Honda CB750 Sandcast

The Restoration Shop => Engine Mechanical => Topic started by: ashimotok0 on February 28, 2010, 09:47:01 pm

Title: Testing the Primary drive assembly
Post by: ashimotok0 on February 28, 2010, 09:47:01 pm

Hi - I posted a thread on the SOHC4 website but I am hoping you guys may have some of the data I need.

http://forums.sohc4.net/index.php?topic=65107.0

Also: http://forums.sohc4.net/index.php?topic=64960.0

I would like to set my primary drive sprocket assembly up on a torsion rig and measure the torque vs angular deflection into a data logger. That way I could determine the softness of the rubbers without de-riveting. Does anyone have an idea about the figures expected? I have three assemblies one '69 K0, one K7 and one F1 There appears to be no discernible free angular movement on the K0 one but I am unsure of the hardness of the rubber inside. after all they are 40 years old now. I intend to put the data onto an Excel graph and freely share the information. I will also share details of the test setup I am using. I already have all of the necessary instrumentation so it won't cost anything apart from my time!!

The basic data I need is:
1) Maximum torque applied on the primary drive sprocket assembly on a standard engine.
2) Hardness of the cush rubbers when new preferably in IRHD (International Rubber Hardness Divisions)
3) Dimensions on a new rubber ( not obtainable as a spare part from Honda and never was to my knowledge!! )
4) Any rubber compounding details.

I am going to use a scrap K7 assembly as a starting point for testing.

I imagine Sandcast owners will have addressed this issue, as, like mine, your primary cush drive may be 40 years old now.

I am aware of the HD ones from M3 but I am after standard engine performance. A German CB750 club manufactures new standard ones but won't sell to non-members.

Cheers Ash D

Title: Re: Testing the Primary drive assembly
Post by: Steve Swan on February 28, 2010, 09:47:27 pm

GREAT post, Ashimoto ! Looking forward to hearing replies !

Could you please 'sign' your name to you post ? So as we can get to know each other on a more personal basis to lessen the "cyber impersonal' effect.

Title: Re: Testing the Primary drive assembly
Post by: Bowswell on December 06, 2012, 02:30:50 pm

http://forums.sohc4.net/index.php?topic=114267.0 (http://forums.sohc4.net/index.php?topic=114267.0)

Title: Re: Testing the Primary drive assembly
Post by: Steve Swan on December 06, 2012, 10:00:59 pm

Hi boswell,

We like to get to know discussion board members on a more personal basis.  Any chance you could include your name with your posts.  We are such a small group, we encourage using our real name, not some pseudoname.  Thank you in advance for your consideration.