QD Belt Temps Field Testing

[AK IQ Pilot]

So, I spent the three day weekend riding with 6 new Pro's, we did a lot of QD belt testing measuring temperature and observed run out and various other things on these new sleds. This may get a little long but I wanted to share my onservations.

All sleds were 800, 155's.

All but one had the '13 drive axle with collar.

All sleds had stock muffler and were virtually stock engine wise.

No sled had any visable run out on the upper or lower pulley. Not measured by a dial indicator but none visable. I will measure my own sleds with a dial indicator ASAP.

I will discuss the three that I have the most data on.

Sled 1. Black non limited has a 2012 drive axle in it and had already sheared teeth on a QD belt in about 55 miles. This happened in powder when climbing and catching traction on wind blown base. Half the teeth sheared and the sled would no longer move. This sled got a new drive belt and it was broken in for 100 miles on flat river running with 6" of fresh snow. During break in the first belt left lots of black particles all over the belt drive area. If you have seen these particles you know what I mean. 2mm x 4mm pieces of thin black belt material. Mold Release material is what some are calling it. Second belt does not have any black particles coming off it and it has about 150 miles on it now.


Sled 2. White Spring order Limited. Broke in the belt with 100 miles of fast river riding with 6" of snow. Plenty of hard pulls on flat ground after the first 50 miles. No evidence of belt material anywhere around drive belt. Sled now has 255 miles of decent to hard riding. No heavy deep snow conditions and no steep hard climbing. Mostly boondocking and tree riding.

Sled 3, mine. White Spring Order Limited. Began the weekend with 5 miles on the odometer. Broke in belt gently with slow and easy trail riding for the first 40 miles. Moderate trail and tree riding the next 50 miles. A few WOT pulls after that. No evidence of belt material anywhere around the drive belt.


Belt temperatures. I checked the drive system and muffler temperatures dozens of times this weekend with a Snap On digital infrared temp gun. All sleds had basically the same belt and pully temps depending on how and where they were ridden just before the check.

Ambient temps were about 15f.

On moderate and slightly agressive trails the belt, pulley, rotor and muffler temps would be as follows.

Drive side of the belt woulld show 95-100 both inside and outside.

Coast side (next to the muffler) would show 100-105 inside and out

Upper pulley would show 125-130 at the hottest part of the pulley which was always on the inside flat under the teeth. The hub face and teeth were always colder by 5 degrees at least.

Lower Pulley would show 80-85 at the hottest part of the pulley.

Brake rotor would show 80-85 at the braking surface but hotter near the hub.

Muffler woulf be about 275 or so at the closest point ot the belt.


Moderate tree riding on relatively flat ground. 20" of dense but not heavy snow.

All across the board the temps were 10* hotter except the brake rotor and lower pulley. They always stayed between 80 & 85F. Muffler was hotter by 25 deg at least.

Moderate to hard pulls on relatively flat ground across 1/2 to 1 mile long swamps. 20" of dense but not heavy snow. 7200-8200 RPM. 45-55 MPH. I would still consider this a relatively light to moderate load for the drive system.

Belt, upper pulley and muffler temps went way up. Both sides of the drive belt reached 135+ at times. Upper pulley saw 155 to 160f. Muffler saw 350+ near the drive belt. Lower pulley and brake were still around 90f.

I have heard that the belt may begin to degrade at 185f. Not sure how accurate this is. I could easily see the drive belt approaching those kinds of temps under heavy loads. That doesn't explain why some sleds have sheared teeth under almost no load but I do think temperature could be a contributing factor with some of these failures.

I have a friend with a new Pro and a small muffler. He feels the drive belt is considerably cooler than the numbers I am posting now. I will try to do some side by side testing with a sled with an aftermarket muffler soon.


I can not explain why some belts throw lots of black particals off and some don't. The first belt on Sled 1 was filthy and sheered teeth in under 50 miles. The second belt is clean and now has 150 miles on it.

