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Help diagnose odd wear marks on P85 sheave

zaasman

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I just noticed these marks on my fixed primary sheave. Any idea what would cause this?

I've got a little over 1000 miles on it, and clean the clutches regularly. I never noticed any such marks before, but now they're quite apparent and the wear can be felt as slight depressions with the finger. They can be seen around the full circumference, but are noticeably more worn on one half.

IMG_5136.jpegIMG_5135.jpegIMG_5132.jpeg
 
R

rmk8001

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Oct 27, 2008
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Those marks resemble the indentions on the backside of the clutch I bet the metal in those spots is dangerously thin now . It looks like your belt has been sanding the clutch face. It looks pretty pitted also. Check your belt for contaminants
 

zaasman

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Those marks resemble the indentions on the backside of the clutch I bet the metal in those spots is dangerously thin now . It looks like your belt has been sanding the clutch face. It looks pretty pitted also. Check your belt for contaminants
I agree with rmk8001, that looks like it's life is about to end.

You guys may well be right, thanks for having a look. I don't have the experience to really know (why I ask here) but honestly I'm not seeing any significant pitting, nor does it seem dangerously thin to me. I'm happy to stand corrected and learn though. I'll have a closer look and try get some better photos. The belt looks clean, though a little glazed. I'll get a photo of that too.
 

kanedog

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Post pics before cleaning and pics of the moveable. I have some thoughts
 
M
Jan 8, 2022
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You guys may well be right, thanks for having a look. I don't have the experience to really know (why I ask here) but honestly I'm not seeing any significant pitting, nor does it seem dangerously thin to me. I'm happy to stand corrected and learn though. I'll have a closer look and try get some better photos. The belt looks clean, though a little glazed. I'll get a photo of that too.
Those groove/scratches near the outer diameter would be very rare.The belt wouldn't be up there unless the belt was too long-in which case the sled would bogg terribly taking off from a stop. Also when the belt is near the outer diameter you will be traveling at/or near top end of your sled' capability. I've had 2 sleds where the belt ran high- both had broken motor mounts or broke torque stops. But you have a different problem it looks like scrapes from metal- look for bent belt shields both top and bottom-check for loose metal in the belly pan,hanging from the hood, the bottom of the belt shield, speedo drive and left foot saddle,Good luck and write back I'm very curious.
 

retiredpop

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Are you getting any noticeable vibrations when riding? Would a broken motor mount cause something like this?
 

kanedog

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You sanded too much, used too heavy of a grit when it was on the machine running. self inflicted. Clutch is now unsafe. Haha.
 

BeartoothBaron

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Do you have a calipers that could measure the thickness of the metal where you see those tulip-shaped marks? A brake disk caliper might do the trick... I also think @rmk8001 is onto something: it definitely looks like those marks slot between the webbing on the backside of the fixed sheave. If the metal is very thin there (I'd say less than .050, but that's a rough guess), then I'd agree that the clutch is scrap. You might get a few more miles out of it, but I'd say too much chance of catastrophic failure to chance it. Finally - if that's the reason for those marks - it's most likely a bad casting, not something you did.
 
C
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Looks to me like you got a bit aggressive on "cleaning".

I polish the clutches with a fine steel wool or fine Scotchbrite. When they're clean of all belt debris I give them a good cleaning with brake cleaner.

When I'm done they don't look dull and sanded like that, they look bright and shiny.

I also only clean when I start seeing belt build up. I'm far too lazy to clean unless it's necessary.
 

LoudHandle

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My bet is belt slipping enough to get the sheaves hot and deform between the cast reinforcement ribs on the back. When you clean the glazed rubber off the hot deformed spots are distinctly apparent by the color variation. You need to find a clutch setup that doesn’t slip ideally. Belt should never get a glazed appearance when not slipping. IMO


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