Troy-Bilt variable speed drive problem

oharris · Jun 9, 2019

Hello,

I have a Troy-Bilt riding mower with the foot pedal to control the drive speed (not sure exactly what the proper term is). The drive belt was severely worn and looked like it could fail at any moment, so I replaced it. It worked great at first with the new drive belt, but after a while it stopped disengaging. (foot completely off the pedal but it still goes forward or reverse depending on what gear it's in) I tried fiddling with it, which made it work correctly for a little bit but then went right back to not disengaging. I tried adjusting the dual idler pulley, which also seemed to work for a few minutes but again went right back to where it was. It's like something is getting stuck and I can unstick it temporarily, but then it gets stuck again.

When I was replacing the belt, I did bend the flange on the drive pulley on the engine. I bent it back as best I could, but it's not perfect. Could this be my problem?

Thanks in advance.

Rivets · Jun 9, 2019

Your problem is probably the fact that you didn’t replace both drive belts at the time. On these units it is always best to replace both at the same time.

Fish · Jun 9, 2019

Also it is very important to use the correct belt, a generic belt of the same length will not work.

oharris · Jun 9, 2019

Thanks for the reply, I did replace both. I ordered them by part number off Amazon. (Couldn't find it anywhere else.)

Also, It may be heat related. It works fine when I start it up cold, but it quickly starts grabbing as it warms up.

Rivets · Jun 9, 2019

Please provide us with the model and serial numbers. There are different numbers that MTD used on that drive system and I’ve found all readily available.

panabiker · Jun 10, 2019

I also replaced the belts recently on my Troy-Bilt, first time since bought in 2005. The new belts are slightly tighter than the worn out ones and it does somewhat engage the transmission even when my foot if off the pedal. But I thought this is normal, just like the automatic car transmission. You are supposed to put your foot on the brake pedal to stop the mower if the lever is on "F" or "R". You may want to check the brake adjustment (and do a cleaning in the caliper and disc area). The mower should stop with a slight press on the brake.

oharris · Jun 10, 2019

panabiker said:
I also replaced the belts recently on my Troy-Bilt, first time since bought in 2005. The new belts are slightly tighter than the worn out ones and it does somewhat engage the transmission even when my foot if off the pedal. But I thought this is normal, just like the automatic car transmission. You are supposed to put your foot on the brake pedal to stop the mower if the lever is on "F" or "R". You may want to check the brake adjustment (and do a cleaning in the caliper and disc area). The mower should stop with a slight press on the brake.

I did clean and adjust the brake, to the point that I can't push the mower with the brake released. It still wasn't enough to overcome the drive. Wouldn't even slow it down.

I took the PTO off and looked at the engine pulley. I tried turning it by hand while holding the belt. It grabbed on the damaged part. I believe this is definately my problem. I have a new one ordered. Hopefully that solves the problem. Any advice on getting the old pulley off? It seems to be rusted in place.

panabiker · Jun 10, 2019

oharris said:
I did clean and adjust the brake, to the point that I can't push the mower with the brake released. It still wasn't enough to overcome the drive. Wouldn't even slow it down.

I took the PTO off and looked at the engine pulley. I tried turning it by hand while holding the belt. It grabbed on the damaged part. I believe this is definately my problem. I have a new one ordered. Hopefully that solves the problem. Any advice on getting the old pulley off? It seems to be rusted in place.

How did you change the drive belt without taking the pulley off first? Anyway, this video shows how the engine pulleys and the drive belts are removed and replaced. This is the video I watched before I did mine.
https://www.youtube.com/watch?v=i5_ly-o3fOE

bertsmobile1 · Jun 10, 2019

Clutching belts must be covered.
Full time drive belts, like your cars fan belt are not covered.
Just like your tyres, when rubber gets hot it gets sticky.
If a sticky belt gets used on a mower drive ( other than a ZTR ) it will not slip when declutched.

OEM MTD belts generally are double wrapped.
cheap "unbranded" belts bought on Amazon or Ebay often are not covered of if they are covered it is with a porus cover that allows the rubber to sort of ouze through making them sticky when hot.

I have even seen uncovered belts both painted blue or red or with a pressed in pattern to make it look like they were covered.
Naturally neither of these worked , the customers were very embarrassed and of course ended up paying for an OEM belt + a call out to fit it.

oharris · Jun 11, 2019

panabiker said:
How did you change the drive belt without taking the pulley off first? Anyway, this video shows how the engine pulleys and the drive belts are removed and replaced. This is the video I watched before I did mine.
https://www.youtube.com/watch?v=i5_ly-o3fOE

That's how it got bent. I tried to pry it off and it just bent. I was then able to get the old one off and the new one on via the bent portion. After that, I fix it, but obviously it wasn't enough.

Troy-Bilt variable speed drive problem

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