Pulley sizes

[TJ5208 1,824]

I'm looking to speed a 8-speed up a little maybe to where it'll run around 20 I'm just not sure on what pulley sizes to go with I'm doing performance upgrades to the motor so horsepower will not be a problem.

[wallfish 17,025]

There's lots of pulley size calculators out there. Here's one.

https://www.blocklayer.com/pulley-belteng

Your horse probably does 7 mph in it's original configuration with 3600 top rpm for the engine. By measuring the original pulley sizes you can calculate what rpm the trans pulley was turning to get 7 mph. Then do the calculations to get the speed you want with different pulley sizes. Bigger on the engine and smaller on the trans. Too small of a pulley means belt slip because of less surface area contact with the belt.  My estimation is 5" engine and 2.5" trans pulley. There are variables like pulley groove size and belt width. DO NOT USE POT METAL PULLEYS. they are designed for electric motor low rpm and WILL explode. Cast or Steel pulleys and search the max rpm for any pulley you buy.

https://www.surpluscenter.com/Pulleys-V-Belts/Finished-Bore-Pulleys/

20 mph is fast so don't trust those original tie rods and make new ones. Heim joints are good for that application. A little tow out helps stabilize the steering too and should stop that "shopping cart" effect.

 

I also filled the trans with lighter motor oil instead of dragging it down with the thick gear oil. At those speeds it will splash lube everything with lighter oil because gear oil slings off and won't creep up the gears to lube the top. If it's slinging gear oil anyway then a lighter oil should sling and splash more than a heavy thick oil would. I don't have any science to back that up but just went by thought and theory on that. Maybe someone with more knowledge or know how could chime in on that thought.

 

 

Edited November 23, 2023 by wallfish

[TJ5208 1,824]

1 hour ago, wallfish said:

20 mph is fast so don't trust those original tie rods and make new ones. Heim joints are good for that application. A little tow out helps stabilize the steering too and should stop that "shopping cart" effect.

It's a 520 forward swept axle

[wallfish 17,025]

9 minutes ago, TJ5208 said:

It's a 520 forward swept axle

Tie rods are good on those machines! tight and right for speeding things up.

The older style ball rusted loose type will require an excellent dental plan. LOL

 

[kpinnc 12,187]

On my repowered 310-8, I changed to a hydro pulley (5.25 inch) up front, and a 4 inch Browning cast iron pulley on the transmission. 

 

Basically low range is now what high range was before. High 3rd gear is around 15mph. This tractor also has the 520-H front axle. It is as fast as I would ever feel safe on a garden tractor. Sometimes it's too fast. If I find a 5 inch pulley for the transmission I will be downgrading. 

 

My brakes will skid the rear wheels. At these speeds, you will want the same or you will be damaging something when you crash. Hopefully not yourself... 

Edited November 27, 2023 by kpinnc

[TJ5208 1,824]

On 11/27/2023 at 11:10 AM, kpinnc said:

On my repowered 310-8, I changed to a hydro pulley (5.25 inch) up front, and a 4 inch Browning cast iron pulley on the transmission. 

 

Basically low range is now what high range was before. High 3rd gear is around 15mph. This tractor also has the 520-H front axle. It is as fast as I would ever feel safe on a garden tractor. Sometimes it's too fast. If I find a 5 inch pulley for the transmission I will be downgrading. 

 

My brakes will skid the rear wheels. At these speeds, you will want the same or you will be damaging something when you crash. Hopefully not yourself... 

So would going bigger on the motor and staying the same on the tranny keep the torque.

[953 nut 55,425]

On 11/27/2023 at 11:10 AM, kpinnc said:

My brakes will skid the rear wheels. At these speeds, you will want the same or you will be damaging something when you crash. Hopefully not yourself

The brakes on a Wheel Horse stop the transmission rather than the two rear wheels.When one rear tire has less traction than the other the tire with the least traction will stop and once it regains traction it WILL send you skidding sideways. All it takes is a few pebbles on the road or bouncing around to lose traction.

