1872 transmission issue

sorner · #1 06-25-2025, 07:13 AM

My 1872 developed a severe leak at the input shaft seal to the transmission, I thought that's no big deal, I've seen this before... I ordered a seal to replace the seal. When I got the seal, I took the charge pump off to replace it, because it's a little easier to do than prying the seal out and risking damaging the input shaft in my opinion. Anyway, when I got it apart the needle bearings in the charge pump all fell out and the shaft was eaten away. What a catastrophe! So, I did a little research and decided to take the hydro pump apart, get the shaft out and replace the shaft. I reached out to Jeff (Parts By Jeff) and he said he could repair the shaft, so I sent it to him, and he repaired it along with a CV drive shaft to lengthen so I could convert it to CV drive shaft. I got the parts back, made sure everything was clean and carefully reassembled the hydro and put it back in the tractor (new cork gasket, oil, etc.), set the linkages up and everything. I took it for a test drive and it will only go about 2/3 speed in forward compared to before, and compared to how it ran before. The speed control goes all the way up and down, so there's no restriction there, but at about 2/3 I notice the speed stops increasing as the handle moves up. Reverse acts normal. I replaced the charge pump with one that had good bearings and new seal, it looks identical to the one that came off. I thought maybe I accidentally installed it backwards so I turned it 180 degrees and it doesn't move at all, so it was not that. So, after this long winded explanation, what could possibly be the issue with my hydro forward speed being restricted to about 2/3 speed?

sorner · #2 06-25-2025, 08:41 AM

I'm thinking I installed the swash plate upside down...

Frank1541 · #3 06-25-2025, 08:43 AM

I made the same mistake. I lot of work for such a simple thing.

Ambush · #4 06-25-2025, 09:25 AM

Probably, but then reverse should be faster. On the bright side, it will take you half the time to do it again.

I’m curious how the shaft bearing area was repaired.

ol'George · #5 06-25-2025, 01:25 PM

Quote:

Originally Posted by Ambush

Probably, but then reverse should be faster. On the bright side, it will take you half the time to do it again.

I’m curious how the shaft bearing area was repaired.

If it was welded and reground back to specks, my concern would be the heat treatment to restore it to the correct hardness.

Grandpa53 · #6 06-25-2025, 01:29 PM

Check that pin on damper plate is at end of slot on control plate with shift lever all the way to forward position. If it is not then linkage is out of adjustment. If it is then something is not put together properly internally. Also make sure trunnion springs are installed correctly with guide buttons inserted in the end of each spring.

Ambush · #7 06-25-2025, 05:36 PM

Quote:

Originally Posted by ol'George

If it was welded and reground back to specks, my concern would be the heat treatment to restore it to the correct hardness.

Critical in a needle bearing surface. And chrome will pound and flake off eventually. Ok for just a seal area though.

sorner · #8 06-25-2025, 08:21 PM

Quote:

Originally Posted by Ambush

Probably, but then reverse should be faster. On the bright side, it will take you half the time to do it again.

I’m curious how the shaft bearing area was repaired.

Jeff (JeffInPa) welded it up and machined it to spec for me. It looks good as new, I trust his work. If it doesn't last, then I'll end up with a replacement pump at some point anyway, I figured I'd try the cheaper route first and learn a thing or two. And Reverse works pretty well, actually.

Quote:

Originally Posted by Grandpa53

Check that pin on damper plate is at end of slot on control plate with shift lever all the way to forward position. If it is not then linkage is out of adjustment. If it is then something is not put together properly internally. Also make sure trunnion springs are installed correctly with guide buttons inserted in the end of each spring.

When I move it all the way forward the trunnion assembly hits a hard stop and starts compressing the spring. That's what tipped me off that I put the swash plate in upside down. I looked at another one I have from another hydro and I noticed one side on the back is higher than the other. That was a stupid mistake because I had it in right the first time and I thought it was in backwards so I took it out and turned it around. Live and learn I guess.

sorner · #9 06-26-2025, 10:07 AM

Well, I took it all apart this morning, and turned the swashplate around and reinstalled everything. Somewhere along the way I got confused and put the trunnion arm on the wrong side. So after I had it all back together and took it over to the transaxle to reinstall I realized it was on the wrong side. So, I had to do it all over AGAIN!

But, now it's right and it's waiting for a cooler time to reinstall the whole assembly and put the tractor back together.

sorner · #10 06-26-2025, 10:39 AM

Quote:

Originally Posted by ol'George

If it was welded and reground back to specks, my concern would be the heat treatment to restore it to the correct hardness.

I emailed Jeff to ask him. He said "I used ER70S TIG filler rod to build the surface up before machining it to the correct size. The repair should be good as new."