clutch engagement on 1970 roadster

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hey folks

i have a 1970 commando with a grabby clutch. if i am careful to slip it over the very brief engagement travel it works fine. but it's too much of an on/off situation to make me happy. no drag, no noises, no vibrations, just an exceptionally brief engagement.

i've adjusted the clutch with no difficulty but the result is simply to move the engagement point. the fluid in the clutch appears to be red ATF, but i don't know whether it's dexron/mercon or type F.

any suggestions on which direction to go before i start in on trial and error? i've never had the cover off this primary so i don't know what kind of plates are in there.
 
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If you have never been into your primary then now might be a good time to open it up and do some maintenance, I opened mine up last week even when things are running great it all part of maintaining everything to make sure things are all good inside, depends on how many miles you ride in a year its always good to check things out, rotor, ALT, chain and clutch plates, clutch centre and oil, it not a hard job to do and also pulling the clutch plates out to give them a clean and inspection and to make sure the primary bolts are all tight and good to see if the chain needs any adjustment or finding any tight spots, its all part of maintenance and looking after our Norton's.
The primary is one of the easier jobs to maintain and its easy to make a clutch removal tool to pull the clutch retaining spring if you don't have one.

Ashley
 
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A commando clutch is unlike a car clutch that has "S' shaped springs between the two friction surfaces primarily to ease into the full engagement.
A commando clutch is almost an "in or out" function. The skill is to learn where the engagement starts and just hold it there momentarily as the bike starts to roll and you also apply throttle.
An unlubed cable makes it harder to control the feathering technique as does the natural sponginess of a bowden cable.
As long as the clutch disengages and is easy to find neutral then the clutch appears to be normal. No maintenance is needed, just practice...
 

illf8ed

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You can get some feel for how the clutch is releasing by putting the bike in gear pull the clutch and push on the kick start. As you release the clutch continue to kick through. It will give you an idea if the clutch engagement is gradual as it should be or If it all of a sudden grabs which it should not. If sticking take the plates apart and clean them. I found replacing all the sureflex and steel plates on my ‘72 750 clutch greatly improved the action and was worth the cost IMO....after 50K plus miles.
 
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folks, thank you for the replies. i'm going to take it apart and look at the plates. like i said, i've never been in there so i'm not sure what i'll find. i'll swap in some fresh Type F as well, so at least i'll know where i'm starting from..

there's definitely something fixable in there. like you said, dave, it's on/off, but there is literally no plate slippage except over about 1/4-inch of lever travel. on the other hand, there isn't any slip and if i just drop the clutch from anywhere above idle it tries to wheelie. the machine is easily rideable but takes silly attention to move from a stop.

otherwise the machine is quite nice. excellent handling except for the slight head shake (i'll live with it). i'll look over the other parts while i'm in there. in the mantime, i'll keep riing it.





might even look for a stronger centre stand spring



again thanks for the suggestions
 

NPeteN

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folks, thank you for the replies. i'm going to take it apart and look at the plates. like i said, i've never been in there so i'm not sure what i'll find. i'll swap in some fresh Type F as well, so at least i'll know where i'm starting from..

there's definitely something fixable in there. like you said, dave, it's on/off, but there is literally no plate slippage except over about 1/4-inch of lever travel. on the other hand, there isn't any slip and if i just drop the clutch from anywhere above idle it tries to wheelie. the machine is easily rideable but takes silly attention to move from a stop.

otherwise the machine is quite nice. excellent handling except for the slight head shake (i'll live with it). i'll look over the other parts while i'm in there. in the mantime, i'll keep riing it.





might even look for a stronger centre stand spring



again thanks for the suggestions
You and I have damn near the same exact bike. Right down to the red oil rag.
Your clutch shouldn't be blasting you into outer space, no doubt after some proper maintenance and setup you will be on your way. How's the pull, keeping your forearm in shape?
 

baz

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What's the history of the bike? IE what plates does it have
How long have they been in there?
I had almost the same on my commando when I first built it, the big difference is I have a belt drive running dry
But the clutch was either on or off
And used to grab like hell
This I think from memory was with STD Norton fibre plates
I stripped it
Cleaned it etc etc but it was still grabby
I changed to Barnet plates and the clutch was transformed !
All other components were unchanged including the stack height
The clutch is superb,it's smooth and light
No drag at all
 

NPeteN

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What's the history of the bike? IE what plates does it have
How long have they been in there?
I had almost the same on my commando when I first built it, the big difference is I have a belt drive running dry
But the clutch was either on or off
And used to grab like hell
This I think from memory was with STD Norton fibre plates
I stripped it
Cleaned it etc etc but it was still grabby
I changed to Barnet plates and the clutch was transformed !
All other components were unchanged including the stack height
The clutch is superb,it's smooth and light
No drag at all
Sound like I should change my plates, my clutch is a monster
 
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the question is what plates are in it now. if someone in the past has installed the old black barnetts they was very aggressive. your bike from stock should have the solid fiber plates. if you take the clutch apart please post pictures as to what plates are in it now.
 

