HEY CLUTCH GURUS-Need help-- diagnosing violent belt "bounce" (erratic belt movement)

[Murph]

HEY CLUTCH GURUS-Need help-- diagnosing violent belt "bounce" (erratic belt movement)

A little history-- exploded a 115 belt in wet heavy snow one week ago-- older 115,not sure how many miles were on it, knew I was going to abuse a belt with the conditions and threw it in. Didn't think a 115 would/ could grenade.... It can.


Went for a ride today with new clutch side vents in wet heavy snow.

Last night cleaned primary, pulled weights, cover, spring and cleaned in soapy water and then put in the dishwasher. Pulled secondary apart, installed Delrin, cleaned re-assembled

Rechecked offset and float with Polaris special tool.

Pro RMK 163, 19-42 gearing, stone stock motor
Running 6-8000 feet

10-62 weights, stock springs (maybe 100 miles on primary spring after original broke at 700 miles)

Beginning of season, brand new 0 mile clutch was sent to Indy Dan for balance

Went for a ride....

Pulled over to check belt/ clutch heat and was unpleasantly surprised... They were HOT.

Also noticed-- may or may not be related, the rpm seemed to "hang" around 3500-4000 before idling back down. At first, thought there was snow in the throttle assembly, but it was clear. If I jammed the brake to lock up the jackshaft I could get it to idle down sooner.

Belt was smoking hot. Secondary seemed a little cooler than primary.

Used a tie down and a tree to elevate the rear of the sled. Pulled off side cover and opened the throttle. Watched belt engage and started to raise rpm-- looking for a misalignment or one of the clutches not opening.

At around 6700-7000 rpm the bottom side of the belt would start bouncing violently when under steady or increasing load/rpm. Where the belt runs between the sheaves on the bottom of the clutches, looked like it was being stretched and compressed( like when someone snaps a leather belt to make noise) The belt would jump up and down on the primary sheaves-- almost looking like it was going to jump out. ( track speed never exceeded 65 mph) this was at 1/2 to 2/3 throttle not wide open. Increased rpm and bouncing got worse, never settled out.

Motor and clutches seemed to be steady, not moving around causing the bounce the primary and secondary were spinning in nice circles, the motor (based on lack of primary movement) seemed to be steady also.

Changed belts, same result.

The observed rpm belt jumping coincides with something I have been feeling while riding. At 7000 rpm, the power delvery seemed to flatten out. It would still pull to 8100 rpm it just would not get there very quickly. The snap was gone. Now seeing the belt jumping up and down the sheaves it makes sense-- power is lost in the sheave scrubbing vertical movement that is producing a ton of heat.

Looking at my primary, when I push on the three towers, with the clutch still installed on motor, two of the towers feel solid, one tower "clicks" and the cover and spider seem to c0ck sideways. I'm thinking at 7000 rpm, the spider cocks slightly sideways and now the belt is running in a non circular orbit around the sheaves making for the violent observed motion.

I am going to swap out the primary and secondary clutches off my 155 and see if it doesn't fix my problem.

Sorry for the long winded post... Just tying to get as much information, observations, and symptoms down.

Anybody ever seen this before? Any suggestions?.....

 

[Zrider]

Murph:

Sounds like you might have a spider problem. Check you cover bushing and also the spider bushing since you stated that the spider is cocking under a load. Swap one clutch at a time; primary first and go from there. Let us know what you find out.

 

[Demo250]

Sounds like you have a case of Arctic Catitis.

 

[Murph]

Anyone seen anything like the above description?

 

[Murph]

Could it be something so simple?

Found "x" on moveable sheave and spring holder(roller) not lined up...

 

[IQRIDR]

More like your "x" problem is the cause, the effect is bad bushings from out-of-balance, then the final result is your belt chattering in the sheaves as your sliding half bushing and cover bushing let the entire sliding assembly continually deflect on the stationary shaft. I bet if you dissemble the clutch, install new bushings, re-align your x's, get it balanced, your problem goes away. But, when those bushings are shot, overall clutch component life will suffer greatly- rollers, roller washers, and weight bushings take a beating in the process. Assuming you are under warranty, try to get it replaced. If not, rebuild the clutch or buy a new one and you'll be set. My .02

p.s. sometimes when you press in the new sheave bushing it will take a ride to break in, and sometimes you have to clearance it slightly with fine scotch brite.

