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  1. #1
    CB750 Member Griffon's Avatar
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    Clutch Lifter Plate

    Hey guys!

    Working on a 1980 F supersport. Just replaced the clutch, and having a problem getting the lifter plate set right. The manual says to "attach plate with 4 bolts and tighten". No torque spec and nothing about how tight against the springs. The 1980 has no notches on the posts for the bolts. Obviously, if you tighten all the way down to the posts, the plates don`t move at all. After reading some of the other posts, I count myself lucky I didn't break the plate. Any advice??

  2. #2
    CB750 Guru amc49's Avatar
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    6 bolts not 4 (DOHC) and you pull them up tight against the end of the posts. There is no torque spec given even in the service manual, just tight. Tighten ALL the bolts evenly at same time and you will never break the plate, you break it by only tightening one or two bolts down to warp the load sideways, being cast aluminum it then breaks.

  3. #3
    CB750 Member Griffon's Avatar
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    Quote Originally Posted by amc49 View Post
    6 bolts not 4 (DOHC) and you pull them up tight against the end of the posts. There is no torque spec given even in the service manual, just tight. Tighten ALL the bolts evenly at same time and you will never break the plate, you break it by only tightening one or two bolts down to warp the load sideways, being cast aluminum it then breaks.
    I know better about the 6 Bolts. Was pretty tired when I was requesting help! When tightened down to the posts, There is no movement at all with the lifter plate or the clutch plates themselves. Also, when the cover is put back on, the lever arm cannot move. Several of my classic honda bike buddies are stumped also... And yes as with anything mechanical, I always torque/tighten things in several steps and in opposing order... Thank you in advance for your input!

  4. #4
    CB750 Guru amc49's Avatar
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    http://www.cb750c.com/modules.php?na...iewtopic&t=301

    Go there and register for free and go to technical documents section to download the OEM service manual in sections, the clutch for one.

    Make sure the springs are not coil bound, if so you will break parts trying to work clutch, springs bound up is a distance spacing/too many parts issue. Make sure as well that the inner hub and outer basket spin freely before plate is bolted down but after center nut on hub is tight. Back the center adjusting screw on outer clutch cover way off to too loose, then go back in. Are you using the factory cush plate made of two riveted together?

  5. #5
    CB750 Member Griffon's Avatar
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    I have an original factory manual. The mystery deepens. No, the inner hub and outer basket do not spin freely (in Neutral with hub nut tight). I have the rotor cover off and can see the engine wants to turn over, which I know that it should be disengaged from the engine in neutral. The clutch plates can wiggle with the lifter plate off. I did put in a new factory cush plate (riveted). I know these are big clues. But I`m still at a loss...

  6. #6
    CB750 Guru amc49's Avatar
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    All clutchplates out, trans in neutral, basket nut tight. The inside hub MUST turn freely (and turning trans input too) or the clutch does nothing. Outer basket is geared to the jackshaft, engine has to turn before it can. The manual shows you the correct spacers to use between the inner and outer, a few people have reported that they may not be the correct thickness to lock up the inner hub on outer basket.

    I may have inserted some confusion by saying outer basket turns freely, I meant inner on outer, the outer cannot turn unless engine does.

  7. #7
    CB750 Member Griffon's Avatar
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    Quote Originally Posted by amc49 View Post
    All clutchplates out, trans in neutral, basket nut tight. The inside hub MUST turn freely (and turning trans input too) or the clutch does nothing. Outer basket is geared to the jackshaft, engine has to turn before it can. The manual shows you the correct spacers to use between the inner and outer, a few people have reported that they may not be the correct thickness to lock up the inner hub on outer basket.

    I may have inserted some confusion by saying outer basket turns freely, I meant inner on outer, the outer cannot turn unless engine does.
    I can turn the inside hub (Clutch center) with the clutch plates still in, freely. Trans in Neutral, Turning the locking nut.

  8. #8
    CB750 Guru amc49's Avatar
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    That works. When you install the plates and the center pressure plate both the inside hub and outside basket lock together to make one unit. Correct would let you press in on the pressure plate center with say 30 lbs. of force to slightly move it in to loosen up on the plates which are otherwise tight. Assuming you do have the center piece in center hole of the plate. The one the outer cover lever presses against.

  9. #9
    CB750 Member Griffon's Avatar
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    That's exactly how I thought it should be. Therein lies the issue. The springs pushing on the lifter plate should force the clutch plates together and engage the clutch. With the 6 bolts down tight, everything is very tight. That center piece should move as you say to disengage the clutch and it won't. This has been a complete engine off the frame, completely disassembled total restore, and yet I`m hung up on this clutch. I have taken the clutch apart several times. Could that riveted plate be the hang up? I wouldn't think so, but I almost feel like my clutch plate pack could be too thick? The clutch is a fairly simple assembly.

  10. #10
    Moderator dirtdigger's Avatar
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    I suggest posting some photo's, may be able to see something you are not catching.

  11. #11
    CB750 Guru amc49's Avatar
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    7 fiber discs with narrow tabs and 1 fiber with wide tabs that goes on last. 8 total fibers. The clutch stack begins and ends with a fiber. 6 steels and 1 steel riveted plate.

    The stack ENDS on the OUTSIDE with the wider tab B fiber plate then a steel then a fiber then rivet plate then fiber and alternate the rest to end with a fiber.

  12. #12
    CB750 Member Griffon's Avatar
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    Click image for larger version. 

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ID:	9032 As per the manual, everything appears installed correctly, and yet when I tighten down the lifter plate, everything is too tight... It's getting kinda funny at this point...Click image for larger version. 

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    Last edited by Griffon; 06-30-2019 at 03:56 PM.

  13. #13
    CB750 Member Griffon's Avatar
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    And yes, The plates are in correct order. With the lifter plate tight, it looks like the springs are almost completely compressed. These are the same springs I took out, so I know they were working fine before this project began. I decided to change the plates out because the clutch felt like it was slipping under load....

  14. #14
    Moderator dirtdigger's Avatar
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    Do you have the old clutch plates? Time to compare old with new and measure thicknesses, stacked hights etc.

  15. #15
    CB750 Guru amc49's Avatar
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    '...yet when I tighten down the lifter plate, everything is too tight...'

    What does that mean to you? They are supposed to be tight at that point. The inner and outer will be firmly locked to each other.

    You should have one thin washer on the outside of trans input shaft bearing in case, then the clutch basket and it must be geared into BOTH the thin and thick primary gears to settle fully against the thin washer behind basket. .

  16. #16
    CB750 Member Griffon's Avatar
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    I do have the thin washer correct. The basket meshes evenly with the primary gear. Everything is exactly as per the manual. With everything installed and tight, and I press on the pressure plate center piece, it won't move. You have been a tremendous help and I really do appreciate you taking the time to help resolve this conundrum.. I really do love all things mechanical and the challenge of figuring stuff out, whether easy or complicated.

  17. #17
    CB750 Member Griffon's Avatar
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    I should also mention I put the old plates back in and got the same result. With the cover installed, the lifter will not move.

  18. #18
    CB750 Guru amc49's Avatar
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    Does the outside cover lever have enough slack in it to be not touching as the cover is final installed? It must have at least some slight loose before hitting the center of clutch solid when worked by hand. Say 1/4", then it hits the clutch to not move.

  19. #19
    CB750 Member Griffon's Avatar
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    Quote Originally Posted by amc49 View Post
    Does the outside cover lever have enough slack in it to be not touching as the cover is final installed? It must have at least some slight loose before hitting the center of clutch solid when worked by hand. Say 1/4", then it hits the clutch to not move.
    Problem solved! At the risk of looking bad,and as a learning experience for anyone else looking, I think I had it right all along. I was trying to push the lifter plate in by thumb (not the actual clutch lever at the bar) when I was trying to diagnose it. A light went off when you asked if the outside cover lever had slack. Of course the new plates are slightly thicker than the old, and the lever wouldn't move when I put the cover on. So I loosened the adjuster, and bam, using the clutch lever, I've got a working clutch. One thing I did different on the way out: I put the locking nut on with the cambered side facing in. The pics in the manual all appear to have it this way. Not sure if that made the difference or not, or if that is right. Can easily change it back. Once again, Thank you, to you guys, for your patience with this. Much appreciated!!!!

  20. #20
    CB750 Guru amc49's Avatar
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    I was waiting for something like that to show up................live and learn. Still doing the same myself. You can't even push the clutch in on a 100 cc bike with a thumb.

    Glad to be of help.

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