N875ED 98 #1 Posted January 8, 2020 So I was successful reducing the input pulley to the transmission on my 312-8 by going to a 3.1" pulley and 78" drive belt. Much better speed range, IMHO, but was wondering if I should go with a heavier gear oil now that all the running gear inside is turning about double speed? I was thinking a 140w might be better than the 90w called for, since I thought it would be better for slinging by the rotating gears. Then again...it might be worse. What do you experts think? Share this post Link to post Share on other sites
8ntruck 7,083 #2 Posted January 8, 2020 Muncie 4 speed transmissions use 90W. They turn fast enough to go over 100mph and are transmitting a whole lot more horsepower and move around much more weight than a Wheel Horse. I'm not a gear oil expert, but I'd think 90W would still be fine in your application. 5 Share this post Link to post Share on other sites
The Tuul Crib 7,337 #3 Posted January 8, 2020 Good point. Share this post Link to post Share on other sites
stevasaurus 22,863 #4 Posted January 8, 2020 I would think that 90 wt would still be fine. I'm considering that you would still mow the lawn at about the old 2nd gear speed, and any snow plowing the original 3rd gear speed. If you are just racing around a go-cart track in the summer, you might just want to check it once to see how the trans is handling it. Remember...no shifting with out being at a complete stop. 5 Share this post Link to post Share on other sites
wallfish 17,079 #5 Posted January 8, 2020 Agree, 90w is fine. I went to 10-30 motor oil for a hot rod tractor with a jack shaft gear up and 2.5" trans pulley. I wanted to lighten the drag of the heavy oil with the faster rotation of the gears. The lighter oil easily splash lubed the entire case and as far as I know, there hasn't been any problem with that trans. 3 Share this post Link to post Share on other sites
N875ED 98 #6 Posted January 8, 2020 Thanks , gentlemen! Share this post Link to post Share on other sites
SALTYWRIGHT 859 #7 Posted January 8, 2020 The hot rod wheel horse walfish talked about I was clocked by gps at over 41 mph and never had trans troubleT 1 Share this post Link to post Share on other sites
Cvans 1,009 #8 Posted January 8, 2020 Many manual trans. use auto trans fluid without problems. 90w should be fine. Share this post Link to post Share on other sites
adsm08 2,175 #9 Posted January 9, 2020 I agree, stick with 90W. Selecting oil weights, from an engineering perspective, is less about how hard the fluid is getting slung around (shear stress is a factor though) and more about is it thin enough to get everywhere it needs to be. Going from a 90 to a 140 will probably mean your fluid isn't thin enough to get into all the crevices in needs to be in. Share this post Link to post Share on other sites
Ed Kennell 38,647 #10 Posted January 9, 2020 90W works fine in my 8 speed. I never clocked it, but the chute is set to deploy at 190MPH. 1 1 5 1 Share this post Link to post Share on other sites
ebinmaine 68,347 #11 Posted January 9, 2020 4 hours ago, Ed Kennell said: 90W works fine in my 8 speed. I never clocked it, but the chute is set to deploy at 190MPH. How many times has the chute puffed out?? 1 Share this post Link to post Share on other sites
Ed Kennell 38,647 #12 Posted January 9, 2020 3 hours ago, ebinmaine said: How many times has the chute puffed out?? None Eric. I am looking for a volunteer driver..... 2 Share this post Link to post Share on other sites
ebinmaine 68,347 #13 Posted January 9, 2020 1 hour ago, Ed Kennell said: None Eric. I am looking for a volunteer driver..... I'll tell Trina. She's about half cracked enough to try something like that. Maybe. 1 1 Share this post Link to post Share on other sites
cafoose 3,355 #14 Posted January 9, 2020 1 hour ago, Ed Kennell said: None Eric. I am looking for a volunteer driver..... 1 2 Share this post Link to post Share on other sites
Tractorhead 9,065 #15 Posted January 9, 2020 4 hours ago, Ed Kennell said: None Eric. I am looking for a volunteer driver..... Is there enough space for, like a Autobahn ? 😎.. Share this post Link to post Share on other sites
Ed Kennell 38,647 #16 Posted January 9, 2020 You mean like this? Share this post Link to post Share on other sites