 

[winter brew]

Make sure your primary is in good condition (as you have planned), if that appears fine, other possibilities are a broken motor mount of getting water/snow on the clutches/belt....make sure those new vents cannot let in even fine snow dust.

 

[Murph]

Thanks for the input.

Winterbrew- thinking my vents are not letting in snow dust. I made them myself with finely perforated aluminum and covered the entire outside with pre-filter. Don't even see any water in there like I used to with the original stock venting.


Re- aligned "x" on spring holder/ roller and moveable sheave- violent hop is gone at 6700 rpm. Just a little bounce as you reach max rpm on the stand-- I'm assuming this is normal as the primary slows down its rate of acceleration towards max rpm. Checked against our other Pro and it does the same near max rpm.

Went riding today with three other Pros in wet heavy snow. First few times we stopped, I checked the other Pros and there belts, clutches were just as hot as mine even though I was breaking most of the trail.

I do seem to be producing a lot of belt dust, enough that it is collecting on the primary towers.

Summer project will be to build an exhaust fan like the mtntk one.

Also need to invest in a PROVEN clutch setup, helixes, weights, etc. would really love to find a setup that keeps clutches cool. Beginning to think that cool clutches are like a unicorn in our wet heavy, snow combined with my riding style that doesn't involve beer, cigarette, chit chat breaks!

Would love to find "lukewarm clutches after a long pull" that I keep hearing about!

 

[AkLogan]

Id love to find a clutching set up that does not blow a belt in 4-500 miles. on 2 11's and a 12. Nothing seems to work. so its become the norm.

 

[AKSNOWRIDER]

try a heel heavy weight..such as mtx's with slp blue/pink primary..and over about 6000 ft I would pull some finish angle out of the helix..from 56/42 down to 60/40 or 58/40...I think the 42 is just too much up that high....

 

[Murph]

Id love to find a clutching set up that does not blow a belt in 4-500 miles. on 2 11's and a 12. Nothing seems to work. so its become the norm.

That's what I have found also. I hate stopping. My only guess about the guys who say their belts and clutches stay cool are either flatlanders, champagne pow riders, or the type of guys that stop every 5-10 minutes.

Really hope I'm wrong about my last statement, but I have yet to ever find a cool clutch.

I'd love to find a setup that proves me wrong.....

6-8000 feet. Stock 155, stock 163.....

 

[AkLogan]

I ride with die hard poo. Both of us have Carl's cycle cut Mtx weights. I'm running the stock secondary with a different spring and he has a tied. His belts don't last any longer then mine do. We both have basically the same venting

 

[AKSNOWRIDER]

logan, I spent a little time messing with the sec spring last season..time and again no matter what I did I found the stock spring worked best..the other 3 I tried all ran noticable hotter then the stocker...up frt the best results always came back to the slp blue/pink with the stocker in back..always the coolest, best performing set..also found..if you have it pulling anything more then 8100 its running hotter and not pulling as hard..just what I found last season..just havent had the time and resources to look into anything more this season....

 

[theultrarider]

logan, I spent a little time messing with the sec spring last season..time and again no matter what I did I found the stock spring worked best..the other 3 I tried all ran noticable hotter then the stocker...up frt the best results always came back to the slp blue/pink with the stocker in back..always the coolest, best performing set..also found..if you have it pulling anything more then 8100 its running hotter and not pulling as hard..just what I found last season..just havent had the time and resources to look into anything more this season....

You know I'm running in mine Mike. Just what you have stated here. And while this IS the best combo I've hit, and clutch temps aren't too bad, I am now on my 5th belt at about 1200 miles. All of which were the bulletproof 1115's. Most have grenaded. Time to try out the cat 048. If they last as long as the poo belt at less than half the price, that will work for me.

 

[2XM3]

I believe the "belt jumping" would happen due to the fact that when you are looking at it there is no load on the track, hence the secondary does not sence any torque feedback and does not "know" where it should be so the belt tension goes away.

Now yes the heats a issue, best bet for mine was stiffer springs and mtx weights...

Interesting thing is I run turbo at 10 psi, 600 miles on same belt, no issues belt looks good runs good temp......??

