Back End-Gearbox

[billy]

hiya chaps,

I'm posting this just to get the answer from someone else. I am sure I know what the issue is. But cause its a bloody big job, I could do with reassurance.

So, about 6 months ago (Novemeber) I changed the half shaft seals and bearings and refirbbed the hydraulic housing.
I then filled up back axle oil and changed gearbox oil while I was at it. (to the full marks)

Now, ive come back to the old girl after about 4 months, and thought i'd better check me levels, as she hasn't run since Jan. I found the gearbox level was, well from the filler cap I couldn't see any oil.

I then looked at the back axle oil. its well over full! like nearly two inches on the dipstick.

I think I know the fault.
Advice would be great. And what else should I be considering when shes apart...


Thanks!
Billy

[Brian]

Your problem is a common one with a Major, it can be the seal on the large gear that will mean splitting the tractor at the rear section or it could be the seal in the PTO housing at the bottom of the gearbox.

You could also do what most of us do with the same problem, connect a pipe to the trailer tipping port and quickly transfer the oil back to the gearbox by using the hydraulic lever. The oil will take time to transfer back so you would possibly have to do it once every six months or so.

[henk]

I have the same problem, but since I'm using my pto for de 3p lift I have to shift les oil back. It's not completly gone, but the problem is getting less.

[billy]

thanks guys,

I would kinda like to fix it properly. Is there a way I can work out which seal is leaking? or would it be best to change both?

I know its quite a job, but once the rear end is off, its only a couple of bolts isn't it?
What else is worth doing if she is split?

Sorry for the questions, just want to know what I'm getting myself into!

[AdrianNPMajor]

Hello Billy
If you choose the seal-replacement option, as opposed to periodic pumping of the oil back to the gearbox, then I'd bite the bullet and do both.
That means splitting the tractor between the gearbox and the rear end, as you know.
Once split, the hard work is done. The upper gearbox seal is easy to get at and replace.
Whilst the tractor is split, it would be a good idea to remove the hydraulic lid and the hydraulic oil filter, apply some degreaser to the floor of the rear axle housing and give it a good power wash. This will remove the 50+ years accumulation of gunk. The effluent will flow out of the front of the now split rear axle housing, thereby ensuring that everything is as clean as a whistle. Clean the hydraulic oil basket filter and reassemble. [Good idea to refill with new oil if the budget will allow.]
It would also be wise to dismantle the brake and clutch pedal assemblies so that you can remove the brake/clutch cross shaft. You can then winkle out the two cross shaft seals and replace those.
Finish by dropping the PTO housing below the gearbox to get at the seal that keeps the gearbox oil from flowing down the PTO shaft tunnel into the rear axle.
The end result of your work will be very satisfying.
Good luck.
Best, Adrian.

[billy]

thanks!!

nice kinda what I already thought! Thanks for making it crystal clear!

I had the hydraulics apart and give it a proper clean out back when I did the half shaft seals, so that part of the job done

I might be asking too much now, but a bit of a parts list would be good.
I'm flicking through the agriline parts book, and I'm a little confused what seal it is I want for the gearbox seal, one is called 'oil seal output shaft' the number is 7395. the other one is 'transmission drive shaft oil seal' the number is 50358.
The first seal has bigger internal and external diameters.

Also I'm assuming its gasketed between the gearbox and backend, can you buy it or has it gotta be a home made paper one with a bit of hilermar.

and....does anyone know a rough weight of the backend, I wanna make sure my lifting gear will do the job

right, I think that's everything...
many thanks

[AdrianNPMajor]

Off the top of my head I can't remember the dimensions of the seals. Once you've removed the old ones, a quick measure with a vernier caliper of the housing and shaft diameters will tell you all you need to know. The seal for the PTO housing needs to be a double-lip seal.
Yes, there is a gasket between the gearbox and rear axle housing. The gasket is available from New Holland. If the tractor hasn't been split before, you may need to make some thin steel wedges to crack the original gasket seal to separate gearbox from rear axle - I had to. A wire brush wheel on the end of an electric drill is great for cleaning up the mating surfaces.
These photos should be helpful.
Best, Adrian.

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[billy]

hiya chaps, sorry for not getting back to you. I put this long weekend aside for splitting the tractor. Good news its the seal is replaced. Bad news is I'm struggling to get it all back together, I can only get the back end 65mm close to the gearbox. I'm guessing the splines aren't aligning!
Anyone got any tips!

