Topic: Clutch Advice Needed ** RESOLVED! **

[BrockSamson]

Honda 1977 CB750K
~22k Miles

Problem:
My clutch was slipping like crazy no matter the clutch adjustment.  I decided to overhaul the entire clutch.  I purchased the following new parts:

1) APE Extra Plate Clutch Kit.
2) Clutch Cable 
3) Clutch Nut Tool from CycleX
4) Impact Screw Driver
5) Clutch Case Gasket

I follow the instructions provided here:
http://www.salocal.com/sohc/tech/clutch/cth1.htm

I also referenced Hondaman's book for better pictures as I was going.

I follow all of the instructions as provided at the link.  The one thing I did do different was remove the clutch cable holder that is attached the clutch case.  I also might have not tightened down the clutch lifter plate enough.  "Snug" is a term that is not very precise so I went with caution to avoid cracking the lifter plate. 

My problem:
I got everything back together and go reattach the clutch cable holder (the thing that holds the cable on one side of the clutch case and on the other side is the ball bearing thing).  I have to adjust the screw so far in that I can't keep the clutch adjustment lock not on.  It is really weird... I only feel resistance against the lifter after its screwed in nearly all the way in and the lock nut just can't stay on.

I have not been able to get the bike to go into gear.  I can only get resistance in the clutch lever down to the adjustment nut barely holding onto a couple threads.  It is like I need to add a spacer to the end of it or get a longer one (I know this can't possibly be the case but just trying to describe the problem appropriately).  I even tried loosing the lifter plate hoping it would get closer to where the adjustment screw would press it... but it was so loose that I am not comfortable with it.

If anyone knows what the hell I am talking about or if they might know what I am doing wrong I would appreciate any advice.

Note:
The 76-78 clutch baskets had a double thick plate.   I believe I read it was to help reduce clutch chatter.  I brought this up to Jay at Ape in an email and he assured me it would not be a problem.  I did go ahead and purchase an extra regular single width plate in case there were problems. 

[HondaMan]

There's a couple of things you can do:

1. When I 'convert' the later clutches like that one from the extra-thick spring plate and slipper top plate (that's the one with the slanted corks, and it caused your original problem, BTW - always does) to be an "extra plate" clutch, I often use the double-spring plate again because many modern clutch plates are a little thinner than the OEM plates were. On the post-1976 bikes, the stock plate thickness for the square-cut plates was about 0.143" new, and the slant-cut plate about .150" to .155" thick. Modern replacement plates are coming in about 0.140" to 0.138" new, so the overall stack comes up a little short (and you run out of adjustment length). Using that dual-steel plate in the stack will help: use it near the end of the stack, either bottom or top. Don't put it in the middle, or it can cause rattle again.

2. Sometimes you can add an extra plate, either a steel one or a cork one. In the earliest 750K0 bikes, there was a similar issue where they used 6 steel and 6 cork plates, because it was thought that the aluminum first plate was not strong enough for the new, powerful engine. So, the first plate into the clutch was steel and the last one was the pressure plate: these clutches had a little spring wire that held the first steel plate still in the hub to also reduce rattle (there were extra tiny holes in the hub to hold this wire). This design quickly gave way to the 6 steel, 7-cork plate arrangement that remained until the end of the 750. In this change, the very early clutch lifter "peg" that pushes on the hub (for disengagement) became shorter for the 7-plate clutches. In the in-between times, there are 3 different (after the sandcast) clutch covers, with 3 different lengths of this "peg": the K1-K2 length with the stronger cover ribs, the K3-K6 version with thinner ribs, and the post-1975 version for the "F" and later bikes. The longest "peg" is on the K1 cover, and that lifter can be pulled out and installed on your post-1976 cover if you need to in the end. It will give you about 3 extra threads to hold the nut onto the arm again. Don't try to just swap the whole cover, or you can end up with the ribs on the cover scraping against the pressure plate, making a lot of aluminum shreds in the crankcase (and lots of noise!).

These sort of things crop up when you start using aftermarket clutch parts: just hang in there and you'll be smarter at the end! 

[BrockSamson]

Hondaman, first let me thank you for the reply and your book.  Invaluable.  I was very intimidated about doing my own clutch and the slip was getting to the point where I couldn't safely ride the bike anymore.  Your book and posts on this website definitely made me feel like it was something I could accomplish.

1)  I noticed the slanted corks on the old friction plats.  All of the friction plates I received are the square-cut.  I believe from what you have said here and from your book or another post you replied to that is a good thing.

