Gates 49C4266 Carbon Belt

Devilmanak

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Tom from Tom's Snowmobile told me about this, when I told him that my sleds seem to really "wake up" around 800 miles. He suggested that it was because my stock belt quit stretching at that point. Something to think about. My 174 T3 is at 775 miles now, and today I noticed that it seemed to have more kick than usual......
 

off trail mike

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Thought I'd put some measuring to our XM belts,which on mine is the 417 300 391. Belt is in excellent shape....no strings and no black rubber on the clutches.

The 417 300 391 spec is a top width of 38.3mm with 26 deg side angle

I'm not going to use the top width to measure because its likely the most variable and least reliable place to measure.

The belt has 1200 miles on it and sled has DJ clutch kit. It's the other side of great clutch kits... fantastic belt life. Compared against a new belt here's what I got.

Measured at the cord (actually just below as the cords protrude somewhat):
New Belt: 35 mm
Used Belt: 34.5 mm (1200 miles)

Measured at bottom of top cog:
New Belt: 36.4 mm
Used Belt: 35.8 mm (1200 miles)

So fairly consistent wear of 0.5-0.6 mm.

I then put that in CAD to see how much the worn belt should drop in the secondary clutch. CAD says 1.3 mm is what it "should" be, but I was measuring something closer to 3.0 mm so the belt was likely running too low in the secondary. The deflection was excessive as well. I adjusted back to "spec" and all now seems to be good.


So, lesson learned for me. I wouldn't go over 500 miles before adjusting and I'll be adjusting clutches much more often given there is both stretch and wear to contend with.

OTM
 

Devilmanak

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If that is where the kick comes in I don't think we are going to make it. My wife's has just over 500 miles I think.
Heh, it wasn't as noticeable this year to me, but on my 13 and 14 rigs, I felt that the power dropped off pretty badly after they came off break-in, then came back after some miles. I really think that the rings aren't seating/bearings loosening up when breaking in, due to the large amount of synthetic oil that they are burning, and once they are off breakin mode, they actually loosen up with regular oil consumption. Just a theory though. Belt adjustment does make a huge difference in how they run, I try to check and adjust mine every ride.
 
Sep 24, 2009
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Yakima Wa
Measured at the cord (actually just below as the cords protrude somewhat):
New Belt: 35 mm
Used Belt: 34.5 mm (1200 miles)

Measured at bottom of top cog:
New Belt: 36.4 mm
Used Belt: 35.8 mm (1200 miles)

So fairly consistent wear of 0.5-0.6 mm.


OTM
My experience is not with the 391, but with the 377 & prior. I've always seen the bottom of the inner cog wear the most, more than double what the outer cog wears. I've never checked the side angle, but I assume it changes. I've never gotten the mileage out of a belt like you're getting, I can feel a big performance loss long before that & my belts measure much more wear than yours with much less mileage. Maybe I need to try one.
 

Goinboardin

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I wonder if the Gates is more sensitive to alignment. I've never had a Doo belt come apart, but the Gates just don't hold up for me. The 391's pulled cords and wore thin but never blew or otherwise failed. The 288's seem to last longest for me. The Gates delaminate in under 500 miles, chunking out the rubber above the cords.
 
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