 

[AK IQ Pilot]

Here is a picture of Sled #1 drive belt area after 150 miles. Perfectly clean with no evidence of drive belt flakes anywhere. This same sled only made it 55 miles on the first belt and the entire area was covered with drive belt flakes. The difference is the first belt was riden in deep heavy snow. Not WOT but definitely a much hotter environment.

Here is a picture of Sled #3 drive belt area after 100 miles. Sled was ridden with light to moderate loads. Only slight belt particles can be seen.

 

[akmclean]

I think you showed some evidence for it NOT being the brake causing the upper pulley high temps. If it was it should be at least as hot as the top pulley. Im pointing my finger at the can-belt clearance.

 

[Jimb]

Not sure I'm late to this discussion but guys here are figuring the can and especially aftermarket cans are causing the qd belt to get too hot and grenade. Maybe need a ceramic coating on the can needed??

 

[winter brew]

Just to add....have some customers running turbos and cooking this area of the sled....VERY hot compared to a stocker and Im not aware of these sleds having any belt issues. 163's riding like a rental. If I hear otherwise I will share the info.
Sorry about the thumbs down, doing this from a phone.

 

[AK IQ Pilot]

I think you showed some evidence for it NOT being the brake causing the upper pulley high temps. If it was it should be at least as hot as the top pulley. Im pointing my finger at the can-belt clearance.

Agreed. I think it's safe to say the heat in the upper pulley is not being caused by the brake rotor. In the testing conditions I performed the braking part of the rotor was always cool. The upper pullet was 35-60* hotter than the brake rotor.

Just to add....have some customers running turbos and cooking this area of the sled....VERY hot compared to a stocker and Im not aware of these sleds having any belt issues. 163's riding like a rental. If I hear otherwise I will share the info.
Sorry about the thumbs down, doing this from a phone.

Dang brew, you hosed me.

Any idea what kind of belt and pulley temperatures your customers may be experiencing. I guess if there have been no failures they may not be all that concerned with belt and pulley temps.


One thing I found particularly interesting is that Sled 1 began developing belt particles immediately on the first belt. It was ridden for 25 miles on a trail before it was taken to the hills. It had lots of belt particles all over the side panel, pulleys and bulkhead before even heading to the hills. Belt 2 has +150 miles and no belt particles what so ever.

Kinda strange.

 

[Goin For Snow]

once the belt takes a set, do the black flakes stop?

 

[Scott]

once the belt takes a set, do the black flakes stop?

Mine did at about 70 miles. Quit cold turkey.

Just for point of reference. I've got 320 miles. No broken drive shaft or broken belt.
Driveshaft was riveted at about 50 miles. No collar put on mine yet.

No visibile wobble to bottom pulley either.

 

[AK IQ Pilot]

once the belt takes a set, do the black flakes stop?

It seems like it. The strange part is some belts develop black flakes and some don't. The instructions with the new QD belt say black belt particles are normal.

 

[LoudHandle]

Has anybody taken a really good look at the sprockets prior to any riding? My thought is, it is not as much the belt needing broke in (although the heat cycle part maybe relevant) but the sprockets deburred of all the casting flash and sharp corners and Polaris too cheap to throw them in a vibratory deburring machine prior to plating?

Seems the CNC hard anodized sprockets do not throw off near as much belt shavings as the die cast nickel plated Polaris sprockets.

As far as brake drag, it looks like your data is proving my theory wrong. Still strange why the differential bottom to top and top belt interface to hub? With the hub being hotter. Anybody checked the male / female spline fit? I don't buy into the can causing the heat load to just the top sprocket hub?

AK IQ pilot, you may want to take some flat black high temp paint and shoot where you are grabbing your data to eliminate the inaccuracies that can be caused by reflection. Very common phenomenon in the thermography world with glossy surfaces. Signal bounces and you are actually measuring the temp somewhere else (much like a mirror). Just a thought. Keep up the good work!

