Small Engines (Lawn Mowers, etc.)/Gear Shift Problem


I have a 2005 Troy Bilt Pony:
Body type number is 13AN779G766.  The engine is a 17.5hp Briggs & Stratton,  Model 31C707, Type 0154-E1, code 0508227E.

My mower has a 7 speed, shift on the fly transmission.  My problem is that it will only go in 7th gear.  The pedal has to come almost all the way up to the top for it to go. I know that these transmission are single speed and work by the belt and pulleys I think.

I am hoping you can help me figure out where or what to do first to fix this issue. I also have a 2004 troy bilt with the same engine, but it is an eight speed shift on the fly.  I noticed that when I rebuilt the brakes on that mower, it will now take off when I first let off the brake pedal. Any suggestions you could offer will be greatly appreciated. Seventh gear is not always the speed I need to go.  Thanks again,


Start by replacing the belts.  Make sure you use MTD belts as MTD makes the mower.  When replacing the belts check the variable pulley assebmly needle bearings, shaft and the center pulley disc to make sure it move freely, no sticking or binding.

Let me know if replacing the belts fixes the speed problem.

Small Engines (Lawn Mowers, etc.)

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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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