Clutch belt tension... interesting

[bryceraisanen]

Ok so last night I unloaded the new used (600 miles) 2013 RMk 800 Pro and took the trail ten miles into Cooke City. Sled ran fine for the most part. I could tell it was idling a little weakly and I figured that was because the belt was too tight, which it was, cause it tried creeping on me a few times on flat ground.

So this morning, I go to start sled to pull it in the shop but it wont start. I had to pull a lot harder than usual. Took the belt off, and gave it a pull and it fired up right away.

Sooo, i monkeyed with the belt tension adjuster on the secondary a bit. Even with the belt sitting 1/8" IN the driven clutch (i usually about 1/8 OUT), the sled would still try move when rotating the primary by hand. What could cause this to possibly be so grippy/tight? I took the clutch off to check the side clearance, and there is a solid 1/16"+ of side clearance. I plan on tightening that up a bit right now, but I don't understand what would make me have to set the belt so far into the secondary for it not to be gripping the drive clutch.... thoughts ideas?? Im using the Polaris 115 belt.

Taking the clutches inside right now for a thorough cleaning and degreasing as well as switching weights.

 

[winter4ever]

If the belt is loose in the secondary then it is probably your sheave clearance on the primary. If not then you could have a motor severely out of alignment, check for broken motor mounts.

If your secondary doesn't have the free play on the jack shaft like it is supposed to maybe its putting tension on the belt as well. And try a different belt.

Just saw you are changing weights too, i believe if you go to a lower profiled weight you change your sheave clearance as well. you said it was ok but maybe put in the stock weights just to see if it cures the problem.

 

[bryceraisanen]

If the belt is loose in the secondary then it is probably your sheave clearance on the primary. If not then you could have a motor severely out of alignment, check for broken motor mounts.

If your secondary doesn't have the free play on the jack shaft like it is supposed to maybe its putting tension on the belt as well. And try a different belt.

Just saw you are changing weights too, i believe if you go to a lower profiled weight you change your sheave clearance as well. you said it was ok but maybe put in the stock weights just to see if it cures the problem.

Theres a good 1/16" of sheave clearance. Gonna check alignment once i put clutches back on. just gettin done cleaning them.

secondary has some freeplay on the shaft. mmmmm i kinda like polaris belts.

stock weights are what were in there. gonna be putting aftermarket ones shortly.

 

[bryceraisanen]

Clutch pics

Sent from my SGH-M919 using Tapatalk

 

[bryceraisanen]

So you can see there is plenty of belt sheave clearance. Too much actually. But you can also see where the belt was rubbing on the sheaves just in the 30 yards i drove it into the shop. I had just cleaned the clutch with a brillo pad and wiped off all the gunk that was there and then went and put the clutches back on to pull it in the shop.

I thought maybe I would find a broken primary spring that was allowing the clutch to close just at idle rpm. No such luck, spring looks fine but I will replace it with new anyway. Sled still wanted to creep on the concrete shop floor...

Also checked alignment with my alignment bar from TEAM. Seems to be perfectly inline right in the middle of the freeplay on the secondary.

You would think if the motor alignment was way outta wack, that the burn marks on the clutch would be a different height on one sheave compared to the other....

 

[rmscustom]

Whats your center to center? Suppose to be 11.5". Have you tried a different belt?

 

[fastmnstealth]

I had the EXACT same problem happen...at Cooke City too LOL. It would drag when idling, idled low, etc. Like the belt got shorter. Normally 1/8" above secondary. Now 1/8-1/4" below secondary, and still would drag.

After adjusting belt deflection and changing belts, etc. I took the sled back to my trailer at the parking lot, thinking I had a broken spring, etc. I took the primary bolt out and the out 1/2 of the clutch came right off. The clutch had broken in half.

Pull the primary bolt out and see if outer sheave/clutch comes with it.

Fortunately, mine was under warranty. It was on my 2012 RMK Assault and it had approx 300mi.

Exxon in town had seen a number of them. They welded the clutch back together and then were able to use a puller. Of course I needed a new clutch. They swapped my spring and weights to the new clutch.

Mark

 

[bryceraisanen]

Had clutch off for the last hour or so. Scrubbed it up real good with soap and water. Couldn't find any evidence of it being broken. I have had a broken clutch before as well, on a different sled. If it was broke, I think I would've noticed while I was cleaning it or changing the weights and spring. I know what you mean tho, on my last one the outer sheave just fell off as soon as I took the bolt out.

When I push/pull up an down on the clutch there isnt much play, if any. Seems motor mounts (black rubber things where the bolt goes through) are solid.

Going to check center to center now...

I will also try a different belt, but all three belts I brought are Polaris 1115 ones.

Fastmnstealth:
I can picture how if the outer half of the clutch was broken, it could make the clutch "wobble" enough to grab the belt slightly. But when I take the belt off and just let it idle, looking at the clutch with my naked eyeball there doesn't appear to be any wobble in it.

