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Old style rocker arms

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G-Man
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Old style rocker arms

Post by G-Man » Wed May 23, 2012 2:09 pm

I just found these in a box of bits and noticed that they are different from any that I've seen before.

Are they an early type? They weigh 10% less than the rockers that I am familiar with and have less metal in the top part of the arm. Any thoughts? They do look like the diagrams in the parts manual. It must have been expensive to make new forging dies.

What I assume to be the later type appears to have been beefed-up but the ones I have here don't see to have unusual wear on them.

G
Attachments
Comparison with 'normal' type
Comparison with 'normal' type
Same critical dimensions but more relief on top.
Same critical dimensions but more relief on top.
Set of four 'different' rockers, all in good shape.
Set of four 'different' rockers, all in good shape.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

LOUD MOUSE
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Re: Old style rocker arms

Post by LOUD MOUSE » Wed May 23, 2012 3:34 pm

Jerry tells me they are EARLY DREAM issue. ..............lm
G-Man wrote:I just found these in a box of bits and noticed that they are different from any that I've seen before.

Are they an early type? They weigh 10% less than the rockers that I am familiar with and have less metal in the top part of the arm. Any thoughts? They do look like the diagrams in the parts manual. It must have been expensive to make new forging dies.

What I assume to be the later type appears to have been beefed-up but the ones I have here don't see to have unusual wear on them.

G

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G-Man
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Post by G-Man » Wed May 23, 2012 3:44 pm

LM

Many thanks for that. Neither of my 1960 Dream motors has anything like these. I wonder if they had failures on the early bikes?

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

jensen
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Post by jensen » Wed May 23, 2012 3:59 pm

Hi,

I found them in a dream '60 engine, and in some CB72 '61 engines.
First I really thought that someone took a grinder to make them lighter, so I threw them away !!!!!!!! (these were worn anyway),

Thanks Jerry (and LM),

Jensen
assembly of Japanese motorcycles requires great peace of mind (Pirsig)

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G-Man
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Post by G-Man » Wed May 23, 2012 5:10 pm

Jensen

These are in excellent condition so they will go in one of my 1960 engines. It would be interesting to know if any of these did fail due to lack of strength or whether Honda just changed them to increase the factor of safety.

They do look like they have been roughly fettled to take off the forging flash.

I assume that the little pad above the cam follower pad on both type is for setting the valve clearance on the assembly line. It's tempting to remove that as it doesn't appear to contribute to the strength of the part'

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

conbs
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Early Rocker Arm

Post by conbs » Fri May 25, 2012 2:52 pm

G, My '64 Dream Parts Manual shows a C721521A part number for rocker arms superseded by CB721521S1 but it does not give a frame range for either. Also, it gives the same part number for all 4 rockers, though the picture seems to show 1 each of the early and late.

I looked at my '60 Dream 305 motor C77E A10071 and sure enough it has the early rockers as you have found.

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