 

[Murph]

I believe the "belt jumping" would happen due to the fact that when you are looking at it there is no load on the track, hence the secondary does not sence any torque feedback and does not "know" where it should be so the belt tension goes away.

Now yes the heats a issue, best bet for mine was stiffer springs and mtx weights...

Interesting thing is I run turbo at 10 psi, 600 miles on same belt, no issues belt looks good runs good temp......??

Agreed regarding the "jumping". It is somewhat normal near peak rpm as the primary slows down its acceleration. Mine was orginally much more violent, I think because of my mis timed secondary. My belt movements look good now.

Just running a lot of heat and producing belt dust. RPM is holding steady 7900-8000 during a pull, no apparent heat fade.

Too be clear, I'm still getting typically getting 500 miles out of belt. Just a lot of heat and eventually a failure (only one grenade the others were all cord pulls) along the way. The belts always look great, right up until a cord pops. I check my clutch alignment religiously, clean my belts and clutches constantly. I'm always reading about guys with 1500-2000 miles per belt. I'm just not seeing it.

As sick as this sounds, I must admit that I am somewhat relieved that you guys are seeing the same short (500 mile) belt life that I am. I thought I was the only one. It seems you guys in AK ride more like I do....hard.

I'm sure I could get 2000+ miles out of a belt.... Trail riding, or taking a break every 5-10 minutes- but that is not going to happen. Even the girlfriend hates trails.

I am really tempted to go the AC belt route. My 115's don't seem like they are worth the money. I used to think the 115 was impervious to blowing up-- I proved that is not the case. If the AC belt can go similar distance with similar performance at half the cost, I'm in. That or Ultimax with a warranty-- not sure how many I can blow in a typical riding season, I wonder what the warranty limit is or how hard it is to warranty?

 

[2XM3]

yeah, kind of weird on the pro, but just a fyi, I did install the slp torque arm right off the bat, and stiffer motor mounts...figure my mod sled has motor pretty much bolted in solid and makes 204 n/a legit hp with 3" track, never has it blown a belt...

I really wonder if the soft moveable mounts are a big part of the problem on the pro.????
Oh, if anybodys wondering I took the stock rubber mounts and filled the "gaps" with liquid rubber to firm them up.

If guys are seeing the turbo airbox bolts hit the bulkhead thats 3/8 or more inch away, thats motors moving a HUGE amount in a sled with no torque arm, and this would put massive side load on the belt.

 

[Timberview01]

Hey Murph,

I live in north Idaho where we only spend time on the trails when getting to the steep. And the trails that we do ride are 100% whooped out. I have a 2011 163 with 1380 miles on it. Last ride (very wet, very deep) I had about 1/4" of cord pop out on the original belt (115.) Maybe mine is the anomaly, but I can't think that ruining a $130 belt every 500 miles should be acceptable.

The crew I ride with are not the boose cruise type - we ride. Most of them do take breaks to cool down the belts, but it is usually a forced break while stuck or upside down. Other than that, it is all go time. And to clarify the type of riding we do - I usually only get about 50 miles to the tank of gas.

My sled is 100% stock.

I hope you find a solution. Couldn't be happier with my Pro and it kind of hurts my feelings to hear of other people losing faith in theirs.

Good luck.

 

[theultrarider]

Now to be fair, we have been blessed with crazy good snow this year. I ride with Aklogan and know his style of riding as well. Knee deep or deeper pow all day, taped to the bar for the most part. Short steep pulls, heavy loads, and usually only get shut down when stuck. Yes we are hard on chit. Look how many Ak sleds fail in many areas where others don't. We are also at sealevel ridng steep and deep. That is about like those of you riding pg turbos at altitude. If there is a weak link anywhere, the Ak guys will generally find it! Well, except for AKSNOWRIDER, he just hauls or fuel and fixes our chit and takes pics

 

[Murph]

...but I can't think that ruining a $130 belt every 500 miles should be acceptable Agreed

And to clarify the type of riding we do - I usually only get about 50 miles to the tank of gas. Same here

My sled is 100% stock.

I hope you find a solution. Couldn't be happier with my Pro and it kind of hurts my feelings to hear of other people losing faith in theirs. ]

I am definitely not "losing faith" just looking for a solution. If I have to buy a new belt every 500 miles, I'll do it. The Pro is just so much fun to ride. Might go with a cheaper belt and just replace them at mileage intervals