Clutch Spring Differences CA77

[teazer]

Here's the photo. On the left is a Barnett MT10 and on the right is the SOHC CB750 race clutch springs I used to get from Norris all those years ago.

Told you it was long...



And of course there is a good set of those in the race bike I just rebuilt to sell. All nice and fresh with new AVON tires both ends and fully MA compliant - no log book though. I'm one of the silly buggers involved in their introduction but I haven't raced over there since, so I never got around to getting one. I can apply for it for the new owner if necessary.

[rzgkane]

Part number for those springs with the white tips?

What I have to offer on this subject I will show with a pic and description as to how I find they work when used in a CB/CL72/77 engine.
#1 is a stock HONDA spring used in the early years and is the tallest with the thinnest wire of the stock/standard CB/CL springs I've removed from engines.
It is easy to release the clutch but my experience is it doesn't engage the clutch well and will in time allow the disc to ware and the clutch to slip.
#2 is the white paint on one end (1966/1967??) issue and does pull a little harder than #1 but gives a good feel at the lever as ya release it and the clutch disc engage smoothly and firm and no problem with the disc
#3 is the 810 HONDA issue and is the hardest of the 3 to release but gives a similar engagement as #2. It is the shortest and has the thickest wire of the three.
This info is from using each of these springs at one time or another as I've owned/ridden the bikes with these springs in the clutch.
No pressure measurement with tools just use over the years.
I install the #2 springs in all the rebuilds I do at this time. ............lm

Here are the dimensions of CB750K SOHC springs compared to CA77(2 versions), and a pic of CB750 Spring in the CA basket.

As you can see, there are differences in free length, wire thicknesses and coil spacing, with any of the three affecting the final installed spring pressure.

The shop manual specs for the spring tension are a little confusing to me.

The C72 specs state "15# at 25mm(.98 of binding length)" and "33-36# at 23mm(.90 max lift)"

The C77 specs state "33.7-34.6#" with no measurement lengths listed.

I will try to measure the tension at the installed length of each to see just how much difference there is.

[LOUD MOUSE]

Who knows. ...............lm

Part number for those springs with the white tips?

What I have to offer on this subject I will show with a pic and description as to how I find they work when used in a CB/CL72/77 engine.
#1 is a stock HONDA spring used in the early years and is the tallest with the thinnest wire of the stock/standard CB/CL springs I've removed from engines.
It is easy to release the clutch but my experience is it doesn't engage the clutch well and will in time allow the disc to ware and the clutch to slip.
#2 is the white paint on one end (1966/1967??) issue and does pull a little harder than #1 but gives a good feel at the lever as ya release it and the clutch disc engage smoothly and firm and no problem with the disc
#3 is the 810 HONDA issue and is the hardest of the 3 to release but gives a similar engagement as #2. It is the shortest and has the thickest wire of the three.
This info is from using each of these springs at one time or another as I've owned/ridden the bikes with these springs in the clutch.
No pressure measurement with tools just use over the years.
I install the #2 springs in all the rebuilds I do at this time. ............lm

Here are the dimensions of CB750K SOHC springs compared to CA77(2 versions), and a pic of CB750 Spring in the CA basket.

As you can see, there are differences in free length, wire thicknesses and coil spacing, with any of the three affecting the final installed spring pressure.

The shop manual specs for the spring tension are a little confusing to me.

The C72 specs state "15# at 25mm(.98 of binding length)" and "33-36# at 23mm(.90 max lift)"

The C77 specs state "33.7-34.6#" with no measurement lengths listed.

I will try to measure the tension at the installed length of each to see just how much difference there is.

[rzgkane]

I was afraid you'd say that.

Who knows. ...............lm

Part number for those springs with the white tips?

What I have to offer on this subject I will show with a pic and description as to how I find they work when used in a CB/CL72/77 engine.
#1 is a stock HONDA spring used in the early years and is the tallest with the thinnest wire of the stock/standard CB/CL springs I've removed from engines.
It is easy to release the clutch but my experience is it doesn't engage the clutch well and will in time allow the disc to ware and the clutch to slip.
#2 is the white paint on one end (1966/1967??) issue and does pull a little harder than #1 but gives a good feel at the lever as ya release it and the clutch disc engage smoothly and firm and no problem with the disc
#3 is the 810 HONDA issue and is the hardest of the 3 to release but gives a similar engagement as #2. It is the shortest and has the thickest wire of the three.
This info is from using each of these springs at one time or another as I've owned/ridden the bikes with these springs in the clutch.
No pressure measurement with tools just use over the years.
I install the #2 springs in all the rebuilds I do at this time. ............lm

Here are the dimensions of CB750K SOHC springs compared to CA77(2 versions), and a pic of CB750 Spring in the CA basket.

As you can see, there are differences in free length, wire thicknesses and coil spacing, with any of the three affecting the final installed spring pressure.

The shop manual specs for the spring tension are a little confusing to me.

The C72 specs state "15# at 25mm(.98 of binding length)" and "33-36# at 23mm(.90 max lift)"

The C77 specs state "33.7-34.6#" with no measurement lengths listed.

I will try to measure the tension at the installed length of each to see just how much difference there is.

[rzgkane]

Below is a pic of the clutch pack before I put the pressure plate on the clutch center. Is there enough teeth showing in the clutch center to bite into the pressure plate? I measured about 3mm of bite. I have a doubled up "A" using one 1.6mm plate and one 2.1mm plate. I can adjust the height of the clutch pack by removing the 2.1mm plate and going with two 1.6mm plates.


IMG_0732 by rzgkane, on Flickr

Also, Ed Moore indentified the clutch as a Cush, with one caveat. There is not enough room on the center to accommodate the double-thick "A" plate and still utilize the retaining wire. See below:


IMG_0736 by rzgkane, on Flickr

[rzgkane]

Look at the images below. Anyone ever seen cracks in this area before? If these are indeed cracks, I'm back to reinstalling the old center, basket and pressure plate.


IMG_0738 by rzgkane, on Flickr


IMG_0739 by rzgkane, on Flickr


IMG_0737 by rzgkane, on Flickr

[brewsky]

Look more like gouges to me.

Might see if you can sand them out or dye test to make sure.