Just got back from Alpine. Rode with a bunch of Pros. Saw 2 in the shop with broken bolts and one broke while we were riding. They all broke a couple of threads into the shaft. That broken bolt is going to be a beotch to get out since it is loctited in. My first instinct was just to retorque to the new specs as I thought the bolts were coming loose. They appear to just be breaking and the "new" bolt is hopefully more durable. BTW, the guy who broke the bolt we just put the pulley back on the shaft and he rode it 5-6 miles back out with no bolt at all. He just kept the side panel un-pined and stopped and checked the pulley often. When he saw it walking out he just pushed it back on the splines.
Take the lower pulley bolt recall seriously!
- Thread starter Matte Murder
- Start date
It's curious that this bolt actually takes any stress.. for me at least.
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sledneck_03
Well-known member
Yah weird there is any bearing stress on it.
I guess too low of torque it spins out, too much it breaks that's why it needs the higher grade bolt?
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What about the bolt backing out a few turns, allowing the pulley to shear it off. What else could it be...
I had the same problem with my edge. Polaris supplied A307 bolts that should not be torqued hard. Then the bolt head breaks off after some use.
While one would think there is little stress on this bolt.
It and the front shaft of the rear suspension are the only things holding this vulnerable section of the tunnel from bowing out and buckling when you exceed the yield strength of the aluminum tunnel sides. We have all seen the results of that, this is a very common area to accordion on the PRO chassis. The other possibility is a batch of fasteners that were made from out of spec. material or received out of spec. heat treatment.
It and the front shaft of the rear suspension are the only things holding this vulnerable section of the tunnel from bowing out and buckling when you exceed the yield strength of the aluminum tunnel sides. We have all seen the results of that, this is a very common area to accordion on the PRO chassis. The other possibility is a batch of fasteners that were made from out of spec. material or received out of spec. heat treatment.
Isn't the torque spec in this (both) of those bolts quite low for the bolt being used? I see they raised the torque but it still seems rather low compared to your "standard" SAE type specs.
JFYI, we do a lot of destructive testing (my normal job) and a bolts rated shear strength is only met when it is torqued to yield, with perfectly aligned surfaces and no shanks....just being under torqued a bolt can lose up to 80% of their rated shear strength....if that makes sense.
JFYI, we do a lot of destructive testing (my normal job) and a bolts rated shear strength is only met when it is torqued to yield, with perfectly aligned surfaces and no shanks....just being under torqued a bolt can lose up to 80% of their rated shear strength....if that makes sense.
I am wondering if the problem is starting at the top? If the top pulley is not squre with the bottom, the belt will tend to walk off and then pull on the lower? My 600 just went in for hte bolt update and the top shaft is shot. We had the bolt tight very early on so this damage was a surprise.
Lol....i cant use the letters f a s t in the Polaris forum....it just doesn't feel right.
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sledneck_03
Well-known member
The nut on the top gear in my chain case is huge, also is a castle nylock nut with a cotter. Bottom is small, think a 1/2" head?
What's the sizes of the bolts on the quick drive?
What's the sizes of the bolts on the quick drive?
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geo
Well-known member
IMO the bolt stress at the lower pulley is coming from the other side of the drive shaft being unsecured. This stress is created by the tunnel flex (levered by the rear suspention) as noted above.
IMO the top bearing is over worked because the QD plate is very flexy on it`s own and needs a little help from additional mounting points to be close rigid enough.
The rigid box structure of a chaincase allowed the oneside-holds-all design before. None of the top bearing failures have been from lack of lubrication. They have been failures from the simple interference fit between the jackshaft and upper bearing being inadequate to provide enough structure for the power transfer.
Theoretically if the two shafts stayed consistant in parallelism and distance, the pulleys would only need shims and circlips for alignment and retaining.
IMO, add all the torque you want to the best bolt strength available and you will stop breaking the bolts but do nothing to add needed rigidity to the stock design.
It`s adequate though. I got 1700 mountain miles with only a little troubleshooting-maintance as did many others.
Poo must have a new chassis around the corner with engine improvements continueing and chassis improvements just add ons.
