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JD X300 lawn mower shredding deck belts

bcoke

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Joined
Mar 8, 2013
Messages
341
Location
Pawlet Vermont
Not sure if this belongs here but my new [july 2019- 35 hour ] JD x300 lawn mower shredded it's beck drive belt. As I was researching how to replace it [you tube videos] I ran across many , many people having the same problem! Example 9 belts in 6 years---- one guy took it to JD dealer to replace [300$ ] than when they started it up in parking lot it shredded itself !!!! dealers claim from defective belts to some saying a design fault and there is a kit to remedy this problem. Belt shredded Saturday the Dealer was closed until Monday will call today to see if they will fix the situation under warranty .........they get $70 just for the belt! Has any GJ members experienced this? any solutions would be helpful........what has dealers said/done about it ? Thanks Bobbycoke
 
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matt_i

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Joined
Mar 14, 2008
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10,728
Location
SE Michigan
There can be a number of issues.

But reasonably new belts usually shred for one reason. 1) they overheat.

It can be caused by several things, bad alignment promotes scrubbing, torque-to-turn is another (the belt is overloaded, spindle or idler could be dragging with bad bearing or too-tight in a tapered roller set), could be touching a guide and rubbing on it, not necessarily statically but when its running there can be a harmonic that causes the profile to "wobble", the belt can also be too loose if a tensioner is present and its travel is restricted or the pivot bound-up...in that case the slipping creates heat.

I would also believe quality control plays a part. I have Woods mowers on my old Farmall tractors and they come with a single belt, probably the longest you've ever seen, running all 3 mower deck spindles, its even more costly at $90-120, and has twists and misalignments between the sheaves to make it even more challenging. There are 15-20 options for belts in the $40 range but they don't last as compared to the OEM belts (my and anecdotal experience suggests its a factor of 3-10x less), so there is definitely some "magic" that the belt manufacturer can put in there...or not. I try not to go more than 2 mows before greasing the tapered roller bearing spindles in the decks...my belief is kept regularly greased they will outlast me.

Its also possible the design is over-flexing the belt with tight radii but that's a hard one to fix.
 

glentre

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Joined
May 21, 2016
Messages
909
Location
Gloucester, Virginia
My JD X304 is about ten years old. The only time I shred a belt is when a beech nut from one of our many beech trees gets stuck in one of the pulley grooves. One time a small stick was the culprit. Hard to see unless you inspect every pulley. If not something stuck in the pulleys, I would think you have a misalignment somewhere. Either you hit something to cause the misalignment or you have a defect from the factory.

Glen
 

glentre

Well-known member
Joined
May 21, 2016
Messages
909
Location
Gloucester, Virginia
My new Cub zero turn threw a belt first time I used it with no problems since I changed it. Not everything that is fresh from the factory works right.

Glen
 

retDAC

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Oct 28, 2011
Messages
1,250
Location
near Huntsville, Ala.
Another possibility is the idler pulleys. If any spin freely, you need new pulley(s). The new ones are a bit stiff due to grease. When the grease has worked its way out, even if you don't see it, the bearings will momentarily seize repeatedly when hot which means the belt is rubbing and overheating. JD parts guy told me that and it seems true since I haven't had to replace any more blade drive belts.
 
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Chuckster in NJ

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Jan 26, 2010
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2,302
Location
Hunterdon County NJ
Check EVERY pulley for proper operation...... Spin them by hand for any noise, grinding, and looseness and grease any zerks while in there. Make sure everything is lined up and clean.
I just replaced an "idler pulley" ($25) on my deck that was not spinning correctly and was getting hot after 15 minutes of operation.
 

Kevin54

MEMBER EMERITUS
Joined
Jan 12, 2005
Messages
29,341
Location
Urbana, Ohio
I have a Cub CUT with a belly mower. Belts were $130 each, and I'd shred 2-3 every season. I took the number from the dealer belt and bought a couple of belts from "Vbelts for less". Never shredded a belt after that.

The original belts from the dealer were just a tad too long, and if I got into heavy grass, the blades would slow down but the belt was still running at speed from the PTO. It would burn the belt. But most times it would flip the belt, pop it off, then it would get wrapped up when the idler released, and shred it or cut it in half. With the new belt from VBelts-for-less, I've been running it for over 3 years now. BTW.....$130 for a dealer belt, $39 from VBelts-for-less.

here is the website.... https://www.vbelts4less.com/
 

infinkc

Well-known member
Joined
Jan 19, 2012
Messages
862
my craftsman just started to shred belts, i am finding cheap belts are not reinforced and just break so fast. I checked all my pulleys and they spun fine, after one mow, these cheap belts look like they were on the mower for years. all cracked and worn
 

LB-1911

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Joined
Sep 24, 2011
Messages
5,742
Location
Northwestern Il.
Not sure if this belongs here but my new [july 2019- 35 hour ] JD x300 lawn mower shredded it's beck drive belt. As I was researching how to replace it [you tube videos] I ran across many , many people having the same problem! Example 9 belts in 6 years---- one guy took it to JD dealer to replace [300$ ] than when they started it up in parking lot it shredded itself !!!! dealers claim from defective belts to some saying a design fault and there is a kit to remedy this problem. Belt shredded Saturday the Dealer was closed until Monday will call today to see if they will fix the situation under warranty .........they get $70 just for the belt! Has any GJ members experienced this? any solutions would be helpful........what has dealers said/done about it ? Thanks Bobbycoke

You may already be aware of the information provided in this previous thread re deck belts. :see: Post #6 @
X300 breaking belts


:beer:
 

kbs2244

Well-known member
Joined
Nov 11, 2006
Messages
14,065
Are you using J D part number belts?
They play with the tensioning so that non J D belts will not work.
 

mcspeed

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Joined
Jul 13, 2017
Messages
82
Not sure this is the same as your issue but my Kubota ZT will throw the belt if I engage the PTO at lower RPM’s. Has happened twice with my better half. Instructed her to get the R’s up before engaging and has not happened again.


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