What is making the heat on top pulley of the QD?
- Thread starter edgey
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akrevrider
Well-known member
Not really sure what the heat is being generated from other than a design issue. I've followed all the proper break in procedures and have added a heat shield. The top pulley still gets hot just not enough to melt rubber.
I wonder if it's an issue with the jackshaft bearing at the brake.
Getting hot?
There is a factory issued service bulletin/update for the top pulley bolt. Could be due too heat. When I went in for my update, they found my bearing was toast.
It all makes sense to me.
Getting hot?
There is a factory issued service bulletin/update for the top pulley bolt. Could be due too heat. When I went in for my update, they found my bearing was toast.
It all makes sense to me.
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From what I've read it is likely caused by the lack of adequate contact (jackshaft shoulder to inner bearing race and opposite side inner bearing race to brake disc hub). As the bearing is a slip fit to the jackshaft if the bearing is not pinched between the jack shaft shoulder and the brake disc via the top sprocket and top sprocket fastener then the jack shaft spins inside the bearing race rather than turning the bearing. As the bearing is hardened the jack shaft wears and the heat is transferred to the bearing, brake hub, QD sprocket, and lastly the belt.
CHECK THE QD FASTENER TORQUE AND VERIFY NO PLAY IN BRAKE DISC, as that is the first place it will be detectable. Any play in either direction (side to side or rotationally) and you need to re-torque. If any play is found in upper shaft. Pull it apart and find out what is wrong, likely bad bearing or groove worn jack shaft at bearing race location.
Hope this is helpful.
CHECK THE QD FASTENER TORQUE AND VERIFY NO PLAY IN BRAKE DISC, as that is the first place it will be detectable. Any play in either direction (side to side or rotationally) and you need to re-torque. If any play is found in upper shaft. Pull it apart and find out what is wrong, likely bad bearing or groove worn jack shaft at bearing race location.
Hope this is helpful.
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Is this an issue on non quick drive sleds as well, just not as aparent because it doesn't get the scrutiny that the qd gets?
The 800 has the updated bolts and the 600 don't they both seemed to get about as hot. I read Geo's post might have to take it apart and put some locatite on the shaft. They need to put a collar bearing on like the xlts had on the drive shaft with the set screws.
If you compare the Q-drive bearing setup to the edge chassis, the jackshaft and driveshaft bearings on the Q-drive side are non-greaseable and are not encased in a reservoir of circulating oil that keeps it both cool and adds oil as needed. On the edge chassis, all jackshaft and driveshaft bearings are either greaseable or incased in an oil reservoir. Most people would regrease the greaseable bearings at least every 500 miles or so, but the bearings encased in a oil reservoir could go forever. So you might expect the Q-drive sealed bearings to need replacement due to the lack of grease/oil being replaced and/or lack of cooling. Once they lose their original grease, perhaps then they will spin on the jackshaft/driveshaft as described above, creating heat from friction. So are there greaseable Q-drive bearings on the 2014?
I respectfully disagree with your analysis; regardless of bearing condition if you do not have it retained as designed (clamped between the jack shaft shoulder and the brake / sprocket stack with the sprocket fastener loaded) it will be a problem. I would venture to go so far as to say a lot of the '13's suffer from this from day one. As the factory fit of the bearing plate to the chassis is suspect and with the clutch side bearing being a press fit, they were reaching the original torque value before achieving a crush on the QD upper bearing. Even the new 45 foot pound torque value may not be enough to achieve the bearing crush on some sleds. Any and all '13 owners should look into this and keep an eye on it during their pre ride checks.
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QD
I also have excessive heat on my top pulley as do the other 3 13 pros I ride with. I removed the upper shaft last night and found nothing noticibly wrong. Bearing was not slipping on shaft. before removing noticed belt right up against shoulder of upper pulley and wonder if this could be the cause of heat, belt trying to be forced off due to in proper alignment. The plate that holds the shafts on the Qd is a joke, flexes at the slightest pessure.
I also have excessive heat on my top pulley as do the other 3 13 pros I ride with. I removed the upper shaft last night and found nothing noticibly wrong. Bearing was not slipping on shaft. before removing noticed belt right up against shoulder of upper pulley and wonder if this could be the cause of heat, belt trying to be forced off due to in proper alignment. The plate that holds the shafts on the Qd is a joke, flexes at the slightest pessure.
