Clutches

Tips and Recommendations from Guru Mike Nixon

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mikenixon
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Clutches

Post #1 by mikenixon » Fri Aug 02, 2019 12:12 am

The most difficulty folks have with clutches is properly adjusting them. Over 46 years of observation tells me this. Japanese bikes are among the easiest to find neutral with among all vintage machines. Yet many of their owners struggle. And largely due to clutch misadjustment, misassembly or bad maintenance. To adjust the clutch correctly, follow this classic three-step procedure.

Step one: Slacken the cable at both ends completely. In other words, retract the cable housing as much as possible. This eliminates the influence of the cable itself on the release (throwout) lever adjustment, the next and most critical step.

Step two: The release lever is that lever down there on the clutch housing. Access the release lever adjuster and after loosening its locknut, rotate the adjustment screw in both directions slightly while with the other hand feeling the release lever pivot one direction then the other as you turn the screw in each direction. This will help familiarize you with the system. It is also a way to ensure that the release mechanism works correctly. Next, turn the adjusting screw clockwise until it stops turning. Don't force it. Once it has gently stopped turning, then rotate the screw in the opposite direction just enough to get the screw off of bottoming. I usually use 1/8 turn. 1 You don't need more than that, and if you understand the release mechanism's role, that should make sense to you. Snug the locknut and check how much the release lever moves. Done correctly, the now-locked-in-place release lever should rotate only about 15 degrees, i.e. about half the distance between the two numbers on a clock face. Call it 7~8mm of movement at the lever's tip. Though both the GL1000 and GL1100 manuals have a procedure that results in more release lever travel than this, this is the best spec. The release lever must move freely, without resistance, but for only 15 degrees. Even a tiny bit less is better than any more. 2

Step three: Now take up the cable's slack at the engine end of the cable, until there is almost none left. This leaves the final slack adjustment to be done at the handlebar end, where by design only very minor tweaks for preference are to be done. Best practice is the final slack at the handlebar lever should be extremely minimal. Again, the GL1000 and GL1100 have their own specific (and different) specs, but the correct slack for both is 1/16 to 1/8 inch movement at the tip of the lever. Very very little. Just perceptible. If you have over time become acclimated to a sloppily-adjusted clutch and can't imagine working with the right setup, give it a try. It's worth it. :-)

If you continue to experience trouble finding neutral or clutch action is inconsistent or difficult, and the clutch parts are factory and are assembled and, as explored here -- adjusted correctly -- then check a few things. First, you do have a factory clutch cable, don't you? It makes a tremendous difference. Stay away from that Motion Pro crap. Much poorer quality than OEM. More on this later. Next, make sure the crankcase oil level is not excessively high. A high oil level increases drag and overheats the clutch, resulting in clutch and shifting issues. Also, be certain the engine idle rpm is not too high. Over the standard 1100 rpm you will have clutch and shifting trouble. And then there's the Barnett. If you have installed a Barnett clutch you will have repeated issues with finding neutral, among other issues. The only real solution is to put a proper clutch in there. 3

Hydraulic conversions, whether aftermarket or based on retrofitted 1200 parts, are fine. Nothing wrong with them. But neither are they necessary. You'll have trouble with the glycol fluid going bad twice as fast as it does in your brakes. And compared with a properly set up cable-operated clutch, there is just no advantage in hydraulics. 4

Most people know that everything *except* the clutch basket (outer) on both the GL1000 & GL1100 comes out in the frame. So pretty good clutch maintenance is easy to accomplish. The official manuals of course list thickness and warpage tests and that's all fine. But they're hardly necessary. You can smell when clutch friction discs are excessively worn. Go ahead, laugh! The special damper (B) disc has apparently given some folks trouble, but in over 46 years I have yet to witness this personally on any of the Honda models that use this disc, and had never even heard of any problems in all the years I worked for shop owners, until reading about it in this forum. The B disc originated midway in the early CB750's production and solved a lurchy clutch, thus Honda fitted it to most models thereafter. 5

If contamination (usually disintegrated friction discs) is evident in your oil, the official manuals recommend flushing the crankcase. Good thing, that. If there are appreciable notches in the basket (outer), this indicates rough use. However, sometimes notches appear and rough use isn't the cause. This happens when certain aftermarket discs have been installed and the dimensions of the discs' tangs are different; their fit isn't as precise as stock. Beware. Resist the urge to file down clutch basket notches. It may be intuitive but it is dead wrong. It will only make things worse. Of course, a damaged clutch basket requires that the engine be removed from the bike as again, the basket does not come out in the frame. 6

On the GL1100 you will note that two special shouldered bolts thread into the pressure plate just as they do in the clutches on the DOHC fours and the CBX models. The GL1100 also has these same bikes' cam-type clutch lifter rather than the three-ball type on the GL1000 and CB750. Experienced mechanics know to gradually tighten or loosen the bolts going through the clutch center into the pressure plate. Criss-cross pattern, the manuals suggest. It isn't hard to break a clutch pressure plate post. It's so easy in fact that some of the new lightweight sport bikes require a special tool for both loosening and tightening. Not so on older bikes, but you do need to take special care.

The GL1100 clutch lever has a steel bush in it. Career Honda mechanics know to keep this bush lubed as it tends to seize to its chrome-plated bolt. Once that happens they will not separate and then the lever's steel bush rotates inside the aluminum lever and tears the lever up. To prevent this, not only do you need to keep the pivot lubed, but also you should tighten the lever's pivot bolt in a special way. Snug it, then back it off a quarter turn before installing and tightening the locknut. This common Honda mechanic technique will make the bolt and bush live more harmoniously with each other. 7

Aftermarket clutch cables are poor economics. Get the factory one. It's plastic-lined and not only operates smoother and with less effort, it lasts decades without frequent relubing. It's a bit surprising to see the rectangular cable lubing tool published in the GL1100 factory manual. That was a mechanic's secret back in the early 1970s when it first appeared on the aftermarket. There are several sources for it now (including the OEMs) and it's a good tool to have. However, don't use WD-40 with it unless you're merely flushing/derusting the cable and intend to follow with an actual lubricant. 8 I know a lot of folks say not to use chain lube but I always do and have never had a problem with it in well over 40 years. Works great. Properly routing the cable is also important because that has a large effect on clutch feel.

Notes:
1 The GL1000 manual says to turn the release lever adjusting screw 3/4 turn, the 81~82 GL1100 says 1 full turn. They're both wrong. The closest to correct is the 83 GL1100 manual which says that after screw adjustment the release lever should move only 15mm, which while about double my recommended 15 degrees, is at least doing it the right way by focusing on the right thing, the amount of movement of the release lever. Obviously, there is no release lever adjustment on the hydraulic-clutch GL1200.

2 Believe me, 1/8 turn works. There's a big difference between knowing something because a book says so and knowing it from firsthand experience. We like to believe that only a pure objective motivates the writers of the official manual. But work on the inside, in the OEM's national headquarters, and you will quickly learn that communication in factory manuals is just like any other written material. It's subject to the usual influences, pressures and inconsistencies.

3 The earliest type Barnett friction discs swell so much more than normal that the clutch really stops working properly when the engine is warm. Pre-oiling the friction discs will not change anything. Not on a Barnett and not on a stock clutch, and you will note that although Honda specified oiling clutch discs in the SOHC manuals, they omitted this in the GL1000 and GL1100 books. No professional mechanic pre-oils clutch discs. They have better things to do with their time.

4 I'm not against hydraulic clutches. I just like keeping things simple, and where a properly adjusted system works and works well, what's to fix?

5 The first time I ever heard of it was when I read of it on this forum. And I have serviced many many Wings. Offhand I would connect it with misuse of the clutch.

6 The price for a used but good clutch basket on certain models of vintage Hondas has reached close to $1000 now. Likely Wing baskets are considerably less. But filing down the clutch fingers will only postpone the inevitable. And the problem will come back worse than before, and faster than before.

7 This seizing bush deal is edemic to all of the clutch levers found on the GL1100 as well nearly all Hondas of the late 1970s and early 1980s. So much so that replacement levers have virtually dried up and only very sub-quality aftermarket ones are to be found.

