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torkd14

Clutch plates toast?

7 posts in this topic

Hey just looking for some opinions on my clutch plates before I go ordering all new steels and frictions.

ImageUploadedByThumper Talk1451410850.986924.jpg

On the left side of the friction plate picture is the plate from the bottom that sits on the basket. The right side plate is from closer to the top and the rest look like it. Why would the bottom plate still look brand new but the rest are toast? These quite obviously all need to be changed out.

ImageUploadedByThumper Talk1451410933.930162.jpg

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Ya let a buddy ride it and he had the clutch toasted on the first hill, had to bring the cable adjustments to maximum slack to get the bike back. Wasn't to pleased lol. I've never seen a clutch burn out on one hill though, I guess I won't be lending him a bike anymore.

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The steels look OK, but you need to be sure they are still flat.  Set them on a known flat surface (saw table, sheet of glass, thick aluminum plate, etc.) and check them for being either bent/wavy or dished.
 
Since they took a plate out of the clutch in '07, it's been a little bit of a weak spot.  The clutch is strong enough, but "just".  If one heats the clutch up enough, he finds he must take up some free play.  If he then forgets to back the cable off again once the clutch cools, he will end up with no free play, and the first heavy load it gets subjected to will result in slipping under full pressure, which of course isn't good.
 
Something to consider:  As the result of a parts department snafu, I ended up with a clutch kit from an '08 YFZ450R quad for my '06.  While the YZ450 clutches all use a stack of 8 #[5TA-16321-00-00 plates (9 for the '06), the quad clutch uses the 5TA plates only at the ends of the stack where they run against aluminum parts.  The other six are plates from an R1 (5VY-16321-00-00).  I have run that clutch for two years of desert racing with a Rekluse Z-Start Pro, and I must say I'm impressed with the abuse it's taken. 

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The steels look OK, but you need to be sure they are still flat.  Set them on a known flat surface (saw table, sheet of glass, thick aluminum plate, etc.) and check them for being either bent/wavy or dished. 

 

 

When checking this does the plate need to be flat all the way around or are there tolerances for it where it can be a little off? If  it is warped how noticable is it to the naked eye? i'm just trying to get a better feel for inspecting this stuff. 

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When checking this does the plate need to be flat all the way around or are there tolerances for it where it can be a little off? If  it is warped how noticable is it to the naked eye? i'm just trying to get a better feel for inspecting this stuff. 

 

The image is from page 2-7 of the 2012 YZ450F( B) model. You don't mention the year, but the one on  the floor looks to have the turbo pipe, so, '10-'13 ish, right?  Should be close.  You can get your own manual for free from Yamaha at either of the two links located down the page of the second post in the Common Threads topic HERE

 

The clutch pressure plate only lifts about .080" mechanically, and you have a total of 15 plates, which in a perfect engineer's world means there would be 16 spaces between everything in the stack that were all .005" wide. Then you want oil in those spaces without causing drag. Hmm.  If each plate was warped .002", all those spaces shrink to .003".  That doesn't sound like a lot to read it, but it's a 40% reduction in the operating clearance.

 

The steel plates are often more prone to warping conically, or "dishing" than bending or wavy kinds of distortion.  Check for both.

 

Also, Yamaha sells clutch kits that include all the plates, new springs, a new gasket, and cost less than the full set of plates bought separately.

clutchspecs.png

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