If you value your life I would advise you to put a pair of go-cart rear disc brakes on the axles.    

[wallfish 17,025]

27 minutes ago, TJ5208 said:

So would going bigger on the motor and staying the same on the tranny keep the torque.

After changing pulleys just use a lower gear to maintain the torque you want or need for a given task.

Are you looking to do 20 MPH on the weekends and then pull a moldboard plow during the week?

 

With the locked brakes and skidding the tires will actually spin different directions because of the pinion gears.  Just like when it's jacked up and rotating one wheel. They stop OK with good WH brakes. One I sold went faster than 20 and could stop it somewhat reasonably. Much better on the street that dirt or turf.

[Lee1977 6,686]

1 hour ago, TJ5208 said:

So would going bigger on the motor and staying the same on the tranny keep the torque.

I tried a 5 1/4" to the stock 6" on my 312-8 with a 16 Vanguard I was way too fast for any areas I have. I also have full height 25" tires on it.

The Mudmower bunch lock the rear axle on Wheel Horses so the brakes work on both wheels.

 

Edited November 30, 2023 by Lee1977

[TJ5208 1,824]

53 minutes ago, wallfish said:

After changing pulleys just use a lower gear to maintain the torque you want or need for a given task.

Are you looking to do 20 MPH on the weekends and then pull a moldboard plow during the week?

 

With the locked brakes and skidding the tires will actually spin different directions because of the pinion gears.  Just like when it's jacked up and rotating one wheel. They stop OK with good WH brakes. One I sold went faster than 20 and could stop it somewhat reasonably. Much better on the street that dirt or turf.

You explained it well. My tractor is a open diff but it locks both all the time I hit the brakes lock both up pulling locks both.

[kpinnc 12,187]

3 hours ago, TJ5208 said:

So would going bigger on the motor and staying the same on the tranny keep the torque.

 

No. Changing either pulley to increase speed equals a reduction in available engine torque. 

 

It's not overly noticable, so long as you make "smaller" incremental pulley changes. But you will definitely notice more governor activity. 

 

I would add one more point: changing the tranny pulley size too much affects clutch engagement as well. 

 

 

Edited November 30, 2023 by kpinnc

[TJ5208 1,824]

2 hours ago, kpinnc said:

 

No. Changing either pulley to increase speed equals a reduction in available engine torque. 

 

It's not overly noticable, so long as you make "smaller" incremental pulley changes. But you will definitely notice more governor activity. 

 

I would add one more point: changing the tranny pulley size too much affects clutch engagement as well. 

 

 

I'm not going wild with it just want something noticeable 

[kpinnc 12,187]

1 minute ago, TJ5208 said:

I'm not going wild with it just want something noticeable 

 

Just changing to a hydro (5.25 inch) pulley up front will add a nice increase in speed, and still preserve the usable function of the hi/lo transmission. 

 

Probably get the same results by changing the tranny to a 5 inch pulley instead. 

[TJ5208 1,824]

8 minutes ago, kpinnc said:

 

Just changing to a hydro (5.25 inch) pulley up front will add a nice increase in speed, and still preserve the usable function of the hi/lo transmission. 

 

Probably get the same results by changing the tranny to a 5 inch pulley instead. 

Do you know of the top speed that would get me.

[wallfish 17,025]

14 hours ago, TJ5208 said:

16 hours ago, kpinnc said:

 

I'm not going wild with it just want something noticeable 

Going 20 like your 1st post stated is a fast ride and certainly quite a bit more than "just something noticeable".

Start with the 5.25 hydro tractor type pulley on the engine first thing first. Run it like that and try it out. Then if it's not enough it can always go with a smaller pulley on the trans for more speed.

If you use that pulley and belt calculator posted earlier you can figure all of this stuff out. Even the proper belt length when you're done swapping pulleys.

[kpinnc 12,187]

4 hours ago, wallfish said:

Start with the 5.25 hydro tractor type pulley on the engine first thing first. Run it like that and try it out. Then if it's not enough it can always go with a smaller pulley on the trans for more speed.