2)  I reused the double-spring plate because my logic was that if APE designed the friction plates to match the width of stock plates it has to be fine.  That double thick plate was put in the 76-78 models as a resolution to a problem and I would want to keep it.  I did place the dual-steel plate in the middle and will move it to either the bottom or top as you suggested. 

3)  Below (If I remember correctly) I am going to list my current configuration with the new extra plate.  Then I am going to list how I should change my configuration adding an extra metal plate to help get more length into the stack.  It also shows the movement of the double plate to the front end.

M == Metal Plate / F == Friction / D == Double Plate.

Current configuration:
F-M-F-M-F-M-F-D-F-M-F-M-F-M-F

New configuration:
F-D-F-M-F-M-F-M-F-M-F-M-F-M-F-M

4)  Does the lifter plate have much to do with this?  If I tighten it more/less will I get less/more play with the peg?

Thanks!

[BrockSamson]

I also wanted to make sure I am on the same page as you:

Despite getting a lot of resistance at the clutch lever I am still unable to shift gears.  If I add the extra bit to the clutch basket stack with that additional plate I will get more play with the peg and I get more play because this pushes everything closer to the peg.  This will in turn allow me to screw it in more and that should give me proper engagement/disengagement of the clutch.  I am assuming that since the stack is short the peg has to go in deeper to press the lifter plate enough to get the clutch to disengage to allow me to change gear into first.  Correct?

[HondaMan]

Hondaman, first let me thank you for the reply and your book.  Invaluable.  I was very intimidated about doing my own clutch and the slip was getting to the point where I couldn't safely ride the bike anymore.  Your book and posts on this website definitely made me feel like it was something I could accomplish.

1)  I noticed the slanted corks on the old friction plats.  All of the friction plates I received are the square-cut.  I believe from what you have said here and from your book or another post you replied to that is a good thing.

2)  I reused the double-spring plate because my logic was that if APE designed the friction plates to match the width of stock plates it has to be fine.  That double thick plate was put in the 76-78 models as a resolution to a problem and I would want to keep it.  I did place the dual-steel plate in the middle and will move it to either the bottom or top as you suggested. 

3)  Below (If I remember correctly) I am going to list my current configuration with the new extra plate.  Then I am going to list how I should change my configuration adding an extra metal plate to help get more length into the stack.  It also shows the movement of the double plate to the front end.

M == Metal Plate / F == Friction / D == Double Plate.

Current configuration:
F-M-F-M-F-M-F-D-F-M-F-M-F-M-F

New configuration:
F-D-F-M-F-M-F-M-F-M-F-M-F-M-F-M

4)  Does the lifter plate have much to do with this?  If I tighten it more/less will I get less/more play with the peg?

Thanks!

The lifter plate: just make sure the splines on the pressure plate match up (i.e., mesh into) to the ones on the hub, then tighten the 4 little bolts about 1 turn at a time until the bolts seat. The final torque is 80-90 inch-lbs.

The dual-steel plate gizmo was added in the post-1976 bikes because of that slipper plate business. When this late starts to slip as you release the clutch lever, the whole stack tends to shudder a little bit as the oil trys to receed from the cork surface on this plate. As it starts to grip, the rest of the plates, which all have squished away their oil already, have a light grip on their steel neighbors. At this point, they all start at once to squish out the last bits of oil, and the clutch makes a "sqwak" sound when cold (or if the oil is old). Having the tiny bit of springiness in the special plate gently increases the pressure after you're done letting the lever go, so the noise doesn't appear.

When the plates are all square-cut, they release their oil all together, already. This was never a problem in the K0-K6 bikes.

What Honda was attempting to solve with this: the F0 and later engines have a real tall 1st gear. This tends to make the bike a little surly in slow traffic as the clutch is pretty sudden, especially with light oils or when hot enough to thin out the 20w[something] oils. This dual-spring plate had debuted on the GL1000 and solved this situation there, where the bike's mass tended to make it lurch, then recoil, then lurch again during a hot pull-away from a stop. It has even more plates than the 750, too, which makes this situation more pronounced.

On the 750, this plate (I called it the "Gold Wing Plate") first appeared in the late K6 bikes (not all of them), then appeared in the center of the stack in the F0/F1, and then came with the 'slipper' plate on top and this dual-plate right behind it after that on the F2/3 and K7/8.

[BrockSamson]

Hondaman, first I want to thank you for the advice and helping me understand how the clutch operates.

I wanted to give you and whoever else is following this an update.  I would like to preface this with that I was close to grown man weeping after what occurred and for those faint of heart I would suggest looking away.

