The Tuul Crib 7,339 #1 Posted February 12, 2021 I'm trying to figure out how to calculate the speed that a 4 inch pulley would be over a 2 1/2 inch one for my fresh 12 hp Kohler . After I put it together then realized I had a 1 inch shaft on the PTO side. Oppps! No biggie it was the only one I had that met specs for a standard sized connecting rod. So I'm sitting looking at this 4 inch pulley that I have with a 1 inch shaft. My question is.... I had a 2 1/2 on it before to work for the newer PTO. I found this four-inch that has the new PTO bolt up and a 1 inch shaft.What size belt would I have to put on the tractor to make it work? Would this police speed it up too much? weeeeeeeeee!!! Share this post Link to post Share on other sites
8ntruck 7,833 #2 Posted February 12, 2021 Changing from a 2 1/2" drive pulley to a 4" pulley will increase the speed of the tractor by a factor of 1.6 - assuming that it is a gear drive. Not sure what the increased pump speed would do on a hydro drive. As far as belt size goes, with one that is 1 3/8" longer should get you close to one that should work. 2 Share this post Link to post Share on other sites
daveoman1966 3,839 #3 Posted February 12, 2021 1.6 is right. You can play with this pulley speed calculator here....https://www.blocklayer.com/pulley-belteng.aspx 1 Share this post Link to post Share on other sites
The Tuul Crib 7,339 #4 Posted February 12, 2021 Sorry I didn't mention that I have an eight speed 5060 trans. Just curious as to what the belt size might be? Share this post Link to post Share on other sites
The Tuul Crib 7,339 #5 Posted February 12, 2021 12 minutes ago, daveoman1966 said: 1.6 is right. You can play with this pulley speed calculator here....https://www.blocklayer.com/pulley-belteng.aspx Thanks for this info this is a big help! Got three different projects going at the same time! It doesn't get any better than!!! this! 1 Share this post Link to post Share on other sites
953 nut 59,917 #6 Posted February 12, 2021 5 mph 8 mph The math is very straightforward. 2.5" 4" You will probably be able to get by with a one inch longer belt. Just go to Tractor Supply and buy one an inch longer and one two inches longer and see what works best. Share this post Link to post Share on other sites
Rob R 973 #7 Posted February 12, 2021 Hi guy you giving me a headache here, I went from a 6" TRANMISSION drive pulley on my 310-8 to a 4.5" pulley and increased the speed in all gears nicely. SO in my twisted mind if you decrease the ENGINE drive pulley you going to slow everything down.... just saying.... 1 Share this post Link to post Share on other sites
Pullstart 66,692 #8 Posted February 12, 2021 16 minutes ago, Rob R said: Hi guy you giving me a headache here, I went from a 6" TRANMISSION drive pulley on my 310-8 to a 4.5" pulley and increased the speed in all gears nicely. SO in my twisted mind if you decrease the ENGINE drive pulley you going to slow everything down.... just saying.... Right. He’s stepping the engine pulley up to 4” from 2.5”. 1 Share this post Link to post Share on other sites
Pullstart 66,692 #9 Posted February 12, 2021 Randy. This is simple. See here. These fellers’ll teach ya somethin’. 1 Share this post Link to post Share on other sites
Pullstart 66,692 #10 Posted February 12, 2021 If them KY guys are hard to understand, try this one! 1 1 Share this post Link to post Share on other sites
Rob R 973 #11 Posted February 12, 2021 12 minutes ago, pullstart said: Right. He’s stepping the engine pulley up to 4” from 2.5”. Okay thanks pullstart thought he was going the other way............ 1 Share this post Link to post Share on other sites
The Tuul Crib 7,339 #12 Posted February 12, 2021 5 hours ago, pullstart said: Randy. This is simple. See here. These fellers’ll teach ya somethin’. That's some good stuff right there! 1 Share this post Link to post Share on other sites
The Tuul Crib 7,339 #13 Posted February 12, 2021 I'm still trying to figure out what size belt goes on it then I believe it was a 7473 to begin with. 82 " Share this post Link to post Share on other sites
daveoman1966 3,839 #14 Posted February 13, 2021 (edited) I gave this earlier...the SAME WEBSITE will tell you the BELT LENGTH In the top left, enter the LARGE pulley diameter and the SMALL pulley dia (4"). Also enter the pulley's CENTER-to-CENTER distance . Clik CALCULATE... The needed belt length will be shown. https://www.blocklayer.com/pulley-belteng.aspx Edited February 13, 2021 by daveoman1966 1 1 Share this post Link to post Share on other sites
KrazeyOlDave 860 #15 Posted February 17, 2021 I’m wanting to speed up my 310-8 also. Reverse is way too slow for starters, and when I plow our private drive, it takes wayyy to long. 30 mph should be fine 😂😂😂 Share this post Link to post Share on other sites
