I need a new clutch...

[TOOLS1]

Here is a couple links to clutches, for, you.
http://www.rekluse.com/index.shtml
http://www.efmautoclutch.com/index.shtml
TOOLS

[shinyribs]

Thats cheating HAHA!  

Has anyone ever shimmed their clutch springs? I figure at this age they have bound to have lost some of their original tension. My clutch only slips when cold,same as I hear the aftermarket clutches are prone to do. Maybe all i need is increased spring tension?  Any thoughts?

[shinyribs]

RE: a clutch on a '76F   others models may apply.I'm not sure which.

These are not my words,but info kindly given to me by someone else:

That clutch consists of 6 "square-cut" fiber plates, one "slant-cut" slip plate, 5 steel plates and a double-stacked spring steel plate to allow the whole pack to slip, using the "slipper plate", if you launch too hard. The reason: the first gear is quite tall, and the dogs on gears 1 and 2 (gear # C5 in particular) tend to chip off under heavy clutch action, causing loss of the L shift fork and the C5-C2 gears. This is long history of rhte post-1975 engines.

The fixes:
1. Get the gearset back-cut by APE. This resolves the tendency of the gears to push each other apart and damage things when under heavy throttle.
2. Lose the double-spring plate in the clutch, and the slanted-cork plate. Add one more steel plate in its place, and install all square-cut cork plates. Although Honda's are pricey, they are also the longest-lasting under all conditions, including racing, in my experience - with one caveat: use Barnett springs on those plates. And be sure to EVENLY tighten the retainer plate (each bolt 1 turn at a time - seriously) when installing/loosening, or you'll be buying another one...
3. DON'T use 10w[something] oils, and DON'T use high-detergent oils. Both will make the plates slip and burn the cork. Use at least 15w40 diesel oils (dragracing) or 20w50 motorcycle or Racing oils (longer races) for good results, as these all have lower detergent. Consider using a zinc additive, too, as this raises oil pressure, increases cam lobe lubrication, and makes the clutch plates break friction quickly and grab evenly when engaged. Most oils after 2002 have almost no zinc in them (thanks to the EPA and a crooked politician, but I digress...).



That "slipper plate" is the one where the cork looks like a pinwheel. The longer groove between the corks causes the oil to take a longer time to exit the plate surface after you "drop the hammer" all the way, so it gives a fraction of a second of slip before final engagement. This was thought to be a 'shock absorber' of sorts (and it really is such) that would help with the fast wear of the 1 & 2 gears on the post-1975 bikes (F0 and later) with the close-ratio gearboxes. It only helped a little, though: today we see many, many more of these later bikes with the C2-C5 (2nd gear) dogs and slots badly worn, as compared to the earlier bikes. It was probably just a little bit too tall...

In the later years, Honda added sometimes whole clutches made of these plates (and some modern sportbikes are like this), for more cushion. It makes a noticeable lack of snap when dropping the clutch quickly. Some magazines of the 1970s era complained about how sudden the Honda 750 clutch engaged: this also played a part in the change. The hub could not fit more than 7 plates without changing the engine cases, which then would protrude into the rider's foot, so adding the squishy dual-spring steel plate(s) and the slip plate became their solution.

On the CB500, almost all the bikes came with ALL slanted "slipper" plates. These bikes frustrated their owners (I was one of those, as was my brother) when racing on production tracks, because you could never get a good, hard shift. We swapped to the square-cut plates, while some folks tried the Barnetts: this was where we discovered the Honda square-cut plates with Barnett springs were king.

If you get plates from your local Honda shop (pricey, but good quality), be sure to pay for them AFTER they show up, if they have to order them. Their parts system got mixed up in California for a while, and Honda was shipping slant-cut slipper plates as stock plates. I got 2 expensive sets of these, and it took me 5 years to use them up, one at a time...  :-\

BTW: I just discovered today that the so-called "Barnett springs" from APE are much too long to fit the CB750 clutch. Looks like a misapplication: don't get them there...


Yes, I think the slipper ones are slightly bigger OD. They came from the CX500 design (NR500, really). But, you can just drop a standard plate in its place. I would suggest inspecting the dual-steel spring plate closely to make sure none of the little rivets have worked loose. Sometimes they do, and this can make a noisy clutch rattle sound, especially in neutral. If loose, try tapping them tighter on their crimped side with a small hammer and rounded-end punch, or ground off large nail (round off the point) to set the rivet(s) a little tighter. Or, if you can locate one of the GL1000 (1978-79) replacement clutch plate for this one, which was an unsprung, thicker steel plate (one piece), it will also stop the noise and will also add a solid lockup to the clutch. The tiny springs in that dual plate are part of the delayed-grab design.

