John Deere X300 breaking belts

[Mr Mower Man]

I have a customer who has had an awful time recently with his deck belt on his 42" John Deere X300. I will say this model has one of the sillier looking belt routing designs I've seen. I don't suppose I'm really smart enough to be an engineer, but I still wonder sometimes what these engineers are thinking. The mower was just here at the beginning of August last year because the belt was coming off, and I replaced the belt and a few components of the tensioner assembly that were worn that may have contributed to the belt coming off. The belt I used was OEM, from a local JD dealer. The customer didn't have any trouble with the belt coming off this time, but it snapped when he engaged the blades in his neighbor's yard.
Thankfully, he had finished his own yard. All deck components look great to me, can't see anything that looks like it would obviously snap a belt. Anyone out there familiar enough with JD models to know if this particular design is finicky when it comes to belts?

[KE4AVB]

So you ran into one those mix masters. Either the 38 or 42 inch decks. Must had work as an interstate designer before designing this belt setup.

Due to the belt load any bearing that has the slightest rough spot can cause this. I have some Husqvarna mowers that I had to basically replace every bearing on the deck. I have since notice it is usually the one with the slight rough spot that does this. Even Kevlar as strong a belt they are they don't like high shock loads. I found this out on my TB Horse years ago. I always need to go forward first if it has been sitting several month as if I try reverse first it snap the belt nearly every time.

I got a hand few these mowers that I service but I don't need to buy the JD belt as my vendor has the belt in Kevlar that are at the JD belt length specs.

[Luffydog]

I have one doing the same thing but all idlers and spindles are good. Frustrating trying to figure it out been back 4 times to shop. Never broke the belt just throwing it off. On the tension idler pulley they make 2 brackets one with one belt guide and the other with 2 belt guides. Their is a serial break on the deck so I just ordered the one with the 2 guides and put it on. Also it doesn't help that they don't throttle it up all the way when they turn the pto on. Maybe you can use this and look in a little deeper at the break in the numbers on the deck and might also check the spring they do loose their tension although they look and feel good allowing just enough slack at times to throw the belt.

[hanz63]

I've not found a belt with the same girth as the OEM. Stens is the closest, but still smaller. If you have an identical belt, would you mind sharing? I had a lady that was hard on these belts. Snap each time -shock failure. Discussed throttling back as mentioned. Still broke them. I had read some scuttlebutt on the pitch and watching that the rear lift / adjuster arm didn't interfere. Still broke them. Now Mrs x , you are using the mow in reverse feature, aren't you? Blank stare. Be sure and tell your customers to use the MIR rather than constantly playing the engage/ disengage game. Now instead of belts per year it is years per belt.

[KE4AVB]

I have one doing the same thing but all idlers and spindles are good. Frustrating trying to figure it out been back 4 times to shop. Never broke the belt just throwing it off. On the tension idler pulley they make 2 brackets one with one belt guide and the other with 2 belt guides. Their is a serial break on the deck so I just ordered the one with the 2 guides and put it on. Also it doesn't help that they don't throttle it up all the way when they turn the pto on. Maybe you can use this and look in a little deeper at the break in the numbers on the deck and might also check the spring they do loose their tension although they look and feel good allowing just enough slack at times to throw the belt.

Those are the 38C (with and without the belt tensioner handle) and 42" without the belt tensioner handle. The 42" with the handle it is the L shaped LH belt retainer I am finding broken off.

I've not found a belt with the same girth as the OEM. Stens is the closest, but still smaller. If you have an identical belt, would you mind sharing? I had a lady that was hard on these belts. Snap each time -shock failure. Discussed throttling back as mentioned. Still broke them. I had read some scuttlebutt on the pitch and watching that the rear lift / adjuster arm didn't interfere. Still broke them. Now Mrs x , you are using the mow in reverse feature, aren't you? Blank stare. Be sure and tell your customers to use the MIR rather than constantly playing the engage/ disengage game. Now instead of belts per year it is years per belt.

A&I and Sunbelt Outdoors Products carries these (basically the same company). Can be gotten through the JD dealer or anyone that sell these brands. Actually if it is the M154601 the JD belt is .490 wide with effective length of 143.409 and the Stens 265-244 is .500 with an effective length of 143.5. The A&I is .500 with an effective length of 143.4

As for the reverse inhibit it is easy to take care of if it is a problem but it is there for safety and liability issues. It only takes one child being ran over in reverse to make it worth the hassle of having it; although, none my personal mowers have an operational reverse inhibit but I restated them before I sell one of them. Personal injury lawyers have make it necessary to have it as operators apparently have no responsibility for their own carelessness.

I already got one mower this year where they bypassed the PTO switch on a manual engaged deck so now it starts with it engaged. Since the customer has turned down the $400 repair estimate (engine needs a cam and deck needs serious repairs [shadetree repairs and other problems]) it not being repaired back to operational status. They went through a lot of hassles removing the switch so they could screw it. Apparently the reverse inhibit was driving them nuts but the Yardman it a lots easier to care of without damaging switches.

[Mr Mower Man]

Be sure and tell your customers to use the MIR rather than constantly playing the engage/ disengage game. Now instead of belts per year it is years per belt.

This is something I will make sure to do, since the customer says it happens only when he engages the blades.

Due to the belt load any bearing that has the slightest rough spot can cause this.

I will look carefully for this too.

I have one doing the same thing but all idlers and spindles are good. Frustrating trying to figure it out been back 4 times to shop. Never broke the belt just throwing it off.

This is the problem it was having last year. I ended up replacing the idler arm since the pivot point had developed some slop. That seemed to fix the problem, but this time the belt snapped.

I said something to the customer when he brought it yesterday about throttling down when he turned the blades on. I don't think he's been doing that. Sounds like shock load is especially important in this mixed up design. But seriously, does anyone have any idea why this convoluted design is supposed to be superior to the simpler ones I see on most everyone else's mowers?