1961 CB72 ProjectSara
Thanks! It will be nice to get this one back together and see the results...... Have you found that CB400F, yet? You need another project.... :-) 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 Hi Jerry
It means a lot to see your kind thoughts. I have had advice from some special people, not least, yourself, on this forum and elsewhere. Give me another 50 years or so and I might come up with something equivalent to what you have done... :-) I hope you're back to fitness again. 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 Before anything could be done with my con-rod small ends I had to make a fixture to hold them securely. I did't want anything flying around the workshop so I came up with a solid steel bar that the rod could be bolted down to. Both small and big ends of the rod are the same width at 18mm so there was noting complicated needed other than to hold it down.
I made up a steel bush to clamp the big end and then made a 'saddle' to hold the small end tight while all of the machining was happening. First job with the rod loaded in was to open up the existing 'slack' small end. This was opened up and reamed it to 16mm. Once I had a measurement for the reamed hole, a bush could be made to suit.  I found these neat telescoping bore gauges on my shelf. Haven't used them for ages but they were just right for getting in to the rod end. The bore came out at around 16.05mm and a bit of interference is necessary to fit the bush, so I aimed at around 16.08. Two bushes were made out of some nice bronze and to keep the bush strong enough to press in I left it with quite a thick wall.  The bush came out pretty close to my intended size and I left the inside diameter at 11.5mm  Using some soft protection in the vise, I pressed in the bushes.  With the rod back in the fixture on the milling machine, the bush was carefully bored out until there was only a thin 1/2mm wall thickness. I did not want to weaken the con-rod so the bush has to be pretty thin. Time will tell if this is enough.  As I got close to the finished size I had a new wrist pin to hand to keep checking the fit. Eventually the pin went in with a satisfying amount of pressure to get it to slide through  It's a little but sad to think that most of the bronze is now a pile of dust on my milling table but I think I have brought these old rods back from the dead. I tried to machine the oil slots in the milling machine but just could not get in the right position. In the end the Dremel came to the rescue with a thin grinding disk.  Last job before reassembly was to make a couple of plugs to seal up the big-end oil galleries and drive them in.  With that done it's now time to bite the bullet and put the bits back together. I am going to chicken out of that as today is Mother's Day in England and it would be a bit rude to stay in the workshop all day...... G
Last edited by G-Man on Sun Mar 15, 2015 1:52 pm, edited 4 times in total.
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F Hah! Yes if you knew my Mother she would have been up for that. A bit chilly for her today and she's happier watching rugby football on TV. She's always kept up with motorcycles though and tolerated three of her sons being bike enthusiasts...
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F It was France Vs Italy this afternoon, I think.... :-)
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
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