Excessive Belt Travel on Primary

Jparker · Dec 25, 2015

I'm pretty new to the sport, I just bought a 2003 rmk vertical especially escape 800. I was pulling a high speed run in a field and grenaded 2 belts. Took it into my shop and check belt tension, made sure no pieces of belt were in the clutch etc.... crank seal is good.

Lifted the track off the ground and ran the sled observing the clutches(dangerous, I know.. but wore face shield), I noticed the belt would have climbed right out of the primary clutch if I gave anymore throttle. I'm pretty damn sure this is why my belts blew up considering I was running wot.

Also the crank shaft has no play in it, has the huge bearing installed. No noticeable shift in the engine, torque stops seem good. The secondary is a team driven clutch with reverse. Any ideas as to what is going on?:face-icon-small-con

sled_guy · Dec 26, 2015

What belt are you running? Do you know if it has stock clutching/clutches?

If the belt climbs out of the clutch it will break.

You can check the belt movement on the clutches by marking them with a line from inside to outside with a marker and then go ride. After riding you will see where the marker has been rubbed off and that will tell you how far you belt is traveling.

sled_guy

Jparker · Dec 26, 2015

Running stock clutches, I spoke with the guy I bought it from and apparently it has been geared down. So at high speed this can be expected? 080 polaris belts.

zilla · Dec 26, 2015

No shouldn't/couldn't be expected. If you say motor is locked in and not moving then the shaft of fixed side of primary clutch must be worn, or something not right in there.. Hmmm? You're not rideing in deep snow right ??

sled_guy · Dec 28, 2015

Well even geared down you shouldn't be able to run it out of the clutches, they are designed to keep the distance the same as they open and close.

I would check the center to center distance between them. Pull the driven off and then measure from the center of the drive clutch shaft to the center of the jackshaft and see what that distance is.

sled_guy

Jparker · Dec 28, 2015

Yeah the snow was fairly deep 3 1/2 feet, I took it out this weekend and marked the clutches they didn't seem to ride up very high but I was also very conservative with speed... I'm thinking I should take another look at those motor mounts. Would I be looking for a twisting action rather than an up and down sort of movement in the engine?

Jparker · Dec 28, 2015

BTW it only ran up about 60 percent of the primary according to the marker... top speed of 58 MPH on a groomed trail. Some wot hill climbing (short duration)

whoisthatguy · Dec 28, 2015

Buy a slightly shorter belt.

volcano buster · Dec 28, 2015

How much deflection when the sled is off?

Could the secondary be propped too far open?

Jparker · Dec 28, 2015

Found the problem

It turns out the problem was the secondary wasn't opening up! The guy on bought it from demonstrated how the reverse worked... the demonstrated how to change a belt, but didn't run the machine forward before opening the secondary. I learned from another thread on here that, that causes the secondary to become stuck closed! Took the secondary apart and reset the helix, now it's working fine. Now I'm wondering how much damage popping 2 belts like that has caused? Son of a ##$# - you would think he would have known better.. this is after I asked him if there was anything I needed to know about the sled. :face-icon-small-fro

Jparker · Dec 28, 2015

volcano buster said:
How much deflection when the sled is off?

Could the secondary be propped too far open?

There is probably about 1.5 inches deflection, 1/16 of belt showing over the secondary.

zilla · Dec 29, 2015

Glad you got it figured out. Him in a rush to show and sell, I guess.
But try and use ( Thread ) the belt removal tool just enough to remove the belt with bare hands still with some effort, that problem can usually be avoided even if opened when just shut off after a reverse.
The secondary will usually pop closed with a small blip of throttle with track on ground, usually.
Seen this one secondary where the guy was threading the tool so far in that he was going thru the large thick washer and cracking the other sheave

Jparker · Dec 29, 2015

zilla said:
Glad you got it figured out. Him in a rush to show and sell, I guess.
But try and use ( Thread ) the belt removal tool just enough to remove the belt with bare hands still with some effort, that problem can usually be avoided even if opened when just shut off after a reverse.
The secondary will usually pop closed with a small blip of throttle with track on ground, usually.
Seen this one secondary where the guy was threading the tool so far in that he was going thru the large thick washer and cracking the other sheave

That would be pretty frustrating! So much can go wrong with a simple belt change on these machines... if I ever sell this one I'll be sure to let the buyer know all these very important details.

I'm thinking I should get the crank run out checked after this fiasco. I'm just trying to decide whether to do it myself or pay to have a shop check it. I'm sorta leaning towards doing it myself, thoughts?

volcano buster · Dec 29, 2015

Pick up a dial indicator at Harbor Freight with a magnetic base and start checking it out.

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Excessive Belt Travel on Primary

Jparker

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sled_guy

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Jparker

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zilla

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Jparker

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Jparker

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whoisthatguy

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volcano buster

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