What's a sheave- sheave 101 - Yamaha Rhino Forum - Rhino Forums.net
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post #1 of 9 (permalink) Old 04-20-2010, 09:05 PM Thread Starter
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What's a sheave- sheave 101

The sheave is the engine driven pulley of the belt drive. The sheave is located under the black plastic cover under the drivers side seat. It consists of 2 sides, the inner side (called the fixed half by Yamaha) and the sliding side. It is the sliding side that is modified to add additional speed to the Rhino.


If you look at the pic below you will see where the belt stopped short of using the entire pulley face.


It may have been done intentionally by Yamaha to limit the top speed.

Inside the sheave are rollerways. It is centrifugal force that forces the rollers to push outward on the ramps in the rollerways, that in turn forces the sliding half of the sheave towards the inner fixed half. That in effect closes the gap in between the two pulleys forcing the belt to ride higher. By the belt riding higher in the pulley the ratio of the belt drive system- Thats why it's really a continously variable transmission (cvt) and not a ''clutch'' at all. The term clutch kit is just a generic term used by everyone in the aftermarket industry.

In this pic you can see the inside of the sheave and the roller ways...



There are 8 rollers in a Rhinos sheave. Depending on the machine the roller will vary in weight to change how fast the sheave will move or ''shift''.

Here they are with the outer cover and cam plate removed. That is where the rollers will rest at idle and when the sheave is fully open.




more coming!
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post #2 of 9 (permalink) Old 04-20-2010, 09:06 PM Thread Starter
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The rollers used in the 450 and 660 Rhino have removable covers. The factory roller on a 700 Rhino is one piece, our rollers for the 700 are 2 piece.

If you are simply replacing the outer sheave half to gain more mph than you do not need to separate the roller weights. If you are adding a duner/sport or big tire kit where you are changing the gram weight of the rollers you will need to separate them from the covers.



The easiest way to do that is to use a socket that just fits inside the roller cover to push the roller out.



You do need to pay attention to which way the roller comes out of the cover. There is a lip on just one side of the cover that, the roller only comes out and goes in oneway.

The lipped side of the roller




More to follow..........
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post #3 of 9 (permalink) Old 04-20-2010, 09:07 PM Thread Starter
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When you are reassembling the sheave you will need to apply grease to the rollers. About a teaspoon for each roller will be enough. Applying a little to the four walls that the slider rides on will not hurt either but after the first time the sheave spins the grease will end up on the walls anyway.



The cam plate is what holds the sheave on the engines output shaft. On the 450 and 660 Rhino the cam plate buttons are each two pieces, a metal insert with a plastic outer.



The 700 model has buttons that are only plastic/nylon. These have been shown to wear out prematurely and can be replaced with the older equivalent.





Either cam plate will look like this when the buttons are installed



On the 450 and 660 machine the metal insert should fit like this if you put it on without the plastic housing. If it does not the cam plate is worn beyond use and needs replacement.



Using a worn cam plate can result in broken rollerway walls as the rollers will be forced to **** to the side.

This is the cam plate installed (less grease)

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post #4 of 9 (permalink) Old 04-20-2010, 09:08 PM Thread Starter
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All Rhino sheaves will have an o-ring under the sheetmetal cover. You need to leave the o-ring in place as it keeps the grease from leaving the inside of the sheave. If you damage yours while dissassembling the sheave it will need to be replaced. It will go in the groove around the outside of the sheave.




The outer cover will be a tight fit over the o-ring. When the sheave is properly assembled it will look like this.



Note the grease inside the two seals, do NOT apply grease to the shaft the sheave rides on, it will end up on the belt. Also note the distance between the sheaves hub and the cam plate. If it doesn't look like this the sheave is NOT assembled correctly!



When installing the sheave it is important to hold the cam plate tightly against the sheaves hub. Otherwise one or more of the rollers may fall out of it's pathway and the sheave will not function correctly.



If this happens at any time during the installation of the sheave you will need to ensure the rollers are still in the right places.

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post #5 of 9 (permalink) Old 04-20-2010, 09:19 PM
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Excellent presentation!
Thanks for the class.
Saludos.

S-Low Flying Proyect
Trinity 734
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post #6 of 9 (permalink) Old 04-21-2010, 01:59 AM
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do u have a write up on the OD sliders? and testing with em ?
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post #7 of 9 (permalink) Old 04-21-2010, 04:51 AM
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thanks! i will be pulling mine apart soon, so this is nice.
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post #8 of 9 (permalink) Old 04-21-2010, 06:28 PM
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Awesome writeup with the pics. this is going to come in handy as i may be looking into the guts of mine soon.
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post #9 of 9 (permalink) Old 04-22-2010, 08:27 AM
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now i finally understand what everyone is talking about when sheaves are mentioned. i just figured there was a primary and secondary clutch like a snowmobile, but these are different but same idea.

07' 660 - 60" Moose plow, warn 2500, headlight/taillight covers, shock covers, rear bumper, front/rear windshields
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