 

[AK IQ Pilot]

Has anybody taken a really good look at the sprockets prior to any riding? My thought is, it is not as much the belt needing broke in (although the heat cycle part maybe relevant) but the sprockets deburred of all the casting flash and sharp corners and Polaris too cheap to throw them in a vibratory deburring machine prior to plating?

Seems the CNC hard anodized sprockets do not throw off near as much belt shavings as the die cast nickel plated Polaris sprockets.

As far as brake drag, it looks like your data is proving my theory wrong. Still strange why the differential bottom to top and top belt interface to hub? With the hub being hotter. Anybody checked the male / female spline fit? I don't buy into the can causing the heat load to just the top sprocket hub?

AK IQ pilot, you may want to take some flat black high temp paint and shoot where you are grabbing your data to eliminate the inaccuracies that can be caused by reflection. Very common phenomenon in the thermography world with glossy surfaces. Signal bounces and you are actually measuring the temp somewhere else (much like a mirror). Just a thought. Keep up the good work!

I was definitely getting reflection inaccuracies like you mentioned. The most difficult temp to measure was the upper sprocket. If I pointed at the flat outer ring of the sprocket I would get a temp that was obviously much cooler than reality, sometimes by a factor of 1/2. Shooting the inside hub of the top sprocket from underneath where is was shaded proved the most accurate method and the basis for most of my data.

Bottom sprocket was far easier to get an accurate temperature from.


Thanks for the feedback. I doubt this really helps anyone solve the belt failure issue bit it may help weed out some things that aren't likely causes.

 

[Teth-Air]

I can not explain why some belts throw lots of black particals off and some don't. The first belt on Sled 1 was filthy and broke in under 50 miles. The second belt is clean and now has 150 miles on it.

Is it possible that the pulleys are actually smoothing out after the break in? My experience would contradict this because my 800 163 and 600 155 both got nearly no break in and neither has had belt problems or showed much black crap from the belts.

 

[mrquick68]

here's my (solid) theory on the pulley temp differential. The smaller upper pull is naturally going to be a bit hotter as its smaller therefore doesn't have the surface area to dissipate as much heat the larger pulley. Secondly, the lower pulley is clearly getting "cooled" by snow/air contact through the driveshaft. The upper pulley has the opposite going on, as everything around it and bolted to it is HOTTER (driven clutch, jackshaft sitting right over a hot engine, etc.) Its close proximity to the can can't help either.

 

[AK IQ Pilot]

here's my (solid) theory on the pulley temp differential. The smaller upper pull is naturally going to be a bit hotter as its smaller therefore doesn't have the surface area to dissipate as much heat the larger pulley. Secondly, the lower pulley is clearly getting "cooled" by snow/air contact through the driveshaft. The upper pulley has the opposite going on, as everything around it and bolted to it is HOTTER (driven clutch, jackshaft sitting right over a hot engine, etc.) Its close proximity to the can can't help either.

Yep, I have the same suspicions. The can is not the only thing cause an increase in temperature but it is likely contributing to the temperature increase to some degree.

 

[winter brew]

Someone could take one for the team and perform a little experiment....someone that has not had any belt issues needs to hold the brake on while full throttle and just cook the poop out of that upper pulley and see if they lose a belt. Im sure Polaris did this a hundred times in the R&D phase of the belt drive. I have a hard time believing its heat related, just not enough heat to effect these materials....the gates site points at tension and pulley runout as the only causes for this type of failure (losing teeth).
Anyone working on a tensioner for these things yet?

 

[mrquick68]

I was hoping you guys were going to offer a tensioner, brew! And some aftermarket cnc gears with a real belt kit. I would love a little lower gearing.

