Topic: Clutch Issues

[rlarkin70]

So here are my clutch symptoms, I want to make sure I understand what is going on.

1. brand new clutch cable
2. bike is a 76 CB550, has been sitting for a year.
3. unknown condition/age of the clutch itself, I can only assume it is original.
4. 33K miles on the odometer. as far as I know this is accurate for the bike.

I have followed the instructions for adjusting the clutch, ie. loosening the cable, then using the adjustment screw to get the two marks to line up. This is not possible, the mark on the clutch arm is always lower than the mark on the case. The only way I can get the clutch to partially disengage is by unscrewing the adjustment screw ALL the way out.

When the cable is completely disconnected, the clutch arm (on the motor) springs all the way down.

So basically, even with all the adjustments at the extremes (adjustment screw out all the way and both cable ends unscrewed to take all possible slack out of the cable) the clutch lever will only partially disengage the clutch when I pull in the lever.

This was enough for me to be able to, with a rolling start, pop the bike into gear and take it around the block a couple of times, and I can shift through all the gears, but if I come to a stop the clutch is still partially engaged and it will stall the bike.

I guess in my mind the symptoms of a worn clutch are when it slips, but in my case it is the opposite. But then again, if the plates are worn down and the springs are pulling everything together that would explain what I am seeing. I think. =)

Am I right in concluding that this is simply a case of worn clutch discs, and I need to replace them? Or are there any other possible causes, such as due to the bike sitting for a while, or some adjustment I am not clueing into?

I took off the clutch cover last night and took a quick peek, everything looks "normal" in there but it was late and I didn't disassemble or measure anything. I guess that's the next step.

-Ron

[Tower]

Measuring the plates and springs is a very good idea.
 
The symptoms are consistent with sticking plates - maybe from varnish or other oil/lack of oil related issues.  Returning the adjuster bolt all the way out should also release the plates unless the springs are really shot.

To ruleout the adjustor as a problem area....Raise the rear wheel.  Unhook the clutch cable from the lower clutch lever.  Turn out the adjustor bolt as far as it will go.  Start the bike. 

 - If the rear wheel is engaged, then you have a serious clutch problem and must dismantle and replace parts. 

 - If the wheel is not turning, then turn in the adjustor bolt untill it does turn.  If you can do this, then at least the adjustor mechanism is working fine.  The problem might be in the cable and handlebar/upper clutch lever.  Of course, a problem with plates and/or springs is still possible.

Either way, measuring the plate thickness, plate warpage, and spring height is advised.

[rlarkin70]

This is indeed the case, unfortunately. If I turn out the adjuster as far as it will go, undo the clutch cable, put the bike in 1st gear, and kick it or hit the starter, the rear wheel is engaged and the bike will lurch forward.

It sounds like I am on the right track in taking apart the clutch, taking some measurements, and replacing as necessary. Sounds like probably new plates and springs.

-Ron

To ruleout the adjustor as a problem area....Raise the rear wheel.  Unhook the clutch cable from the lower clutch lever.  Turn out the adjustor bolt as far as it will go.  Start the bike. 

 - If the rear wheel is engaged, then you have a serious clutch problem and must dismantle and replace parts. 

[rlarkin70]

I dug into the clutch last night...removed and disassembled it. Here are some photos. I need to get a caliper so I can take some measurements. I also need to find the exact specifications, since the Clymer and Honda shop manuals have differing numbers for the tolerances. Of course I will go with what Honda says firsthand.

Some observations:

1. everything looks to be in decent shape, no major obvious issues. I can't tell just by looking if the clutch plates are worn. The metal plates have some indentations in them for oil I assume. You can see that some of the indentations are "worn" around the perimeter of the plates.

2. the discs themselves look OK, but again, I can't tell by eyeball if they are worn I need to measure. Going with just a ruler the 1 thicker plate is about 3.5-4mm and the thinner plates are about 2.5-3mm. Again, I need a caliper to properly measure them.

3. The springs are about 36-37mm uncompressed. I think this fits into what Honda recommends.

4. I laid the metal plates on a glass table top, and they are all flat.

So from what I can tell so far, it sounds like maybe I just need to replace the clutch discs. I can get a Barnett "kit" that includes new discs, metal plates, and springs for $120 which I might just do since I have it all apart. If I go with just the discs they're about $45-$60, from what I have seen out there.

There are some things I need to figure out, for example, the Clymer and Honda manuals mention a washer that slides on the shaft before you take out the split ring to free the clutch, so you can take it off. Mine had a couple of very THIN shims, but no washer.

Also, the discs do not look like the stock discs, based on the pictures in the Honda shop manual. So if the bike has 33K on it, and the discs have already been replaced once, its hard for me to believe the bike is going through clutches that fast. I have heard of bikes going 50K plus on the original clutch. Heck, my old 83 Prelude went almost 200K before I had to replace the clutch on it! Of course, every old bike is a bit of a mystery...that's part of the "fun" I guess.

Anyways, tonight I will take measurements of everything, and find the correct specs for the tolerances. Also, I am going to look more closely at the clutch arm and adjustment bolt to make sure that all looks normal. Then time to decide what to do... ie. replace the discs only, or the whole thing.

-Ron

[TwoTired]

Unless you plan to race the bike, I would not use the Barnett pieces.

The springs are stronger.  For a street bike, that means greater left hand fatigue.

I found the Barnett frictions were very hard to adjust to get both no slippage and no drag.  Finding neutral when hot was always difficult.

I just found this thread.  But, I was thinking as I read it that you were not adjusting the clutch correctly.
However, now that you have the cover off, you can see how the release mechanism works.
The arm on the outside turns a cam for the release on the inside.  Make sure the marks on the outside coincide with the cam ramp engagement on the inside.
The outside adjustment merely positions the actuator arm close to the clutch rod, so the actuating cam has the greatest effect.

Once the cover adjustment is performed, then use the cable adjustment to get the lever in a comfortable position to operate, while still getting full disengagement.

One thought.  To help with adjustment after assembly, mark the outer actuation lever to coincide with the internal cam position against the inner clutch actuating lever.  You will be interested in the minimum and maximum cam points, as those will be the full engagement and maximum disengagement of the clutch disks.  However, unless the actuation cam is worn, adjust the clutch just at the edge of full engagement, ought to get you full disengagement, using full clutch lever travel.

This is hard to explain, so my apologies if this writing is too difficult to understand.

I did compare your clutch disk pics to my Honda pieces (new parts with Honda numbers on the bag).  And, they don't look the same.  So, you may already have a Barnett clutch in your possession.  But, I can't recall from the visual if that is what you do have.  It's been years since I saw the last one.
I can take pics if you feel it necessary.

Lastly, the stack height of all the disks is important.  There are two different kinds of steels and two kinds of frictions in the Honda pack.  And, this height will interact with the clutch engagement adjustment.  If the stack is too small, you may be outside the range of the Honda adjustment.

BTW, I have a 74 CB550 with original clutch and 42,000 miles on it.  It doesn't quite grab like new, any more, but it still works. I certainly abused it in the late 70s and 80s.   

Cheers,

[Tower]

Those are definately not OEM plates.

Spring height should be about 35-36 mm

If you have removed the clutch cable from the lower clutch lever and unscrewed the adjustor bolt to its maximum and you still can't disengage the clutch, then it definately means the plates are sticking together. 
This can happen for several reasons:

• the adjustor mechanism is broken, the shaft is warped, the pressure plate is stuck etc (you may want to read my other clutch-related posts, somewhere in there is a technique for testing the adjustor mechanism)
• the springs are too long and/or the pressure plate was not bolted down correctly
• the plates are "glueing" to each other due to varnish acting like glue or warpage from lack of oil, or foreign material such as abraded cork/steel.
• the plates are an incorrect thickness (too thick) or there are too many plates in the basket
• the basket is too short or the ribs are blocked by burrs or foreign material

Edit: If the last assembly was not correct, then simply re-assembling might be all that is needed.

[rlarkin70]

Guys, thanks for that advise, it was very helpful.

Tower- I will search for your post relating to the adjustor mechanism. I will take a close look at the arm/cam/adjustor tonight to see what the issue might be.

Two Tired- I did understand what you were saying, and I like the idea of marking the outside lever position as it relates to the inside cam. Also, re: the Barnett clutch springs, that is good to know. I don't want to get tired just shifting gears.

I think, for now, Im going to look at the actuating arm/cam tonight, and see what might be causing my problems. Then try and re-assemble everything to spec, and see if there is any improvement.

-Ron

[rlarkin70]

Lastly, the stack height of all the disks is important.  There are two different kinds of steels and two kinds of frictions in the Honda pack.  And, this height will interact with the clutch engagement adjustment.  If the stack is too small, you may be outside the range of the Honda adjustment.

One more thing...

When I disassembled the clutch stack, I noticed there were 7 friction discs. 6 of them were of one thickness, and one of them was thicker. The thicker one at the outside of the stack.

There were 6 steel plates. 5 are the same, but one is quite a bit thicker. It looks like 2 plates riveted together. I have attached a picture.

I did not measure the total height of all of the discs, but I will. Any idea what the thickness SHOULD be?

[Tower]

In 1976 a new clutch was introduced along with the 1 1/2" (37 mm) springs with 240 lb tension.  A rivetted centre steel plate and a lengthened clutch housing, by an additional 1/4", identify these clutches.  So it appears you may have the longer clutch  - or, you may have an older clutch with the wrong set of plates - just kidding, its not likely  

Plate specs should be in your Honda Repair Manual or a Clymer manual for 1976 Honda SOHC4s. (2.4 - 2.7 mm?)

Edit: Re-read your post and it sounds like you have a shim in your clutch centre (between the snap ring and joint piece) Don't forget to measure that shim's thickness before reassembling.Only if the looseness of the plates is greater than 0.1mm should a spacer be added. (A dial gauge is needed to measure the looseness of the hub on the shaft)    Someone may have added a shim that is too thick.  e.g. If the clutch plates weren't soaked long enough in oil, before assembly, they would give the appearance of being too loose at first.  Then, when enough oil is absorbed during a ride, the assembly becomes too tight.

[rlarkin70]

Thanks Tower. Yes, there were 2 shims there. I will check to make sure they should be, based on the 0.1mm tolerance. I remember reading this in the Honda shop manual.

I have been trying to re-assemble the clutch, but ran into some more questions....I am hoping for some help. See the pictures below, I will try and keep the questions simple.

A. photo 1 shows the clutch pressure plate with the arrow pointed to the edge where it "steps down". Photo 2 shows a clutch disc sitting down "against" the pressure plate. Photo 3 shows how the disc just sits on the higher portion of the clutch plate, with the resulting gap. Is this normal? To me it seems that the disc should drop down so it is sitting against the flat, lower area on the pressure plate. The inside diameter of the disc is too small to allow this to happen.

B. photo 4 shows the clutch center, with a steel plate on it. Two of the arrows point to some holes on the clutch center itself. There are several sets of these around the perimeter of it. The other arrow points to a "hole" in the clutch plate. There are 2 of them in the photo. Does it matter what the alignment of these gaps/holes is? Should the holes in all of the plates line up? Should they be staggered? Does their position need to match up with the holes on the clutch center?  My thoughts are that it does not matter, and that these are just holes to allow the oil to flow through the clutch assembly.

Thanks for any help on these. I'm learning a lot with this project. =)

-Ron

[Tower]

The pressure plate on the CB550s may act like a clutch plate (judging by how the disks and plates are arranged and by the shop manual diagrams), and since all clutch friction disks should be sandwitched between plates, I'd guess, with some certainty, that the clutch friction disk should sit flush with the pressure plate.  But, I'm only guessing.  On some early clutches there is a smaller clutch plate and clutch plate stopper ring that fit into the assembly, but those clutches didn't have the heavy gauge integrated pressure plate ring that the CB550s have.  Perhaps someone with a 76 CB550 can confirm this.

Edit: Are all the friction disks the same inside diameter?  There may be one in the set that is wider.  Otherwise, you may have found the reason the plates are pressed together and unable to separate.

The holes in the clutch centre pass oil to the clutch plates and disks.  One trick when rebuilding clutches is to drill more holes in the clutch centre.  Specifically,  drill a hole in the centre of three of the grooves.  Space the holes evenly around the hub so as not to unbalance the hub and evenly away from the grooves that already have holes.  Put a micro bevel on both ends of the holes you drill and on the OEM holes as well.  Don't make the bevel too large as that might weaken the hub and take away from oil pressure.  With the addition of the extra oil holes, the lifespan of your clutch plates and disks will increase many-fold.

Holes in the clutch plates will never align with the holes in the hub, so don't worry where they are placed. Oil travels along the hub grooves and is thrown outwards to the clutch outer basket by the friction disks, so the plate holes don't serve much purpose.

[rlarkin70]

Edit: Are all the friction disks the same inside diameter?  There may be one in the set that is wider.  Otherwise, you may have found the reason the plates are pressed together and unable to separate.

Thanks Tower. Yes, I checked all of the discs and they have the same ID, none of them fit over the friction plate. When I look at the friction plate there are wear marks on that flat portion, so it looks like at some point a clutch plate (or spacer or something) has been pressed flush with it. But the current discs do not.

The only thing I can think of is that the discs were replaced with an incorrect size (!!!) at some point. It is hard for me to believe though, and I just can't help but assume that it is either supposed to site on the edge of the step-up on the friction plate (which seems strange) or else I am just doing something wrong on the re-assembly. But based on the shop manual, Clymer manual, and all the diagrams I have including the parts list for the CB550F, the disc goes on right next to the friction plate.

I'm really scratching my head on this one!

Does anyone happen to have an OEM clutch disc for a Honda CB550F and could measure the inside diameter?

[crazypj]

Edit: Are all the friction disks the same inside diameter?  There may be one in the set that is wider.  Otherwise, you may have found the reason the plates are pressed together and unable to separate.

Thanks Tower. Yes, I checked all of the discs and they have the same ID, none of them fit over the friction plate. When I look at the friction plate there are wear marks on that flat portion, so it looks like at some point a clutch plate (or spacer or something) has been pressed flush with it. But the current discs do not.

The only thing I can think of is that the discs were replaced with an incorrect size (!!!) at some point. It is hard for me to believe though, and I just can't help but assume that it is either supposed to site on the edge of the step-up on the friction plate (which seems strange) or else I am just doing something wrong on the re-assembly. But based on the shop manual, Clymer manual, and all the diagrams I have including the parts list for the CB550F, the disc goes on right next to the friction plate.

I'm really scratching my head on this one!

Does anyone happen to have an OEM clutch disc for a Honda CB550F and could measure the inside diameter?

 I see your in St. Pete.
If you were closer to Orlando I would come over and fix it for you. ( or at least find out exact problem)
PJ
PJ

[rlarkin70]

Thanks for the offer PJ. Ever done a clutch job on your 77? Do you happen to remember if that clutch disc should sit flush against the pressure plate?  I think I can get this clutch issue fixed, right now it just boils down to whether my clutch disc is the right size and sitting properly against the pressure plate.

[TwoTired]

So, I pierced the new sealed bags to measure the disks (which to me is mental cruelty since they aren't being immediately installed.)  Getting over the trauma, the #4 friction disk, at the pressure plate, has an I.D. of 4.733 inches.

Here is the stack with number corresponding to the Cb550F parts catalog drawing, as assembled onto the inner drum for the newer style. Engine S/N from 1139189 .
5- Friction- 0.141
6 - Plate - .078
4- Friction- .109
6 - Plate - .078
4- Friction- .109
6 - Plate - .078
4- Friction- .109
7 - Double sandwich plate - .190
4- Friction- .109
6 - Plate - .078
4- Friction- .109
6 - Plate - .078
4- Friction- .109

550Fs prior to Engine S/N from 1139189 list a 6 plate above instead of the 7 Double.

Not explained, but assumed, is that you use a different shims (no. 15) to compensate for the different stack height.
Wonder where to find the Honda spec for that?

Cheers,

[rlarkin70]

Two Tired-  Thank you!!! You have solved the mystery. But really...you didn't have to go tearing into your NOS bag(s).      Now I feel guilty....and I might have to buy those off you now! =)  Actually, the truth is, I am going to need a new set of clutch discs.

Here's why... 

The ID of the #4 friction discs in my set (all 6 of them) is a hair over 4 9/16". So the wrong discs were put in the clutch.

The funny thing is, the wider #5 friction disc DOES HAVE the right ID of just a hair under 4 3/4" and fits just fine over the pressure plate. Of course the larger disc goes at the opposite end of the assembly, so that does me no good.

My guess is, that the PO tried to replace the clutch discs himself. He used the wrong size #4 discs, and was never able to get the clutch adjusted properly afterwards. He let the bike sit, then sold it to (lucky) me. The evidence of this theory is 1. the clutch cover gasket was a hack job of using the old torn gasket along with some liquid type gasket material to fill in the gaps, and 2. there is no evidence of wear on the "too small" disc that was sitting on the pressure plate. Plus the bike was not rideable as it was set up. Well, I did manage to ride it around the block several times but I had to find neutral before coming to a stop or it would stall the bike. And finding neutral with half a clutch is not easy!

So, the mystery is solved. Thanks to TwoTired!      At least I know why the clutch is not releasing properly, and that I will need to order a new set of discs. What a weird problem.

[fastbroshi]

Bump. 

  Just read this for the first time and thought it would be good info for those having fits with their clutch.

[coyotecowboy]

[edit]  Nevermind......Broshi is bringing posts back from the dead