Engine Double Pulley - Need Help

[jshep1102]

Hi guys! I need some help finding an engine double pulley for my mower. I'm in the process of swapping an engine into my Husqvarna YTA 18542 mower (model 960450055).

The donor engine (Briggs 40H777-0241-E1) came out of a Husqvarna GT2254 (Model 96025000201). The donor mower utilized an electric clutch to engage the deck blades but the receiving mower uses a manual lever to engage the deck. Therefore, I need a double pulley for this new engine that will drive the transmission and the deck on my mower. I have a dozen of these type double pulleys but none fit on this new engine. The crankshaft on the engine is 1 1/8" in diameter and my pile of unusable pulleys all fit 1" or smaller crankshafts. Do you guys know where I can get a double pulley to fit a 1 1/8" crankshaft? Ideally, the upper pulley needs to be 3 3/8" so it'll fit inside the belt guards. The lower pulley isn't as important as I can get a belt to fit it to drive the deck.
Ebay has a multitude of these pulleys but VERY few ever list the size of the bore. I've written several of the sellers but they either don't reply or want to know my mower model number so they can sell me one that'll fit an engine that's no longer in the mower.
Thanks for any help you can provide!
Jerry

 

[MParr]

Do you have a local Motion Industries, Bearings and Drives or other industrial supply company near by? Draw you a diagram of what you need and take it to them. You can also take the double pulley from your old engine down and tell them that you need one that is similar only it needs a 1 1/8” bore.

 

[Scrubcadet10]

might take a look at these https://www.milfordpower.com/Double-Pulleys-s/2472.htm

 

[bertsmobile1]

Go to any engineering supply company and buy a pair of steel pulleys and some heavy walled tubing
Drill out the grub screw and replace it with one that has an inner diameter the same diameter as the keyway
Cut the tube so the pulley spacing is the same as the original
Grind the last 2 turns of thread on the pulley grub screws so they are a tight fit in the keyway
assemble on the shaft , tighten the grub screws the tack weld together
Remove and do a full weld around the tube on each pulley
Drill 1 or 2 more grub screw holes in the tube & thread them to take 2 more grub screws modified as per the pulley ones
If you want, weld a heavy washer ( plate is using aluminium ) on the end for the bolt to push on
THe alternative is to weld them all together then get the whole assembly broached to take a square steel drive key but that is usually expensive with a double pulley due to the lenght of the key slot
The 4 grub screws will happily take the place of the drive key
The whole assembly needs to be a little longer than the PTO shaft length so the bolt clamps them together and takes the strain off the welds

 

[MParr]

After looking at the original parts diagram, @bertsmobile1 is correct on how it should be done.

 

[jshep1102]

Thanks for the options guys! I figured I was going to have to make one since I couldn't find one with that large of a bore. Was hoping I just s**ked at searching and you guys would point me in the right direction. Turns out, I was right. You pointed me in the right direction but one that involves a little more work.
I have the upper pulley that was on the donor mower (above the clutch) but it's a larger diameter (4 1/8 vs 3 3/8 (estimated based on belt guard dimension it'll have to fit inside)). My math says the larger pulley is about 1.5X the circumference of the smaller pulley. I can get a longer belt to account for that difference but do you guys think that'll overspeed the transmission or make mowing at the increased speed difficult or to fast for effective grass cutting?

 

[MParr]

Thanks for the options guys! I figured I was going to have to make one since I couldn't find one with that large of a bore. Was hoping I just s**ked at searching and you guys would point me in the right direction. Turns out, I was right. You pointed me in the right direction but one that involves a little more work.
I have the upper pulley that was on the donor mower (above the clutch) but it's a larger diameter (4 1/8 vs 3 3/8 (estimated based on belt guard dimension it'll have to fit inside)). My math says the larger pulley is about 1.5X the circumference of the smaller pulley. I can get a longer belt to account for that difference but do you guys think that'll overspeed the transmission or make mowing at the increased speed difficult or to fast for effective grass cutting?

You need to keep the outside diameter of the pulleys as close to original as possible.

 

[bertsmobile1]

You should be able to get a transmission pulley from a mower shop.
The aftermarket parts suppliers all list their pulleys by diameter.
Keep the transmission pulley the same size as hydro drives are very sensitive to input speeds and faster is definatly not better .
The deck pulley is not as important as all that does is change the blade speed
If you can't get an exact match go larger rather than smaller because the quality of cut is directly proportional to blade tip speed
An OEM top pulley will have a keyway cut in it so that makes things a little easier as you can fit a short key to the top of the PTO shaft if it's key slot is long enough

 

[MParr]

You will need two pulleys. Buy one pulley as close to the original upper in diameter. You will need the other to be very close in diameter as the original lower. Make sure they are bored to fit the Briggs crankshaft end. Also, they keys need to fit. Measure the shaft between the pulleys on the original. Now, buy you a piece of mechanical tubing that is 1 1/8” inside diameter and that is about 1/16” longer. Take all of your pieces to a machine shop. Have the mechanical tubing reamed with a 1 1/8” reamer. Also, have it faced. This will need to be done on a lathe. Then, have it TIG welded together. A good machine shop should have the mechanical tubing on hand and they can fix you right up. Make sure you take the old double pulley with you.
When done, you should have a good performing machine. Good luck! ?

 

[jshep1102]

Great recommendations guys!! However, I got lucky and am now going to a Plan "B". My father-in-law has a 21HP briggs with a smaller crankshaft diameter that one of my own double pulleys will fit. I'll save the engine with the larger crankshaft along with its original upper pulley and clutch as an organ donor for a later mower in need of a new heart.
I really appreciate the responses. I felt like I hit the jackpot when I saw you 3 respond to my post. I read your replies to other posts almost every day and learn from your feedback to others. With your feedback, this site has resolved WAY more problems than just the single original post asking for your help. Thanks again!!