Sent from my Galaxy Nexus using Tapatalk 2

 

[AK IQ Pilot]

Someone could take one for the team and perform a little experiment....someone that has not had any belt issues needs to hold the brake on while full throttle and just cook the poop out of that upper pulley and see if they lose a belt. Im sure Polaris did this a hundred times in the R&D phase of the belt drive. I have a hard time believing its heat related, just not enough heat to effect these materials....the gates site points at tension and pulley runout as the only causes for this type of failure (losing teeth).
Anyone working on a tensioner for these things yet?

Ummmmm. Actually improper design for the load is the #1 cause listed. Misalignment is another. Less than 6 cogs engaged is another. Back side idler is another. Belt under tensioned is another. Worn Sprocket is another.

EXTREME runout is listed as a failure mechanism. The manual says run out should be <.003 for a sprocket the size of the upper and <.004 for a sprocket the size of the lower for optimum drive belt efficiency. They do not specify what extreme runout might be.

How will a tensioner prevent tooth shear. The belt is already tensioned enough as clearly indicated in the Gates Drive System Design Manual.

One thing the manual specifically says is to never store the belt at temperatures above 115f.

Here is something else the manual specifically says about temperature.

Temperature
"Belt performance is generally unaffected in ambient temperature environments between -65° and 185°F (-34° and 85°C). Temperature extremes beyond these limits should be reviewed by Gates Power Transmission Product Application."

We have already proven the belt can and does get very hot. One poster reported recording belt temperature approaching 200f. If 185f is the limit and some people who have had belts fail are reporting 200f it seems logical that belt temperature can play a roll in tooth shear simply because the belt may be improperly designed for the application which is the #1 cause of tooth shear.


Anyone interested in reading the Gates Drive System Design Manual the link is below. It's 117 pages but a fairly quick read if you are interested.


Gates Drive System Design Manual

 

[1Mike900]

Just thinking out loud, what is the spacing of the inside of the cogs when bent into the dia. of the upper sprocket? Does the gap between teeth tighten up, as opposed to the straight section? If so are the teeth of the upper sprocket adjusted for this width, or the same spacing as the bottom sprocket? Could the belt teeth be scrubbing upon entry and exiting and creating heat? I am sure more than 6 teeth needs to be in contact with the upper pulley as in a tensioner design where it properly wraps around with less tooth load! Also wouldn't a tensioner take up some shock load when the track locks up on soft to hard pack? Just a few questions to think about. Mike

 

[AK IQ Pilot]

Just thinking out loud, what is the spacing of the inside of the cogs when bent into the dia. of the upper sprocket? Does the gap between teeth tighten up, as opposed to the straight section? If so are the teeth of the upper sprocket adjusted for this width, or the same spacing as the bottom sprocket? Could the belt teeth be scrubbing upon entry and exiting and creating heat? I am sure more than 6 teeth needs to be in contact with the upper pulley as in a tensioner design where it properly wraps around with less tooth load! Also wouldn't a tensioner take up some shock load when the track locks up on soft to hard pack? Just a few questions to think about. Mike

All good questions Mike. I have wrapped the belt around both the upper and lower sprocket to look at tooth engagement. When the belt is arched around the sprocket the tooth engagement looks very good, nice and tight around the entire curvature of the tooth for all the teeth engaged. When you place the sprocket in the belt laying flat there is not good tooth engagement. There would be lots of "scrubbing" to use your term. It appears there is decent tooth engagement and minimal scrubbing. I am going to read more in the Gates Drive Design Manual about this tomorrow.

With regards to shock loads and a tensioner. According to the Manual the idler should always be on the coast side of the belt. Never on the load side of the belt. Both the CMX and C3 systems have the idler on the coast side of the belt. The manual specifies how much belt deflection is acceptable for a given application. If you have to much belt deflection you need an idler. Not enough you need a longer belt. The Quick Drive is well within the acceptable limits on belt deflection according to how I read the manual. The tension on the load side of the belt is almost always constant (unless you hit the brakes). The tension on the coast varies based on how much load you are putting through the drive train.

