1966 876 w/5052 Sunstrand transmission

[ponydude 0]

My tractor has developed a serious leak. Seems to be behind the cam block on the front of the transmission. The owners manual hs nothing on this item, just the transmission assembly. Any help would be greatly appreciated.

[Volfandt 7]

My 876's HST also had a leak behind the cam block when I 1st got it Theres 2 oil rings behind the block, a large one that seals the block to the pump housing an a small one that seals the trunion shaft where it goes through the cam block.

It appeared that someone had tried to install new o rings and crushed the large one. I say this as it would have leaked big time had it been like this since new....

Theres no groove to hold the large O ring in place while one bolts the cam block housing back up and it's too easy to crush that O ring. Wheel Horse made a kit that supposedly sealed that cam block better but i have no idea what it consisted of.

in any case, after i crushed the new large O ring I ordered I ended up just cutting up an old inner tube to make a seal and it's held for approx 3 yrs now.

To get at that cam block and remove the cam you'll have to drive out a drive pin and the only way I could figure on how to get at that assembly was to unbolt the hst from the tractor and roll it back. i rigged up a dolly to hold the front of the HST up while i rolled it away and it worked out pretty good.

I did a long thread on the repair over on MTF but I'll post a few pics that you might find helpful.

1) tractor split

2) the cam block

3) the crushed OEM O ring

4) the 2 new O rings (I crushed the large one, and reused the small one)

5) you can see the large seal i made out of an inner tube bottom right. I had to use trial an error and you can see a seal I made at the top left that didn't work.

Good luck

Dave

[ponydude 0]

I can't thank you enough for this information. Finished the repairs to mine today and everything looks good. The repairs also gave me the motivation to address some other items that needed serious attention.

The tractor is kinda a family heirloom since my father bought it used in 1967 with a new motor. I still have the original invoice where he paid $641.58 for it and the 36" mower and an additional $91.80 for the 42" dozer blade. The mower deck is long gone, but the dozer blade has been invaluable to me. Guess it will go to one of my boys at some point in time.

The machine has mowed a lot of grass and pushed everything from dirt in Indiana, chicken manure in Florida, snow in Virginia, to dirt, brush, snow, and whatever in North Carolina.

Than you, again for your very helpful information!

[jay in nc 210]

welcome to redsquare, we are having a meet & greet april 28 at my home north of selma nc. there will be plenty of horses to look at., plenty of food & lots of things to do & people of like minds to meet. details in redsquare herd forum. hope you can make it Jay

[jfdegnan 3]

I recently repaired my HST cam block leak on Wheel Horse 877.  The leaks had been getting worse over the last couple of years.  Very temperature sensitive at the end. 

 

I am 100% certain that my unit has never been apart.  I found the small gasket to be an a “standard” O-ring style.   The small gasket was very hard.   I found the larger gasket to be a "square" O-Ring and not a “standard”  O-Ring.   The larger O-Ring was sitting in the middle of the “holding” or “positioning” shim when I removed it.  The shim is about 0.040” thick.

 

“Square” O-rings gaskets are not rounded on the outer diameter.  I am certain that the removed gasket was not shaped to be square from years of installation.  It is fairly obvious under microscope. 

 

I used a 026 70A (hardness) Square 1-1/4"ID, 1-3/8" OD with 1/16" Width. Thickness is 0.066” for the larger gasket. The .066 thickness allows gasket to extend beyond positioning shim.  It appeared that WH wanted this gasket to be square on the outside so that it could be held/sit inside the shim circle opening.  Making it easier for installation.  Appeared that way to me.

 

I used a 116 70A (hardness) Round ¾” ID, 15/16” OD O-Ring.

 

The “026” and “116” labels are industry labelled sizes.

 

I put it back together with no leaks (fingers crossed).

 

Many thanks to Volfandt and others who have led the charge on this topic.

BR

JimD

[953 nut 55,836]

@jfdegnan, that was a very good followup on this old Sundstrand  thread. Thanks for sharing with us.