DogT

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My Apr 69 production date bike has always been critical to adjust. I even got the clutch seal, and a few other things that was supposed to make it work better. Nothing worked. It's just critical. I can only back off the clutch adjuster (the large center screw) a tiny amount after setting it up or it either slips or grabs. But when it's set up right, and I get used to it, it works fine. I even tried getting the different thickness backing plates from OB to try to adjust the stack height, but it didn't do anything except mess it up. I've been through it back and forth. dynodave has all the measurements for stack height which mine is right on, but still, it's a very critical setup. Still the original plates and parts, except for the bearings. It's been like this from the day I got it.

That said, when you pull the clutch lever, once you break over the spring, the lever should be easy to hold, kinda like pulling a compound bow. If it's not like that, it's not right. But mine is certainly not a 2 finger pull, until it breaks over, then I can hold it with 1 finger. But I need most of them to let it loose or pull it through. I'm sure a new teflon cable would help. Cable routing can be an issue also.
 

texasSlick

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Would notching of the clutch center contribute to this "On/Off" situation?

In any event, you should look for notching when you get into the primary and inspect the clutch.

Slick
 
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You and I have damn near the same exact bike. Right down to the red oil rag.
Your clutch shouldn't be blasting you into outer space, no doubt after some proper maintenance and setup you will be on your way. How's the pull, keeping your forearm in shape?
sorry i've been gone messing with triumphs



pull is fine, nothing like the over-tightened newby i have in a triumph that makes me look like popeye.
 
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What's the history of the bike? IE what plates does it have
How long have they been in there?
I had almost the same on my commando when I first built it, the big difference is I have a belt drive running dry
But the clutch was either on or off
And used to grab like hell
This I think from memory was with STD Norton fibre plates
I stripped it
Cleaned it etc etc but it was still grabby
I changed to Barnet plates and the clutch was transformed !
All other components were unchanged including the stack height
The clutch is superb,it's smooth and light
No drag at all
damn

somehow i ended up with two accounts here. i'll keep this one.

the machine i have has an older history here:


it was a chopper reclamation that was done very well. i don't recall whether the PO did the clutch plates. he did just about everything else.
 

NPeteN

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damn

somehow i ended up with two accounts here. i'll keep this one.

the machine i have has an older history here:


it was a chopper reclamation that was done very well. i don't recall whether the PO did the clutch plates. he did just about everything else.
I remember that thread and that bike, pretty neat.
 
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the question is what plates are in it now. if someone in the past has installed the old black barnetts they was very aggressive. your bike from stock should have the solid fiber plates. if you take the clutch apart please post pictures as to what plates are in it now.
i will do that. ive got something else on the lift at the moment, but it's in line.
 
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Would notching of the clutch center contribute to this "On/Off" situation?

In any event, you should look for notching when you get into the primary and inspect the clutch.

Slick
its not acting like the basket is notched up. no problem engaging or disengaging the clutch, and it frees up right away. but i'll have to look
 
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My Apr 69 production date bike has always been critical to adjust. I even got the clutch seal, and a few other things that was supposed to make it work better. Nothing worked. It's just critical. I can only back off the clutch adjuster (the large center screw) a tiny amount after setting it up or it either slips or grabs. But when it's set up right, and I get used to it, it works fine. I even tried getting the different thickness backing plates from OB to try to adjust the stack height, but it didn't do anything except mess it up. I've been through it back and forth. dynodave has all the measurements for stack height which mine is right on, but still, it's a very critical setup. Still the original plates and parts, except for the bearings. It's been like this from the day I got it.

That said, when you pull the clutch lever, once you break over the spring, the lever should be easy to hold, kinda like pulling a compound bow. If it's not like that, it's not right. But mine is certainly not a 2 finger pull, until it breaks over, then I can hold it with 1 finger. But I need most of them to let it loose or pull it through. I'm sure a new teflon cable would help. Cable routing can be an issue also.
wel, i have generally just set the clutch adjustment using casual clearance. on th estuff i'm more familiar with, pressure plate free play is generally, enough, okay, not enough . . . with no more sophistication than that. if i can solve th eproblem with fussiness, that will save me time and trouble.

but inspection is still a better idea
 
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dynodave has all the measurements for stack height which mine is right on, but still, it's a very critical setup.
Complete misunderstanding of the information. My article tells you how to measure the EXISTING stack height built by the factory NOT what it should be built or set to for a change of performance....

Quick engagement is for the most part unavoidable except by practice and good cable condition.
Suggest you review this: http://atlanticgreen.com/clutchpak.htm
Thru 70- bonded segment 06-0749 is possible, probably not solid fiber
This is not "surflex" (which is a company name: http://www.surflexclutches.com ) used by under educated folks.... not a particular product? like 122M1, 122M8, 122M12 (get your italian dictionary)
 
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DogT

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I often times wonder if there aren't variations in the 'pressure' of the diaphram springs that makes for such variances in setups. Years ago when I was working on it, miniscule changes in the stack height one way or the other would make it either grab or slip. There is a bit of tolerance with the adjusment screw, but on my bike very little. Stock original plates. At this point the next guy is going to worry about it if he/she wants.
 
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