Is the bearing the same on the other end of the jackshaft?
Essentially yes, the QD side is a standard 6205 whereas the clutch bearing is the standard spherical race bearing they have been using since the beginning of time. Essentially the same quanity and size of balls and all other internal dimensions.
I'm not buying into WITG's theory that the chain case bearings lived due to the oil cooling the bearings. As the clutch side has just as much stress on it if not more and uses bearings with the same internal dimensions. Grease cavity is comparable and even the non-greasable version lasts for thousands of miles without fail. While plausible at a glance, IMO, it has no basis nor merit.
My money is on the brake pads dragging on the rotor.The faster you go the faster it draggs.
IMO the heat is coming from the small radius and amount of torque being applied to the pulley/belt from the engine. The lower pulley is much larger and is able disperse the heat better, has more contact with teeth, and a larger diameter for the belt to bend around.
If that is the case, it is due to Polaris utilizing the HTD tooth profile, as the C3 drive that uses the Gates G2 tooth profile does not build the detrimental amount of heat in the top sprocket. But in my opinion it is the sliding friction of shaft and bearing race, because once you get a proper fitment (read, blueprint the QD, good bearings, good shaft, proper fit and alignment) all the issues disappear.
Heat on top pulley
You guys might want to put this on for size. A couple of posts below someone lost his belt because it walked off the top pulley because of a pulley installation error. Think about it. In 20 miles the belt wanted to walk 36mm outward. With the pulley flange there, the belt can't walk off. The sideward force hasn't disappeared however. The right side of the belt can't move, but the left hand side is trying to move at the rate of 35mm/20 mile. The belt is constantly crunching in on itself and sliding a little on the pulley. It is hard to emagine that this force could be so strong that it is poping the heads off the bolts, but it could be. It would certainly explain the heat.
You guys might want to put this on for size. A couple of posts below someone lost his belt because it walked off the top pulley because of a pulley installation error. Think about it. In 20 miles the belt wanted to walk 36mm outward. With the pulley flange there, the belt can't walk off. The sideward force hasn't disappeared however. The right side of the belt can't move, but the left hand side is trying to move at the rate of 35mm/20 mile. The belt is constantly crunching in on itself and sliding a little on the pulley. It is hard to emagine that this force could be so strong that it is poping the heads off the bolts, but it could be. It would certainly explain the heat.
perhaps it not that they need shimming, but instead that the plane in which the operate is not parallel? If the chassis flexs as much as we think it does, and the backing plate for the QD is that weak, then it makes sense they are not parallel.
One thing i have noticed is the faster i go, the hotter the upper pulley gets. Throttle position/load doesn't seem to affect the temperature. It has everything to do with speed. More speed, more heat! Hmm.
IMO the other reason for that is the anchient HTD or similar tooth profile like the first blower belts in the '50-60's. The modern Gates PolyChain and others use a GT2 tooth profile ( more like an involute gear tooth) to eliminate this sliding friction. With the tunnel box structure flexing out of square in multiple planes it makes sense that the belt / sprockets / fasteners are seeing more load / wear than the engineers assumed they would. Engineering is not an exact mathematical equation unless you know all the forces involved or years of practical knowledge to accurately guess what those maximum values may be. In today's world, computer modeling is only as good as the information that is input into the software. So to be cost effective they take their best guesses and hope for the best. On the prototypes they likely ran some strain gauges to confirm that their guesses were in the ballpark. Sometimes they come up short. The other thing is the overhung shaft due to the brake disk being inboard of the upper sprocket may well be too flexible and under load constantly flexing downward as it spins. You will notice that the actual shaft on the CMX is a much larger diameter and the sprocket contact area is much greater. Also on the Harley style primary belt drives they have resorted to outboard bearings to eliminate shaft flexation and maintain alignment.
On a side note: if anyone has a '13 QD for sale, I'm in the market for a couple more. I want to pull the splined end out of one shaft and install it in the opposite end of another. Allowing me to run the brake on the clutch side below the driven clutch. With a longer 9" plus center to center, which allows for a 9tooth driver, 3"pitch, 3" lug track to fit with 1/2"-5/8" clearance at the smallest choke point. Doing it this way the sprockets could be moved closer to the bearing and may well decrease the overhung load enough to eliminate most of the issues people have been expirencing. Maybe similar to what they have up their sleeve for the '15 chassis to celebrate their anniversary?
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