So I take apart the clutch (for what feels like the 10th time) and I rearrange the clutch friction plates, double plate and metal plates as described above.  everything is packed in tight.  I ratchet down the lifter plate until it is nice and snug.  Then bolt together the clutch housing. 

I attach the clutch cable and start the adjustments.  I have to take it to its limits again but I am FINALLY able to get the bike to go into 1st.  Which is a huge improvement to not being able to get it to do anything.  The problem now is that once in first it lurches forward instantly.  No good.

So I think to myself that I am moving into the right direction and with a little more adjustment room I can get this thing where it needs to be.  So I pull everything apart yet again.  I sit back and look at everything and notice that the hole that the adjustment peg pushes into is pretty deep... deep enough to fit a very small nut that would allow the peg to start applying pressure earlier.  So I put the nut in and try to screw the clutch case back on.  It wont go on... the nut is TOO much and I can't even get the housing back on.  So I pry the nut out and start thinking of something smaller.  Well I had some stainless steel ties from the exhaust wrap.  So I bend those over and over to form a piece that is basically 50% of the size of the nut I put in.  So I place that in the hole and bolt everything back up again.

I start to do my adjustments.  I can feel it getting pressure earlier!  Excitement is starting to build.  I pull in the clutch lever and the bike goes into 1st and back to neutral with ease!  I run and grab my helmet and hop on the bike.  I start it up and let the bike idle for awhile so it was warm and ready to go.  So I go to pull in the clutch and drop into first and as I pull I hear "CRACK CRACK CRACK CRACK" and all the pressure in the clutch lever goes away and I am left with a limp lever.  I also feel something hit me in the side of the leg really hard.

I get off my bike and this is what I see:









If you look at the last picture in the tunnel where you feed the clutch cable a bit of metal is missing.  I did that on accident and it took a chip out a few weeks back.  It seems that was the point of failure for the entire clutch housing.  This then continued up to the top left of the clutch housing.

I am so defeated.  Oh the thing that hit me in the leg was the lock bolt that was holding onto the adjuster.  I guess as the metal crumpled outwards it forced the lock nut off the adjuster. 

Is this something that has ever happened to anyone?  Did I do something obviously wrong?  Is it believable that such a small chip in the clutch case housing could cause this kind of failure?

My plan is to take a week off from the bike and step back from it.  Spend that time to source another clutch case housing and probably the rest of the clutch parts just in case I have another failure of some sort (lifter plate crack).

Thanks for the help... its time for a few beers.

[madmtnmotors]

2. Sometimes you can add an extra plate, EITHER a steel one OR a cork one.

I am going to list my current configuration with the new extra plate.  Then I am going to list how I should change my configuration adding an extra metal plate to help get more length into the stack.  It also shows the movement of the double plate to the front end.

M == Metal Plate / F == Friction / D == Double Plate.

Current configuration:
F-M-F-M-F-M-F-D-F-M-F-M-F-M-F

New configuration:
F-D-F-M-F-M-F-M-F-M-F-M-F-M-F-M

Hondaman says "either a steel one or a cork one".

Stock setup is: F-M-F-M-F-M-F-D-F-M-F-M-F which is seven friction and six metal yet you list:

"Current configuration: F-M-F-M-F-M-F-D-F-M-F-M-F-M-F" which is EIGHT friction and SEVEN metal. This setup reflects the addition of TWO plates, one friction and one metal.

Then you list:

"New configuration: F-D-F-M-F-M-F-M-F-M-F-M-F-M-F-M" which is EIGHT friction and EIGHT metal. This setup reflects the addition of THREE plates, one friction and TWO metal!

Unless I'm missing something, you're clutch stack is too tall...

[BrockSamson]

When did things become too tall?  If I remember correctly my kit came with two metal plates and the extra friction ones.

When I pack the basket it was literally filled to the brim but didn't overflow the basket and this was with my first configuration of 8 friction / 7 Metal.  It looked like it was exactly how you would expect it to be (but what do I know, haha).

I packed in the 8th metal today and I was able to get everything together but I questioned whether it was going to be ok.  I can tell you that I don't think this was what caused the catastrophic failure.  I was more worried about chatter or something. 

[BrockSamson]

You know what, I probably miscounted.  For some reason I could have sworn I had 3 extra metal plates.  2 from the kit and 1 that I bought extra in case I needed to replace the metal plate.  You know... when I was looking at it today I think I did count 7 friction.  I also looked up the APE description and it says one friction one metal extra.  So my stack probably is:

F-D-F-M-F-M-F-M-F-M-F-M-F-M

That would include the extra metal plate that probably shouldn't be there.

