Topic: Does this 750 clutch look right?

[Johnny340]

I went to hook up a clutch cable and after adjusting the actuator the lever would only pull half way to the bar and then stop.  So I have taken the clutch apart to see what it looks like and I see a weird double steel plate in the middle??  It has six friction plates plus the 'B' friction plate.  Can you tell from the pics below if the spacing looks correct for these new clutch plates?  Why else would the lever only pull part way then stop?  Thx!

[madmtnmotors]

Why else would the lever only pull part way then stop?  Thx!

Care is required when adjusting the "actuator" or clutch lifter. When turning the center rod in it is easy to miss the "point of contact" where the lifter rod meets the throwout bearing making it easy to continue on which is actually disengaging the clutch as you continue to turn the lifter rod. I recommend using the smallest screwdriver you can find that will still fit the lifter rod. Back it off and try adjusting again making sure you don't mistake contact with the throwout bearing for "just a little resistance". It is easy to do and I have made this mistake more than once myself.

The double steel was added to later clutches to help promote smoother/quieter clutch operation.

[goaarongo]

Did it come with the motor?  I'm working on a '78 cb750 and it has a stack like that.  I compared it to the '74 model that I'm replacing and there are differences.  The basket is a bit different on models that came with this, the clutch springs are longer, and that top friction disc is an odd size.

That double metal ring caught my eye too and that's why I ended up disassembling both.  madmtnmotors is probably right though - make sure its adjusted correctly before anything else. 

[754]

I think double ring is late style, and the clutch covers are different.
 I may have a late clutch cover.
 Do you have any other clutches ? I think you motor is late ?

[scottly]

The later clutches with the double plate have a deeper clutch basket; IIRC this started in the mid K7 run? If you are trying to fit a late type disc pack into an early basket, it may not fit..
EDIT Found some documentation on the subject:
 

[Jerry Rxman Griffin aka MuthaF'er]

Flip the assembled complete clutch over and give us another picture.

[trigger]

Check the thickness of the plates, 120mm x 140mm can come up to 3.75 mm  Add up all those extra mm and you have a problem.

[Jerry Rxman Griffin aka MuthaF'er]

When you install the plates into the basket and install the lifter too you could be off 1 tooth between the lifter and basket. I don't have one in front of me so I could be telling you wrong. If so it will be thicker and not fit together correctly.

[Johnny340]

Thanks for all the replies guys!  I put it back together and checked the adjustment and when adjusted properly, the lever still only pulls half way and then stops solid with no clutch disengagement at all.  I will have a chance tomorrow to measure and take more pictures as it seems this could be another hodge-podge of late & early parts 

[RRBuGGz]

That stack and double steel ring looks like a later model.  I have the same stack in my '78 750k.  I happen to have another early basket and stack, not sure what year  but the stack and the basket are definitely shorter than the stack/basket in the '78.  I can measure the stack/basket differences between the early and later setups I have if that helps.

[madmtnmotors]

Lets start with the engine serial number so we know what year engine we are dealing with.

[Johnny340]

Lets start with the engine serial number so we know what year engine we are dealing with.

Here's one pic of the engine number before I go for the day. The number is: CB750E-2551700
Something that jumps out at me after reading the 'field fix' in Scott's picture is that I have that special plate in the field fix but I still have a total of seven friction plates...so one was never 'removed' as part of this fix??

[Johnny340]

So that's an F1 1976 engine?
When I look at the clutch before I take it apart it apart again, it actually looks like there should be another plate in it as seen by the space to the first friction disc tabs.  Also the springs look almost coil bound??

More pics:

[madmtnmotors]

There is a "splined washer" the goes between the clutch outer drum and the pressure plate. This splined washer will sometimes stick to the back of the pressure plate and then fall off unnoticed when the pressure plate is removed. Can you verify this splined washer behind the pressure plate?

[HondaMan]

All of the 750 clutches after the K5 came with the double-steel slipper plate somewhere in the stack. There are 3 different arrangements: the first one was with the double-steel plates right behind the top plate (which has wider ears in the basket than the other plates), which had slant-cut corks on them in the "F" bikes, square-cut in most of the K6 bikes (but not all: the K6/F0 swapped lots of parts on the production lines...).

Beginning in the F1/K7, the double-steel plates moved toward the middle of the stack, usually 2 from the back side. In the F2/3 and the K8, the springs got a little longer.

when you put that cupped washer back in (the one that holds the center hub in place), be SURE to put the hollow side toward the engine. This spring-preloads the basket out against the hub to make the stack stable when you are letting the clutch lever out.

The adjustment at the end: loosen the 6mm nut on the adjuster lever with the cable adjusters set all the way 'in' for max loose length of the cable. Then turn the screw adjuster until you feel it stop (pretty hard), and back off about 1/8 to 1/4 turn, lock the nut down again. Then turn the adjuster at the handlebar out 1 turn, lock it down. Now pull the lever: it should move 1/2" to 3/4" before pulling hard up against the clutch stack. This distance will grow a little when the engine gets warmed up, hence the "range" adjustment statements. I like mine at 1/2" free play, cold, for reference.

[Johnny340]

There is a "splined washer" the goes between the clutch outer drum and the pressure plate. This splined washer will sometimes stick to the back of the pressure plate and then fall off unnoticed when the pressure plate is removed. Can you verify this splined washer behind the pressure plate?

This splined washer is in place.

when you put that cupped washer back in (the one that holds the center hub in place), be SURE to put the hollow side toward the engine. This spring-preloads the basket out against the hub to make the stack stable when you are letting the clutch lever out.

The adjustment at the end: loosen the 6mm nut on the adjuster lever with the cable adjusters set all the way 'in' for max loose length of the cable. Then turn the screw adjuster until you feel it stop (pretty hard), and back off about 1/8 to 1/4 turn, lock the nut down again. Then turn the adjuster at the handlebar out 1 turn, lock it down. Now pull the lever: it should move 1/2" to 3/4" before pulling hard up against the clutch stack. This distance will grow a little when the engine gets warmed up, hence the "range" adjustment statements. I like mine at 1/2" free play, cold, for reference.

The cupped washer is oriented correctly and I'm quite sure I have it adjusted correctly but it still doesn't release the clutch. 

Have a look at these pics to see if it looks like the basket is in enough and the plates are seated alright.  Does it look like the clutch should release with this spacing?  I'm having trouble visualizing how it could move much with only 1mm of nut overhang into the bearing seat. The nut is fixed right??

Also, I had some other clutch springs from another F model and they were way shorter but still within the 'greater than 30.5mm' spec.  I tried them and it made no difference..  Look what else is broken now 

[madmtnmotors]

I wouldn't worry about the broken lifter plate for now, at least not until you figure out the original problem. There's enough meat on there to continue testing and diagnosis.

I went to hook up a clutch cable and after adjusting the actuator the lever would only pull half way to the bar and then stop.

What brought this on? What work had you done prior to this? Was the clutch functioning properly before?

[scottly]

I measured my K7 clutch parts today, and the clutch hub is 3.5mm longer on the splines than yours, while the stack of plates is the same thickness as yours. You're basically stuffing twelve pounds of crap into a ten pound bag. Also, regarding the basket and how it looked like a extra plate could be fitted, that may be the later style basket, which is also deeper to accommodate the thicker pack. Measure the distance from the cover mounting surface to the edge of a "finger"; I got about 3.5mm with the K7 basket, so would expect 7mm with an earlier basket.

[Jerry Rxman Griffin aka MuthaF'er]

Lets start with the engine serial number so we know what year engine we are dealing with.

Here's one pic of the engine number before I go for the day. The number is: CB750E-2551700
Something that jumps out at me after reading the 'field fix' in Scott's picture is that I have that special plate in the field fix but I still have a total of seven friction plates...so one was never 'removed' as part of this fix??

F1 engine, field fix double plate with all 7 fibers is NOT going to work. Remove a fiber. Otherwise you need a 77/78 basket and 77/78 clutch cover as you are running all the guts for the 77/78 clutch pack.

[754]

Scott, i see a deeceeohE in that pic..
It seems what is happening is you have some mixed parts but it's hard to tell without any reference.
 .. I have some used lifter plates, and maybe a late clutch cover (not sure).
  Not sure which cover you need.,

[PeWe]

With the shorter clutch hub as used by K6 and earlier with old clutch cover, replace the double steel by a std steel plate. 7 fibers will help to grip. The outer fiber has wider tabs.

I think the double steel and deeper clutch hub was introduced late US K6?
My EU K6 did not have double steel and deeper hub. Not the K6 clutch I bought on eBay from USA either.
I have however, an F2 clutch that have it.

[scottly]

Scott, i see a deeceeohE in that pic..

Yeah, going to swap out the original abused carbs that came on the bike with a pair I bought years ago; been having accelerator pump issues with the old left side carb, and I want to fix it while I have the seat and tank off.

[754]

Yeah I am down  to 2 sets of Webers ,  and 1 set of Dellortos  on a Manifold  plus a spare pair.... lol..

[Johnny340]

I measured my K7 clutch parts today, and the clutch hub is 3.5mm longer on the splines than yours, while the stack of plates is the same thickness as yours. You're basically stuffing twelve pounds of crap into a ten pound bag. Also, regarding the basket and how it looked like a extra plate could be fitted, that may be the later style basket, which is also deeper to accommodate the thicker pack. Measure the distance from the cover mounting surface to the edge of a "finger"; I got about 3.5mm with the K7 basket, so would expect 7mm with an earlier basket.

Makes sense! My basket measures 5mm to the edge of the gasket sealing surface btw.
I'll try removing a fiber plate as suggested by Jerry or try a regular metal plate like PeWe suggested.

I wouldn't worry about the broken lifter plate for now, at least not until you figure out the original problem. There's enough meat on there to continue testing and diagnosis.
What brought this on? What work had you done prior to this? Was the clutch functioning properly before?

This has never functioned before and is part of a rebuild that I took over (clutch was already 'done') and I have no history on any of these parts either.

[madmtnmotors]

This has never functioned before and is part of a rebuild that I took over (clutch was already 'done') and I have no history on any of these parts either.

That helps us determine what we are looking at. Looks like we need to determine which outer basket is being used and then determine the appropriate stack, pressure plate, springs, and inner hub that will match.