Troy Bilt Bronco Automatic transmission - variable speed pulley falls off

Wm2014

Forum Newbie
Hi everyone, looking for any advice and trying to see if someone else is having this same problem. I have had my Troy Bilt Automatic Bronco for 3 years and the variable speed drive pulley has fallen off 4 times. Is this a common problem with this model or just for me? How can I repair this? Thanks for any advice or experience you can share.
 
Thanks very much but I really want to know if anyone else has had this issue. I can fix it but I don't think I should have this problem so often. The guy I'm in contact with at Loews has talked to MTD and they don't want to help fix it, But I think there's a problem with the machine because it started falling off after only 1 month of use. If no one else has this problem, mine must be a lemon.
 
Just replace the locknut!!!!

If you want help there, at least post the model numbers off of the tag under the seat!
 
Hi everyone, looking for any advice and trying to see if someone else is having this same problem. I have had my Troy Bilt Automatic Bronco for 3 years and the variable speed drive pulley has fallen off 4 times. Is this a common problem with this model or just for me? How can I repair this? Thanks for any advice or experience you can share.

Yes this keeps happening to me as well. I bought my troy bilt back in 2016. It first happened to me about a month ago. Pulley fell off and I could see the threading was bad so I ordered an entirely new pulley. I replaced it and it happened again. The third time I fixed it I put some lock tight on the retention bolt. Got a solid 20 minutes of mowing done and it came off completely. I noticed that the pulley seemed really hot. hotter then it should be. The bolt and washer were extremely hot as well. I checked the bearings and everything seems fine there. Was wondering if you ever found out the cause.
 
I also have a 2016 Bronco Troy Bilt automatic transmission riding mower and had to replace the variable speed pulley three times.
 
Falls off is not much of a description for people to be able to offer useful suggestions as there are quite a few ways a pulley can "fall off" .
We also need a common base to work from so lets use this diagram ( if it is for your mower ) and the item numbers to keep things simple.
https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/troy-bilt/13-lawn-tractors/2016-models/13wv78ks011-bronco-2016/drive
If this is not your mower we need the model number should be 13??????? so we can find the right diagram.
I have about 4 bronco's in the repair run & have never had any fall off.
 
Did anyone ever get a good answer on why this is happening?
Model#: 13WV78KS011
Mine keeps coming off I put it back in put a bolt and a washer and it works for a bit then it falls right off. The pulley is hot and the bolt has made a large hole on the washer(guessing from being hot)and that’s why it slips off.Model#: 13WV78KS011
 
First both of the 6203-2RS bearings needs replacing. Second new screw (bolt) and washer need to be installed using blue Loctite. MTD used red Loctite but I prefer the blue version over the red as you migh need to take apart again later. MTD 710-05339A version is a captive washer type of the 5/16-24 X .75 Grd 5 screw. Torque to standard torque of 14 ft-lbs.
 
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