"APE "Extra plate" clutch kits are the strongest clutches avaialble for your motorcycle. They have become the industry standard...the best. Although designed for racing applications, they are perfect for performance street bikes. They do not grab and chatter . APE clutch kits feature an extra friction plate for 14% more clutch surface. From your all out nitrous drag racer, to "killer" horsepower street bike, or just your well tuned stocker. The APE "Extra Disc' clutch is a must. Kits include friction plates, extra steel plate, and heavy duty spring kit. Installs just like a stock clutch."

Yeah I probably had a brain fart when figuring that out.  I hadn't looked at the clutch basket for awhile when I wrote that post.

When I take the thing apart again I will be CERTAIN to count and write it down.

[madmtnmotors]

So my stack probably is: F-D-F-M-F-M-F-M-F-M-F-M-F-M

Yeah I probably had a brain fart when figuring that out.  I hadn't looked at the clutch basket for awhile when I wrote that post.

When I take the thing apart again I will be CERTAIN to count and write it down.

Ahhh... now that configuration would fall more in line with Hondaman's recommendation.    But now we're back to scratching our heads!   

[BrockSamson]

Yeah whenever I get all the parts replaced I am going to remove that plate I added and just add the little nut into where the peg presses the lifter plate again.  I really do not want chatter or any additional noise.  The bike makes enough noise as it is.

[MCRider]

I've lost track of the plate issue, assuming you've got that figured.

My observation in your photo: the adjuster screw, from which you said the locknut departed and hit your leg, is buried in the cam. It should have enough threads exposed to the away side of the bike to easily thread the locknut on fully.

Have you turned the adjuster screw in before the picture was taken.  If not this should be addressed with everything else.

I'm reading about the nut you're putting in the lifter. Sounds like a bad idea. IT should work fine with the original design. Take a look at a fish and be sure you've got all the lifter parts accounted for, and the bearing.

[BrockSamson]

I took the picture immediately after getting off the bike.  I didn't bother touching anything because I knew there was not a damn thing I could do.  I then laid on the pavement for a couple minutes letting my frustration simmer down, got up cleaned up the tools and rolled the bike into the garage. 

I had the lock nut about 3/4 of the way on.  From the pictures I have seen that is about right.  It looks like that because the clutch case cover has bent outwards.  Where things are now it would have been impossible to get the lock nut on. 

When I pull everything apart I will have the fish next to me and I will account for all the parts.  For what its worth I double checked the directions I was using and each part was placed back together as I did it.  I did not have any missing parts.

Hondaman was saying in a previous post in this thread that he has seen the friction plates come up short and cause this problem and then he provided a couple solutions.  I have a  digital meter and I can measure everything up this weekend and report that back to you guys.

From what I could tell I just didn't see a problem with adding a spacer in the hole to get me the extra reach and therefore giving me the extra threads to work with.  It seemed like a great solution at the time.  I see what you are saying though MCRider... it could be a sign of some other problem like a missing part.

[BrockSamson]

I am now fearing what that lifter plate could look like... Maybe something failed there and the springs snapped the plate into the clutch case cover and bent everything outwards.  Ugh. 

[BrockSamson]

I found a new clutch case for $30 that looks to have a great condition adjuster... given that my adjuster probably doesn't have threads on the end after the clutch explosion I think I got very lucky finding that on ebay.

[madmtnmotors]

Be sure to check the depth of the three screw pockets on the inside of the clutch cover for the outer tin cover. The earlier clutch covers have one screw boss (the one nearest the kickshaft) that extends about an extra 1/4" into the clutch cavity. This will hit the clutch hub unless this extra material is removed. Check the depth of the stiffening webs on the inside as well. Like I indicated in the earlier post within the sister thread under "parts wanted", the earlier covers can be used on the later models with a little fine tuning. Not that anyone on ebay would intentionally mislead...  but some sellers may not even realize the difference. 

[BrockSamson]

Thanks for looking out.  I will be sure to compare it to what I already have.

The question still stands:

If I find no parts missing does anyone see a problem with adding a small nut into the indention where the pressure plate accepts the pin from the clutch cover?  It worked perfect for those two or three clutch pulls before the case exploded.

[MCRider]

2 things. See the picture of the cover you just bought. That's how the nut should look on the adjuster screw. The screw should be sticking out enough from the thing it threads into (cam) to get a nut AND washer on it and still have a thread to spare.

This is regardless of the condition of the cover.

Second: as to the nut. 10s of thousands of bikes are running around without a crutch nut. IMO it is imperative you get the original design to work properly first. THEN try some modifications once you've proven it to yourself.

