Clutch Maintenance

[Irv]

What is the proper height in relation to the sheave?

Blue Dave wrote.
"The secondary clutch can be adjusted for the width difference between a new belt and a worn belt by simply adding or removing shim washers on the three bolts that act to set the sheave separation."


I am also curious on this as I just purchased a new belt, and going by my current one, it sits too low in the secondary.
Just thinking here, but if mine currently sits low, then I will have to remove washers?
I did get 3 when I purchased the sled and they are on the small side, but I assume those are them?
Should the belt not sit slightly above the sheaves on the secondary?

Thanks in advance

Usually a new belt will sit higher in the secondary clutch sheaves because it should be wider than a worn belt. Removing washers or installing thinner shim washers will cause the three bolts to spread the sheaves more which will cause the belt to sit lower. Adding shim washers under the bolt heads will cause the sheaves to be closer together which in turn will cause the belt to sit higher in the sheaves. The manual says that the top of the belt should be between 0.5 mm below to 1.5 mm above the secondary sheaves. Of course you should always confirm the correct center to center measurement between the primary and secondary clutches first. If the center to center is correct (268.5 mm) and the belt width is within range (32.5 to 34.5 mm) then you can look at the height of the belt in the secondary.

After making an adjustment to the secondary shims and re-installing the belt make sure that you run the sled on a stand spinning the track a bit and letting it roll to a stop before re-measuring the belt height in the secondary. This ensures that the secondary clutch is completely closed when you make the measurement. I like to run my belt height on the high end of the acceptable range (1.5 mm above the sheaves) because this gives a better hole shot and back shift. However because of manufacturing tolerances in the belt length you may get some belt squeal or creeping at idle with a belt which is at the short end of the length tolerance range with the height set at the high end of the secondary adjustment range. Basically I like my belt to be as tight as possible without squealing or creeping.

Excellent info and pics Blue Dave, I appreciate your effort!

After my New Years day ride I checked my belt position with the new belt installed and it is practically level or even with the top of my secondary sheaves.

I had no belt squeel and it pulled real hard, especially with Ulmer's clutch kit installed so I think I am good to go?

Again, thanks for explaining this to me with the info and pics!

 

[darv]

A good thing to do is when you buy new belts go to a dealer that has a couple an measure them and get ones that match size old racers trick if you want the best performance buy the after market one it works better but it will not last as long as the yamaha one.

 

[Blue Dave]

Irv,

You are fine if your belt is flush with the sheave as you are within the specified range of -0.5 mm to +1.5 mm. I run mine 1.5 mm above the sheave which is at the high end of the specified range as shown in the picture.

 

[Irv]

Irv,

You are fine if your belt is flush with the sheave as you are within the specified range of -0.5 mm to +1.5 mm. I run mine 1.5 mm above the sheave which is at the high end of the specified range as shown in the picture.

Good to know Blue Dave, mine is just slightly lower than your's in that pic.

I was surprised to see where my belt was when I looked after my ride as it wasn't sitting as high after I installed it and spun the track a few times.

Glad I didn't adjust it prior and waited until after I rode/tried it.

Thanks again Dave,

 

[actionjack]

I usually find that right after changing a belt it will sit artificially low in the secondary. I was just showing some friends yesterday how to change a belt with a 12mm wrench and when we put the belt back on each time it was low in the sheaves.

 

[apex55]

I usually find that right after changing a belt it will sit artificially low in the secondary. I was just showing some friends yesterday how to change a belt with a 12mm wrench

?????

 

[Blue Dave]

I usually find that right after changing a belt it will sit artificially low in the secondary. I was just showing some friends yesterday how to change a belt with a 12mm wrench and when we put the belt back on each time it was low in the sheaves.

When you first install the belt it is still holding the secondary more open than normal and consequently the belt will be sitting lower than it should be at rest. . You need to put the sled on a jack stand and spin the track and let it glide to a stop (no brake) then shut off the engine. Then the belt will be where it should be at rest.

 

[stomper]

I usually find that right after changing a belt it will sit artificially low in the secondary. I was just showing some friends yesterday how to change a belt with a 12mm wrench

?????

X2
How do you change a belt with a 12mm wrench?

 

[Wilstoon]

x3

 

[grader]

you put the wrench on one of the helix nuts and use it to open the sheaves, easy with the extra leverage.

 

[CaptCaper]

My sled will grab too fast for me. Stock drive train,etc. My belt is above like the picture above. If I lower the belt in the secondary will it stop the sudden engagement and take off ? Sled will take off too fast for me.

 

[Blue Dave]

My sled will grab too fast for me. Stock drive train,etc. My belt is above like the picture above. If I lower the belt in the secondary will it stop the sudden engagement and take off ? Sled will take off too fast for me.

If it is not squealing and/or creeping then the issue is not with the belt position in the secondary clutch. The engagement RPM is a function of the primary clutch. You could try a softer primary spring for a lower engagement RPM.

 

[marq]

My sled will grab too fast for me. Stock drive train,etc. My belt is above like the picture above. If I lower the belt in the secondary will it stop the sudden engagement and take off ? Sled will take off too fast for me.

If it is not squealing and/or creeping then the issue is not with the belt position in the secondary clutch. The engagement RPM is a function of the primary clutch. You could try a softer primary spring for a lower engagement RPM.

Also, if everything in the clutching is stock and it has early engagement I would be looking for a broken primary spring or a stuck weight...

 

[CaptCaper]

Thanks..