C-120 Cracked Transaxle/Gearcase

[WHX?? 48,814]

It's 11 pm there you boys best get to bed! Big day tomorrow...

[WHX?? 48,814]

Up n attem boys gates open at 9!

Who's gonna be first in line!?!

[Handy Don 12,212]

The owner of the cracked gear case stopped by where @wallfish and I are set up and explained he’d found a spanking good deal on a complete transaxle so he is in a good, good mood!

[RoadScholar 23]

Absolutely! It was great to meet @Handy Don, @Pullstart, @squonk, and @wallfish today (thanks to Pullstart's nifty flag). This is a truly fantastic event, with acres of Wheel Horse everything! I started the day out wandering in the wilderness from tent to tent - "Excuse me kind sir, but I'm looking for a transaxle for a '75 C-120 Hydro?" Most common answer: "Oh, I've got one of those back at home, but I didn't bring any transaxles today." (Variant: "we brought a bunch of those last year, but no one looked at them, so we left them home.") In one of the barns at the back, I came across a vendor with a pile of stuff on the ground marked "FREE." Lo and behold, there was my transaxle (with hydro assembly as well). At least I'm 99% sure its a match, but the price was right and the hubs turn!  I plan to start the transplant this weekend.

 

Thanks to @Achto for initially pointing me to this event, and to everyone else for their encouragement. I could not have imagined that there was such a treasure trove of parts available -- in addition, I have collected a number of business cards for future reference, and from a couple of those folks who "have one at home" just in case there's any issues with the one I got.

 

Will keep you posted with updates to this topic.

[squonk 41,067]

I should have given you one of my cards . They come in handy at the BBQ joint if you need to floss!

 

Best of luck with the transplant!

[953 nut 55,187]

@RoadScholar, Enjoyed talking with you and hope everything works out for you.

[953 nut 55,187]

@RoadScholar, Enjoyed talking with you and hope everything works out for you.

[squonk 41,067]

14 hours ago, WHX?? said:

Up n attem boys gates open at 9!

Who's gonna be first in line!?!

I think @stevebo was out in his truck at 2:30 AM revving his engine!

[RoadScholar 23]

Hoo Boy, up to my neck in the Big Muddy on this transaxle swap. I've hit a wall and need some info before proceeding further. As some of you know, I picked up a free transaxle and hydro unit at the WHCC event -- I couldn't see any ID marks but the transaxle case visually matched the broken one from my C-120. So, for free, what the heck, I took it home with me. It was clear that the two hydro units were different, and after i got the freebie on the bench and cleaned up a bit, I found the heavily encrusted ID tag, which revealed it to be a 90-2046. The still-functioning hydro unit from my broken transaxle is a 90-1136.

 

The transaxle mounting bolt patterns appeared to be the same, except the 90-2046 has 5 bolts, and the 90-1136 has only 4. So, I went ahead and took the two hydro units off their respective transaxles, and that's where the collision with the wall occurred.

 

The driver gear on the motor shaft of the 90-2046 is smaller than the motor gear on the 90-1136, and correspondingly, the mating transaxle gear, Here's the 90-2046:

 

 

And the 90-1136:

 

 

The other thing I have noticed about the 90-2046 is that it does not have a push valve like the 90-1136.

 

So, obviously, the hydro swap to the new transaxle appears to be not feasible. I'm not up for going down the rabbit hole of opening the transaxles and swapping parts around.

The main question I have is:

 

Can i just go ahead and use the "new" transaxle with the 90-2046 to replace the cracked tranny on my C-120? Other than the push valve issue, everything else seems to fit -- the parking brake linkage, transaxle mounting holes, and the cam follower linkage all look to line right up. For the record: here are the two units side by side. You can see the gearing difference (90-1136 is on the right),

 

 

I'm guessing with the gearing change, I might end up with more power but less speed. But, does anyone see any land mines buried in that path forward?

 

Thanks!

[squonk 41,067]

Use the complete used transaxle. Did you get a gasket for it? Silicone is a big NO-NO! 

