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Blowing belts still........ugh

I

i'llDooit

Well-known member
Nov 27, 2007
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Duvall washington
to drop belt temps the right TIP weight is required, the more the better (keeping proper RPM) and LESS pivot bolt weight...

softer pdrive spring...

stiffer QRS spring...

HMMMMM sounds like my kit-BJ

What are operating clutch temps with your kit BJ? Is 190 for the primary a good number?
 

BIG JOHN

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Nov 26, 2007
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Minnesoooota
that is a little high but there are variables...add more tip weight, keep belt tight plus my motor mount shim helps more than doos-BJ
 

turboless terry

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Jan 15, 2008
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Big Timber, MT
My guess is that is an unlucky fluke. Something put together wrong or kinked
Our 17 has 875 miles on original belt. This is my wife's sled but I have rode it as much as her. I have had it in really deep snow and never let out of it. I think a bunch of people just got unlucky and got sleds that were out of specs. I am not updating something that is not broke. It has never ran over 7900 from day one.
My 18 turbo only has 300 miles on original belt. No problems as of yet. Sometimes I think you are not as hard on belts, with a turbo, because you don't have to hammer them as hard to get the same things done.
 

Andystoy

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Nov 27, 2016
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Good clutching, alignment and belt deflection are the most important part of optimum belt life but not the sole cause of belt heat etc. Some other things to consider are 1) sheave cleanliness especially after blowing a belt; pieces and fuss gets into everything 2) cleaning the residue off the clutch faces regularly 3)Underwood air temperature: the intake grill is located at the front and the lower one is almost always plugged with snow (riding in powder) the upper can also be partially or completely plugged. If you restrict cooling air flow Underwood air temperature goes up immediately. Since the stock machine has no other air intake except the footwells the clutch cooling system becomes a heater so clutch and belt temperatures skyrocket until your belt fails.
Riding in deep powder requires more power input resulting in the clutch system and belt having to transfer more energy to the track. More throttle results in Y pipe temperatures that could be 1100F(not sure where the ECM controls maximum pipe temperature) only inches from the clutch intake.
4) Snow ingestion, wet snow plugs air vents very quickly, dry snow passes through into the pipe area most of which melts or is vaporized on contact. Some snow and water drop down and freeze in the steering boot area. I believe the 2018 summits came stock with Doo front screens. These will reduce air flow a bit more than an open grill probably reduce plugging and reduce some but not all snow injection. One after market screen uses a membrane to prevent most snow injection and plugging but resulting in less airflow than the screen or open grill. Those who have seen excess steam under the hood probably had enough vapor to reduce the friction of the drive system resulting in increased slippage, resulting in over RPM and heat resulting in belt failure. Don't believe this get a vaporizer near the drive system when on a lift run the throttle at a constant speed and watch the belt trying to keep traction. Don't stand where you'll be smacked by the belt if it fails.
5)The operator of the vehicle controls the throttle input, no two riders are the same and riding the exact same area will have different clutch temperatures. Add deep snow with plugged off air flow and some snow ingestion resulting in high Underwood temperatures contribute to shorten belt life. Checking some of the things I mentioned hopefully will result in less failures but not prevent all failures. Something to ponder over a cool one? Safe riding.
 

turboless terry

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Jan 15, 2008
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Big Timber, MT
The 850s don't have much venting. Every time I have been out the front vents were plugged off completely. I had my wife's 17 in a legitimate 5 feet of blower powder the beginning of November. Never shut it off or let out of it all day. Made it 38 miles before I was out of gas. About 4 hours worth. It did have the front vents, that the 18 comes with, since new. Don't know how they get any air under the hood but it never bogged or twitched all day.
 
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