Differential lock doesn't work?

[bmaverick]

They've been messing with the old archived stuff again!

I found the photo is still listed in my 'Attachments' and it was used in this 2011 post. Tell me if the photo and diagram are visible to you at this link:

Trans case lock seem not to work anymore

A few months ago It worked great when I had to cross one of my creeks, today, I had one wheel slipping and stomped the pedal, and it did not engage. I have not gone to the manual yet, and it was getting dark, the pedal stayed down and had to pull it up with my heel. Any thoughts? This is on a 186D

www.tractorbynet.com

The repaired shift fork is #12 in the diagram, and the worn area built up by welding is near the line drawn from '12' to the part.

Here's my photo again - before the worn spot was filled in by a weld.

I like reading old threads. Something is there to glean from.

 

[smitty888]

So, it appears that my situation is a little different than most. I did some testing with my YM2000 chained to a tree, and the diff lock did not work when I pressed the pedal down, but it did work when I pulled the pedal up. With this information, I figured that I was having the same issue as California.

I then pulled off the two U bolts to remove the right side fender. I had to undo the PTO linkage as it is part of the diff lock shaft, then I removed the snap ring holding the diff lock shaft in. I disconnected the 3 point lift arms at the end of the arms, not near the transmission of the tractor. I unbolted the hydraulic fluid feed at the top of the transmission case, then undid the 6 bolts holding the hydraulic piston system onto the gearbox of the tractor. After pulling that off, I had to drive out the roll pin in the diff lock lever on the outside of the transmission case so I could rotate the lever enough to get access to the roll pin on the inside of the transmission case. It was kind of a pain, but once I got it driven out, the diff lock shaft slid out of the transmission case. From there, I was able to remove the spring, then remove the diff lock shift fork.

I was surprised to find very minimal wear on the ramp of the shift fork, but pretty extreme wear on the contact face of the fork. Unfortunately, the wear resulted in a raised lip that dug into the piece that the fork mates with deep in the transmission. I went ahead and ordered a new shift fork from Hoye; I'm hoping the mating piece will be ok.

 

[careyo63]

Haven't been inside mine to look at it. But it seems there was "alot" of pressure on it to cut that grove. For awhile. Well done!!..... And Welcome

 

[smitty888]

Thank you for the warm welcome!

Unfortunately, I do not have great news. I paid $200 for the new differential lock shift fork and an extra $30 for 2 day shipping, and it showed up 4 days after I ordered it :/

Regardless, when it arrived, the whole part was painted. As I don't want paint chipping off in the transmission, I had to use a wire wheel to remove the paint from the surfaces that engage the differential lock collar. Additionally, because it was painted, it did not slide on to the differential lock shaft. After removing all the paint from the bore of the shift fork, it finally slid on. Unfortunately, the new shift fork cannot slide onto the differential lock collar because the top of the fork is taller than the original and hits the case inside. I think my only choice now is to grind it shorter until it fits.

In the midst of all this, the O ring on the differential lock shaft broke. Does anyone know what size this is?

I love Hoye and all that they do to keep old tractors working, but part quality is frustrating sometimes. Heads-up to anyone who orders one of these: it won't be a perfect fit and some modification will be necessary.

Update: I contacted Hoye, and they said they would address the problem Monday. They have really excellent customer service.

 

[smitty888]

So for an update, Hoye and I went back and forth several times to try to figure out what was going on. Hoye requested a used shift fork from their boneyard and compared it with a new one identical to the one that they sent me. They claimed that both are the same size and that the part number is the correct part number from the manual.

They said that it looks like part 60 from this manual: TRANSMISSION_INTERNAL: Yanmar Tractor Parts could be worn from pictures that I sent, thus making the new part hard to fit correctly. I don't think this would result in what I was experiencing, but they suggested grinding down the top end of the shift fork to get it to fit. They suggested to be subtle on the grinding and check to fit often.

I went ahead and ground the topside of the shift fork until it slid into place, see picture below.

I used a flap disc and eventually got it ground enough. I used (2) #12 o-rings from Home Depot to replace the o rings on the diff lock pedal, measurements 5/8 in. I.D. x 13/16 in. O.D. x 3/32 in. wall thickness. These are ***-160 o-rings on Hoye's website. In order to get the compression spring that rides against the diff lock shift fork back into the transmission, I had to use a c-clamp to compress the spring. Once it was compressed, I was able to slide it off of the c clamp pad and against the shift fork. From there, it was a matter of installing the roll pins again and putting everything back together. Everything seemed to work ok, but it is yet to be tested. The diff lock shift fork was tight on the diff lock pedal, which has me a little worried.

 

[bmaverick]

So for an update, Hoye and I went back and forth several times to try to figure out what was going on. Hoye requested a used shift fork from their boneyard and compared it with a new one identical to the one that they sent me. They claimed that both are the same size and that the part number is the correct part number from the manual.

They said that it looks like part 60 from this manual: TRANSMISSION_INTERNAL: Yanmar Tractor Parts could be worn from pictures that I sent, thus making the new part hard to fit correctly. I don't think this would result in what I was experiencing, but they suggested grinding down the top end of the shift fork to get it to fit. They suggested to be subtle on the grinding and check to fit often.

I went ahead and ground the topside of the shift fork until it slid into place, see picture below.

View attachment 751718

I used a flap disc and eventually got it ground enough. I used (2) #12 o-rings from Home Depot to replace the o rings on the diff lock pedal, measurements 5/8 in. I.D. x 13/16 in. O.D. x 3/32 in. wall thickness. These are ***-160 o-rings on Hoye's website. In order to get the compression spring that rides against the diff lock shift fork back into the transmission, I had to use a c-clamp to compress the spring. Once it was compressed, I was able to slide it off of the c clamp pad and against the shift fork. From there, it was a matter of installing the roll pins again and putting everything back together. Everything seemed to work ok, but it is yet to be tested. The diff lock shift fork was tight on the diff lock pedal, which has me a little worried.

From the sounds of things, There could be an original Yanmar p/n then superseded by another Yanmar p/n. This isn't the first time something like this has happened. I would suppose Hoye's advice was more spot on to get things to work for you.

As your YM2000 has a US equal and there are 2 or 3 parts manuals and other changes over those model years, it's amazing you got a part to work. There were Tree Frog green version and 2 Red Apple versions.

 

[smitty888]

Unfortunately, I have more bad news on this.

My dad used the tractor to plow snow last week, and the diff lock did not work as it should. When pressing down or pulling up on the diff lock lever, the spinning tire on one side of the tractor merely switched to the other side.

For example, if the right side wheel is spinning and the diff lock lever gets depressed, the right side wheel will stop spinning and then the left side wheel will start spinning. I have not taken it apart to see what's wrong yet.

 

[winston1]

Never heard of this before. It is normal for tire with least resistance to spin but when pressing differential lock both tires should spin. Your symptoms are very puzzling to me. I think your going to have to open up to get to the bottom of what is going on.

 

[bmaverick]

Unfortunately, I have more bad news on this.

My dad used the tractor to plow snow last week, and the diff lock did not work as it should. When pressing down or pulling up on the diff lock lever, the spinning tire on one side of the tractor merely switched to the other side.

For example, if the right side wheel is spinning and the diff lock lever gets depressed, the right side wheel will stop spinning and then the left side wheel will start spinning. I have not taken it apart to see what's wrong yet.

Sounds like the diff lock bridge for both is not engaging right, instead its just switching.

 

[smitty888]

Are you referring to part 60 as the diff lock bridge?

TRANSMISSION_INTERNAL: Yanmar Tractor Parts

www.hoyetractor.com