A Clutch Education

[admin]

camman - 12/09/06 at 9:11pm

Hello, I need to be educated on how a Hodaka clutch operates. Here is my case;
Subject: Combat Wombat
Problem: Clutch not disengaging, (I think that's the correct term) or in other words, cannot stop the bike by pulling in the clutch and braking, it just keeps going or dies. There is full clutch lever movement at the handlebar however.
Remedies already tried: I adjusted the clutch lever free play at the case cover to 3/32". Checked oil level. Removed and disassembled clutch. I have not checked for warped plates or friction disc thickness yet. Just wanted to check in and see if I was on the right track before buying a new clutch set. Thank you.
8)

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Forum Admin - 12/09/06 at 9:57pm

Camman by some chance did you or someone else just rebuild the motor ?? My first thought is that the snap ring that holds the right main bearing may be either missing or not snapped in place. This may be the reason your bike dies when you grab the clutch lever. What this does is moves the crank assy to the left and the crank is rubbing against the left inside case. Just a guess at this point.
Or has the bike sat for a long period of time ? If so them possibly the steel clutch plates may have rusted and seized to the friction plates. The clutch may need to be disassembled , inspected and possibly the steel plates cleaned on a wire wheel. My 2 cents and all this is only a guess at this time.
Paul

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Bullfrog - 12/10/06 at 12:33am

Are there any noises which seem sort of un-natural which coincide with pulling in the clutch lever? Such a noise would sort of reinforce the main bearing thought Paul mentioned.
I too am curious, is this a very recent clutch rebuild? Or has it sat around a long time. If it has been sitting around a long time, you may find that it will "break loose" and start working after you ride it a while. -- After a long term of sitting around, ALL the oil squeezes out from between the steels and friction discs and they develop such an affinity for each other that they just don't want to separate. A little well warmed oil and multiple clutch actuations will often convince the steels and friction discs to resume their more normal relationship of "sometimes together" and "sometimes apart".
Also, I bumped into the same sort of problem once (no noise associated with actuating the clutch) and finally found that the clutch bushing was too short. When I put in the proper length bushing, everything was just fine. For the life of me, I can't figure out where the short bushing came from or why I had it.
Ed

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camman - 12/10/06 at 8:31pm

There has been no recent rebuild or strange noises, and perhaps I mislead you. The bike dies due to stopping, like what happens to a new rider when they stop and forget to pull in the clutch. In this case, the clutch pulled in, it just doesn't work. The bike did sit for awhile however the clutch operated fine just prior to the problem developing. The problem arose after teaching my three nephews how to ride for the first time. The clutch had a lot of "feathering" from the new riders. Thanks for your detective work. Any other suggestion.
Chris Miller in Oregon

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Bullfrog - 12/10/06 at 9:41pm

With that clarification, I'm thinking you might have a broken friction disc. (ie, it was working fine - got a major workout from learning riders -- stopped working) So I think it is time to "go in and have a peek" at the clutch internals.
When the clutch was re-built, did you happen to use the "old style" all fiber friction discs? They don't break often, but they are more prone to failure than the newer aluminum/friction ring clutch discs.
Ed

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camman - 12/10/06 at 11:08pm

Ed, I haven't rebuilt this clutch so I don't know how old it is. I disassembled the clutch, no broken friction discs, they are the old style. They do show some wear and the worst of the 5 is .010" under the inner (non wear) surface thickness. I don't have the thickness specs?? The inner thrust washer and pinion bushing show significant wear, notably the washer which has a deep groove on the inner face. Am I looking at a complete rebuild?

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Bullfrog - 12/11/06 at 2:28am

Ah-ha (as in a Eureka moment)! I think you may have found it!
If the inner thrust washer has a wear ring which lets the inner end of the clutch bushing sit significantly more "inboard" than it should (and the end of the clutch bushing is worn down a bit too), you'll end up with the same effect I had with the short clutch bushing.
With a significantly worn clutch bushing and inner thrust washer, when you tighten up the clutch nut it presses the Clutch Hub (944012) against the pinion gear rather than against the end of the clutch bushing (as intended). With this "fault", the clutch hub and and the pinion gear are "locked together" all the time.
So I'd recommend inspecting whether or not the outer end of the clutch bushing extends "proud" of the pinion gear/clutch rotor gear/clutch thrust washer(outer) - if not, the inner thrust washer and clutch bushing need to be replaced.
Ed

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camman - 2/11/06 at 10:16pm

I checked the pinion bushing and it is just ever so slightly proud of the outer washer as you described. The end of the bushing is worn, kind of mushroomed on the end. In addition, the bushing is quite sloppy on the shaft so a replacement of both the bushing and washer are in order. To be honest, I am still having difficulty visualizing how the clutch works but as long as it works, I good with it. Maybe you can draw a picture for me at next years Hodaka Days. Thanks Ed for your expertise—it is always appreciated.

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Bullfrog - 12/12/06 at 11:41am

While you have things opened up, it would be good to check the condition of the internal "teeth" of the clutch cage. If the aluminum is all "wash boardy", the steel plates can't move without grabbing/hanging up - resulting in the clutch being an "ON/OFF" switch.
Also, check for sharp edges on the teeth of the steel plates. Those sharp edges dig into the aluminum of the clutch cage and prevent smooth movement. There is a scan of a drawing showing "blue printing" those sharp edges off the steel plates in the Photos section of the Yahoo Hodaka Owners Group (in the Ed's Photos folder).
If you check (and fix, as necessary) those things, and replace the thrust washer and clutch bushing, you ought to end up with very nice clutch action.
Ed

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