end of the clip? Just forget it or replace the clip, it will be a bit of a job? Photo shows the refitted clip. Dave

[AdrianNPMajor]

Hello Dave
If the spring clip is back in its seat, it will be fine.
Rust is evident in this photo. Same issue as in the rear end. It could be that your gear assembly took a little more energy to get it to move, causing the clip to fly.
When I approach jobs like this I try to work out how the guys in the factory would have assembled it, then work backwards from there.
In this instance I think they would have installed the seal first, then tapped the assembled gear shaft (bearings clipped into place on the shaft) in through the opening covered by the end plate.
You have just reversed this process to replace the seal.
Once you put new oil in the gearbox and rear end, listen out for a sigh from the old girl!
Best, Adrian.

[Daves rusty bits]

Quick update, seals are finished and working. I was hoping to replace one of the axle seals while I was at it but pressure of work means it will have to be done later. Took the top cover off the back axle, it was fairly clean inside or so I thought until I looked at the filter in the bottom.



I gave it all a good clean ready for the new oil, will get a new filter gauze for when I do the axle seal.

Then to finish off this job I found part of a shim and a cigarette butt in the bottom of the axle.


More trouble? Dave

[Brian]

If that item is slightly dome shaped it is most likely a thrust washer from the dif. spider. Don't know about the cigarette butt though, what brand is it?

[Daves rusty bits]

Didn`t notice Brian, but there wasn`t any lipstick on it !