There are 10 teeth fully engaged on the top sprocket. More than enough IMO.

We will keep working this issue until we come up with a solution. Meanwhile the rumor is the 2014 QD system might get hard anodized pulleys and a new belt.

 

[mountainhorse]

Ak IQ Pilot....

Great write up!!! Thank you for taking the time to present this here and give us some great info.

Please don't take these questions as a challenge... I'm sincerely interested in the conversation and logic of this.

Originally Posted by AK IQ Pilot:
How will a tensioner prevent tooth shear. The belt is already tensioned enough as clearly indicated in the Gates Drive System Design Manual.

What numbers are you using in your calculations for proper tension values?

How are you accurately measuring deflection?
1/64 of an inch or a couple of lbs here or there makes a big difference.

Gates is providing values for the 8mm and 14mm belts (M & Y)... the Polaris belt is 11mm; are you extrapolating for this from the info in the table.

At this point also... there has been no definitive answer as to what belt (aramid or Carbon) belt is being used, the composition or mfg of the belt used by Polaris. Different belt design/materials will have very different characteristics in use.

I found the simple method/description from the Aircraft drive mfg in this link helpful and intuitive.
http://www.epi-eng.com/mechanical_engineering_basics/belt_drive_properties.htm#tr

The CVT system with a torque sensitive rpm compensation throws a curve into the calculations. Also the variable nature of snow and shock loads typical to the operation of the system presents some serious "fudge factor" needed.

A run-in belt will change in tension (AKA Preload) from new... which is why Polaris recommends break in IMO... What is properly tensioned when all the surfaces are not worn in with a new belt is not properly tensioned with a used belt and compromise is needed in the fixed center design of the QuickDrive system.

In a toothed belt drive... "self tensioning" can be a big factor in problems with a toothed drive system.

Given MFG tolerances of the chasis, shafts, pulleys, belts in addition to the variation of temperature and it's effect on dimensions of the parts involved.... I still believe that a mechanism to compensate for these variables would be valuable... ie a tensioner.

Some Quickdrives are having problems, others are not... and HP does not seem to be the major contributing factor to determine success/failure as some are High HP turbos and others are stockers. The system is definitely in the ballpark... the "wrench in the machine" IMO, are these real world variables inherent to mass produced vehicles.

I would really like to see the 2014 gain a pound and get an eccentric tensioner along with a provided Krikit gauge that can be used to properly adjust Quickdrive belt preload throughout the lifespan of the belt... plus the added benefit of changeable ratios and adjustable preload when doubling the HP/Torque with a Turbo which would need more preload (HP is a BIG factor in the formula for tension)




My 2 cents.
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Self-Generated Tension
Monday, November 12, 2012

posted by Phil at 1:32 PM

All synchronous belt drives exhibit a self-generating or self-tightening characteristic when transmitting a load. Laboratory testing has shown this characteristic to be similar with all tooth profiles. The designer/user should be aware that self-tensioning can result in increased bearing and shaft loads and reduced drive performance; i.e., short belt life. This can be avoided by following proper tensioning procedures.

While belt overtensioning can impose higher bearing and shaft loads and lead to reduced belt life, undertensioning can result in self-tensioning. Properly designed and tensioned drives will not be significantly affected by self-generated tension.

When a belt is too loose for the design load, the self-tensioning characteristic results in the belt teeth climbing out of the sprocket grooves, leading to increased stresses on the belt teeth, accelerated tooth wear and reduced belt life. When a belt is severely undertensioned, this self-tensioning characteristic can result in the belt ratcheting (jumping teeth). When this occurs, significant shaft separation forces are instantaneously developed in the drive, resulting in damage to bearings, shafts, and other drive components including the belt.

NOTE: This is true for all synchronous belts.

Maximum drive performance and belt life are achieved when the belt is properly tensioned for the design load and maintained at the proper tension throughout the lifespan of the belt.

.