You might also find an old trick will work to add an extra friction plate overall: reverse the order of the first plate into the stack, making it steel instead of cork. Then, install the cork/steel/cork...stack, using only single-steel plates, losing the squishy one altogether. This can allow room for one extra cork plate overall. Not all of the hubs will fit this: the late K3 thru K5 hubs did, and the F2/3 hubs did, IIRC. I haven't done this in a long time..

[shinyribs]

It's official,my clutch is toast. But as usual,I have questions.

Are the friction surfaces supposed to ride on the aluminum surfaces? Seems like there should be a steel there to me. Is it possible my plates are stacked wrong?

My outer 'slipper' plate has a few teeth missing in the friction area on the steel side,and ALL of the friction material is gone on the pressure plate side. I could be calling the pressure plate the wrong name. This is my first time in a clutch.

Also,the clutch spring free length of the springs I pulled out is 1.271"
FSM calls for 1.2575 free length with a serviceable limit of 1.201"
The new springs I have measure from 1.382"-1.386"
All of my springs measure too long which I understand is a good way to destroy a lifter plate.What should I do here?

My friction plates measure 0.138"
FSM calls for 0.1347"-0.1409" with a serviceable limit of 0.122"
My plates are nearly as thick as new?! Are they swollen? They are also very dark. Should they be?Again,what should I do here?

Also,where the outer/slipper plate lost all of its friction material it put some score marks on the pressure plate( NAME?). Can I just dress these marks out,or does it need to be replaced?


Confession time: This clutch was working perfectly fine until I started dumping to ride wheelies. So should I just consider the stripped outer/slipper plate a result of my actions, replace that one part,put it all back in and keep rockin'? Or should I address things while I have it apart?

My outer/slipper plate

Steel side


Pressure plate side


What I am calling the pressure plate. Hard to make out the scoring.It's very minimal,but it is there.


No scoring on this inner piece.You can see very little wear form the friction plate,but you can mostly still see the machining marks from where it was made,so I think this piece is plenty healthy

[pat english]

sorry,i didnt read the full thread..you need some clutch plates?i can send you the ones in my other engine(the one that im stripping) if you want..maybe theyll work..let me know.i can put them in the huge box comin youre way..

[shinyribs]

My 6 inner plates are almost full thickness,I just dont know if they are scorched or not. My 7th outer plate is a goner,but I think only some of the later bikes had that plate. Not sure of the year cutoffs on that.

I really appreciate the offer,but I'm not sure what I need to do at this point. For one,I guess I need to drop the pan and look for my missing clutch particles

[pat english]

right on..i really have no idea..what are inner plates?friction plates?

[shinyribs]

Pat,dont use the same names for parts that I do.More than likely my names are all wrong. The plates in the clutch pack that have the actual clutch material on them are what I was calling the friction plates. I have six friction plates that are all one size. The innermost plates. Then I have one outer friction plate that is a little larger in diameter. It goes on the very outside of the pack. I was saying inner and outer hoping to just be able to get my point across. Hope I didnt confuse you like I did myself.

Pulled the pan tonight and found some of the remnants of my clutch. Not enough to be all of it,of course. I suppose it's had been chewed up and pumped through all sorts of sensitive areas. yay. Is there any other areas known for collecting debris I should try to get to? Or am I just stuck with a standard oil change and hope it flushes out?

These pieces feel more like hardened plastic than they do cork. You know how brittle and crunbly an old plastic oil line on a car oil pressure gauge gets? That is what these pieces feel like? Is this normal,or a sign of burnt friction material? When they call these plates cork,does that mean cork like a cork in a bottle,or what?

Lots of little chunks,too. And a few little slivers of aluminum. I'm pretty sure the aluminum came off the pressure plate. But the screen on the oil pump was spotless. Should I disassemble the oil pump and clean it out anyway? Any secrets/tips to doing this? Or should I just tear the pump down for good measure while I'm already in there?



Any ideas gang?

[TOOLS1]

It's very common to find little aluminum shavings in these engines, so don't worry about it. Just flush out the bottom with a spray can of carb/break cleaner, and install a new clutch. Get one of those I recommended earlier. They are bullet proof. I know some guys that run the Dakar, and swear by them.
TOOLS

[shinyribs]

Tools,the Barnett you put in Geralds bike.Does it chatter? The only reason I didnt go ahead and get a Barnett (other than trying to save money)  is I have heard people complain about chatter and slipping when cold. Could be installer error,too. How is the pull with the barnetts? Or  can you specify stock or heavy springs?

Thanks for the advice.I'm just trying to learn these things rather than just swap old parts for new parts. You know what I mean?

[shinyribs]

Tools,what do you think about the pump? Open it up or leave it be?

[TOOLS1]

If it went through the screen it probable is not big enough to hurt anything. Just flush it out with mineral spirits.
TOOLS

[shinyribs]

Thank you sir