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XC Sled Dog
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30 Posts
Discussion Starter #1
Sled: 1997 Polaris XC 600 with a P-85 primary clutch.

I recently had my clutch serviced/rebuilt. After I got it back on my sled I noticed that there was about 3/16" of gap between my belt and the face of the inner sheave after I pushed the belt tight to one side. I have three belts, all used a bit but not too bad, and I used the widest one to gauge the gap, so I know a brand new belt will be a little wider, but not that much. Everything I've read says you should have a .020 gap, which is about 1/60 of an inch. MY QUESTION IS, How important is that gap? I haven't been able to really get out and ride it yet but did notice a slight bog or delay after the clutch engaged at around 5100 rpm in my yard. It will be a pain to remove the clutch, drive it back to the repair shop, and complain to get them to re shim it (technically I didn't specify a width to them, I only assumed that it would be set correct). How much performance will I truly gain from the correct belt to sheave face gap? Also, how much width is truly lost between a new belt and a used belt?

All replies and advice are appreciated!
 

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Super Moderator
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17,859 Posts
If you are interested in getting optimum performance and speed from the sled, the gap is critical. If you ride for enjoyment and enjoy the performance of the sled as it is, it's not. With too much clearance, the flyweights have to move farther before engagement occurs. You notice this as increased RPM on engagement. You may also not get the belt to full shift because the weights will be done pushing the movable sheave before the belt fully shifts. That will cause lack of top end MPH.

There is a pretty good performance benefit from a used belt that is narrow to the correct width belt new. For most trail riding, there will be little improvement in how the sled performs, as you aren't at the full shift point or at the engagement point. If the engagement RPM increase and lack of top end are problems that bother you, it may be worth it to have the clutch re-shimmed. Shimming to 0.020 using a new belt will ensure your performance doesn't degrade too much as the belt wears.
 

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XC Sled Dog
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30 Posts
Discussion Starter #3
Thanks. I went home to get a more accurate measurement with a calipers and a feeler gauge. I have a 1 5/16"+ belt with a 1/8"+ gap. The total is just shy of 1 1/2". I went online and found a Dayco HPX belt and a Gates Xtreme belt that are each listed at 1 7/16" brand new. If that is the case, and assuming both belts are a true 1 7/16", I figure my gap would be .031, not the strong 1/8" (0.156) I have now.

BC Dan - MY NEW QUESTION IS, Would fixing the small difference (.011) between the new belt gap of .031 and .020 be worth it if I have to buy a clutch puller for $27, remove the clutch, drive it to the dealer, haggle about doing the shimming for free, go pick it up, and reinstalling the clutch?
 

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Super Moderator
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I have had sleds with gaps like that. I didn't shim 'em. I don't race and don't really care that the sleds are the fastest out there. I'm more of a
"ride 'em off the trailer, ride 'em back on the trailer at end of the day = a good day"
kind of guy. Can you get better performance? Sure. Is it worth it? You have to answer that ;)
 
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