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Super major diff locked on.

Posted: Sun Apr 18, 2021 6:15 pm
by Nickm
Hi all,

Recently bought my favourite tractor. A super major.
It's really great and in pretty good condition.
Seems to mostly all work, except for one thing which I knew about when I bought it.

The differential is permanently locked.
So steering is badly affected.

So I've tried to find info as to fix it, but it's hard to come by.
I've got the brake off and have got down to the exposed bearings on the pinion shaft.
Any info I've found says pull out the pinion shaft.
Never was the phrase 'easier said than done' more accurate.

That's not going to come out. Unless somehow I manage to pull much harder.

Any advice gratefully received.
(To be honest doing work like this scares me to death as I've not done it before).
Would post a pic but not sure how.

Re: Super major diff locked on.

Posted: Sun Apr 18, 2021 7:24 pm
by mathias1
Hello Nick,

Welcome!
When using the differential lock, the tractor just will go straight forward.
The small pedal to the right pushes on a spring loaded shaft. Maybe the shaft is stuck, or it isn't coming out.
You will have to disassemble the right brake and brake housing to get deeper into this, so you got this far.
The pinion shaft is really a pull out, but can be difficult.
A solution might be disassembling the left side brake and brake housing and see if you can pull out that one. If that works, you can put a piece of metal inside and knock the right side gently out.
Do you have the rear wheel off?

Re: Super major diff locked on.

Posted: Sun Apr 18, 2021 8:17 pm
by Nickm
Thanks for that info.
Yes,. The wheel is off.
I'll try pulling it out again. But if it still won't move then I'll do as you suggest and take the other wheel and brake off to get around the back of it.

Re: Super major diff locked on.

Posted: Sun Apr 18, 2021 10:13 pm
by mathias1
Is there movement in the dif shaft sitting in the middle?

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 12:03 am
by Billy26F5
Remove the RH brake cover and check the pedal is free to move, if it isn't it should be easy enough to free it. If the pedal moves fine, dismantle the RH brake and remove its housing and the bull pinion and carrier, being careful to note the number of shims there are and making sure yo don't loose any of them. To do this you'll also need to remove the top cover and the RH final reduction gear. Make sure you lift the top cover absolutely level until it's cleared the feed and return pipes. To remove the final reduction gear, you'll need to undo the large LH thread nut and remove the axle shaft about 3" (remember to open out the seal housing). Examine the bull pinion. If the operating rod is stuck it shouldn't be too difficult to free it. If everything is fine you'll need to dismantle the other side and remove the diff and crown wheel assy, open up the diff to see what there is inside, Billy had a broken differential pinion and had similar symptoms. Hopefully this should find something.
Sandy

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 12:57 pm
by Nickm
The diff shaft in the middle does not move.

It did go in and out before. But after taking the brake off and putting some bolts back in as in the picture (I hope I can attach this picture), it doesn't move.

Thanks Billy for the stuff about removing the cover under the seat.

I'll let you know how it goes as and when I can work on it.

Current state....
Image

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 1:05 pm
by Billy26F5
I think you'll need to dismantle further and check all the diff lock bits.
Sandy

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 7:40 pm
by mathias1
The shaft is sitting to deep. The nut at the end must be missing.
This should be how it should look like:
DSCN6851.JPG
DSCN6849.JPG

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 8:06 pm
by Nickm
Nut at the end missing.
That would explain the problem for sure.
Guess I'll be draining the oil then.

I'll try to dismantle the other side. Get a look from there and maybe push the diff lock pinion shaft out that way as suggested.

If it is that, then I might be able to find the missing nut and refit it properly.

(Tried for approx half hour today to pull out the pinion shaft. I'm fairly strong, but it wouldn't budge).

Failing all that it'll have to be the cover under the seat coming off.

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 8:08 pm
by mathias1
Nick,

See first if you could get the shaft out by pushing from the other side.
While you are here it's a good idea to renew seals etc..

You will have to check if you have all parts.
A drawing can be found here:
https://www.mycnhistore.com/eu/en/newho ... 5056875BD6

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 8:40 pm
by Emiel
Hi,

My suggestion would be to take the hydraulic top cover of. It’s heavy but you”ll have a clear view on what’s happening inside.

