Belt keeps popping off.

[StarTech]

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.

Bull I personally know it matters as I maintained Husqvarna HWT625s for a local nursery where belt being off a by 1/4 caused problems and these MTD CVTs are just as touchy where it actual can cause speed changes.

 

[Rich A]

Thanks very much for all the detailed replies. I'm going to take the tractor apart while waiting for the new belt to arrive and will post some pictures with hopefully better views of the system.

But some comments here first:
To quote ILENGINE: "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"

What and where is that "anti rotate bracket" you are referencing? I ask because when the belt does pop off, it can be found intact and laying free. I can reach under the tractor and just pull it out. As you probably know the main tranny large pulley belt can not be squeezed into place because the space between the pulley and chassis is too small to get a new belt installed. AND when that belt pops off it does so with such force that the belt is forced past that very very tight space. There is no burning or fraying etc. But it looks like the force of engaging the drive system is "warping" the geometry of things that causes a mis-alignment of the belt where it CAN get past that opening and maybe because the tranny is "moving"?

So what exactly IS that anti-rotate bracket? There is a possibilty this could be the result of some damage done when I was backing up in the woods and ran over a hidden snow covered stump. That is when this whole belt problem started last winter. I will take some better pictures and hope you can point out this area of concern. I can not thank you guys enough .. Pictures to follow later.

 

[Craftsman Garage]

That probably bent the frame mounts if I had to guess.

 

[ILENGINE]

Item 50 part number 683-04176A sub to 783-04567B

But some comments here first:
To quote ILENGINE: "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"

What and where is that "anti rotate bracket" you are referencing? I ask because when the belt does pop off, it can be found intact and laying free. I can reach under the tractor and just pull it out. As you probably know the main tranny large pulley belt can not be squeezed into place because the space between the pulley and chassis is too small to get a new belt installed. AND when that belt pops off it does so with such force that the belt is forced past that very very tight space. There is no burning or fraying etc. But it looks like the force of engaging the drive system is "warping" the geometry of things that causes a mis-alignment of the belt where it CAN get past that opening and maybe because the tranny is "moving"?

So what exactly IS that anti-rotate bracket? There is a possibilty this could be the result of some damage done when I was backing up in the woods and ran over a hidden snow covered stump. That is when this whole belt problem started last winter. I will take some better pictures and hope you can point out this area of concern. I can not thank you guys enough .. Pictures to follow later.

 

[hlw49]

There is not tension on the short belt it has a spring on the arm that put tension on the belt. IPL does not show it were you can tell where it goes. I think it item no 25 on the IPL. It hooks on the idler arm and pulls the idler toward the frame on the right side there is a large hole with a smaller hole in front of the large hole the hook on the spring goes through the large hole and hooks in the small hole.

 

[Rich A]

There is not tension on the short belt it has a spring on the arm that put tension on the belt. IPL does not show it were you can tell where it goes. I think it item no 25 on the IPL. It hooks on the idler arm and pulls the idler toward the frame on the right side there is a large hole with a smaller hole in front of the large hole the hook on the spring goes through the large hole and hooks in the small hole.

Yeah I know .. The spring in the picture was disconnected. It's not an issue. I've changed belts and had this thing apart several times over the years. This current problem is something different and new from anything I've experienced in the last 8 or so years I've been using it. For everyone reading .. thanks to all the info and suggestions here, I think I have it figured out.

Look at my image above .. to Ilengine thanks. I now know what #50 is called. <grin> I've got the tractor up on jacks and removed the large lug wheels and body and the problem is now visible. Looks like I have a damaged tranny case (top right of tranny axle housing is cracked open) and the frame where the tranny mounting bolts are located 2 long bolts at bottom left of picture) is slightly bent. Sorry the bolt item #'s got cropped out of pic.

So looking at it carefully, I think I can repair the frame. The tranny does work but has signs of worn gears and as I noted the right side top is cracked open. I'll probably get a new transmission for it. I DO see something more clearly now. It looke like that main large trans pully #40 is tilted down a few degrees from being horizontal with the chassis. The other pulleys are equally aligned and horizontally level with the chassis. Like the chassis rail is 180 degree flat level and those two pulleys 56 and 43 are also at 180 degree level.

Like they are "--- ---- " BUT the large one is like " \ " High to the rear and a 1/2 inch low to the front. Part # 50 doesn't look like it's bent and I'm wondering if those two screws #'s 53 can be loosened to tilt the tranny a little for alignment? Sorry I haven't touched that #50 bracket yet, and just wondering that IS adjustable. I definitely have some signs of damage to that left side (not shown) frame area. Looks like I might be able to reapair that.

Guess best thing at this point is hunt for a new tranny cus of that nasty broken right axle housing?

The brackets 44 and 51 are brand new. #51 came with a new pulley as a kit. Tomorrow I'll see what's up with #50 and if it's bent or can be adjusted etc. The issue is definately damage to the frame on one side where the tranny is mounted to the frame. Arrgghhh. I hope I can salvage this before the snow starts this winter.

 

[Craftsman Garage]

That probably bent the frame mounts if I had to guess.

What did I tell ya!