 

[winter4ever]

Polaris's fancy new low enertia system has finally done it, its just too efficient..lol. make sure you got all the washers on your secondary on the correct sides. You said it was aligned so they should be, just throwing out ideas. must be center to center distance, but it looks like it only rubbed on one side of the clutch, which seems like a misalignment, or off center secondary.

 

[geo]

The rub marks are pretty normal from what I have seen on a long track, stock clutched and geared sled running it's carbide runners across dry ground. Especially with freshly scrubbed sheaves and belt.
Engine is spinning 4000ish and secondary is spinning 20ish.
All sleds have some (quite a bit actually) drag from the belt (even when in spec) and will pull over easier when the belt is off. I'm saying that because you may have a TPS setting issue causing a bit of hard starting-low idle and assuming it is excessive belt drag. The 115 belt is stiff too.

The rest needs more info please.

Couple of things to check and post. Float, OD of belt, C to C. In case something is wrong. I included float because of how you used your alignment bar.

The book way of checking deflection is a straight bar across the top of the belt and pushing down in the middle should show about 1.25" of deflection. Properly set it will show some drag when cold. 'Cause the stiff belt is round in an "un round" situation.
I always use this method and don`t care too much about the creep or don`t creep method because that is how they spec a belt length in pretty much all CVT systems. There is little or no side pressure on the belt at idle. All friction is created between the shaft and inside cord of the belt.

Most alignment bars ask you to push the secondary into the bearing behind and check. Then add float (another topic).
Some are universal and require you measure clearances (not just make it touch) between sheave and tool at both front and back on secondary. Those measurements may vary depending on sled.
Not familiar with the Team one but I do know they list the same tool for a couple of different brands.

On my sled (the Poo Pro), with everything set to spec, the belt sits above the secondary (about the bottom 3rd of the top cogs), creeps at idle (on a trackstand) if I spray some water on the front of the sliders when cold (room temp) and after a min or so of blipping the belt up and down will stop the creeping.
The belt still has drag on the primary shaft but is now a little more flexy.

 

[AdrenalineAddict]

Could be a cracked spider binding up the buttons in the tower or possibly the moveable inner sheave bushing sliding in and out and binding when the clutch opens back up at idle.

 

[fastmnstealth]

Had clutch off for the last hour or so. Scrubbed it up real good with soap and water. Couldn't find any evidence of it being broken.

Boy, I thought I had a slam dunk solution there. I noticed that you posted on BCB thread about riding around Long Lake. Did you get this issue resolved?

 

[bryceraisanen]

Ill post up in a couple minutes. I gotta go 10-200 and stat!

 

[bryceraisanen]

Soooo long story short, I'm still scratchin my head.

Winter4Ever: Those pictures are of both sheaves even though it looks like they are the same side.

Heres what I did:

Took secondary apart and inspected it. Didn't find anything unusual. While I had it apart I put in a new black/purple with one delrin washer underneath the spring cup. Pretty much a standard setup. Just trying to set a baseline here.

Took primary apart and inspected everything for wear. Everything looked and felt nice and smooth. Only 600 miles total on the sled. While in there, I installed a new black/green 120-340 polaris spring. Also put in my mds weights with one hex nut in the first hole.

Put everything back together and installed on sled. THIS TIME, I pulled one of my extra belts outta the suitcase and installed that instead of the original one that was giving me problems. I started with the secondary as tight as it goes, and then backed it off slowly until the was no more creep when I lifted up the back of the sled. VOILA! Belt now sitting roughly an 1/8" proud of the secondary clutch. Now I know this isn't the scientific way to do things, but I'm working in the snowbank mind you.

So WTF? Both belts are the same part number from Polaris. I don't recall exactly how much use each has seen. They've been kickin around my travel bags for a couple years. I was pretty sure I just broke them in with 30 or so miles back in the day, and then put em in storage for times like this.

So as far as I'm concerned, all of the wrenching I did should NOT have had any effect on this. Just simple swapping weights and springs. Shoulda just tried the other belt in the first place; but I have never run into anything like this.

Sidenote, I don't know if there is a "scientific" way to measure center-to-center, but just using a carpenters measuring tape and my eyeball as best I could, looked like 11.5 inches to me.

 

[bryceraisanen]

The rub marks are pretty normal from what I have seen on a long track, stock clutched and geared sled running it's carbide runners across dry ground. Especially with freshly scrubbed sheaves and belt.
Engine is spinning 4000ish and secondary is spinning 20ish.
All sleds have some (quite a bit actually) drag from the belt (even when in spec) and will pull over easier when the belt is off. I'm saying that because you may have a TPS setting issue causing a bit of hard starting-low idle and assuming it is excessive belt drag. The 115 belt is stiff too.

The rest needs more info please.

Couple of things to check and post. Float, OD of belt, C to C. In case something is wrong. I included float because of how you used your alignment bar.

The book way of checking deflection is a straight bar across the top of the belt and pushing down in the middle should show about 1.25" of deflection. Properly set it will show some drag when cold. 'Cause the stiff belt is round in an "un round" situation.
I always use this method and don`t care too much about the creep or don`t creep method because that is how they spec a belt length in pretty much all CVT systems. There is little or no side pressure on the belt at idle. All friction is created between the shaft and inside cord of the belt.

Most alignment bars ask you to push the secondary into the bearing behind and check. Then add float (another topic).
Some are universal and require you measure clearances (not just make it touch) between sheave and tool at both front and back on secondary. Those measurements may vary depending on sled.
Not familiar with the Team one but I do know they list the same tool for a couple of different brands.

On my sled (the Poo Pro), with everything set to spec, the belt sits above the secondary (about the bottom 3rd of the top cogs), creeps at idle (on a trackstand) if I spray some water on the front of the sliders when cold (room temp) and after a min or so of blipping the belt up and down will stop the creeping.
The belt still has drag on the primary shaft but is now a little more flexy.

1) Anythings possible. Started real easy the rest of the day after the aforementioned rigamarole...

2) Float almost exactly 1/16". I got the proper gap with the alignment bar when holding the secondary right in the middle of its float range. So it could theoretically go either way about 1/32" if it wanted to. Outside diameter of belt is yet to be determined, but at this point looking highly suspicious. Center to center looked good.

3) Understood. Just didn't think I would have to get too technical because of how far outta whack it seemed. A guy like you woulda been able to tell from a mile away. If you have to have the belt sitting IN the driven by 3/8" to stop the creep, somethings wrong. At that point, the gear ratio of the clutches themselves isn't even right.

4) Yes, stiff belts tend to creep, more than warm ones, all else the same.

Whew! Of all the Snowesting I've done, I haven't heard much about belts being outta spec. I hope I ain't the guinea pig in this department like I am in every other (feels like).

 

[geo]

I doubt it's belt too. Why don't you post a pic of belt installed and you checking defection.

 

[bryceraisanen]

I would/will but my tools are locked in the shop for the night. Can't get in there till 6 am. Seemed to run real good today beltwise. Still have some clutching work to do.

 

[diamonddave]

Could be a cracked spider binding up the buttons in the tower or possibly the moveable inner sheave bushing sliding in and out and binding when the clutch opens back up at idle.

These are (were) good possibilities if primary spring isn't broken.

What primary spring was in there? Could you post a pic?

Geo is correct about different weights affecting belt to sheeve clearance.

I would also be checking the belts width with a caliper.

 

[bryceraisanen]

These are (were) good possibilities if primary spring isn't broken.

What primary spring was in there? Could you post a pic?

Geo is correct about different weights affecting belt to sheeve clearance.

I would also be checking the belts width with a caliper.

Polaris black green 120-340, looks fine. Yes I can take a pic of it tmrw, its in the tool bag now.

I understand different weights can affect sheave clearance. I have been monitoring clearance and in all cases, the clearance has been excessive. Nowhere even close to tight.

Ugh! The cracked spider thing has me wondering now. Here's why. When I put the clutch back on the sled after having disassembled it and looked it over, it would fire up and idle just fine. But if I tapped the gas just enough to engage, then it would want to creep even after idling down. Will give the spider a good inspectagation in the morning.

I will be following up with belt widths, but for the sake of this particular situation, the width couldn't have made a difference. There was almost 1/16" of sheave clearance with both belts.

 

[Kraven]

MEASURING CENTER TO CENTER

Soooo long story short, I'm still scratchin my head.

Winter4Ever: Those pictures are of both sheaves even though it looks like they are the same side.

Heres what I did:

Took secondary apart and inspected it. Didn't find anything unusual. While I had it apart I put in a new black/purple with one delrin washer underneath the spring cup. Pretty much a standard setup. Just trying to set a baseline here.

Took primary apart and inspected everything for wear. Everything looked and felt nice and smooth. Only 600 miles total on the sled. While in there, I installed a new black/green 120-340 polaris spring. Also put in my mds weights with one hex nut in the first hole.

Put everything back together and installed on sled. THIS TIME, I pulled one of my extra belts outta the suitcase and installed that instead of the original one that was giving me problems. I started with the secondary as tight as it goes, and then backed it off slowly until the was no more creep when I lifted up the back of the sled. VOILA! Belt now sitting roughly an 1/8" proud of the secondary clutch. Now I know this isn't the scientific way to do things, but I'm working in the snowbank mind you.

So WTF? Both belts are the same part number from Polaris. I don't recall exactly how much use each has seen. They've been kickin around my travel bags for a couple years. I was pretty sure I just broke them in with 30 or so miles back in the day, and then put em in storage for times like this.

So as far as I'm concerned, all of the wrenching I did should NOT have had any effect on this. Just simple swapping weights and springs. Shoulda just tried the other belt in the first place; but I have never run into anything like this.

Sidenote, I don't know if there is a "scientific" way to measure center-to-center, but just using a carpenters measuring tape and my eyeball as best I could, looked like 11.5 inches to me.

On the bold & underlined for measuring center to center

Remove BOTH clutches

BUTT the measuring tape (preferably a straight 12" metal ruler) up against the jack-shaft & look for EXACTLY 11.00" at the crank center

(11.5" c/c deducting for half of the jack-shaft that is 1" diameter)

Sounds like your c/c is long, causing the tight/short belt scenario