MT125 - Tractor speed slow in forward and reverse, significant play in pedals [Solved]

[flashbolt600]

Hi everyone,

I've been searching around for some solutions to this but have not been able to pinpoint the exact issue. Hoping to get some feedback or direction on possible repair options before taking the tractor over to the dealer to save on downtime. Tractor has around 120 hours on it.

Several weeks ago I was out in the woods clearing brush and cutting trails. Just using the loader and backhoe to push over some trees and dig up some stumps. Mostly new growth, nothing over ~2in thick. Lots of saplings. Being in the woods there is a lot of backwards and forwards movement, navigating around some tight trails.

Later in that session I noticed both forward and reverse speeds start to slow. I figured it could be overheating so I shut the machine down and let it rest for a few days. Couple days later I go to mow the lawn, same issue.

Since I was in the woods, I figured I could have knocked something out of alinement, bent something, etc.. so I started troubleshooting. More detail with respect to what I have done is below, but basically it seems the pedals have significant play and are not catching the control rod until they are 70% depressed or more. I've adjusted the HST control rod in an effort to tighten this connection, but if I keep the pedals in a horizontal position I still have the issue of pedal play although the HST rod is tight between part #11 and #12 as seen below. As an experiment, by adjusting the control rod I changed the horizonal positioning of each pedal to increase their stroke. I did this first for forward, then for reverse, and I was able to achieve normal speeds. Based on this, I figure the hydraulic system is functioning normally (loader/backhoe also functioning normally), and this is likely and issue with the pedals.

Based on the picture below, I figure the issue lies where part #12 connects to the pedal arm assembly (Marked as A in image below). I see in the manual there is a troubleshooting recommendation referring to the HST arm bolt being loose and can be repaired using adhesive. I was wondering if anyone is familiar with which bolt they are referring to and what type of adhesive would be required. The dealer was hesitant to provide any recommendations over the phone without seeing the machine so hoping someone else has had a similar issue and can provide some insight.

Troubleshooting done thus far:

1. Adjustment of HST Control Rod. No damage found, appears to be functioning normally
2. Removal and inspection of damper - no issues
3. Hydraulic oil levels checked and normal
4. Check for coiled pins in the pedal assembly and HST control arm, both in place
5. Checked tightness of all bolts in pedal assembly, all tight

Images referenced:

 

[Eagle1]

I had that problem on my XG because the Heim Joints were loose on the adjustable rod. Your's seems like a different setup. However if you have a real play in the pedals you need to track it down. There should very little fee movement before the swash plate is moving. If you watch the movement of every item from the pedal to the HST you should see where the linkage has some slop. Could a bolt/nut loose or a missing roll pin.

 

[Diggin It]

If I'm seeing that diagram right, Item 10 should be a roll pin that goes through a hole in the shaft on Item 12 and a hole in a collar on Item 9. Note where the letter 'A' on both parts indicating continuation within the drawing. Without that pin, the pedals aren't connected to the transaxle.

It may have fallen out, or be partially sheared. I replaced mine once and it fell out again. I replaced it with a #4 stove bolt and lock nut. Haven't had any trouble since. It's kind of hard to get to though and I had to take the MMM off.

But in my case, I lost all motion, the pedals just flopped loosely, so it may not be exactly the same situation.

 

[Cycledude]

Is your tractor equipped with a skid plate to protect all the stuff underneath ? For the type of work you seem to be doing it definitely should have a skid plate

 

[flashbolt600]

I had that problem on my XG because the Heim Joints were loose on the adjustable rod. Your's seems like a different setup. However if you have a real play in the pedals you need to track it down. There should very little fee movement before the swash plate is moving. If you watch the movement of every item from the pedal to the HST you should see where the linkage has some slop. Could a bolt/nut loose or a missing roll pin.

If I'm seeing that diagram right, Item 10 should be a roll pin that goes through a hole in the shaft on Item 12 and a hole in a collar on Item 9. Note where the letter 'A' on both parts indicating continuation within the drawing. Without that pin, the pedals aren't connected to the transaxle.

It may have fallen out, or be partially sheared. I replaced mine once and it fell out again. I replaced it with a #4 stove bolt and lock nut. Haven't had any trouble since. It's kind of hard to get to though and I had to take the MMM off.

But in my case, I lost all motion, the pedals just flopped loosely, so it may not be exactly the same situation.

Nailed it. I removed the snap ring with a pair of pliers and was able to push the broken pin out with an Allen key. Picture included below for reference.

For anyone else encountering a similar issues, relevant part numbers are:
Pin: 40460615
Snap Ring: 40029272

Note there is a similar assembly noted as part #11 on the diagram above.

Thanks everyone,