If there is more damage inside then it will need to come of anyway and it’s a great opportunity to give the rear and a good clean out.

If the nut is of, question is, where is it now?

Regards
Emiel

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 11:09 pm
by Billy26F5
I think the spring that brings the operating rod back out is broken, try and see if you can pull out the operating rod.
Sandy

Re: Super major diff locked on.

Posted: Mon Apr 19, 2021 11:43 pm
by shepp
The push rod should protrude about 1.3 inches or 33mm from the end of the bull pinion shaft when the diff lock is disengaged, if it is less than this then the lock is stuck engaged as you report. This could be due to the rod being seized in the bull pinion shaft, there is a strong return spring just in the end of the pinion shaft that returns the rod when the pedal is released, and an "O" ring seals the rod to pinion shaft joint. Give the rod a good soaking with penetrating oil where it enters the pinion shaft, some might get past the O ring, gently tap the pinion shaft with a copper hammer to shake up any corrosion between the rod and pinion shaft and apply more penetrating oil.
After letting the penetrating oil work put a pair of mole grips on the end of the rod and gently try to turn the rod in one direction then back, if it frees keep rocking in one direction then the other. If the rod is properly free it should be possible to continually rotate it, the construction allows this so it will not do any damage. If the rod frees to rotate but does not pop out try pulling on the mole grips whilst turning the rod back and forth. If the rod frees and pops out then that is where your issue is, you will need to get the bull pinion shaft out and it comes out complete with the bearing so the bearing outer race has to be free on the bearing housing casting so make sure everything is clean and soaked with penetrating oil. If the bull pinion shaft and bearing will still not withdraw you could try a heat gun on the bearing housing. Once the bull pinion shaft is out remove the split pin and castellated nut, withdraw the push rod, clean everything up with fine emery cloth and wash clean with petrol, fit a new O ring, grease the rod up and reassemble the rod in the pinion shaft and set the castellated nut so that the rod protrusion from the end of the pinion shaft is 33mm, then fit a new split pin. Reassemble the unit of coupling, push rod and pinion shaft and bearing into the housing.

If all the above does not let the rod out then the diff lock coupling is stuck either IN the left hand differential pinion gear female or ON the right hand bull pinion shaft male or possibly both, this could be due to oil glaze or corrosion or burring on the machined surfaces.

If the rod is free to rotate and the castellated nut had come off then you would be able to completely withdraw the rod from the bull pinion shaft, so it is unlikely that the nut will have come off.

If the problem IS due to the diff lock coupling being stuck in the left side diff pinion then you will need to remove the left hand brake assembly and bull pinion shaft, and insert a suitable long drift into the left hand diff pinion to contact the castellated nut or coupling and gently tap the whole right hand assembly of pushrod, coupling, bull pinion shaft and bearing out, be careful!

Hopefully your issue will be a stuck push rod in the bull pinion shaft.

Re: Super major diff locked on.

Posted: Tue Apr 20, 2021 12:28 am
by Billy26F5
Don't use heat, bearings can easily fail from this as the heat treatments are lost. Allow plenty of time for the oil or diesel to work (at least overnight but preferably two or three days).
Sandy

Re: Super major diff locked on.

Posted: Tue Apr 20, 2021 1:22 pm
by shepp
An electric heat gun is just a more powerful hair dryer, more heat less air flow. It will not get the bearing housing casting even near to the temperature that it will rise to in a days work. However sometimes just that little expansion of the housing is all that is needed to allow the bearing and bull pinion shaft to withdraw. They are good for freeing steering wheels off the shaft, pull pre-load the steering wheel either side, apply heat evenly to the wheel centre boss, unless they are badly corroded the wheel will usually eventually spring off. Unlike a direct flame if you keep the gun moving they will not cause paint surface damage.

Re: Super major diff locked on.

Posted: Fri Apr 23, 2021 6:38 pm
by Nickm
Thanks to all for some excellent info and advice

In the last few days i have removed the other brake and housing. Here's a photo hopefully....

Image

As luck would have it, I can't shift this one either!

It seems as solidly set in position as the problem side.

I have thought about using heat, but with oil around the bearings etc I've not resorted to that yet.
Here's a photo from the top of the diff lock side.
Gives a better view of how far the diff lock pin is protruding. ( I'll have to go out later and see exactly how far it's protruding).

