[Spaceman78]

EDIT: Do not try this. I stripped my cam plate splines. I'm working on a better idea, which I'll post in another thread if it works.


OK, so I finally got around to getting some clutch mods done. I did a shim mod which lowers the overall gearing for pulling bigger tires easier. It does not affect RPM or shifting. I clocked my secondary for higher shift out RPM, but for this thread, I'll stick to the shim. Shims are available very cheap from different places. They are called arbor shims. I don't have a local place to buy them and I didn't want to wait for delivery from an on-line seller, so I made my own.

First, the disclaimers. If you make your own shim, you could screw something up and damage your machine and void the warranty.
Also, if you do the shim mod with a proper professionally made shim, you still may screw something up and damage your machine and void the warranty.

For those of you who want to try it, here's how it's done. First a couple of pics of a shim I made from a washer. This is not the one I used because I lost it while trying to finish it. But, it looks better than the one I used, so I used the pics I took before I lost it.

The dimensions are ID is 1". the OD is 1.5". the thickness is 1mm.


This is the maximum thickness I could use. Any thicker and there wouldn't be enough spline on the shaft for the cam plate. I forgot to take a pic of the splines though.

[Spaceman78]

You take the movable side of the primary off, followed by the collar. Slide the shim on the shaft up to the fixed side of the pulley. Then slide the collar back own and reassemble the primary. Be sure there is sufficient spline contact between the cam plate and shaft. Also, make sure the rollers are in the channels correctly and hold the cam plate and pulley together until you get the nut on, so the rollers stay in place.  I'm sorry I forgot to take pics of the assembly process.

[Spaceman78]

Another thing to watch is clearance between the belt and housing. The shim spreads the primary open farther, allowing the belt to ride lower in the primary. This allows the belt to ride higher on the secondary. Make sure the belt doesn't rub the housing. Remember, as the belt wears, it'll ride even lower in the primary and therefor, higher on the secondary. So be sure to have some extra clearance, so it doesn't rub later.

[Spaceman78]

This simple mod changed my pulley ratio from a stock 2.5:1 to a modified 3.25:1. This may be too low for many, but is great for pulling 30s with 1.75" tread through the deep mud. You can use a thinner shim to get a slightly higher ratio. Any thicker and the cam plate splines may strip causing serious problems.

[NMKawierider]

This might be the answer to a problem I have had in that starting or take-off in some situations in high range is a problem and I know is hard on my wet clutch but starting in low range is too low and requires stopping and selecting high range again after the situation. I have some actual shims for my Brute's secondary for belt adjustments that may fit the bill perfectly in a number of widths. Like you say, a little bit goes a long way in ratio changes. It looks like the thickness of your washer is about the maximum and still have spline left for the cam plate.

Nice post...and nice idea.

[Spaceman78]

Thanks. Yeah, it'll help you get moving. It'll also help you keep going easier. The draw back I forgot is top speed. It will slow your top end down about 5-10 mph. That's not an issue for me. I don't ride 70. I rarely hit 50. If you don't mind a drop in speed and you're careful not to mess anything up, there really isn't any other con. Especially be careful of the splines. With Yamahas, which is where I started doing this stuff, we use 1.5 and even 2mm. There's just not enough spline on these shafts for that much shim. On my old Grizzly 660, I had 1.5mm and only changed my ratio from about 2.4:1 up to around 3:1, so I was very surprised to see so much difference with just 1mm on my Z8.

[bigjimstewart]

This might be the answer to a problem I have had in that starting or take-off in some situations in high range is a problem

I wish there was a youtube video on this because I've never taken a clutch off before.

[NMKawierider]

I wish there was a youtube video on this because I've never taken a clutch off before.

Its not hard but when I do mine again I'll do a full video on all parts of it.

[Jogon30]

@nmkawi how's about when u do yours you make a extra shim??? Lol so I can slap it in mine...

[NMKawierider]

@nmkawi how's about when u do yours you make a extra shim??? Lol so I can slap it in mine...

Lol..Ok, I actually want to use a store-bought shim so I know exact thickness and that there won't be any balancing issues so let me see what I have to do. Like I said earlier, I have some for the Brute that look to be the right size but won't know until I get it open.

[ACIDICJO]

Let us know what you go with NMK. This may be something I'll have to do as well.

[NMKawierider]

I will. And just a thought for us that have the sliders, one of the selling points for me over the rollers was that not only did they claim to let the primary open a hair farther for a lower ratio on starts, but they also slid up farther to get a little more top end. If that's true, then the top end loss using the shim may only be what we gained with the sliders...so back to stock top end, which I can live with

 

[Spaceman78]

I thought about that too, but I didn't know how much top-end you gain with sliders.

As for whether your Brute shim will fit, as I said before, the inside diameter is 1" and the outside is 1.5". They could be very slightly larger on the inside and slightly larger or smaller on the outside, but they should be very close to the right size, so not to cause a problem. It should be very close to the same size as the collar on the shaft.

[NMKawierider]

I thought about that too, but I didn't know how much top-end you gain with sliders.

As for whether your Brute shim will fit, as I said before, the inside diameter is 1" and the outside is 1.5". They could be very slightly larger on the inside and slightly larger or smaller on the outside, but they should be very close to the right size, so not to cause a problem. It should be very close to the same size as the collar on the shaft.

Right because what we are actually doing is extending the collar..right?  so we want it to fit the shaft just like the collar.

[Spaceman78]

Yeah, that's basically what it does. The main concern with the OD is that it's not big enough to rub the belt. It doesn't have to be exactly the size of the collar, but remember it lets the belt ride lower in the front pulley. If the belt touches the shim, it'll wear one corner of the belt very badly at least. It may cause other problems that I'm not aware of too.