John Deere SX-85 will not go into reverse, or move backwards

Question

I have John Deere SX-85 riding lawnmower which comes with a Peerless 910 series transaxle. It has mowed the lawn twice since the installation of all new belts over the winter. During the second mow, it stopped moving in reverse.

We have used the reverse on the mower numerous times and know about the safety mechanisms required in order to reverse. i listed Hyperlinks to the safety mechanisms below because they could be failing and causing the problem, albeit doubtful.

It will not go in reverse. Even with engine off, mower blades disengaged, and in neutral, i cannot even pull it backwards manually. I can push forwards however and the lawnmower still mows grass in forward direction. I will have to pick up the 367 pound lawn mower to get it out of the garage!

Engine Stops When shift lever is moved to the R (REVERSE) position and Attachment Is Engaged Normal condition. (See Using Reverse Implement Option in the OPERATING section.)

Testing Reverse Implement Option (RIO) http://manuals.deere.com/cceomview/OMM143122_E0/Output/143122e05.html#32294

Using The Reverse Implement Option (RIO) http://manuals.deere.com/cceomview/OMM143122_E0/Output/143122e05.html#34176

Answer 1

I know this is an old question, but my bet is the chain for reverse broke inside the transaxle and balled up against the housing locking the rear wheels...only when you engage the reverse gear. It could have even cracked the case on the right side where the chain lives, have a look.

It's a bit tedious going back together but you can split the cases of the transmission to see what the problem is. No oil to worry about, just grease. Used to be able to buy parts but it's been over 10 years since I've last tried.

General pic for reference, should be similar to your 910. The shifter shaft slides the collar on the bottom shaft which has triangular points on springy "fingers" that engage key ways inside the 5 forward gears on the left. For reverse, the rear portion of the fingers engage the sprocket.

Answer 2

You have three choices.

Transmission rebuild

Nice option, as it doesn't mean buying anymore huge parts and you're just throwing out what's broken, but can turn out pretty expensive - especially if your time is worth anything. Essentially, you have to open up the transmission and find anything that is broken and replace it. This can be long and replacement parts can be expensive. My advice: look before you leap.

Transmission replacement

Nice option as well, though I am somewhat biased against it, reason being, again, you'll easily pay $300 USD for it. Being a John Deere, it might be worth it all the same: it's a call you have to make. You can also watch local ads and internet ads for parts tractors if you can wait a few years.

If you are a bit of a metal worker, you can also look into putting a different transmission on your tractor. Though it can be a lot of work, it can be a certain amount cheaper, as you can just buy whatever transmission in the area someone wants to get rid of, or, again, a parts tractor.

Buy a new tractor

Obviously, the easiest option. But also (probably) the most expensive. If you have a scrap pile in your garage, you can always get another broken one and combine parts.

TL,DR:

Count the cost, make the investment, do your research, and have fun!