Hello, John Talley here with partzilla.com. Now as you're aware, most of today's four-wheelers use
what's called a constantly variable transmission or CVT for short. Now although the details of each
manufacturer's version of the CVT are different, they all basically work the same way. In short,
they use a belt drive to transmit power from the engine to the wheels, where the belt is moved
either in or out on a set of sheaves to control what's essentially called the gearing. Now if those
sheaves won't move and push and pull the belt in or out, it may be time to rebuild the clutch, and in
this video we're going to show you the basics of how to get that done. So if you're ready, let's go.
Okay guys, in this video we'll be using a 2011 Polaris Sportsman 850 XP as a reference, but
you'll find the CVT clutch system on say, like a Yamaha or a Kawasaki ATV it will be very similar
to work on. Now the main differences will be the specs, like your torque settings, so you'll
need to get a hold one of those service manuals. But the basic process is going to be the same.
Now you'll need some standard tools in your tool box: sockets,
a good ratchet, torque wrench as always. But you also need a couple specialty tools. You may need
a primary clutch drive puller and a secondary clutch drive compression tool,
but you may need something different if you are dealing with a different make and model of ATV.
Now the first thing you'll want to do is remove the clutch cover . On some machines you'll be able
to do this without having to remove anything else, but as you can see with our Polaris Sportsman
850, we had to remove a frame strut so we could get to that cover. We also pulled off the wheel
to make working on the clutch a little bit easier. Now with the clutch cover removed, you want to go
ahead and remove the drive belt. We have a separate video showing you how to do that,
and I've put a link to that particular step-by-step video in the description below.
Okay guys, once the drive belt is off, you can remove the primary clutch and the secondary
clutch assemblies. Now take note here: the bolt holding the primary clutch on this particular
model has a reverse thread, so you'll need to turn it clockwise to loosen it
and then counterclockwise when it comes time to tighten it. Now your unit may or may not have this
particular setup. With the primary clutch bolt out of the way, you'll need to use the primary
clutch drive puller I mentioned earlier to break the primary clutch assembly free from the housing,
because there's no way you're going to be able to handle removing it by hand. Now with the primary
and secondary clutch components off the vehicle, we can now see how a CVT clutch works. The two sheaves
of the primary clutch are spread apart from one another. This is because there's a clutch spring
within the assembly that's pushing them apart. You can also see that there are three flywheel weights
in the primary clutch housing. The primary clutch assembly is directly attached to the crankshaft,
so as the engine runs, the rotation of the crankshaft causes the assembly to rotate with
it. Now as the speed of the engine increases, the RPMs increase and the speed to which the primary
clutch is rotating also increases, of course. As it rotates faster, the primary clutch generates
centrifugal force on those weights, and they begin to overcome the force of the clutch spring.
As the force of the spring is overcome, the outer sheaves begin to move inwards
toward the inner sheave. Now this movement pinches down on the belt engaging it, and
thus transferring the rotational power from the primary clutch to the secondary clutch.
Now let's take a look at this clutch and see what kind of shape it's in.
The first thing we need to inspect is the drive belt. Start by running your finger along each
side of the belt, feeling for any uneven patches or wear. Next, take a look at the belt's teeth, checking
for any that may be cracked or damaged. Then just examine the overall condition of the drive belt.
A healthy belt will be flexible, and an older belt will feel well dry and stiff. Moving on
to the primary and secondary clutches, run your finger across the faces of each sheave.
The sheaves should be perfectly smooth, with no grooves or channels dug into them.
Next give each sheave a visual inspection. They should be a bright metallic color, and if a sheave
has become discolored or darkened, it has glazed and may need to be replaced. Though first, you
might want to try using some contact cleaner and a scotch brite pad to knock off that glaze and give
the belts a clean lightly scuffed surface they can bite into. Now to take apart the primary clutch.
You're going to start by marking where the outer plate is in relation to the inner plate. They are
balanced, and when you reinstall the plate you'll want to make sure it's in the same orientation.
Now here's where that clutch compression tool comes in. It helps keep pressure on the clutch
spring so that you can remove the outer plate. Now if you do have to replace the weights, be
sure to purchase identical weights as those that are already installed on the clutch.
This is because most of the manufacturers design their CVT clutches to fit multiple different
models. Now each of those vehicles will have a slightly different clutch setup, and it really
depends on the vehicle's engine power to weight ratio and so on. This means the clutch will require
weights and a spring that are vehicle specific. For example, there are four different types of weights
that are compatible with the primary clutch used in our 2011 Polaris Sportsman 850 here.
Each weight is designed for a different ATV model, and only one is suitable for our Sportsman 850.
Now for the same reason, if you have to replace the entire primary clutch assembly, the new assembly
will not come with the weights or clutch spring. You'll have to use the ones that came from your
original clutch assembly or either purchase new ones. Now if you do have to replace the weights
or transfer them from an old clutch assembly to a new one, I highly recommend that you install new
shoulder bolts and flex lock nuts on each of them. They're inexpensive, and fitting new ones gives you
peace of mind that they're working perfectly once you put everything back together again.
Now reinstalling a CVT clutch is as simple as reversing what you did to take it apart.
Remember that the mounting bolt for the primary clutch has a reverse thread, so it needs to be
turned counterclockwise to tighten it. Also make sure that you tighten the primary and
secondary clutch bolts to the torque setting in the vehicle's user manual, which for our
Polaris Sportsman 850 are 47 foot-pounds for the primary and 37 foot-pounds for the secondary.
Well there you have it guys and girls, it's just not that tough to figure out.
Well listen, if you need these parts or anything else for your machine, why don't you come see us
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