Clutch conversion

[Champion750]

Hello all knowing XS650 owners,
I'm building a new engine for flat track racing and the engine I'm using is from an '82 Special II. I've been told that If I'm going to be running any kind of decent horsepower I should convert my 6 disc clutch to a 7 disc.
So now I'm working with Michael Morse at 650 Central and he tells me the only thing I need to change is the "inner clutch hub" (see pics). He did some research on part numbers and has told me that I need to use one from a '74 thru '79 engine.

Has anyone ever done this conversion before and can you add any info on this? I'm wondering if my '82 inner clutch hub can be machined to make this conversion work. Possible?

Any helpful info from experienced minds or just general thoughts would be welcome.

Thanks,

Robert

 

[ippytattoo]

I have done the conversion from a 6 plate dampened inner clutch hub to an earlier 7 plate clutch. Aside from the inner clutch hub the only other thing you would need is 214-16119-00-00 SPRING,BELLEVILLE which are still available. I have also had a later inner hub machined to match the earlier 7 plate clutches so you can do either one. I have some info in my Alto 8-pack clutch shop thread if you would like to take a look also if you are going to the trouble of converting your clutch to the earlier 7 plate clutch you may want to take a look at my 8-pack clutch offering. They work very well and actually cost less than 7 friction plates from the other sources.

 

[Champion750]

Hey ippy, thx for the reply.

What is a spring belleville? Is it the spring washer that sits behind the clutch nut?

 

[ippytattoo]

Yes it is a conical spring washer. According to the parts diagrams I can find starting in '78 the clutches went to the 6-plate dampened inner hubs and used a lock washer that has tabs that go into slots in the inner hub but the earlier ones just used a conical spring washer and a flat washer. Personally I like the lock washer with the tabs but the earlier hubs don't have the provisions for the locking tabs.

 

[jay760]

The template I use goes from 6 plate to 8 plate, inner hub you take down so the plate will just fit above the lip that's left, can't remember exact measurements, but you have to take about 1mm off the part that sticks out on the back then turn the whole of the back down so it misses the outer basket, pressure plate then needs some taken off both sides bottom to allow for plates, top so it misses the casing,
This was copied from the original template that Halco tuning used in the UK, there are a couple of threads on here about it or go to xscafe https://thexscafedotcom.wordpress.com/2011/01/09/xs650-8-plate-clutch/ the only thing missing on there is skimming the back off the inner hub

 

[ippytattoo]

With the Alto friction plates there is no need to skim the backside of the inner hub or remove material from the pressure plate. If you are going from a 6 plate dampened inner hub all you need to do with the Alto friction plates in order to achieve an 8 plate clutch is outlined here.

 

[Champion750]

Thanks for all the info.

I think an 8 plate clutch is overkill and too much trouble. A 7 plate clutch will be fine and way simpler to convert. I should only have to substitute one part. It's just a matter of finding the correct part.

 

[ippytattoo]

In all honesty if you are swapping the inner hub for a 7 plate clutch there is no more trouble to go to an Alto 8-plate clutch. If you are looking at it from the stand point of modifying the dampened inner hub for an 8 plate clutch I actually have a modified inner hub sitting in my shop. But I am not going to twist your arm or anything I just want you to have all the info. With a inner hub from a 74-78 there is no machining required at all to go to an Alto 8-plate clutch and if you were going to replace the friction plates the Alto 8-pack clutch kit is less than most if not all of the 7 plate sets out there.

Clayton

PS here is a NOS inner clutch boss on ebay

 

[Champion750]

Ok Ippy, you talked me into it. How do I get one of these 8 plate kits?

 

[weaselbeak]

If it's just for racing, why not just pop in some stiffer springs?

 

[ippytattoo]

LOL! All of the info is in my shops thread but the easiest way to get an Alto 8-pack clutch is to paypal me $70 to ippytattoo@cableone.net and PM me here. I have 8 in stock and ready for new homes.

 

[Champion750]

Ok, picked up a clutch hub from ebay. It's for a '75 year engine and its the hub pictured on the right. The hub on the left is from the '82 engine I'm building. The '75 hub is meant for a 7 disk clutch and the '82 for a 6 disk.

The left most pic shows the different thickness in the "flange" area where the disk rests. The back side profile of the two hubs differs slightly (hard to see in the photo) and the '75 hub has no groove for the retaining wire to hold the steel disk like on the '82 hub. Also the two have very similar part numbers, the '75 not having the last two digits.

This '75 hub is the one that will allow me to run the 8 disk conversion without mods.

 

[ippytattoo]

You got a good one there. If want to see what it takes to make the later inner hub work with the 8-pack clutch just remove the retaining wire and the parts underneath. When you remove the steel plate, spring plate and other plate out you will see a landing at the very bottom of the flanged area. If you have the hub machined so that everything is flat with that landing it works as well as the mid-run inner hubs.

Clayton

 

[650performance]

Champion, you'll be glad you went to the 8 discs. The pack will handle 70 rear wheel HP with no slippage, is gentler on the steel plates which means less warping and you don't have to use excessively stiff springs. The reduced stress on individual plates translates to less frequent replacement of components, which saves both trackside hassle and $.

 

[hooser]

Just add 3 heavy clutch springs, every other one. We have never had a clutch slip with good plates and this spring combination. We make 70hp. Gary

 

[TwoManyXS1Bs]

Another 'minor' advantage in going to the 8-disc clutch is that the engagement fingers of the steel discs and friction discs will be 'misaligned' with the original worn notches on the hub splines and basket fingers. Some of those engagement 'fingers' will be riding on fresh surfaces...

 

[650performance]

Hooser, I agree that you can get by with heavier springs and 7 plates with 70 RWHP, and perhaps it is due to the quality of the aftermarket steel plates available today, but I routinely experienced plate warpage which affected the "feel" of the clutch and made it too grabby. Going to 8 plates solved the problem. My interests relate to road racing, while yours (I believe) are more dirt track oriented, so perhaps that's the difference.

 

[hooser]

Did yours slip or grab?

 

[650performance]

If I used heavy springs with 7 plates (that were all in good shape; flat, etc.) it never slipped but the feel would begin to deteriorate after, say, four practices and a couple of races. Unless promptly refreshed it would shortly become excessively grabby on lower gear downshifts and starts. Upon teardown, a feeler gauge on a flat plate would reveal warping of the steel plates. After switching to 8 plates it would work just fine for half a season.
Also, the OEM Yamaha steel plates were markedly superior in terms of resisting warp to any aftermarket plates I have found.

 

[hooser]

Good to know, we don't shift once in top gear. I could see where Road racing would put more stress on it. Thanks, Gary