Replacing seals on trunnion shaft.
 

Hello everyone. I have a IH made Cub Cadet 782 that has a seal leaking on the trunnion shaft of the hydro transmission. The seal that is leaking is on the opposite side of the trunnion. I've never replaced one of these seals before and was wondering best way to go about getting seal out. I probably will have to pull the tranny to be able to do the work. Hoping all you have to do is remove the snap ring and washer and somehow pry and pull on the seal and get it out that way. Any ideas would sure be appreciated.:bigthink::beerchug:

put a small hole in the seal and screw a wood srew into it and you should be able to pull it out with some vise grips.

Thanks Tim. I assume I will have to pull the transmission to be able to do the work?

ive always done it with the trans out so im not sure it can be done in the tractor.

Tim, I was thinking of drilling a hole in the frame to be able to do what you suggest. I have a 1-1/16" drill to put the hole in frame.

Just take the rear out. Don't be one of those owners who hacks up a machine just to avoid less than 30 min worth of work. :bash2::bash2: It's not like you have to change that seal all the time. This is probably the first time it's ever been changed.

im with Jon on this one, removing the rear end is easy and doesn't take much time.

Ok..... probably longer than 30 minutes.... but like Tim said, it's easy and doesn't take that long.

Ok I will pull the tranny. Thanks Jon and Tim.

Maybe I should add, roll the whole rear end out with hydro attached.
Don't know if you understood that, or at least I do it that way and it is a simple
job, it really isn't that bad.
I'm with the 30 min, ---hour @ most guys if you haven't done it before.
I just pulled one on a 1650 today, wished it was as simple as yours, I have the hydro apart, as it is the seal on the trunion lever side.
We will help if you have questions.

Once you get in there, would be a good time to clean everything up real good and take a look around for any other worn parts or possible problems/leaks.

I'd probably spend a hours cleaning things up and maybe even touching up paint to make it look as good as possible, but then that's just me!!
Good luck w/the seal!

Thanks for the hint to clean and look over everything. This has been a great tractor so I will for sure look for any thing else that needs attention. I have done the trunnion repair on a couple of my other 782's so used to pulling rear ends as well as replacing gasket between transmission and the rear end housing.

Hello ol'George,
Thanks for the information to just pull the rear end. I though about that after I sent last message to Jon and Tim. I would be much easier to just disconnect everything and roll the whole rear end with the transmission still attached to do the seal replacement. Also give me a chance to remove 35 years of dirt and grime.

Pay attention to where the dirt is caked on. This is one of those while-you're-at it moments. Might consider doing the shaft seals on the hydro, as well as the cork seal and have a good look at the axle seals.

I'm big on "if it ain't broke, don't fix it". Done many "while I was there" repairs and ended up with problems. If a seal isn't leaking, and it's not a 6 hour job to get to it..... leave it alone. Same with gaskets. Don't know how many times I've replaced a seal that wasn't leaking (because I was "there") just to have it leak after changing. Pull the rear, fix the trunion seal and put it back together unless you find another leak.

I have a hard time believing that the worlds best mechanic gets leaks.:biggrin2:

Unless I was taking the hydro apart for another reason, I'd probably leave the shaft seals alone, too. (If it ain't broke...). There is very little movement of the trunnion shafts, so I don't imagine they wear the seals much. I've yet to see a leaking trunnion shaft seal, but, then again, I've only worked on 6 or 7 hydro tractors. So my sample may not be statistically significant...

LOL Tim!! It happens.
I make mistakes too.... I just don't usually share them. :biggrin2: Mistakes build experience. Without them, I wouldn't have found out what works and what doesn't! :beerchug:


You know, I agree about the shaft movement. I don't know if the needle bearing wears a little or if it's the fact that they don't move much.... but my 1811 for example, I've replaced the trunion seal on the RH side 3 times since I've owned it (if memory serves). Then, there was my 125 (that I gave to my brother over Christmas). The hydro on it had never been out, so original seals in it. Also, I have yet to have a LH trunion seal leak. Guys talk about leaking trunion seals on here pretty often, and they too have a RH one leaking. It's always the right side. Someday, I'm going so sit on a bucked and think about it and figure out why that is..... :bigthink::bigthink::bigthink:

