Clutch pads, stock or ?

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Bob K

New Member
Mar 5, 2009
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Insanediego
My clutch slips/skips just a bit under maximum hill climbing.
It works well in all other conditions.
I will have to check the adjustment. My question is:
Are clean, adjusted, stock clutch pads good enough?
If I'm in there any ways, I don't mind dropping a few bucks on the red
(better?) pads.
Any first hand experience would be greatly appreciated.
Thanks.
Bob K
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
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San Diego, Kaliforgnia
Check for the usual things.
Clutch cable has a small amount of slack in it when the hand lever is released.
No grease or oil anywhere on the clutch's friction surfaces or the friction pads.

If you have alot of miles on the clutch you may need to turn the flower nut in 1/2 turn or thereabouts to compensate for the friction pad wear.
If you are not familiar with this, let us know. There is a wrong way and a right way to do it. Both will work, one could do damage though.

Swapping the pads out for the more aggressive red ones can't hurt either.
I have no first hand experience with them though, I have never needed them...yet.
 
crassius

crassius

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Sep 30, 2012
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can't hurt to go to red pads, but if your problem is elsewhere, it won't help

was the clutch working and then failed, or is this a new build?

if new, it prob just needs a good adjust
 
crassius

crassius

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Sep 30, 2012
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sounds like an adjustment should fix it - first 100miles, the cable will stretch a bit and all pads that were a bit higher than the rest, will wear down a bit
 
B

Bob K

New Member
Mar 5, 2009
16
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Insanediego
Thank you all for your replies. The clutch cable is adjusted properly.
From your replies, the stock clutch pads seem to be good enough for a
mildly modified motor.
So, I'll just open up the clutch cover and do an adjustment.
I'll check for grease contamination as well.

Gratefully,

Bob K
 

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locutus_1

New Member
Oct 31, 2010
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california
Bob K said:
My clutch slips/skips just a bit under maximum hill climbing.
It works well in all other conditions.
I will have to check the adjustment. My question is:
Are clean, adjusted, stock clutch pads good enough?
If I'm in there any ways, I don't mind dropping a few bucks on the red
(better?) pads.
Any first hand experience would be greatly appreciated.
Thanks.
Bob K
Click to expand...

change out the spring and the ball bearing it uses to engage the clutch.. make sure its adjusted so there is no slack.. in the cable..

pull it apart and use brake cleaner or iso 90% alcohol to clean off the pads and where it rubs..

and dont take off from a dead stop with the motor they wear out the pads faster.. oh and the pads well they are freaking tires lol not true clutches..

other than that you can get a auto clutch there around 50 bucks and 25 for the pull start... worth it better than the felt clutches
 
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Bob K

New Member
Mar 5, 2009
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Insanediego
I pulled the clutch cover off and I have the pink pads. I cleaned them and
lapped the clutch cover. I re-adjusted the clutch flower nut, and it operates the same.
Slips a little on start up. Slips a little under maximum load up hill. I can live with this as long as I am not damageing anything..

As a side note to anyone who has tried the McMaster Carr clutch material.

Is it worth the effort? I know these clutches are just barely good enough.

But, is the MMCarr material better than available pucks? I mean, I checked the co-effecient of friction of a lot of clutch compounds out there , and the
MMCarr is as good as anything available. Or should I just spend the money
on a centrifugal clutch and be done with it?

THAT is the question !

Bob K
 
maurtis

maurtis

New Member
Dec 14, 2011
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Kyle, TX
It is odd that no one mentioned adjusting the internal clutch spring yet, the main source of your clutch tension...

I heard people talking about how hard their clutch lever was to pull, people breaking clutch levers, needing clutch rollers, etc. Mine was always pretty easy to pull, but I also had an issue with the clutch slipping on startup after the engine was run hard then put away for a few minutes (like going to the store).

I adjusted the heck out of the flower nut to no avail, turns out the flower nut is NOT the main source of clutch pressure. You can search for threads on adjusting the internal clutch spring, it is fairly easy.

Once I tightened my internal clutch spring, my clutch lever was harder to pull in but I had no more issues with slippage when starting. Until I went to a high compression head, then I had to tighten it so much that I needed a clutch roller, one of Al.Fisherman's and it worked great.

