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Model 917.275972

So, I'd just replaced the ground drive belt last week (with the one from Sears, confirmed part numbers were right), no issues cutting last week. Got about 3/4 of the way through the cut this week, and as I started up a hill that I've been up hundreds of times, I get about halfway up and just suddenly the drive disengaged and I take off rolling backwards (thus providing impetus for me to move up the work on fixing the brake...). There was no warning before this, the blades never cut out, the engine continued running normally. Once stopped, letting off the brake pedal resulted in no movement at all, just like when the old belt had finally given up the ghost and slipped loose. I toggle the shifter, though, and the mower takes off just like normal, and I finished the rest of the cut without incident, even went on up the same hill again without trouble.

Any ideas what might've caused this? Did I just have the belt slip, or should I be looking at something else that's possibly worn out or damaged?

Does that have the two speed final drive? Might shift it back and forth a couple times to make sure those gears are engaged fully.

tom3 said:

Does that have the two speed final drive? Might shift it back and forth a couple times to make sure those gears are engaged fully.

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Are you talking about the high/low range lever?

Yes. That does have a neutral position.

I'll give it a once over. Thanks for the suggestion!

So, I had it slip again on a mostly level area today, and I think I found this issue. Seems like it will actually engage drive if the shifter lever isn't all the way over like it usually should be. Apparently its grabbing enough and then slipping free if I don't get it all the way over. There was about an inch or so difference in the place it would activate versus where it should have been before it activated.

That is quite an old mower so the shift linkages are quite worn
This is allowing it to only partially select drive which when put under excess stress allows the gear to drop out.
So yes, fix the brake .
There is no easy fix other than to pull the selector shafts out & replacing the worn parts if they are available.

bertsmobile1 said:

That is quite an old mower so the shift linkages are quite worn
This is allowing it to only partially select drive which when put under excess stress allows the gear to drop out.
So yes, fix the brake .
There is no easy fix other than to pull the selector shafts out & replacing the worn parts if they are available.

Click to expand...

Appreciate the info!

I'll have to look into it and add it to my list for what needs to be done (was down to replacing the brake, solenoid, and blades). Had another issue crop up today, though. Seemed to be losing some speed and uphill power during the last half of my cut, then when I pulled it in to park it started backfiring repeatedly, more when I throttled up.

For the tans it sounds like the detent groove is getting worn. These trans have a shift fork that rides along a rod with 2 groves in it. The shift forks have a spring and a metal ball in them that kind of lock into the groove. You should be able to feel this through the shifter when you shift into a gear. What can happen is the edges of the groove can wear down allowing the ball to just out easier when you hit a bump. You can open up the transaxle and rotate the rod slightly so that the groove has a fresh edge. These really are a solid transaxle worth a little fixing.