Primary chain rub on top bolt hole boss of left outer cover

[LOUD MOUSE]

The early outer basket will have the raised casting at the contact area for the aluminum friction go over the edge at the sprocket.
The Cush will have that edge turn back to the other edge and ya may find a oil grove cut into the bushing which rides on the trans shaft.
The center hub and pressure plate have a raised circle in the middle.
This is one of those "easy for me" but tough to describe. ....lm

I thought it was in this thread, but it might have been in one of the threads I found when I searched the subject initially.

I believe it was LM that said he always replaces his clutch basket with the version that has a cush drive included. How do you tell if you have the cush drive basket (or is it the hub?).

Both my '65 clutch and my '67 appear to be the same, except for the keeper wire hole count. I supposed the cush drive cushions could be between the alum basket and the steel plate that is riveted along with the sproket to the basket. But it seems to be an awfully thin space for any kind of cushions.

Are the cush drive clutches obvious to identify?

Thanks,
Rob

[jensen]

Hi Dave,

I measure the (maximum) distance between the two sprockets (clutch and primary sprocket) between the tooth of both sprockets in a straight line (on the axis to axis line of both sprockets)

It's difficult to see on the picture, if necessary, I will take a new picture or make a drawing.

I used a new clutch and a new primary sprocket. If you take a used primary sprocket and a used clutch, these figures will be different (larger).

Jensen

btw, the maximum "stretch" of the chain between an 19.9 and the 24.1 mm is twice the difference, thus 8.4 mm. That doesn't mean that the chain is 8.4 mm longer, since the "stretch" is also due to the smaller diameter of the pins

[davomoto]

Excellent! Thanks for posting that info jensen. I have several used chains, and I'm always trying to figure out which is in the best shape.

Davo

[Snakeoil]

Jensen,

May I ask a favor of you? Would you please measure across the diameter of the clutch sprocket in several places on a new clutch basket assembly at the bottom of the sprocket teeth and tell me what you get?

I just measured my worn primary sprocket against my NOS sprocket and although the tips of the teeth are worn on the worn sprocket, the root diameters of the sprocket are identical if not a tiny bit larger than the NOS sprocket. I realize that the sprockets where more on the flanks of the teeth as this is where the mating surfaces rub, but any looseness that is sprocket related should be caused by wear at the root where the root radius increases circumferentially. So I would expect there to be some root diameter wear.

My clutch sprocket, which appears to be in excellent condition measures 136.1mm to 136.0 mm. Being 47 teeth, it is not a true diameter, but the root radius makes the measurements all similar provided the wear is similar.

I was also thinking that if you did a similar measurement for a smaller group of teeth, say 12, it would give you an idea of wear as compared to a NOS sprocket.

My intent for all this anal measuring is for those of us who do not have boxes of NOS part lying around. If you get an engine that has worn sprockets and a fairly new replacement chain, you might measure excess chain slack and think it is the chain when in fact it is the sprockets. Being able to measure the sprockets for wear would be helpful. Or is sprocket wear no common on these engines?

Primary side is going back together today. I have all my new parts, including NOS case screws that I bought because I thought the new paint deserved new shiney screws.
regards,
Rob

[jensen]

Hi,

No problem, tonight I will measure a few NOS clutch baskets and provide the data,

Jensen

[jensen]

Hi,

As promised :

first measurement : 136 +0.05
second measurement : 136 +0.05
third measurement : 136 +0.00

measurements are 120 degrees around the circle,

Jensen

[G-Man]

Jensen

Those are really good measurements and very useful for determining wear. I am going to make a note for future reference. Because those chains are very wide I don't think the traditional methods are very useful.

Thanks!

G