[AdrianNPMajor]

Hello Billy
Well done for replacing the upper seal. You won't be doing that job again.
If you look at the photos higher up the thread, there's just a male/female meshing of splines. Nothing else prevents the gearbox and rear axle from coming back together.
Presumably the rear end is still on its wheels and you are dangling the gearbox from a lift. As you bring gearbox and rear axle together, you need to rotate the gearbox clockwise/anticlockwise to get the splines to mesh. Pretty sure you have done this. As there is no factor that could introduce a 65mm interference, you need to back the gearbox away and have look to see that nothing foreign has become involved.
The splines mesh before the mating flanges touch. As you are dealing with a gasket and sealer, it's a good idea to cut the heads off two or three sacrificial bolts to act as dowels, so that, after the splines have meshed, you can rotate the dangling gearbox to line up with the dowels, thereby ensuring that the sealer/gasket union takes place in correct alignment. [Hacksaw slots in the end of the dowels so that you can extract them.]
Report back if you still have problems.
Good luck.
Adrian

[billy]

thanks for the reply, yeah basically what I was thinking.

I've been bringing the back axle forward using studding.


is there a good way of knowing where the splines are? because there set around an inch or so in, so quite hard to locate.


oh the picture was on removal but I'm basically doing the opposite on fitting.

[Brian]

Moving the rear axle away makes the job more difficult as the splines rotate as you move it forward. Put the gearbox into gear and see if you can turn it to help line up. Have you got the PTO shaft out of the tractor or are you trying to line that up as well?

[AdrianNPMajor]

Apologies. It's just dawned on me that the gearbox is still attached to the engine and front axle.
So you can't rotate the gearbox.
As Brian says, you'll have to stick her in gear and use a lever through the selector plate aperture to rotate the gears to line up the splines as you bring the two sections together.
I speak as someone who's never split a tractor in this manner. Brian will have lost count of the times he's done it.
Best, Adrian.

[billy]

Evening guys, after reading the feedback I attempted a slightly different method. I blocked up the back axle and chocked the wheels, then put a trolley jack under the gearbox end and tried to pull it from that way. I messed around trying to get her in gear, and couldn't, so I don't know if it was me just being thick.

Anyway, it hasn't really helped, still struggling to get the splines it mesh. I know this is the sort of thing that will suddenly just happen and in no time it'll be all bolted up, but its beginning to really drain me. Tomorrow night I'm going to try pulling the gearbox well away, and roughly marking where the splines are.

Brian the PTO is out, both the shaft and the gear part from under the gearbox.

I'm sure its just me being dense , I'll give it a another go tomorrow evening after work.

Thanks for your feedback guys!

[Brian]

Cannot think what your problem is, there is only one set of splines and they usually go straight in. I used to put the tractor in gear and turn the engine by the fan or by a screwdriver in the timing plate, it only has to move the width of a spline to line up. With your rods in position it should go easily.

Can you get a couple of bolts or even a pair of "G" clamps just to hold her together whilst you try and turn the engine/gearbox? You must have one set of splines movable and one set fixed which you have with your blocks against the wheels.

If you get a bit of pressure on the splines and turn the gearbox you will usually here/feel a click then the back end will try and turn stopping you turning the engine/gearbox. At that point you can wriggle the parts together with a little help from the drawing bolts until you get to the dowels and can get some of the normal bolts in on either side.

[billy]

Good News! I managed to get it into gear, then turned the engine over, and the spline slotted in! Sometimes I hate being inexperienced!!

But....I have lost a nut. I thought they were 7/16 UNF. But that meant it was 11/16 spanner. all the others were 5/8 spanner. So I'm guessing the back axle to gear box bolts are special. if they are anyone know where I can get them from. Thanks

[oehrick]

Congrats on getting it together Billy, shame you need to split it again to find that nut

Its known as Sods Law over here! when things can go wrong, they do - although spend enough time in Engineering & Mechanicing and its generally accepted that he was being optimistic.

With the Fordsons you are at least fortunate that while made in the UK, they tended to use those funny Yankee threads like UNF & UNC instead of good old Whitworth so at least you will not have to go far to find replacements.

Happy hunting