C-120 8-Speed Won't Shift Into First or Reverse

[iaintavinit 7]

Recently picked up a cheap C-120 as a project and was told all I had to do was put a new shift lever into it. The original one had the ball busted off the end of it. Ended up finding out it was owned by a kid who hacked and modified just about everything on it for use as his mud mower or something. Hood was filled with holes and all the wiring was a rat's nest. Was spray painted too and looks like absolute hell. When I thought it was the end of the problems I got the shifter all situated and it still wouldn't drive because the clutch needed work. After some hacking and welding and such I built a new clutch setup an got it to drive.

 

Second and third both work fine in high and low but the trans won't shift into first or reverse. I'm assuming it has some rust on the 1/R shift cluster but I'm not too familiar with the inside of the unidrive transmissions. I can get it to go into gear if I take the shifter out and use a long 3/8" extension to pry the fork into the correct position but it's way too stiff to do with the handle and don't want to force it and end up busting the ball off the end of this one too.

 

I traded an older Briggs 8hp I had for another WORKING 8-speed transaxle so I'm set already but I do want to fix the original to keep as a spare. Anyone else have any problems like this with their 8 speeds? I'd love to fix this without tearing it all apart but I have a feeling that's what I'll need to do. No oil showed up on the dipstick so who knows how long it's been dry.

[stevasaurus 22,868]

Hi, and welcome to Red Square 

I'm pretty sure you have the #5091 8 speed transmission with an 8 pinion differential.  I am going to recommend, because of the kid from before and no oil on the dip stick, that you open it up.  It is fairly easy to do and we can walk you through the process.  Usually, once apart, you just have to wire wheel the gears and shafts and change out the seals and gasket.  If there is a ton of rust, electrolysis works real good, but let's see what you have first.  Here is a thread with videos that  (while not your trans) is close enough so you get the idea.  Actually, the only difference is the differential.  Without knowing what that kid was doing, you are just better off going in and take a look.  I'm also going to link the manual for doing the trans work...your transmission is "Section V". 

 

 

 

 

[WHX?? 49,171]

Steve knows & sounds like it's coming apart. Probably rusted up beyond flushing with a solvent. Don't worry lots of help here and parts as well. 

[Daddy Don 907]

[ebinmaine 68,391]

5 hours ago, iaintavinit said:

love to fix this ...... tearing it all apart .... I have a feeling that's what I'll need to do

 to 

 

 

Don't have any concern whatsoever about ripping into that transmission. They're unbelievably easy to work on.

Steve knows those things better than he knows the back of his own hand.

I tore into my first one this past summer and had gears and seals all over the place.

I watched his video as I was putting it back together and it went great.

 

[953 nut 55,812]

       You already are doing far better than most to have done what you mentioned.        You've saved the    and I'm sure you can save that transmission too.         

[iaintavinit 7]

Thanks for all the welcome messages! Glad to be a part of such a nice group.

 

I really don't have any fear of tearing that transmission apart. I've had 6 speed Tuff Torqs apart, Peerless 700, 820, 900, 2300 and MST, Dana 4360, Roper 633A, I've been inside a lot of them. I did end up swapping the trans last night with the new one I got but haven't seen it drive yet as the wiring is all torn out of the tractor at the moment. It shifts into all gears and hi/lo perfectly, though. I will change the oil as I do whenever I get a new tractor. Correct me if I'm wrong but I believe these take somewhere around 2 quarts of 80w-90 gear lube. I thought at first this was a C-120 but I'm noticing a lot of differences between this one and the C-120 we removed my new transmission from. Maybe this is, maybe this isn't, or maybe it's just an older model. Any way to definitively tell (like a model tag, castings or stampings, etc?) looking for something more than just the model stickers since those have obviously been painted over.

 

Steve - Thank you for your response and link to the manual. I believe I may have the service manual for the Wheel Horse transaxles somewhere. I'll probably tear this one apart this weekend and post an update.

 

Also all you military vets, thank you for your service. Your sacrifice, hard work and determination protecting our country and freedom doesn't go unnoticed.

 

Thanks for all the help!

[953 nut 55,812]

C-120 was made from '74 to '77 and there were changes made in that time. Couldn't find a '74 brochure, but here are '75 and '77.

 

[ebinmaine 68,391]

6 hours ago, iaintavinit said:

Any way to definitively tell (like a model tag, castings or stampings, etc?) looking for something more than just the model stickers since those have obviously been painted over.

You're correct about the gear oil.

 

You should have a tag on the left side of the dash support. Likely a couple rivet holes there or the tag is well hidden under paint like the stickers.

 

The area near the the shifter (with the plate off) looks older.

The rest does look like a C1**.

May be a bit of a conflagration of mistookulated peecyparts.

 

Still a Wheelhorse and still a great rig when you get it up an cookin...

[The Tuul Crib 7,337]

On 3/4/2019 at 2:10 PM, stevasaurus said:

Hi, and welcome to Red Square 

I'm pretty sure you have the #5091 8 speed transmission with an 8 pinion differential.  I am going to recommend, because of the kid from before and no oil on the dip stick, that you open it up.  It is fairly easy to do and we can walk you through the process.  Usually, once apart, you just have to wire wheel the gears and shafts and change out the seals and gasket.  If there is a ton of rust, electrolysis works real good, but let's see what you have first.  Here is a thread with videos that  (while not your trans) is close enough so you get the idea.  Actually, the only difference is the differential.  Without knowing what that kid was doing, you are just better off going in and take a look.  I'm also going to link the manual for doing the trans work...your transmission is "Section V". 

 

 

 

 

[The Tuul Crib 7,337]

to 

[The Tuul Crib 7,337]

On 3/4/2019 at 6:39 PM, ebinmaine said:

 to 

 

 

Don't have any concern whatsoever about ripping into that transmission. They're unbelievably easy to work on.

Steve knows those things better than he knows the back of his own hand.

I tore into my first one this past summer and had gears and seals all over the place.

I watched his video as I was putting it back together and it went great.

 

I’m with you on this one Eric. Did mine and it was extremely easy! Thanx to @stevasaurus and his  tutorial video!