IMO the top bearing is over worked because the QD plate is very flexy on it`s own and needs a little help from additional mounting points to be close rigid enough.
The rigid box structure of a chaincase allowed the oneside-holds-all design before. None of the top bearing failures have been from lack of lubrication. They have been failures from the simple interference fit between the jackshaft and upper bearing being inadequate to provide enough structure for the power transfer.
Theoretically if the two shafts stayed consistant in parallelism and distance, the pulleys would only need shims and circlips for alignment and retaining.
IMO, add all the torque you want to the best bolt strength available and you will stop breaking the bolts but do nothing to add needed rigidity to the stock design.
It`s adequate though. I got 1700 mountain miles with only a little troubleshooting-maintance as did many others.
Poo must have a new chassis around the corner with engine improvements continueing and chassis improvements just add ons.
Sure would be nice if Poo was more open about their "issues" on the Pro. I don't buy the bolt is breaking from tunnel flexing. That shaft assembly is massively stronger than the tunnel. You could take a sledgehammer to the inside of that tunnel and even a grade 5 bolt wouldn't fail. Even beating on the lower pulley itself would be really hard to get that bolt to fail INSIDE the shaft. Also, that sled was ridden out at least 5 miles with no bolt. Doesn't add up...
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geo
Well-known member
My point exactly Matte. The force required to break that bolt with a single strike would be huge but multiple smaller strikes could cause the failure over time.
I doubt the belt is strong enough to break it in that direction too. The top pulley will take any outward force from the belt because the outer guide flange is on it.
So here's my theory from reading in between the lines and things I felt on mine from the season.
The biggest difference in structure between the 13 shaft to 12 shaft IMO is the aluminum end on the clutch side. We've seen some failures here where the shaft came loose and worn to a smaller diameter.
My sled developes a noticable vibration through my feet that comes and goes. Read of others noticing this too. My vibration can happen on a high speed trail run with little or no snow in the tunnel or in waist deep snow where you don't even see the tunnel.
This vibration that comes and goes has caused me no issues other than it is noticeable, not right and I haven't been able to put my finger on it yet.
I think the drive shaft is pulling out of this bearing slightly (causing the vibration I feel) and snapping back in making things feel good again. I think the snapping back is causing the bolt failures and contributed to the failures of the other end stud (like a slide hammer). I think the reason for this is the difference in expansion rates of the aluminum end and the steel inner race. I think the press fit design is inadequate here unless bonding is used too. I think I'll install a bolt and washer on this end to retain the inner race to the shaft for next year. I think I won't know if I'm right till next year lol.
Lot of "I thinks" but that's the definition of theory and my theory at least until something comes up that makes sence to me.
The lower bolt is breaking but not coming loose. The upper bolt is loosening but not breaking. That's why I don't buy the loss of torque theory.
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rmscustom
Well-known member
Interesting post Geo...
"I think the drive shaft is pulling out of this bearing slightly (causing the vibration I feel) and snapping back in making things feel good again. I think the snapping back is causing the bolt failures and contributed to the failures of the other end stud (like a slide hammer)."
I wonder if this is what I'm feeling with my left foot when I'm on some nasty whooped trails? It feels like something is broke or it's trying to stab the track once in a while but I can never find anything wrong.
"I think the drive shaft is pulling out of this bearing slightly (causing the vibration I feel) and snapping back in making things feel good again. I think the snapping back is causing the bolt failures and contributed to the failures of the other end stud (like a slide hammer)."
I wonder if this is what I'm feeling with my left foot when I'm on some nasty whooped trails? It feels like something is broke or it's trying to stab the track once in a while but I can never find anything wrong.
I just found a '13 PRO with this exact issue! Owned by the dealer himself, 472 miles and the aluminum stub shaft was at least 1/16" undersized! So much for the press fit! I installed a new shaft and Loctited the bearing in place in an effort to make it last more than 500 miles. We will see, the QD looked good and I did the Geo mod where the two rivets are behind the upper bearing plate. Read about it in the top sprocket heat post.
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ak
Well-known member
On the driveshaft correct?
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