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stevef1201
08-31-2010, 12:40 PM
I currently have a 6 and 1/2 inch pulley on the engine shaft and am looking to change it to a 7 and 1/2 or 8 inch pulley to increase blade speed. Where in the heck would I find such a thing?
Any leads would be helpful

SuperiorPower
08-31-2010, 02:37 PM
I would not recommend doing that. It could cause you to have lots of unforeseen mechanical problems. With that in mind, I can not in good conscience give you places to get pulleys that would permit you to modify the mechanical construction of your mower. Higher blade speeds on a mower, not designed for such speeds, could cause additional vibration, fatigue, premature failure of bearings and other important components.

Remember, larger pulleys would also require longer belts. How would you know the belt size needed?

But the bottom line is, I have to ask, why would you want to increase your blade tip speed? After all, the manufacturer designed it to operate at the best blade tip speed for your mower. I would not modify that.

Steve
08-31-2010, 04:27 PM
Correct me if I am wrong here, but by doing that, you may increase the speed but you lower the cutting power.

Conversely if you make the pulley smaller, you lower the speed but increase the torque.

Just like a bicycle with multiple gears.

Somewhere in between max speed and max torque, the manufacturers find the optimal setting for both.

You can't increase speed and torque without using a larger engine.

stevef1201
08-31-2010, 05:42 PM
I replaced a 13.5 hp motor with a 22 hp motor, so that takes care of the power problems Steve. My Mechanic says that increasing blade speed will not cause any great problems as long I keep the blades balanced, which he says he can do when he sharpens them (which he does every two days for me-free! He is my next door neighbor whose grass I cut free)

Steve
08-31-2010, 05:51 PM
Theoretically, you should be able to order any sized pulley you want

http://www.mowpart.com/Pulleys/c505/index.html

Then you will need to use a piece of string or rope and wrap it around the pulleys. Mark the length and then measure it to figure out what sized belt you will need.

Let us know how it works and take some pics.

What made you change the engine?

CheapNEasy
08-31-2010, 10:14 PM
Keep in mind as Superior Power said....

Just because you upped the engine size, doesnt mean the DECK, Spindles, Bearings, and blades will adjust to the upped pulley.

Increased torque and speed adds stress to all of these components.

Just because you could put a 454 into miata does not mean that the miata's rear end, frame, etc... will support this load... additional torque.... etc....


Would really suck to get out, with your "suped up" mower, cutting a clients lawn and have your spindle housing bust, spindle break, deck pulley fail, belt snap, deck split from the additional torque..... etc...... etc..... etc...

Just a little food for thought, a "cheap upgrade" can cost you your mower....


Maybe think about getting a better set of blades, higher lift and mulching instead.


My advice, take it or leave it.

CheapNEasy
08-31-2010, 10:19 PM
I currently have a 6 and 1/2 inch pulley on the engine shaft and am looking to change it to a 7 and 1/2 or 8 inch pulley to increase blade speed. Where in the heck would I find such a thing?
Any leads would be helpful

Wait, pulley on the shaft? What type of mower are you even running?

To increase the pulley on the engine side, to make the blades faster, would require a new clutch.... The other pulley would run the hydro drive. As for rebuilding the clutch.... I myself would NEVER change the clutch pulley size. After all they are quite expensive.

Once again, I suggest not reworking your most vital piece of equipment, the engineers have designed it to work fluidly with all the components.

Invest in a new set of blades to compensate, this would be your best option.

Steve
09-08-2010, 12:02 PM
Any updates on this? Did you experiment with the new pulleys?