After changing all belts, riding mower moves on its own

[cadman33619]

Hi all. i just changed the 3 belts on my 2015 Troy Bilt Bronco riding mower. Now when i put it into gear (forward or reverse) it jerks forward (or backward) and starts moving without me pressing the pedal. The clutch/brake pedal has little effect is stopping it. Also, when i put it into neutral, it continues creeping forward. Almost as if the belts are too tight... but when i inspect, they are same as before i changed them. The main belt (longer one) has some play in it and is not very tight. all pullies move easily. I'm not sure what i could have done wrong.

any ideas?

 

[ILENGINE]

Did you use OEM Troybilt/MTD/Cub Cadet belt or generic size doesn't fit correctly belts.

 

[cadman33619]

2 are oem... 1 is not, the smaller (upper) belt. but i did compare for size and thickness/shape. It matched up.

 

[Auto Doc's]

Without a service manual we can do nothing more than guess. My guess is that there is a drive belt adjustment procedure that needs to take place.

EDIT: 5/6/25 8:59CST

Double check each belt for correct basic routing. The tapered inside of most belts go into a "V" of a pulley, while the flat back of the belt will run against the flat face of some other pullies. The routing could just be off.

It is difficult on most mowers doing this on your back, so I suggest you raise the frontend if possible, to get an accurate visual of what is going on.

Another problem that I have seen happen, is a belt getting placed on the outsider of a belt guide stem bolt instead of on the pulley correctly. The stem bolt guides (if present) usually have to be loosened up to allow for the belt to slip in and fit a pulley. The guides don't have to be fully removed in most cases, but they do need to be close to the pulley when the job is finished, this ensures the belt to not flop around and jump off the pullies.

The rule to follow here is if it does not fit comfortably, don't force or pry the belt into place.