Craftsman 917.287121 keeps throwing drive belt

[dart451]

Anyone out there having similar problems with this tractor? Last year at the same time, I brought in this customer's Craftsman 20hp tractor in for the same problem. It threw the drive belt, damaged the upper transmission cooling fan and wedged itself. This time, the fan looks ok but I'm gonna have to remove the fan to un-wedge the belt. The belt was replaced last year at the same time and it looks good. Any suggestions?

[RJRacing]

check for a broken front trans mount allowing the trans to rock forward

[38racing]

check for a broken front trans mount allowing the trans to rock forward

Friend of mine had that on a husqvarna. Got some warranty coverage on the repair.

[bgsengine]

Had a Cub Cadet in a few years ago with a cracked frame doing the same thing... basically any twisting or torquing of the transmission - most often happens when changing directions it throws belt..

[KE4AVB]

Same thing can happen if the pulley and/or input shaft is loose. Plus check belt path and make sure that all the belt retainers and idlers are in good shape.

Note: If using aftermarket belts double check their lengths and compare OEM specs. These AM belts can be the wrong size. I have been having a terrible time getting the correct belts in after market. So much so that I have completely given up on buying them. I just tried two belts that JD was offering as aftermarket replacements. I couldn't even get them on then I checked their length and both were over an inch short. Just inform Sunbelt Outdoors that I will no longer buy their belts, even though they very good belts when right. I just don't have the patience any more to wait 2 days, find out they are wrong, re-order and wait another 2 days; just to get the same problem again.

I can't even trust Stens OEM spec'd belts either as they sent two belts last year was over an inch too long. They said their OEM belts can vary by +- 1/2" even when right.

[dart451]

I need to see if I can locate the front tranny mount...I thought there were just mounts on each side of the axle...

[KE4AVB]

Where do you get your OEM belts, one's you're comfortable with KE4AVB? It seems I ALWAYS get AM belts and yes, I have had trouble in the past...

Currently from Gardner (Dixie Sales) and RBI for Husqvarna (AYP), MTD, and the Briggs belts. The Briggs belts I can also get through Power Distributors and Sunbelt as both are Briggs distributors too.

The JD belts are from the local dealer that is giving me a small discount off their list prices but every little bit helps. And I price these accordingly.

I got in with Sunbelt back '09 but wasn't able to get the others cooperate until last year. Matter of fact RBI took 6 months after I signed up for dealer to even call me back.

I do recommend that you get a v-belt measuring tool. It does come in handy at times or at least does for me. Now mine does have two extension added so I measure up to 170" belts instead of just the 110" that the base tool has. Yes the tool is a little pricey but I found it worth if nothing else for the just knowing what I dealing with.

[KE4AVB]

I need to see if I can locate the front tranny mount...I thought there were just mounts on each side of the axle...

Look-up your on https://www.searspartsdirect.com/model-number/917287121/0247/1509200.html. Ground drive page will show what you might be missing.

[dart451]

Yes, I was looking at the diagram on the Sears parts website but I do not see anything that says front transmission mount. I do find Lawn Tractor Torque strap and Torque bracket...perhaps I need to find if they're in tact...

[dart451]

Ok, the front transmission mount is nice and tight. Had to remove the tranny fan to dislodge the belt. I put this belt, (532125907) last year, don't remember where I bought it. It is supposedly a 90". Checked all the keepers, all the pulleys look...can't see a single thing wrong. However, after I installed the belt, I am seeing a very noticeable lack of speed in forward! Going up a slight hill, it can barely make it! So, I can only assume the belt is too long or stretched out quite a bit. Sounds like a good idea to get a belt measuring tool!