Wheelhorse3128 7 #1 Posted December 28, 2025 Hi I have a wheelhorse 312 8 and I am wondering if I can swap the pulley off the transaxle and swap it with the one on the engine to get more speed. Is this possible to do. Share this post Link to post Share on other sites
ebinmaine 77,079 #2 Posted December 28, 2025 The engine and transmission pulleys have different size center bores so a simple swap can't be done. To do the swap you'll need 2 new pulleys. VERY IMPORTANT: The belt GUARD is the belt GUIDE which is your clutch. You'll also need to fabricate a new belt guard or heavily modify the existing one. 2 3 Share this post Link to post Share on other sites
Wheelhorse3128 7 #3 Posted December 28, 2025 Ok thanks can it be done by just changing the pulley on the transaxle? 1 Share this post Link to post Share on other sites
953 nut 63,969 #4 Posted December 28, 2025 The one on your engine has a 1 1/8" bore and the input to the transaxle is 3/4" Eric @ebinmaine answered while I was typing. Glad you found us, Please introduce yourself, tell us about your Wheel Horse and how you came to own it. 1 Share this post Link to post Share on other sites
ebinmaine 77,079 #5 Posted December 28, 2025 Just now, Wheelhorse3128 said: Ok thanks can it be done by just changing the pulley on the transaxle? Finding a smaller transmission pulley should be easy. You'll still need to compensate for the belt guard. What's the desired outcome and/or need to add speed? Share this post Link to post Share on other sites
Wheelhorse3128 7 #6 Posted December 28, 2025 More speed Share this post Link to post Share on other sites
Wheelhorse3128 7 #7 Posted December 28, 2025 2 minutes ago, 953 nut said: The one on your engine has a 1 1/8" bore and the input to the transaxle is 3/4" Eric @ebinmaine answered while I was typing. Glad you found us, Please introduce yourself, tell us about your Wheel Horse and how you came to own it. I have a wheelhorse 312 8 that I got for my birthday earlier this year 1 Share this post Link to post Share on other sites
ebinmaine 77,079 #8 Posted December 28, 2025 Just now, Wheelhorse3128 said: More speed Here in our Herd my S/O Trina has a tractor that used to go about 10.5 - 11 mph. That sounds pretty sedate until you try it. Stock Wheelhorse speed is about 6 - 6.5 mph. By swapping the transmission pulley down to a 4" you'll get maybe 7.5 - 8 mph. Be SURE to check the tie rods and the rest of the steering system for tight joints. Garden Tractors in general weren't originally built for zooming so there's more than just a pulley swap to be done. 5 Share this post Link to post Share on other sites
Wheelhorse3128 7 #9 Posted December 28, 2025 8 minutes ago, 953 nut said: The one on your engine has a 1 1/8" bore and the input to the transaxle is 3/4" Eric @ebinmaine answered while I was typing. Glad you found us, Please introduce yourself, tell us about your Wheel Horse and how you came to own it. I have a wheelhorse 312 8 that I got for my birthday earlier this year 1 Share this post Link to post Share on other sites
Wheelhorse3128 7 #10 Posted December 28, 2025 Do you know what bore and size of keyway I need if I buy a 3 inch pulley ? Share this post Link to post Share on other sites
ebinmaine 77,079 #11 Posted December 28, 2025 2 minutes ago, Wheelhorse3128 said: Do you know what bore and size of keyway I need if I buy a 3 inch pulley ? 15 minutes ago, 953 nut said: input to the transaxle is 3/4" Not sure on the key size. Keep in mind there's a minimum diameter that any belt wants to curve. Your tractor uses a 5/8" wide belt. That's a tough, tight curve at 3" which is why the engine pulley was put at 4". Also remember a new cloth sided belt will be required. Experimentation with proper sizing is likely needed. 3 Share this post Link to post Share on other sites
Wheelhorse3128 7 #12 Posted December 28, 2025 Ok thanks 1 Share this post Link to post Share on other sites
cleat 8,715 #13 Posted December 28, 2025 My 520-8 clone that I built still has the larger engine pulley from when it was Hydro. Hydro engine pulleys are easy to find. Getting a belt to fit both for length and clearance was the hardest part. 4 Share this post Link to post Share on other sites
Ed Kennell 44,666 #14 Posted December 28, 2025 When I built the low rider and used a small tranny pulley, I added a stationary idler pulley to make better contact on the pulley. Also built a custom clutch tensioner pulley and added belt support pins and belt brake for declutching. What ever you do, please remember the belt must be stopped to change gears. 3 1 Share this post Link to post Share on other sites
Wheelhorse3128 7 #15 Posted December 28, 2025 Wow that build looks really good and thanks for the infomation 1 Share this post Link to post Share on other sites
Wishin4a416 2,467 #16 Posted December 28, 2025 This one has been on FB marketplace for awhile. 1 Share this post Link to post Share on other sites
ri702bill 11,140 #17 Posted December 28, 2025 1 hour ago, ebinmaine said: Be SURE to check the tie rods and the rest of the steering system for tight joints. Garden Tractors in general weren't originally built for zooming so there's more than just a pulley swap to be done. Words of WH wisdom there.... And - be sure your brake band is in optimum condition & adjusted correctly! What goes fast must also be able to be stopped.... 4 1 Share this post Link to post Share on other sites
ebinmaine 77,079 #18 Posted December 28, 2025 16 minutes ago, Wishin4a416 said: This one has been .... 21 minutes ago, Wheelhorse3128 said: build Notice that the belt isn't supported. Do NOT set up this way. 1 1 Share this post Link to post Share on other sites
Ed Kennell 44,666 #19 Posted December 28, 2025 6 hours ago, Wheelhorse3128 said: Wow that build looks really good and thanks for the infomation Thanks, here is the other side of the clutch showing the foot and hand levers. Additional tension can be put on the drive belt by pulling on the hand lever. 2 1 Share this post Link to post Share on other sites
Wheelhorse3128 7 #20 Posted December 28, 2025 How fast dose that go? 1 Share this post Link to post Share on other sites
kpinnc 17,018 #21 Posted December 29, 2025 (edited) On 12/28/2025 at 7:15 AM, 953 nut said: the input to the transaxle is 3/4" Actually for an 8 speed the input shaft OD is 5/8. 4 speeds have 3/4 input shafts. As has already been said, be careful changing pulleys. Smaller changes work better. I've found for more speed, 4 inch pulleys at the transmission are quite a large change in speed. This also makes low range work much better for mowing, etc. Much more than this makes the clutch quite a bit more difficult to engage "gently", and wheelies are NOT good for your frame and front axle. Not to mention you can injure the operator. Edited December 29, 2025 by kpinnc 1 Share this post Link to post Share on other sites
Wheelhorse3128 7 #22 Posted December 29, 2025 Thanks just measure it aswell and it is 5/8 Share this post Link to post Share on other sites
groundhog47 445 #23 Posted December 29, 2025 (edited) @Wheelhorse3128 If not a lot of extra speed is needed two different engine pulleys are available. I believe it's the auto trans engine that has the larger diameter. Rear input, I don't know if same or smaller. You might be able to find some engine pulley diameter size by doing a search in "TOPICS" . The general knowledge of these members, not myself, is amazing. A hole other option is wheel increasing rear diameter, but fender clearance comes into the equation. Anyway, welcome to RED SQUARE This post, Drive pulley diameter: manual vs hydro, has some information . wh500special and ebinmaine and Speed By Nutiket Edited December 29, 2025 by groundhog47 additional reply 1 Share this post Link to post Share on other sites