[stevasaurus 22,717]

There is one thing to know about hydros...things need to be super clean, spotless.  Those pumps and outside cases should have been steam-cleaned before opening.  Any of those grass bits could could kill your project.  

[daveoman1966 3,751]

The other thing I have noticed about the 90-2046 is that it does not have a push valve like the 90-1136.

The PUSH/TOW valve for the 90-2046 hydrogear is on the top of the pump end cap---not the side lie the C-120. 

 

[kpinnc 12,004]

4 minutes ago, stevasaurus said:

There is one thing to know about hydros...things need to be super clean,

 

Agreed 1000%!

 

I would place a plastic bag over that pump and vacuum those ports very well before reassembly. 

[squonk 41,067]

The transmission in you C-120 is a Sunstrand piston piston type. The transmission you got at the show is a hydro gear. Depending on what year your original transmission was you may need to use different oil. Hydro gears used automatic trans fluid. Piston piston transmissions switched to motor oil around 1973

[daveoman1966 3,751]

I have both side of the trans case if that's what you want...OR----I can put a complete trans (less pump) from a C-120 in your lap---OR.---.a C-120 w/out engine...   

I am in n/w PA---about 40miles south of Lake Erie.  

[RoadScholar 23]

Thanks, @squonk, I managed to score a new/old stock gasket on Ebay. Thanks also to those with comments about maintaining a clean work environment. I admit the photos look pretty gnarly (they were taken right after I opened the units up), but believe it or not, I have taken great care to keep the machined surfaces clean and have kept the holes plugged with wadded paper towels.

 

I really would have like to degreased and power washed both cases beforehand, but for various aggravating circumstances that did not happen. @kpinnc, I like your idea of the plastic bag and final vacuuming (I've been vacuuming as I go along). Twenty-twenty hindsight is always informative, and I now have a reference project to look back on should I have to do this again.

 

Also, thanks to @daveoman1966 regarding the tow valve info. After I posted earlier, I found a reference to it in a service manual, which refers to it as a "free wheeling valve." Same operation as the push valve, but the service manual didn't specify the on/off behavior. Thanks for sharing! And I appreciate your offer of a C-120 transaxle, but right now, I'm just trying to get a working tractor, and it's a pretty good hike up to your neck of the woods, so I think I'll forge ahead and put in the hydro gear pump, motor, and transaxle.

 

It bugs me that I'll end up with a 1975 tractor with a hydro/transaxle that is from somewhere between 1968 and 1973 (according to the master model list). But as I said, I really need to get this baby back on the grass, so we will see. I'll still have my original 90-1136 hydro unit, so who knows -- maybe next WHCC I'll pick up a matching C-120 transaxle and make it right! At least I'll have a bit more of a clue the second time around...

 

One more question - in @daveoman1966's photo of the tow valve, just above the valve you can see a slender spiral tube that runs under the hydro unit and sticks out just behind the tool box. What is it, and what is it for? I have one on my tractor but i can't find it on any parts list or figure out what it's for.

 

Thanks!

 

 

[8ntruck 6,998]

That spiral tube is a cable guide for the implement lift cable that runs between the hitch and the rock shaft under the console.

[daveoman1966 3,751]

Whether you use the C-120 as original (90-1136) or somehow swap the hydrogear (90-2046) onto it, I  strongly urge  you to refurbish the internals of the hyd pump (& motor if 90-1136 route).  Either one is at least 50 years old....& I can almost guarantee you that either one/both have internal wear, and that wear will result in way less than optimum performance.  This is NOT DIFFICULT...   Look at some of the pics in these two files....notice the wear on the soft brass components.  THAT is what needs attention.  

