105 Drivetrain issue - stopped moving
 

I finished fixing some motor problems today, that involved a carb rebuild. I was driving around a bit making sure the carb was adjusted well and did some fast starts (too fast apparently) - One start if seems like something broke/popped and now it won't move much.

Forward or reverse, I either get no movement, or occasionally very little. Any ideas on what the issue might be?

In the past 8 or so years I have replaced the sheer pins on both ends of the driveshaft and rag joint and changed the hydro fluid and filter.

I'm guessing I need to split the tractor and see what broke, but not sure if I should open up the hydro unit again? It did have a slight leak I think, could it just be low fluid?

I took a look underneath and the rear end seems to be shifting some, not sure what that may indicate: https://youtu.be/bNIPOwN0C0k

I would start with tightening your transaxle mounting hardware, and then look at your spiral pins at the front and rear of the drive shaft.

I would also add that you verify your relief valves are not pressed in!

I forgot about this, with the transaxle rocking like that I could easily see them striking the underside of the tunnel cover/extension cover

Ooo that would be interesting, but kind of lines up to how I can get it moving slowly sometimes.

Needed to clean up my shed to make some room to work on it, so have not yet taken a look.

Took some more of it apart and cleaned up some dirt to try to figure out what is going on.

• Driveshaft appears fine and connected through the rag joint, all spinning
• Forward/reverse lever appears to still be connected fine
• Topped up the hyrdo fluid - I did not see any obvious carniage inside the unit, but only was peaking through the fill hole.

I took two more videos if anyone could take a look to help me figure out next steps. I'm not sure if I should split the tractor to get a better look at the driveshaft etc next or take the cover off the hyrdo unit to look inside.

View with the seat cover and fenders off: https://www.youtube.com/shorts/ob-udd-a-1Y

View from underneath: https://www.youtube.com/shorts/eMyr0T2xFuM

Edit: looking at the video again. The shaft coming out the back of the hydro unit it not spinning for the most part. Does that just point to a broken roll pin? I see everything spinning going into the unit from what I can tell, but maybe it just sheered off in the middle of the shaft so it looks fine from the outside?

Broken roll pin at front of hydro. The shaft at back of hydro is a thru shaft and turns whenever motor is running.

Well that’s good I didn’t ruin the hydro unit. If I recall, the easiest way to replace that is to split the tractor correct?

Got it all back together today after splitting it to replace the sheer pin. Also got it cleaned up a bit while apart.

Running great now after the carb rebuild that did before the sheer pin broke.

Did you replace the pins with Spirol pins and NOT split pins??

Yes, I had a spare roll-pin from the last time I did this year ago, just replaced the rear one.

The front one is actually a solid pin, not sure why that one is solid and the rear one is a roll-pin, I believe they are both the proper part numbers though.

I did debate swapping the front one out for a roll-pin, would make sense for that one to be the weak point since it doesn't require splitting the tractor to replace. I'd be interested if anyone has a roll-pin at the engine side of the driveshaft as well, as I still may do that in the future.

Yes, the front coupler pin is a hardened pin.
The rears should be HD Spirol pins and not split roll pins.
You will probably be working on this again next year if you use it on a regular basis.

About 8 years ago when I first started using this for routine mowing, I did go through a couple of spirol pins and roll pins, among other issues. Think I just had some kinks to work out since it had been probably 20-30 years since it saw routine use.

The past 3 or 4 years though have been pretty good, not too many issues up until now. I did replace both the front and rear couplers on the driveshaft and the rag joint, so that may have helped take some slack out that may have been wearing on the pins.

Overall though, splitting the tractor was easier and quicker than I remembered. You can tell these were built to be serviced and repaired, rather than disposable like most modern stuff.