1,000ft

[74Nitro]

I did some reading up on refacing the surface. It's not really recommended. I assume even a light resurfacing will change the spring rates throughout the range. Perhaps a washer in the spring cup could help to correct this. Idk....I sure wish it was that easy.

I wouldn't worry about spring rate changes at all. There's other things to watch before that, but I'd think that 10-20 thousandths cleans up the sheaves.
I am now of the opinion that the 8DN is just to hard of a belt and I blame it for the wear on sheaves. I'm just not seeing the wear on the Yamaha clutch sheaves anymore that use the 8jp or ultimax xs.

 

[Doc Harley]

I wouldn't worry about spring rate changes at all. There's other things to watch before that, but I'd think that 10-20 thousandths cleans up the sheaves.
I am now of the opinion that the 8DN is just to hard of a belt and I blame it for the wear on sheaves. I'm just not seeing the wear on the Yamaha clutch sheaves anymore that use the 8jp or ultimax xs.

Ok....I got a snowmobile tech/machine shop by me, I'll give him a call.
Even though the groove is exceptable I'd rather do my best to clean things up.

 

[Turboflash]

Ok....I got a snowmobile tech/machine shop by me, I'll give him a call.
Even though the groove is exceptable I'd rather do my best to clean things up.

Check belt clearance after machining. Might have to move spider in a touch.

 

[Doc Harley]

I talked to my guy and he can mill/lathe some off. He did echo 74Nitro's concerns that .020 to .030 thousands would be too much.
Im not exactly sure what that would look like when inspecting the primary?

 

[74Nitro]

I talked to my guy and he can mill/lathe some off. He did echo 74Nitro's concerns that .020 to .030 thousands would be too much.
Im not exactly sure what that would look like when inspecting the primary?

Should be plenty of used sheaves or clutches out there?

 

[Doc Harley]

Should be plenty of used sheaves or clutches out there?

Yes, no problem finding them. Going to take a peek at another one on Sunday.
I suppose I can be picky as I have all kinds of time.

 

[KnappAttack]

Your not going to find a used clutch out there without a slight engagement grove I'm afraid. Dont let that scare you. Even if you machine it out it will come back in a short time, just no way around it on a trail sled really. Don't overthink it or waste your time machining it for that slight imperfection. Take a look at your existing clutch to see what I mean.

 

[74Nitro]

Yes, no problem finding them. Going to take a peek at another one on Sunday.
I suppose I can be picky as I have all kinds of time.

Are you talking about an engagement groove, or grooving half way up the sheave?
I was under the impression it was the latter since you mentioned belt failing issues.
I apologize if I misunderstood.

 

[Doc Harley]

Your not going to find a used clutch out there without a slight engagement grove I'm afraid. Dont let that scare you. Even if you machine it out it will come back in a short time, just no way around it on a trail sled really. Don't overthink it or waste your time machining it for that slight imperfection. Take a look at your existing clutch to see what I mean.

Right on.... I'll do my best to overcome my OCD. Not going to be easy.

Are you talking about an engagement groove, or grooving half way up the sheave?
I was under the impression it was the latter since you mentioned belt failing issues.
I apologize if I misunderstood.

My stock clutch is eating rollers, which is not a horrible situation. Zero belt issues.
The replacement primary (old Apex) has engagement glooves.

 

[RobX-1]

The one I picked up from Travis cleaned up nicely. Sure, I would've preferred there was no oxidation on the clutch but after all, it is called Barn of Parts:

 

[Doc Harley]

The one I picked up from Travis cleaned up nicely. Sure, I would've preferred there was no oxidation on the clutch but after all, it is called Barn of Parts:

View attachment 179860

Looks mint! But that tie rod don't! Just breathe.....

 

[RobX-1]

Looks mint! But that tie rod don't! Just breathe.....

That's because that Apex (ie. non-EPS) has BOP's MPS kit which comes with bent tie rods. I believe it was Knapp that mentioned when he ran the MPS kit, he did not use the bent tie rods.

 

[Turboflash]

You only need the bent tie rod if you use hole 3 (the one farthest out). Other 2 holes you can use the stock tie rods.

 

[RobX-1]

You only need the bent tie rod if you use hole 3 (the one farthest out). Other 2 holes you can use the stock tie rods.

We're sort of digressing here from the OP but I really appreciate you passing along that info as I did not realize and as you can see, am only using the first hole as I thought just that little difference made a huge difference.

 

[RobX-1]

Yes, no problem finding them. Going to take a peek at another one on Sunday.
I suppose I can be picky as I have all kinds of time.

One thing you will find as I suspect these older primaries with the set screws for the rollers AND the clutch weight will be hard to come by, is that the primary may not have the roller set screws but will have them for the clutch weights. This is the original primary I am replacing where the moveable sheeve cracked; will keep since the spider is good:

If the primary you are looking at is still loaded (ie. weights, springs, etc), the roller set screws may be hard to see but should be visible; or lack thereof: