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Old 04-28-2014, 07:59 PM   #1
apt13 OP
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clutch symptom, let's figure it out!

Hey guys, seems nobody was interested in my previous clutch post, so i've backed up a bit and would like to know some general things. I am hoping you all can help me out once again.

after returning from a multiday trip last fall, a mile from home, i noticed that when starting from stop, essentially in the "friction zone" i was experiencing what i can only describe as "slipping" or "dragging" or maybe something else? i've looked up random clutch symptoms for awhile and maybe it's "shuddering' or "juddering"? i can't really say as i've never experienced clutch issues throughout my years.

the bike shifts through everything fine and easy. all gears. it never slips out of gear or anything like that. once i shift it into 1st, everything seems totally normal, but that "in between" stage it feels like something isn't working quite right. if i really jam the lever off/on, instead of being slow and steady about it, i guess that works. but having "jammed it" for years in various hardcore and punk bands, it's just not my thing anymore. i like to take it easy, haha

since this long trip where i've first noticed it, i've only been riding around locally, and don't notice it at all, but lately i've been riding longer, and it seems that after a few hours, the symptom comes back, and instantly makes me nervous.

"slipping" is probably not the correct description as i get what that means, but when i verbally try and tell someone what i "feel," all i can say is it feels like its slippery back there until i let the clutch lever all the way out.

is this possibly just a cable adjustment issue?

thanks in advance!
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Old 04-28-2014, 10:23 PM   #2
Rob Farmer
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are we talking about the 78 in your sig line?

I had a strange one a while back on my 78. It turned out to be the spot welds on the clutch pressure plate had all come away, this in turn had snapped the clutch push rod. The pushrods are prone to snapping on the pre 81 bikes so it's worth checking to see if it's all in one piece.

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Old 04-28-2014, 10:58 PM   #3
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The following applies to my '83 R80, so may not be relevant.

I was recently experiencing an occasional, and apparently random effect while taking off in first where I felt a strange combination of clutch slip and a feeling like the engine was 'bogging', like it was going to stall but not quite - weird effect. Couldn't work it out, clutch was clean, well within spec thickness. So I put a new clutch plate in and the problem hasn't recurred.

Only thing I could put it down to was some contamination of the friction material. One day I will investigate, but that will be in the coming wet season - now is riding weather, not workshop weather.

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Old 04-28-2014, 11:56 PM   #4
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Quote:
Originally Posted by apt
clutch symptom, let's figure it out!
Hey guys, seems nobody was interested in my previous clutch post, so i've backed up a bit and would like to know some general things. I am hoping you all can help me out once again.
Uhh, I guess people refrained:

Quote:
Originally Posted by previous _post
also, not interested in starting another EZ clutch debate. so please refrain.
"EZ clutch question. real quick"

You've got a nonstandard accessory that no one is up on adjusting. I'd guess it may be adjustment. Or some thing. Maybe call Benchmark, or run the bike over to the Benchmark shop?
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Old 04-29-2014, 12:56 AM   #5
pommie john
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The first thing we need to do is standardise our descriptive language.

Clutch slip is when the clutch cannot transmit all the power to the transmission ( and thence to the rear wheel). When a clutch slips, the engine will increase revs when you apply throttle, but the bike won't increase in speed.
Clutch slip usually happens in higher gears unless the clutch is really rooted.

Clutch drag is when the clutch does not fully disengage. When you are stopped but in gear, the bike creeps forward slowly. Usually when a clutch drags it's hard to engage gears when stationary.


Either of these effects can be caused by poor adjustment ( or many other things).
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Old 04-29-2014, 10:40 AM   #6
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that's pretty much exactly the same thing i'm feeling. i know that "slipping" and "dragging" aren't really the correct terms to describe it, but that's the only thing my mind wants to say. haven't taken it all apart yet, but i suppose that would be the next step at some point if the adjustments don't work.


Quote:
Originally Posted by greentreephrog View Post
The following applies to my '83 R80, so may not be relevant.

I was recently experiencing an occasional, and apparently random effect while taking off in first where I felt a strange combination of clutch slip and a feeling like the engine was 'bogging', like it was going to stall but not quite - weird effect. Couldn't work it out, clutch was clean, well within spec thickness. So I put a new clutch plate in and the problem hasn't recurred.

Only thing I could put it down to was some contamination of the friction material. One day I will investigate, but that will be in the coming wet season - now is riding weather, not workshop weather.

Peter H
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Old 04-29-2014, 10:41 AM   #7
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thanks.
yeah i knew that "slip" and "drag" weren't the right terms, i just didn't know how to describe the feeling i was getting.

but i do appreciate the focus of the correct terminology.


Quote:
Originally Posted by pommie john View Post
The first thing we need to do is standardise our descriptive language.

Clutch slip is when the clutch cannot transmit all the power to the transmission ( and thence to the rear wheel). When a clutch slips, the engine will increase revs when you apply throttle, but the bike won't increase in speed.
Clutch slip usually happens in higher gears unless the clutch is really rooted.

Clutch drag is when the clutch does not fully disengage. When you are stopped but in gear, the bike creeps forward slowly. Usually when a clutch drags it's hard to engage gears when stationary.


Either of these effects can be caused by poor adjustment ( or many other things).
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Old 04-29-2014, 10:52 AM   #8
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my original thread i wanted specific info about adjustments for people that used the EZ clutch. i did end up calling Vech and he confirmed that i am adjusting everything correctly. so there's that. It has never really caused me any problems and I have kept it adjusted to spec for years. I was just having a brain fart and wanted to know how everyone else does it, as it's obvious many people use them. but i didnt want to get in a back and forth about the merits and demerits of using one, as that has been done to death.

this posting is a general question about a specific symptom or clutch feeling i am getting and wondering if anyone else ever had the same symptom, regardless of whether they have this accessory or not.

havent really been able to find any info on this symptom.

but i'll try some more cable/lever adjustments and see how that works out. i suppose the next step would be to pull it all out and see whats up.


Quote:
Originally Posted by Bill Harris View Post
Uhh, I guess people refrained:



"EZ clutch question. real quick"

You've got a nonstandard accessory that no one is up on adjusting. I'd guess it may be adjustment. Or some thing. Maybe call Benchmark, or run the bike over to the Benchmark shop?
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Old 04-30-2014, 12:39 AM   #9
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It's really hard to diagnose problem like this even when the bike's right in front of you, let alone over the internet!

All I can suggest is do the cheap and easy things first.

Cable adjustment. I don't know how you should adjust a EZ clutch, but since I ride with a standard ( post '81) clutch I don't now why you need to make the clutch lighter, it's a nice easy clutch on my bike. Maybe you could take it back to a standard BMW clutch lever and see if it helps.


Check the push rod is not binding in the transmission back cover. That's a common fault.

Check the release bearing is not falling apart.

And check the bearing in the lever on the back of the tranny, thay pick up road dirt.

After that it starts to get harder and you might have to take the transmission out, although that's not too hard.
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Old 04-30-2014, 08:16 AM   #10
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From what I understand, the sweet zone of adjustment on an EZ clutch is much tighter than on a standard one, and my experience with standard clutches is that a properly adjusted clutch will get you more than 1/2 way to a decent gearchange.

With your bike there is a clip that stops the bolt on which the clutch arm rotates migrating upwards. These clips, rot through and fall off, the bolts migrates upwards and you find that you have no clutch and need a new gearbox end cover. Worth checking. And replacing the bolt with one that can be secured with a nylock nut.
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Old 05-03-2014, 09:07 AM   #11
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well i finally got around to looking at things.

i took apart the clutch arm as something easy to do and look at and clean, and the piece of the pushrod came out with it, so i can only assume it snapped, in about the same place yours shows. it was also very oily/greasy in there.

so i assume now i'll have to pull the transmission and look at the rest of it. i am not familiar with working on the actual clutch. i know there is some special blocking tool i need to actually pull the clutch out right?


Quote:
Originally Posted by Rob Farmer View Post
are we talking about the 78 in your sig line?

I had a strange one a while back on my 78. It turned out to be the spot welds on the clutch pressure plate had all come away, this in turn had snapped the clutch push rod. The pushrods are prone to snapping on the pre 81 bikes so it's worth checking to see if it's all in one piece.

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Old 05-03-2014, 01:37 PM   #12
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The rod is not all that hard to replace, but pulling the tranny and checking everything else is an excellent idea. That way, even if the clutch itself is good, you will then know what you have.

There is a "special" tool used when working on the clutch, but many have made their own for cheap. Almost all Airhead owners tend to be frugal. If you do a little searching in the forum, I am certain you will find some pictures of what others have made. I use the tool that BMW recommended, but have the luxury of have a really good friend that is a BMW trained technician, from back when these things were new. He has all the right tools.
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Old 05-03-2014, 01:44 PM   #13
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is it possible to replace the rod without removing the gearbox? the books say to remove the gearbox, but seems like alot of work just to replace the pushrod, haha.

Quote:
Originally Posted by DaveBall View Post
The rod is not all that hard to replace, but pulling the tranny and checking everything else is an excellent idea. That way, even if the clutch itself is good, you will then know what you have.

There is a "special" tool used when working on the clutch, but many have made their own for cheap. Almost all Airhead owners tend to be frugal. If you do a little searching in the forum, I am certain you will find some pictures of what others have made. I use the tool that BMW recommended, but have the luxury of have a really good friend that is a BMW trained technician, from back when these things were new. He has all the right tools.
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Old 05-03-2014, 07:09 PM   #14
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In a word, no. There isn't room to do it with the trans in place.
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Old 05-03-2014, 11:03 PM   #15
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The fun comes when you cannot remove the gearbox because the pushrod is sticking out of the input shaft into the clutch plate. It won't come out until you've scratched the frame and bloodied your knuckles...all part of the bonding process. Don't order a stainless equivalent pushrod otherwise you'll be repeating the whole process again very soon. You need a genuine pushrod.

Don't forget to remove the old felt washer and look forward to getting the new washer in properly...the 80 on clutch will seem an attractive proposition.

It's worth taking the clutch apart to make sure the pressure plate is still intact. To do this you will need the clutch let down tool which is just a set of nuts and bolts that let you take the pressure off slowly.

Good luck.
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