Make mower go faster, smaller pulley

crazyoldtractor

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If I were to put a smaller pulley on the rear of my old craftsman 5 speed maual to make it go faster, how fast could I get it to go. And how small of I pulley could I get away with without loosing so much torque that I wouldn't be able to get a a big hill? The engine is a 1985 B&S 11HP flathead.
 

Black Bart

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If I were to put a smaller pulley on the rear of my old craftsman 5 speed maual to make it go faster, how fast could I get it to go. And how small of I pulley could I get away with without loosing so much torque that I wouldn't be able to get a a big hill? The engine is a 1985 B&S 11HP flathead.

Why do you want to go so fast are you going to race it.
 

crazyoldtractor

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No, not gonna race it. Its just fun to ride it around on my trails but doesn't go that fast. Its my beat up tractor I use for utility, towing stuff around, pulling, and fun.
 

KennyV

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It will be twice as fast if you half the circumference.... BUT it will have a bit less than half the torque.
You will also have a problem with belt slipping on a smaller pulley...

So you will have to determine how much torque you want to be left with... :smile:KennyV
 

jmurray01

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It will be twice as fast if you half the circumference.... BUT it will have a bit less than half the torque.
You will also have a problem with belt slipping on a smaller pulley...

So you will have to determine how much torque you want to be left with... :smile:KennyV
Yep, I was just going to say, you'll loose torque, which on a mower, is low at the best of times.

I'd reduce the pulley circumference by 1/4 if I were you.

You will increase the speed a little bit, but still retain a reasonable amount of torque.
 

Black Bart

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If you have room I would put larger pulley on the engine rather than smaller one on the transaxle because you will gain pulley surface and that means NO belt slip.
Then you can start shopping for a bigger engine to put on it. :biggrin:
 

jmurray01

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If you have room I would put larger pulley on the engine rather than smaller one on the transaxle because you will gain pulley surface and that means NO belt slip.
Then you can start shopping for a bigger engine to put on it. :biggrin:
Ah, of course, I didn't think of that!
 

Duramax

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If you have room I would put larger pulley on the engine rather than smaller one on the transaxle because you will gain pulley surface and that means NO belt slip.
Then you can start shopping for a bigger engine to put on it. :biggrin:

will a regular drive belt stretch withought breaking if you do that?
 

Dangeroustoys56

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This isnt a hydro is it? Hydros cant be modifed or theyll self destruct. Its not a matter of making it faster, youll need to do more then that- like brakes, steering, ect.

My first couple of mod tractors were failures, not in the speed aspect, but saftey - barreling around and no brakes = trip to the ER .

One the transmission broke on me - luckily as i was just taking off, if it happened while at speed, id be lucky not to be paralyzed.

The second was way too fast for a 90% stock tractor - after more then a couple near bad crashes, i took it apart- was too dangerous to drive it.

My current mods in progress will have good brakes, lowering, ect - built to handle faster speeds, not just thrown together like my previous machines.
 

Duramax

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This isnt a hydro is it? Hydros cant be modifed or theyll self destruct. Its not a matter of making it faster, youll need to do more then that- like brakes, steering, ect.

My first couple of mod tractors were failures, not in the speed aspect, but saftey - barreling around and no brakes = trip to the ER .

One the transmission broke on me - luckily as i was just taking off, if it happened while at speed, id be lucky not to be paralyzed.

The second was way too fast for a 90% stock tractor - after more then a couple near bad crashes, i took it apart- was too dangerous to drive it.

My current mods in progress will have good brakes, lowering, ect - built to handle faster speeds, not just thrown together like my previous machines.

whats wrong with hydro's and why?
mine is a hydro
 
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