Re: I need a new clutch
Posted by shinyribs on Jun 28, 2012; 3:34am
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/I-need-a-new-clutch-tp4023610p4023705.html
Here are some things I found. I can't verify the accuracy of these,soooo dont consider it as gospel:
On the CB750's there were three more-or-less distinct clutch configurations.
Type A (K0,K1,K2):
Is the original and might be called the "Extra disk short basket design"
This design has a slightly larger clutch disk at the base of the inner basket and was notorious for chatter - probably because the springs were weak and the plates and disks did not have sufficient rigidity to dampen vibrations.
Type B (K3, K4, K5, F):
Might be called the "Sprung short basket design"
This design removed the extra disk and strengthened the springs. Chatter was much less evident.
Type C (K6, K7, K8, F2):
Might be called the "Long basket design"
Longer basket and internal parts, longer and stronger springs, and a double rivetted centre plate, solved the chatter problem and significantly strengthened the clutch.
Parts were only somewhat interchangeable, but only in certain combinations.
An extra plate (as in the aftermarket variety) is of dubious benefit in any of these designs. Stronger springs are a benefit, but have the downside of putting even more pressure on the weakest link in the chain, i.e. the clutch pressure plate.
And another:
Did you try searching from the Tech Forums page under something like "APE clutch"? There has been a number of discussions on this site about it . . .As much as I appreciate the support that companies like APE give to our aging beasts, I must say that I was not particularly pleased with their extra plate clutch kit. One issue is that although the kit is claimed to work with all years of the SOHC 750, it is not truly compatible with the the late "deeper" basket clutches that Honda began using somewhere around 75/76. These clutches have the double thick center steel and the outer most friction disc has a wider tang to fit into a widened section at the end of the clutch basket fingers. The stack height with the APE kit and the stock the double center steel is too tall to fit, so you must omit the double plate and source an additional regular thickness steel to replace it. This leaves you with a stack height slightly less than stock and likely less than ideal. Also, no wider tanged friction disc is supplied so the outer most disc is a very loose fit in the wider section of the clutch basket fingers. This is not ideal. The setup worked OK but finding neutral was particularly difficult and occasionally the clutch would emit a nasty screeching/buzzing noise upon initial cold take off. Replacing the APE setup with new stock parts and a set of heavy duty springs has resulted in a nicely performing clutch that handles the power of my project's 836 motor. I have read a few other reports on this site suggesting that the increased stack height of the APE kit in the earlier style clutches (which is presumably what it was designed for) made for difficult neutral engagement. . .Overall, my feeling is that you are better off with OEM frictions and steels in good condition and heavy duty springs (for performance applications) than using an extra plate kit. I honestly don't think it is proper to advertise the kit as being compatible with all years the SOHC 750s . . . .
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/I-need-a-new-clutch-tp4023610p4023705.html
Here are some things I found. I can't verify the accuracy of these,soooo dont consider it as gospel:
On the CB750's there were three more-or-less distinct clutch configurations.
Type A (K0,K1,K2):
Is the original and might be called the "Extra disk short basket design"
This design has a slightly larger clutch disk at the base of the inner basket and was notorious for chatter - probably because the springs were weak and the plates and disks did not have sufficient rigidity to dampen vibrations.
Type B (K3, K4, K5, F):
Might be called the "Sprung short basket design"
This design removed the extra disk and strengthened the springs. Chatter was much less evident.
Type C (K6, K7, K8, F2):
Might be called the "Long basket design"
Longer basket and internal parts, longer and stronger springs, and a double rivetted centre plate, solved the chatter problem and significantly strengthened the clutch.
Parts were only somewhat interchangeable, but only in certain combinations.
An extra plate (as in the aftermarket variety) is of dubious benefit in any of these designs. Stronger springs are a benefit, but have the downside of putting even more pressure on the weakest link in the chain, i.e. the clutch pressure plate.
And another:
Did you try searching from the Tech Forums page under something like "APE clutch"? There has been a number of discussions on this site about it . . .As much as I appreciate the support that companies like APE give to our aging beasts, I must say that I was not particularly pleased with their extra plate clutch kit. One issue is that although the kit is claimed to work with all years of the SOHC 750, it is not truly compatible with the the late "deeper" basket clutches that Honda began using somewhere around 75/76. These clutches have the double thick center steel and the outer most friction disc has a wider tang to fit into a widened section at the end of the clutch basket fingers. The stack height with the APE kit and the stock the double center steel is too tall to fit, so you must omit the double plate and source an additional regular thickness steel to replace it. This leaves you with a stack height slightly less than stock and likely less than ideal. Also, no wider tanged friction disc is supplied so the outer most disc is a very loose fit in the wider section of the clutch basket fingers. This is not ideal. The setup worked OK but finding neutral was particularly difficult and occasionally the clutch would emit a nasty screeching/buzzing noise upon initial cold take off. Replacing the APE setup with new stock parts and a set of heavy duty springs has resulted in a nicely performing clutch that handles the power of my project's 836 motor. I have read a few other reports on this site suggesting that the increased stack height of the APE kit in the earlier style clutches (which is presumably what it was designed for) made for difficult neutral engagement. . .Overall, my feeling is that you are better off with OEM frictions and steels in good condition and heavy duty springs (for performance applications) than using an extra plate kit. I honestly don't think it is proper to advertise the kit as being compatible with all years the SOHC 750s . . . .
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