Image

It did spring in and out fine before I took the brake to pieces, although obviously never disengaged the diff lock. After I dismantled the brake and put some bolts back into the surround and tried pushing it in, it no longer sprung back out.

Anyhow, if I fail to pull out either pinion shaft, the only option left is to remove the large top cover.

At least then, things will be clear.

Re: Super major diff locked on.

Posted: Fri Apr 23, 2021 7:42 pm
by Nickm
The diff push pin is sticking out by only 23 mm.

Re: Super major diff locked on.

Posted: Fri Apr 23, 2021 10:03 pm
by Billy26F5
I recommend you remove the top cover and try removing the bull pinions and carriers, this means you'll need to loosen the axle shafts (remember the LH thread and to loosen the seal casings) and move the final reduction gears out the way first. You should be able to get them out then.
Here are some pics of Billy, a bit different but basically the same.
Image
Image
Image
Image
Image
Image
Sandy

Re: Super major diff locked on.

Posted: Tue Apr 27, 2021 12:18 pm
by Nickm
I'm sure you are right Sandy.
I'm putting it off a little because I've got so much to do at the moment.
But mainly because it's a really big deal to do all this work on the tractor for me as I have little experience.
But I'll get to it very soon.
Doesn't make it easier as the tractor has a cab.
I don't really want a cab, so I've got to take that off too.

I like your tree stump supports in those pictures.
I've got a couple of them stuck under the tractor right now as well.

Re: Super major diff locked on.

Posted: Tue Apr 27, 2021 2:39 pm
by shepp
Have you tried a pair of mole grips on the end of the pushrod and see if you can tap them or prise them to pull the pushrod out? Will the pushrod rotate freely? Sometimes the smallest bit of dirt or oil glaze on the splines can cause issues bigger and than would be expected! Before dismantling further I would certainly try a well secured pair of mole grips and a slide hammer on the pushrod and some gentle taps.

Re: Super major diff locked on.

Posted: Tue Apr 27, 2021 8:53 pm
by Billy26F5
You might want to soak it in diesel before you try pulling it out again, it might improve your chances, having said that, I think you should give the rear end a good clean out while you're doing this.
Sandy

Re: Super major diff locked on.

Posted: Wed Apr 28, 2021 6:55 pm
by Nickm
Well I might well try the push rod again in the way you describe when I've further dismantled stuff for a good view of everything.
So I spent a good while this morning dismantling a bit more.
Removed seat and then all bolts to the rear axle cover.

Imagehébergeur d image gratuit pour forum

As has been said, probably a good idea to clean a few things out and see where probable missing piece(s) are.

But, after removing the 12 bolts to the cover I could not move the cover. Let alone take it off.

I would well imagine it is a bit stuck after 60 years. But I don't want to damage stuff and really force it so thought I'd ask here if there's anything else to undo first? And how heavy is this cover? It's going to be pretty heavy I'm sure and don't want to damage anything when moving it either.

Re: Super major diff locked on.

Posted: Wed Apr 28, 2021 7:17 pm
by mathias1
There are 2 bolts under the lift arms.did you remove those?

Re: Super major diff locked on.

Posted: Wed Apr 28, 2021 9:13 pm
by Billy26F5
As Mathias says look at those, although there are indeed 12 bolts. The cover is very heavy and a lifting unit would probably help you to get it out. Make sure you lift it square, as otherwise the feed and return pipe holder will crack.
Sandy

Re: Super major diff locked on.

Posted: Fri Apr 30, 2021 8:09 pm
by Nickm
Image

Spent ages getting the top cover off. It really is heavy and awkward to do

Anyhow, I think now I need to remove the reduction gear etc.
I think Sandy described this earlier on, but I'm still a bit unsure of a couple of things.

Is this the big gear at the rear on the right?
Does the large nut unscrew in a clockwise direction?
How do you then move the axle shaft to remove the gear?

Then if the cradle containing the pinion shaft can be removed, where exactly are these shims to look out for?

Hopefully after that I might be able to get to the problem area.

Thanks to everyone for all the advice so far. Wouldn't have got anywhere without it.