So I would check on that as well. I did eventually get a centrifugal clutch (but without a pull start), and it was a very nice addition, but not necessary.
 
crassius

crassius

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Sep 30, 2012
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Yes, there is a lot going on in the clutch mechanism. Adjusting the inner spring is the last resort to getting the slippage to stop, and usually works, but often leaves the clutch harder to pull. Just waiting for all the pads to wear down to the same height (takes maybe a couple hundred miles) will sometimes stop the slippage.

Often, the cause is not in the clutch itself, but in the locking point of the hand lever which causes the adjustment of the flower nut to be bit off. Options are to try a different lever or to rotate the clutch arm a bit on it's splines to change the distance of throw in the arm. There are also levers out there that have three different points for the lock, so that one can be selected that pulls further before adjusting the flower nut.

A lot of time can be spent getting this just right.
 
maurtis

maurtis

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Dec 14, 2011
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Kyle, TX
crassius said:
Yes, there is a lot going on in the clutch mechanism. Adjusting the inner spring is the last resort to getting the slippage to stop, and usually works, but often leaves the clutch harder to pull. Just waiting for all the pads to wear down to the same height (takes maybe a couple hundred miles) will sometimes stop the slippage.

Often, the cause is not in the clutch itself, but in the locking point of the hand lever which causes the adjustment of the flower nut to be bit off. Options are to try a different lever or to rotate the clutch arm a bit on it's splines to change the distance of throw in the arm. There are also levers out there that have three different points for the lock, so that one can be selected that pulls further before adjusting the flower nut.

A lot of time can be spent getting this just right.
Click to expand...
True, but depending on how firm his clutch lever is changing the tension on the clutch spring may not be a last resort at all. If there is too little tension, spending countless hours dancing with sanding clutch pads, adjusting flower nuts, etc, will be wasted effort. That is exactly what I did and wish I had started with my clutch spring since there was nothing wrong with any of the other components.

It is a dance, but if the band is not playing loud enough to hear the music it makes it hard to keep the rhythm.
 
biknut

biknut

Well-Known Member
Sep 28, 2010
6,632
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Dallas
All the problems with clutch slipping in my motors were always traced back to the same problem. The pads are too tight a fit in the clutch gear. The fix is to file the edges of the pads so they fit loosely in the clutch gear.

When they're too tight, they tend to only contact one friction plate properly, and the other plate only gets light contact.

A properly set up china girl clutch is the best clutch in motor bicycling
 
crassius

crassius

Well-Known Member
Sep 30, 2012
4,032
158
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USA
biknut said:
All the problems with clutch slipping in my motors were always traced back to the same problem. The pads are too tight a fit in the clutch gear. The fix is to file the edges of the pads so they fit loosely in the clutch gear.

When they're too tight, they tend to only contact one friction plate properly, and the other plate only gets light contact.

A properly set up china girl clutch is the best clutch in motor bicycling
Click to expand...
yes, seen that with the red pads - got to trim them with an exacto knife till they fit through the hole - new, they look like they were poured in wet and hardened in place
 
maurtis

maurtis

New Member
Dec 14, 2011
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Kyle, TX
Bob K said:
OK. so I have some things to try out. Tell me, which centrifugal
clutch did you get?. Does it make the bike smoother?
Click to expand...
I picked one up off of eBay, probably from BGF. People have said they thought it smoothed out their idle with a flywheel effect. Mine did not seem have a major effect on smoothness of the motor, it was just nice to be able to stop at stopsigns and such and not have to pull the clutch (a ton of stopsigns in my neighborhood) and nice to have the ability to take off without pedaling when I was feeling lazy. Having a high compression head helped with the low end torque too...
 
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Bob K

New Member
Mar 5, 2009
16
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Insanediego
Thank you gentlemen! The pads WERE just crammed in and only contacting the outer clutch plate. I resized them to fit AND I sanded them down to the same thickness + or - .005" as they were worn unevenly. I would like to add some pictures that show what you gentlemen were talking about.
One picture shows that NO contact was being made with the back plate. I alternated these pads to show this. The other picture shows the ridge that
was formed by a "disaffected chinese laborer". The clutch now works perfectly!

Bob K
 

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maurtis

maurtis

New Member
Dec 14, 2011
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Kyle, TX
Fantastic! Glad it was an easy fix. The new red pads look a lot better than the cloth/rubber/wire old pads (of which, mine needed sanding too).

Grats on the fix, ride on!
 
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