HELP!!!! PULLEY SWAP

New Member Join date : 2014-01-17 Points : 3977 Posts : 4

i want to swap the pulleys on my 11hp craftsman to go at least 25mph it has two forward speeds and reverse what size pulleys should i use to accomplish my goal

Subject: Re: HELP!!!! PULLEY SWAP February 23rd 2015, 10:28 am

try a 4" rear and a 5" front

Subject: Re: HELP!!!! PULLEY SWAP February 23rd 2015, 11:00 am

a 1 to 1 ratio should do so a 5 in pulley to a 5in

Subject: Re: HELP!!!! PULLEY SWAP February 23rd 2015, 9:59 pm

I run a 4.5" on the motor to a 3" on the transaxle. With 19-20" tires and without the governor she cruises right around 25. Now when I am cranking the high rpms from my motor I could pass out my dad on his side-x-side who was doing 25.

Your gear ratio can depend on a lot of little stuff too. Like for example ,the bigger tires you run, the faster it'll go. Also if you take the governor off your engine it may speed up a little bit.

The bigger the pulley on the motor the faster it'll go, just remember that. lol

Subject: Re: HELP!!!! PULLEY SWAP February 25th 2015, 1:09 am

Right now I run dead on 20mph. I don't know what my front pulley is, but its the factory one with the trans and deck drive. I run a 3" on the rear with a 6 speed and 20" tractor supply atv tires. Also, stock clutch with stock spring plus 3 trampoline springs. With my setup I use a 86" belt.

A little advice. Don't use cast aluminum 3" pulley on the rear. The shaft part got wore out in a week, because of the belt tension. It is so loose, at a idle it sounds like a rod knocking. If you use cast aluminum pulley on the rear, go no smaller than 4", I used one for 5 months before I wanted to go faster.

Subject: Re: HELP!!!! PULLEY SWAP February 25th 2015, 7:15 pm

Not to bring the hate or anything, but from an engineering perspective, I would not suggest a 3" rear pulley and gobs of spring tension. 3" is really too small to get an effective amount of grip under a large load without artificial enhancement, such as your trampoline springs. So what the problem is?

All that tension is creating one hell of a radial load on the engine's crankshaft bearings and the tranny input shaft bearings. Much better to use larger pullies and save the added stress.

***Get YOUR official "Doc Locked, And Ready To Rock!" Stickers by clicking here!***
***Official Sprocket's Garage vinyl graphics and tees for sale HERE!***

Put down the wrench, and come out with your hands up!-Doc "Tranny Crusher" Sprocket, ATLTF Forum Admin, Thinkerer and Tinkerer, and all-around good dood. Wink

Gen. Mayhem- https://www.atltf.com/t2597-general-mayhem-race-tractor
MULE- https://www.atltf.com/t2153-lawn-boy-utltv
MULEII- https://www.atltf.com/t3328-1970-john-deere-112-the-beginnings-of-mule-ii
MULEIII https://www.atltf.com/t4263-mule3-brainstorming-ideas-etc#58287
Wrench, Wheel, Wreck, Repeat...

Subject: Re: HELP!!!! PULLEY SWAP February 25th 2015, 8:10 pm

Doc Sprocket wrote:: Not to bring the hate or anything, but from an engineering perspective, I would not suggest a 3" rear pulley and gobs of spring tension. 3" is really too small to get an effective amount of grip under a large load without artificial enhancement, such as your trampoline springs. So what the problem is?

All that tension is creating one hell of a radial load on the engine's crankshaft bearings and the tranny input shaft bearings. Much better to use larger pullies and save the added stress.

When I find a good way to build a clutch for a bigger pulley setup I'm going to shoot for a 6" to 5".

» MTD Lawn Machine Mudder!!!!
» Racing mower: pulley swap
» Pulley swap
» HELP pulley swap
» I need help with my pulley swap! :(