SUNDSTRAND HYDROGEAR refurb.pdf SUNDSTRAND Piston-Piston PUMP & MOTOR Refurb.pdf

[RoadScholar 23]

@daveoman1966, thanks for the advice and encouragement. I actually did review these documents a week or two ago as i was trying to plan my way forward. This tractor is my one and only, and Job One is to get it rolling again as soon as reasonably possible. I think i can do that now by installing the 90-2046 and its transaxle, after which the pressure will be off and I will then have the 90-1136 to work on at my convenience. I agree doing the hydro refurb on the the 90-1136 would be worth the effort, and being able to take my time at it would make it much more enjoyable, and ideally a learning experience (and done in a cleaner environment ). Assuming I can get that done, and locate a matching transaxle, I can then swap them back into the C-120 for an authentic repair. I will then have a spare 90-2046 and transaxle that I can pass along to a good home for free, the same way it came to me. Kind of an extended story line for a repair, but that's the way it seems to be shaping up --  sometimes you just have to go with the flow.

 

Thanks again to everyone for your patient responses and guidance. I'll post updates as the project moves along.

[RoadScholar 23]

Hello all, just wanted to report that the transplant operation was a success, and i was able to mow today with no observable problems. Yay!

 

So yes, you can swap a 90-2046 & mating transaxle for a 90-1136 & mating transaxle. However, there were some bumps along the way, and unless you have a lot more experience at this than I did when I started it, you should be aware of these points:

 

- As the hydro pump/motor casting looks identical in both units, my initial thought was that I could keep my 90-1136 and bolt it onto the 90-2046  transaxle. They even use the same gasket. But ... wrong! The fly in the ointment is that the gearing is different from one to the other. (see my earlier post above). Upshot: time spent on taking both of the hydro pumps/motors off of their respective transaxles, when I could have just used the 90-2046 as I received it. However, this did give me the opportunity to inspect the innards of the 90-2046 transaxle, which turned out to be just fine. The different gearing means a bit less speed and a bit more power, but driving it today, I really didn't notice any appreciable difference. "Fast" is fast enough.

 

- The 90-2046 I got did not have the drive pulley attached. No big deal, thought I, I'll just take the pulley off my 90-1136. Wrong! The 90-1136 pulley has a splined shaft, and the 90-2046 has a smooth shaft with a key and set-screw. Oh well. A visit to eBay turned up the needed pulley at a reasonable price.

 

- And I now have to use transmission oil in the 90-2046 instead of the 30w motor oil that is used in the 90-1136. Now that I think about it, there's another reason why I couldn't have used the 90-1136 hydro and pump on the 90-2046 transaxle. But, I didn't find out about the different oil requirement  until later on in the project.

 

Overall, that would be the biggest issue I had -- "you don't know what you don't know."  I am extremely grateful for this forum and the vast amount of information and advice available on it -- without it, I couldn't have succeeded. Although there were a few instances of hair-tearing despair along the way. One aggravating issue I had was with the parking brake assembly, which I failed to take a photo of during disassembly. The brake lever on the transaxle was bent in such as way as to look legit but it did not work (probably happened just being moved around). Needless to say, the forum came through with the exact photo I needed to set it up correctly.

 

Looking ahead, here in northern Virginia we usually have 4-6 weeks of "down time" between fall and winter, when there's no mowing to be done, but no snow on the ground either. So, I'll probably take advantage of that window to do some more work, and if it all works out, possibly even get another 90-1136 transaxle and look at refurbing the hydro pump and motor as @daveoman1966 has suggested, and put the whole thing back into its original configuration. It may seem like a round-about way of repairing the original cracked transaxle problem, but I'm inclined to look at the whole thing as an extended learning experience. And for now, I have a working tractor for the cost of a gasket and a drive pulley.

 

My other takeaway from this project is a expanded and profound appreciation for the engineers and craftsman who designed and built this tractor. These are truly great machines that reflect the best that American engineering can produce.

 

[daveoman1966 3,751]

Glad you got it worked out...   As to the last comment your post: An old geezer once told me that there were some pretty fart smellers in the Wheelhorse factory there in South Bend.  He's right. 

 

[953 nut 55,187]

            Glad you were able to get back out on the lawn and look forward to seeing you and your C-120 at the Big Show next year.