Author Topic: cb750 clutch question  (Read 1856 times)

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Offline elroy

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cb750 clutch question
« on: September 08, 2010, 05:49:30 PM »
So I have a basically stock cb750k4, with the classic clutch/primary chain rattle. Its pretty bad, makes you cringe at idle.

Anyways, I saw online that a possible fix for the clutch rattle is replacing one of the inner metal plates, with that of a goldwing clutch B plate from a similar year. So I bought one on ebay, drained the oil from the bike, pulled the clutch cover off just to discover that I don't have the tool needed to pull off the nut retaining the basket. @$#!

I replaced the components as best I could, replaced the oil and started the bike. The clutch slips completely, I can let go of the clutch lever in first and the bike idles fine.

What could be going on here? I tightened the bolts retaining the lifter plate all the way down, Is this wrong? I failed to take note of the position or tightness of these bolts before I began disassembly. Other than the rattle, the clutch worked perfectly before I started messing with it.

~elroy

Offline mystic_1

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Re: cb750 clutch question
« Reply #1 on: September 08, 2010, 07:56:52 PM »
If you mean the four bolts that hold the lifter plate against the clutch springs, yes those should be tight.  Be careful to tighten them gradually and evenly, there's a risk of cracking the pressure plate otherwise.

Have you adjusted the clutch lifter yet?  Loosen the locknut, turn the screw in until you meet resistance, back out 1/4 turn, then tighten the locknut.

Hmm, you didn't leave the clutch springs out by any chance, did you?  Just askin'

mystic_1
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My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline MCRider

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Re: cb750 clutch question
« Reply #2 on: September 08, 2010, 08:35:14 PM »
To develop Mystics comments a bit. When you remove the clutch lifter plate covering the 4 springs, the piece with the 4 posts (pressure plate) becomes free to drop into the clutch basket a bit. You must draw it back towards you and wiggle it so its notches mesh back into the splines of its mating piece (clutch center). You cannot see these notches at the stage you are at.

I'm pretty sure about this, but I'm working from a distant memory, and may be way off base. I do know that if the pieces are not meshed back together and you crank on the bolts above the springs, you can break the clutch lifter plate.

Wait for someone else to confirm this or tell me to go to bed.

Could just be the clutch adjuster per Mystic.
« Last Edit: September 08, 2010, 08:37:31 PM by MCRider »
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline elroy

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Re: cb750 clutch question
« Reply #3 on: September 10, 2010, 01:23:11 PM »
Yep I ended up cracking the lifter plate trying to get it back on.

Offline nancy

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Re: cb750 clutch question
« Reply #4 on: September 10, 2010, 02:14:42 PM »
Elroy. Bummer on the lifter plate. MCRider is correct. My memory is more recent and painful as I have had my clutch out 3 times and 3 times on reassembly the basket asssembly fell away ever so slightly and after reasembly I had no clutch - you can tell as you pull the cable, the lifter assembly pops right out of place. Only way is to develp a feel for how to wiggle it in - AND,...use 2 of the spring mount /lifter bolts and temporarily screw them into the basket so you can hold onto the bolts as you slide the assembly in...and sort of pull on the bolts as you push on everything else!
The lifter plate is NOT, NOT, NOT to be bolted down TIGHT - it is torqued to about 6-8 ft pounds only. Very gently, one 1/4  turn each around the clock.

Offline MCRider

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Re: cb750 clutch question
« Reply #5 on: September 10, 2010, 02:36:16 PM »
Elroy. Bummer on the lifter plate. MCRider is correct. My memory is more recent and painful as I have had my clutch out 3 times and 3 times on reassembly the basket asssembly fell away ever so slightly and after reasembly I had no clutch - you can tell as you pull the cable, the lifter assembly pops right out of place. Only way is to develp a feel for how to wiggle it in - AND,...use 2 of the spring mount /lifter bolts and temporarily screw them into the basket so you can hold onto the bolts as you slide the assembly in...and sort of pull on the bolts as you push on everything else!
The lifter plate is NOT, NOT, NOT to be bolted down TIGHT - it is torqued to about 6-8 ft pounds only. Very gently, one 1/4  turn each around the clock.
hey at 57 the old memory is still with me, mostly!  I'll be reassembling my clutch soon within 2 weeks i hope so I've been thinking about it. The parts are in the parts cleaner.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline elroy

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Re: cb750 clutch question
« Reply #6 on: September 10, 2010, 04:07:02 PM »
Thanks, I knew it had to be something simple like that, because although I did crack the plate on the corner, it shouldn't have affected whether or not I lost clutch control completely, because I could still bolt the plate down. I'll try you're method when I get the chance, anyways I have a new(used) plate coming in the mail. Next time I'll be extra careful.

Offline nancy

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Re: cb750 clutch question
« Reply #7 on: September 12, 2010, 09:40:14 PM »