Belt keeps popping off.

[Rich A]

Craftsman 2011 - 247.28881 7 speed Shift-on-the-Go lawn tractor.

What would cause the smaller vari-speed belt to instantly pop off when engaging clutch? Could this be caused by a miss-adjusted part of the linkage? The user manual does not have any instructions for brake or clutch adjustments and says to "contact the nearest service center" for those repairs. I thought the problem was the smaller idler pulley bracket which was slightly out of line and tilted downward a few degrees. I've since replaced ALL the brackets and belts with new OEM parts and the slight tilt of that idler pulley is exactly the same with the new part purchaced. I've tried various manufacturers belts as well as supposed OEM MTD parts from Sears, MTD etc. And also found some NOS parts that had the original brackets. Nothing works. Help !!

 

[Barrett50]

I'm new here, my first post. You have replaced the belt. Is the belt the exact same width as the old belt? Just from the photo, it appears the new belt is too wide for the idler pulley. Or - is the idler pulley tilting on the driven axis when engaged? If you still have it, use the old belt and see if the issue remains.

 

[Scrubcadet10]

double check that model number, it's pulling up a completely different drive system

 

[Auto Doc's]

I agree the small idler pulley is too narrow for the belt being used. A belt should never ride far to the outside of the "V" of the pulley.

 

[Scrubcadet10]

That belt isn't tensioned in the picture, so it may sit fine in the pulley when applied

 

[StarTech]

247.288810 appears the OP dropped the ending zero.

Which belt are you using? OEM belt PN 954-0241A [954-05040] which is 5/8 x 35-1/4 or the one Sears is claiming is the replacement belt [490-501-Y087 5/8 x 35-11/16]. If using the longer belt that may be the problem as nearly a half inch is quite a bit on the smaller size since adding 1/2 to circumference increases the diameter by nearly a 1/4 inch and these CVT systems are very sensitive to belt width and lengths.

 

[Rich A]

Thanks everyone. I think "StarTech" has the best grasp of this problem. Yeah, the "model number" is strange when trying to get info. The printed manual that came with the thing is a 28881. The actual model of the tractor from the chassis label is 247.288810, Serial 1C301B80276, and was manufactured 03/2011.

The proper number for the upper drive belt should be 954-0241A. I have THREE new belts here From Sears Part's Direct, Stens, MTD and all were ordered as replacements for the 954-0241A orignal part. Should be a 5/8 inch x 35.25 in belt. One belt was 35.5, another was 36 and a third was 35.0. They all don't work. I can't seem to find one that is exactly 35.25. The widths are all close to 5/8 inch. but the "V" dimensions look slightly different.

Gonna try yet another supplier and told them to MEASURE the physical product and send me a photo of the measurement before shipping <sigh>

The upper drive belt part number appears on the hood label as well as printed parts manual.
954-0241A

I was asking about how to "adjust" the linkage BECAUSE I thought I could make a mechanical adjustment that might get one of the slightly too big or too short belts to work. Am now waiting for the 4th new belt .. It's strange that the belt length is so "critical". But StarTech got me thinking ...

 

[StarTech]

Being a '11 model has you checked the CVT pulley bearings [6203-2RS]?

And there is no adjustment related to the CVT pulley to transaxle belt.

But here is a question where exactly is the belt coming off? Could be transaxle rotating causing to come off its pulley. The anti screws do break off at times or simply fall out.

 

[Tiger Small Engine]

Thanks everyone. I think "StarTech" has the best grasp of this problem. Yeah, the "model number" is strange when trying to get info. The printed manual that came with the thing is a 28881. The actual model of the tractor from the chassis label is 247.288810, Serial 1C301B80276, and was manufactured 03/2011.

The proper number for the upper drive belt should be 954-0241A. I have THREE new belts here From Sears Part's Direct, Stens, MTD and all were ordered as replacements for the 954-0241A orignal part. Should be a 5/8 inch x 35.25 in belt. One belt was 35.5, another was 36 and a third was 35.0. They all don't work. I can't seem to find one that is exactly 35.25. The widths are all close to 5/8 inch. but the "V" dimensions look slightly different.

Gonna try yet another supplier and told them to MEASURE the physical product and send me a photo of the measurement before shipping <sigh>

The upper drive belt part number appears on the hood label as well as printed parts manual.
954-0241A

I was asking about how to "adjust" the linkage BECAUSE I thought I could make a mechanical adjustment that might get one of the slightly too big or too short belts to work. Am now waiting for the 4th new belt .. It's strange that the belt length is so "critical". But StarTech got me thinking ...

No belt length is that critical to a 1/4” inch. There is something else most likely going on that is wrong causing problems with 3 belts so far.

 

[ILENGINE]

Being a '11 model has you checked the CVT pulley bearings [6203-2RS]?

And there is no adjustment related to the CVT pulley to transaxle belt.

But here is a question where exactly is the belt coming off? Could be transaxle rotating causing to come off its pulley. The anti screws do break off at times or simply fall out.

I suspect the anti rotate bracket has come off or not connected allowing the tranny to tilt. Picture of frame to axle mounting bolts kind of show hints of something not correct, like possible cracking around mounting bolts.