I had a Right side trunion seal leak on my Ih 782, couple of years back and currently the left (read, take hydro apart) currently
on my '74 1650,--- just waiting for seals/gsket from John Deere:bigeyes:
Sorry did I leave the cat out of the Bag?
I shouldn't have said that, er well my apologies BUT the Parts bags are Yellow:biggrin2:
and the parts are identical and they are less expensive-- so it goes:bigthink:

J.Mech:
Thinking, the Left has 2 spring pins in the trunion holding the shaft, it will not allow the shaft to cock ever so slightly in the trunion like the R side.
I have seen evidence of working(Galling) of R shaft in the trunion bore. and on the shaft, but dam the seal should be able to allow that and do it's job.
but the seals are not large comparing OD to ID.-- maybe, only thing I can come up with.

You can get the seals at NAPA. They're like $7.50. SKF 6763

$4.73 from Deere AM3426T

Probably a combination of Id andOd too close and that it doesn't spin completely
around. Much like a ball bearing will wear itself out if it doesn't rotate far enough
needle bearings dont need to turn as far

I just did a set of hydro seals this weekend. Out of the tractor, it is a half a beer job. If you have to pull the rear, from scratch, it is a three beer job

You decide which is preferred...:beerchug::beerchug:

What about the possibility of the trunion shaft having more leverage on the right side as the movement is controlled from the left side so the right would have more force and more wear on it's area than the left?

Should be just the opposite. Since it is controlled from the left, that shaft has switching side/directional load. The other (RH) side only has the pressure from the pump on it. By all theory, it should be the other way around. I would have thought the LH side would be the one to always leak.

I thought my theory made sense, but it is just that, a theory.
2 pins in the trunion allow no cocking of the L shaft in the seal, 1 pin allows the R shaft to cock/wobble around as it is a slip fit in the trunion, Granted it is a minute amount.
Wonder if putting 2 pins in the right side would give equal seal life?:bigthink:

Would one side run warmer than the other? Sometimes age/heat hardening of the elastomer is more important than load

I just had one apart the other day. Only one pin in both sides. Parts book only shows one pin in both...... :bigthink:


Nope. Same.
All I've ever had to change the seal wasn't hard. By all theory, that trans shouldn't ever be able to run hot enough to cook a seal. That would be over 200°.


My best guess is that the LH side is more protected having all that linkage in front of it. I would also be willing to bet that if I would disassemble the hydro and change the bearing it would stop the issue..... but that's just a guess.

Jonathan,
I find that interesting, as you say only 1 pin shown per shaft in the parts look up on parts tree, and the same thing in the service manuals listed here on our site for both the QL and the 82 series,-- but also, they say
" note: there are two pins used in the control side". and go on to describe how to drive them out carefully, not too far.
I can tell you I removed 2 pins from the control side a couple of days ago on the 1650 hydro and re installed 2 pins on that side and one pin on the other side.
Confusing to say the least!
Bottom line I would say better two than one since they specifically make mention of two even though they omitted one in the diagram.

Interesting also, while looking up parts for the hydro on JDparts they showed both pins on the control shaft, so it goes, always muddy waters somewhere.
FWIW:
Somebody is gonna ask why I go to my local green dealer for parts,---:bigthink: because I have an account there, there don't charge shipping on stock orders, they get me most anything I need, and besides competitively priced, they are 5 miles up the road, works for me.

I've had a few of these hydro's apart. Some have had 2 some one. Who knows why some are that way. Two would make sense, but when I was putting that one the other day back together I didn't give it any thought, nor did I have another pin, so it got one. Two is not a bad thing. I think the shaft fits the swashplate tight enough that I don't really think that putting two in the far side would matter, but who knows. Next time you do one, give it a shot and let us know in 5 or 6 or 10 years if it leaks, LOL. :biggrin2:


As far as getting parts at Deere, I don't think anyone here said anything about it. Same parts, different bag, different price. I'm fine with it. :beerchug: