Lets talk Clutches

[dr1979-340]

I have fixed up two 1979 340 Drifters and this is the 1st season testing them out.  I didn't take the clutches apart, just blew them out and cleaned them up a bit.

The sleds sure react differently from each other.  According to the shop manual the clutch should engage at 3500 rpm's, which both do.  The one that had less wear and tear on it when restored has a lot more zip on take-off and seems to top out at about 50 mph.  I think that's all you can expect from it. 

The other one was much more worn.  I'm guessing that it had at least 2000 more miles on it.  That's the one that I'm wondering about.
I had it out last weekend and it would only get to 30 mph sometime at 6000 rpm.  Other times it would get up to around 40 mph.  It felt like I was applying the brake during acceleration.

Question:  Are the clutch parts something that should be replaced when restoring?  Maybe a new spring? 

I've read the shop manual and am confused by "drive converter engagement" and "shifting" in the troubleshooting section of the manual.

[rminier]

"Let's talk clutches"....LOL...I love to talk...or type.
 Your Drifters came with ArcticCat "Hex" clutches..so called because of the hexagonal shape of the center bushing. Bombardier (SkiDoo) called their clutch during the same time frame a "square shaft" clutch....same deal...their center bushing was square shaped.
 Both clutches worked great when they were new. Trouble was, they transmitted all of the engine torque right near the crankshaft centerline, at those center bushings, which led to rapid wear, and binding of the shifting as those center bushings wore.
 Polaris came out with a better idea, which Comet, Kawasaki (with their own in house clutch) and everyone else adapted, that moved the torque transfer points out to the outer perimeter of the drive clutch, with plastic buttons or shoes making contact with an aluminum surface. This led to much more efficient torque transfer, longer life, and cooler operation. They still have center bushings, but their only function was a sliding surface for the moveable sheeve to slide in and out.
 Back to your Hex clutch....grab the inner sheave of your drive clutch with one hand, and try to rock the outer sheave back and forth. If you have much more than 1/8" play, it is suggested the center bushing needs replaced....yours probably has a lot more than that.
 Clutches suck....you have to get the proper puller, hunt down replacement parts, etc. etc.
 You probably need a new center bushing at the very least. You need to check the rollers and ramps to make sure nothing is too badly worn out, and the rollers are clean and spin freely. Your spring is probably OK, unless it's broken.
 You might look and clean the secondary clutch. They are pretty simple critters compared to the drive clutch. Just make sure the spring isn't broken, and the 3 little plastic shoes aren't worn down to metal.
 Kawasaki did start using their own clutch on the '81 440 Drifter. If you find a good used Kawi clutch, we could get the right ramps and weight figured out for your 340.....

[rminier]

 An option to keep in mind...you can buy a brand new Comet "Duster" clutch from lots of places for 250 bucks that would be a direct bolt on and go.
 I know....lots of money, but you have to weigh the cost in parts and the time to rebuild an old clutch....just thought I would mention this.
 BUT...before even thinking about doing that, verify your secondary clutch is all good, and the drive clutch needs a lot of new parts.

[dr1979-340]

Thanks guys!!  That's what I needed to hear.  I recently did find out that the clutch is an Arctic Cat clutch.  I found a parts list pdf file for it, so I've been looking at what replacement parts cost.  I think I'll probably start with the bushings and go from there.

If I remember my Kawasaki history correctly, Arctic Cat built (assembled) the Drifters at a factory in Nebraska for Kawasaki USA.