sundstrand pump pulley/pto pulley sizes

[Greentored 3,217]

All went well with the C120 donor hydro swap into my 1277 yesterday til it came time to swap pump pulleys. The 1277 is a keyed shaft, maybe 4" dia, the C120 is splined and about 6" dia. I did not want to mess with ratios- was told thats bad on a hydro.

I did manage to get the keyed pulley on the splined shaft for a test drive- lets just skip the procedure I used and suffice to say it did not damage anything and it worked, but I certainly dont trust it.

SO- with the C having a larger pump pulley than the 1277, is it safe to assume the C also had a corresponding larger engine pulley to match? If I were to just use the larger pulleys, the belt engagement idler hits the larger pump pulley, and the belt guard would have to be revamped as well, so id like to stay with the 1277 pulleys. Did any of our hydro horses come with a smaller diameter splined pump pulley, or is this going to be another trip to Tractor Supply, the lathe, and welder?

Thanks in advance fellas!

[ebinmaine 68,345]

I can't answer specifically about the hydro because the mongrel that I was trying to build was a manual.

What I found at that point was that 1967 was the last year that Wheelhorse used a 2 inch diameter pulley on the engine for a manual transmission.

 

After that they increased the size of the engine pulley to 4 inch and the size of the transmission pulley up to about 6 inch... so as to have more friction area to help the belt grab.

 

If you have a Tractor Supply that can help you with the key slot pulley that is the same diameter as the c120, that would be the way to go.

 

There are online sources that may also be able to help you such as Zoro, McMaster-Carr, or multiple sites on fleabay.

[Greentored 3,217]

4 hours ago, ebinmaine said:

I can't answer specifically about the hydro because the mongrel that I was trying to build was a manual.

What I found at that point was that 1967 was the last year that Wheelhorse used a 2 inch diameter pulley on the engine for a manual transmission.

 

After that they increased the size of the engine pulley to 4 inch and the size of the transmission pulley up to about 6 inch... so as to have more friction area to help the belt grab.

 

If you have a Tractor Supply that can help you with the key slot pulley that is the same diameter as the c120, that would be the way to go.

 

There are online sources that may also be able to help you such as Zoro, McMaster-Carr, or multiple sites on fleabay.

I gotta go the other way bud haha- need that small pulley to keep the same ratio as the original 1277 engine pulley. Got a feeling I may have to sacrifice the C120 splined pulley, cut it down into a hub, then cut a keyway in it and run to Tractor Supply for a 1 1/8 or larger bore 4" pulley and go about it that way.

Oh yes, Tractor Supply knows me very well

[ebinmaine 68,345]

I don't think I'd get too worried about sacrificing a pulley from a transmission as common as a c120.

[Greentored 3,217]

4 hours ago, ebinmaine said:

I don't think I'd get too worried about sacrificing a pulley from a transmission as common as a c120.

Looks like thats where its headed 👍

[Greentored 3,217]

Problem solved! Picked up a 1 1/8” hub and pulley from Tractor supply and used a press fit and 3/16 key to assemble the splined ‘hub’ to the new pulley and hub. Fan will be here Friday.
Lot of work for a pulley but anything to keep this old iron running👍

Edited May 20, 2020 by Greentored