Just my opinion but thats how I would approach it.

[madmtnmotors]

2 things. See the picture of the cover you just bought. That's how the nut should look on the adjuster screw. The screw should be sticking out enough from the thing it threads into (cam) to get a nut AND washer on it and still have a thread to spare.

This is regardless of the condition of the cover.

Second: as to the nut. 10s of thousands of bikes are running around without a crutch nut. IMO it is imperative you get the original design to work properly first. THEN try some modifications once you've proven it to yourself.

Just my opinion but thats how I would approach it.

I concur. The adjustment screw should only leave 1/8 to 1/4 turn (out) of the adjustment screw here when adjusted/assembled properly. This adjustment could be taken all the way to nothing... but as your plates wear this gap would then revert to a negative, keeping tension on the hub leading to clutch slippage. The smaller, 1/8 turn out would engage later (near the top of the clutch lever pull) and might require more frequent adjustment. I don't think "zero gap" here is adviseable.

[BrockSamson]

I think the first thing I need to do is measure the new friction plates and the metal plates and see what that comes out to.  Hondaman suspected the stack was coming up short.  I will say that when I packed the basket it filled and was just about perfectly level with the top of the basket BEFORE putting that extra metal plate in. 

The very next thing will be to identify and account for each part in the fish.  I will say that each part was accounted for that was called out during the installation procedures.

[bollingball]

I have a 78 750K and will be looking at my clutch this winter. Might do HondaMan's oil hole improvement. I read your entire post or thread. What I don't understand is why you felt the need to NOT use genuine Honda parts? Is your motor built so strong they are not good enough or do they cost too much? It just seems (and I could be wrong) that most of your issues were caused by non stock parts and the proper way to install them. Am I missing something? I just want to know before I start buying parts for my stock motor. As far as that mod you made with the little nut I can see making up for wear but it seems you put all new parts. I would want to know 100% for sure why that would need to be done and it looks like that is the way you are thinking. Good luck I know you will figure this out. Just hope it does not take to many more parts. I can picture you on the ground looking up and saying my me. I have been down that road.

Ken

[madmtnmotors]

I have a 78 750K and will be looking at my clutch this winter. Might do HondaMan's oil hole improvement. I read your entire post or thread. What I don't understand is why you felt the need to NOT use genuine Honda parts? Is your motor built so strong they are not good enough or do they cost too much? It just seems (and I could be wrong) that most of your issues were caused by non stock parts and the proper way to install them. Am I missing something? I just want to know before I start buying parts for my stock motor. As far as that mod you made with the little nut I can see making up for wear but it seems you put all new parts. I would want to know 100% for sure why that would need to be done and it looks like that is the way you are thinking. Good luck I know you will figure this out. Just hope it does not take to many more parts. I can picture you on the ground looking up and saying my me. I have been down that road.

Ken

I used Part-n-More friction plates in my 750K8 with the stock metal plates with no issues. No extra plates added.

[BrockSamson]

Right, chose not to go with OEM parts.  APE is a reputable dealer here and the claim that "they are perfect for performance street bikes. They do not grab and chatter ." was something that appealed to me.  I only have a 4 into 1 exhaust but if in the Winter when I do my rebuild and I choose to make more power I have a clutch I know will without a doubt handle whatever I do.  My thought was that I should spend the very minimal amount of extra money to get a performance clutch so I don't have to repurchase parts.  There is no doubt that the clutch is overkill for my motor.

There are downsides that you can find such as claims of having a harder clutch pull.  The clutch pull is stiffer, but obviously I have not ridden so I can not report anything more or the long term fatigue this could cause on my hand.

This has without a doubt been a pain in the ass and many more hours have been put in this than should be needed.  I think there is something fundamentally wrong within the entire clutch assembly as opposed to this being a problem with the clutch kit itself.

Keep an eye on this thread.  I will be posting measurements and such and I will certainly be posting whatever resolution I come to.  Hopefully I can definitively find the flaw in either my reassembly or in a failed or missing part.

Just like working on carbs... I will know this clutch assembly inside and out.

[MCRider]

I would say no problem with APE. And no problem with better clutch in general. I have had one for so long I forget the manufacturer, Barnett, Ape, Action 4s?

There is simply a missing or misplaced part either in the software (understanding) or the hardware. You'll figure it out.

Just remember in either APEs case or Hondas case, there are 10s of thousands of these things running around with perfectly functioning clutches. You don't have to conjure up a fix unique to you to make it work.

[HondaMan]

However you "stack 'em ", don't go beyond the edges of that basket. That just won't work (we won't discuss WHY I know this, however...).