8 WD-40 is great for a lot of things. But not lubrication. It is more solvent than lubricant.

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Re: Clutches

Post #2 by 05c50 » Fri Aug 02, 2019 8:06 am

Mike, nice write up and many good points to think about. Like many mechanical things, understanding how it works will help repair and adjust it properly. The clutch lever, cable and release lever (lifter) are good examples. I'd like your thoughts on engine temperature impacting clutch adjustment. On some bikes, I've found that adjusting a clutch with a cold engine will not necessarily give the best adjustment results. Thanks

.....Paul

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Re: Clutches

Post #3 by mikenixon » Sun Aug 04, 2019 7:05 pm

05c50 wrote:Mike, nice write up and many good points to think about. Like many mechanical things, understanding how it works will help repair and adjust it properly. The clutch lever, cable and release lever (lifter) are good examples. I'd like your thoughts on engine temperature impacting clutch adjustment. On some bikes, I've found that adjusting a clutch with a cold engine will not necessarily give the best adjustment results. Thanks

.....Paul


Good point, Paul. However, in my experience, I have found the only difference a hot engine makes is increased freeplay at the handlebar lever. There is a reason Honda does not specify a hot engine. Most folks would mis-adjust the clutch if they did it hot. Get it perfect when hot and when cold it will be wrong. So what we do is, we shoot for a very small amount of freeplay when cold, it will look like too little but it's not, there is some. Then when hot and the freeplay has increased, well, it's more than we would have liked, but it's correct because it is as close as we can get to perfect given the fact that it changes with temperature. I invariably find that I have to reeducate my customers regarding clutch lever freeplay.

And make no mistake, handlebar lever freeplay is only one piece of clutch adjustment. I have yet to meet a customer who finds the correct handlebar lever freeplay comfortable and intuitive. They all want three to four times as much, because they have been riding for decades in many cases with incorrectly-adjusted clutches.

Freeplay is only one piece because it's the release lever (what you would call the "throwout lever" in a car) that is the big deal, the focus, in clutch adjustment. Handlebar lever freeplay is only the "fit to the customer" aspect of the adjustment. On the other hand, having the release lever set correctly changes the feel of the clutch completely, and that's because when it's correct the clutch works as designed. I don't think more than one out of five Hondas with cable operated clutches have them adjusted correctly.

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Re: Clutches

Post #4 by Old Fogey » Thu Aug 08, 2019 4:43 pm

Mike, there is another possibility for inability or difficulty to change gear. Not directly a clutch problem, admittedly.
http://wingovations.com/scavenge-pump-p ... 4579471109

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Re: Clutches

Post #5 by digschopper » Thu Aug 08, 2019 9:39 pm

Mike,great info here. Aren't there ANY aftermarket cables that last?My problem is ive changed my bars,so a stock cable is too short. It seems I've painted myself into a corner.

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Re: Clutches

Post #6 by mikenixon » Fri Aug 09, 2019 6:30 am

Old Fogey wrote:Mike, there is another possibility for inability or difficulty to change gear. Not directly a clutch problem, admittedly.
http://wingovations.com/scavenge-pump-p ... 4579471109


Interesting. Have not encountered this. Related to oil volume of course but in a different way. Thanks, Old Fogey!

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Re: Clutches

Post #7 by mikenixon » Fri Aug 09, 2019 6:47 am

digschopper wrote:Mike,great info here. Aren't there ANY aftermarket cables that last?My problem is ive changed my bars,so a stock cable is too short. It seems I've painted myself into a corner.


Back in the day we used to scope out all the clutch cables Honda produced and nine times out of ten we could find one similar to our original but a different length. This worked because unlike other brands Honda never used the same cable twice between models. At the same time however Honda seldom used the same style terminus except within a model series, say all SOHC fours, for example. so finding a different length cable across model types -- such as twins to fours -- didn't often work. I've never needed to try this on a Wing but knowing how unique the GL1000 cable is, to cite just one model, I suspect it will be difficult. And of course you need a dealer who stocks a lot of cables, which is a thing of the past.

You're probably stuck with Motion Pro or one of the other alternatives, but I would keep looking. In my experience they're really crappy cables. Even Barnett are better and I hate saying it. Perhaps a Kawasaki or ?

At least you're on the longer cable side of the equation instead of shorter, meaning routing won't add to the dilemma.

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Re: Clutches

Post #8 by digschopper » Mon Aug 12, 2019 12:14 pm

Thanks Mike. You just saved me hours of wasted searching!

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Re: Clutches

Post #9 by mikenixon » Tue Aug 13, 2019 6:49 am

digschopper wrote:Thanks Mike. You just saved me hours of wasted searching!


Well, I am glad to hear that! Found something that works, did you?

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Re: Clutches

Post #10 by digschopper » Wed Aug 14, 2019 3:30 pm

Not yet. I assume dual throttle cables shouldn't be such a project?

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Re: Clutches

Post #11 by mikenixon » Thu Aug 15, 2019 6:44 am

digschopper wrote:Not yet. I assume dual throttle cables shouldn't be such a project?


Hmm, don't know.


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