1961 CB72 Project

G-Man · Post by **G-Man** » Sat Sep 20, 2014 1:48 pm

I managed to get a start on the painting today. Frame tank and swing arm got a coat of etch primer and I filled in the pits with knifing putty. Tomorrow I'll get some filler primer on and get the parts nicely smoothed out. I have some repairs to do on the chain guard and rear fender before I can get some paint on those.

G

frame by graham.curtis, on Flickr

G-Man · Post by **G-Man** » Sun Sep 21, 2014 12:30 pm

I noticed that there was some work to do on the swing arm where the chain guard bracket had been repaired rather untidily. I ground back the existing weld and re-did the joint with a neater gas-weld.

The stand pivot suffered the typical CB72 wear caused by slack pivot bolts. I thought it would be OK but when I checked it with a 10mm bar it was obvious that it needed fixing. These early bikes have a short stand so any wear would be a problem.

worn stand pivot by graham.curtis, on Flickr

I ground out some of the metal to make the weld easier.

grinding.jpg by graham.curtis, on Flickr

Each hole got welded up, taking care to leave the unworn part at the bottom as a reference.

weld by graham.curtis, on Flickr

Once the holes were welded up I ground the faces flat, re-drilled the holes and refinished with etch-primer.

This should give the fresh bolts something to work with.

finished by graham.curtis, on Flickr

After the rectification work I was able to give all of the parts another couple of coats of primer.

more parts by graham.curtis, on Flickr

smccrory · Post by **smccrory** » Sun Sep 21, 2014 12:45 pm

Looking great!

G-Man · Post by **G-Man** » Fri Sep 26, 2014 2:11 pm

I heaved a sigh of relief as I saw the wonderful job that Prestige Electroplating had made of some rather sorry-looking parts from this bike. Also a relief was seeing some of the parts that are unique to these early bikes. Now that they are shiny it is clear to see the difference from later models.

Chrome from Prestige by graham.curtis, on Flickr

The gear shifter has a pronounced oval section compared with the later bikes.

gearshift 1 by graham.curtis, on Flickr

You can see that lovely narrow section in the next pic...

gearshift 2 by graham.curtis, on Flickr

The rod ends are beautifully shaped compared with the later versions which are much cheaper to manufacture

gearshift 3 by graham.curtis, on Flickr

The front brake (single) lever is held on with a chrome plated nut and carries a chrome plated return spring. The rear linkages is similar to other early bikes with a nut to hold the levers on to the spline.

brake linkages by graham.curtis, on Flickr

Rear shocks are unique to the early bikes. The preload ring sits on a sturdy "L" shaped stop which is brazed rather than spot welded to the shock body. The preload ring and collets are steel rather than alloy. These two items would appear to negate any weight saving from the use of alloy covers.

Rear Shocks by graham.curtis, on Flickr

I am looking to get in a couple of good painting days this weekend so we might see some shiny blue and silver cycle parts soon...

G

Eljeef · Post by **Eljeef** » Fri Sep 26, 2014 8:13 pm

Great work. Love to see such detailed effort.

G-Man · Post by **G-Man** » Sat Sep 27, 2014 12:21 am

Thanks!

This one's becoming a bit of an obsession. :-)

G

G-Man · Post by **G-Man** » Sun Sep 28, 2014 11:59 am

Saturday was a bit of a disappointment weather-wise but I managed to get some primer on most of the parts that are going to be blue. Today the sun came out and I was able to make some real progress. The blue is a Volkswagen color originally matched to the inner chain guard on my C72 and double checked against the paint inside the headlamp of this CB72.

I have to do my painting outside so I need good still warm days to stand a chance of making a good job. We are having a 'late summer' here so I have been able to catch up a little bit this weekend. The parts that I haven't done will probably have to wait until spring next year.

spray booth by graham.curtis, on Flickr

I made an early start and got the final wet sanding and priming out of the way and then was able to get some color onto the parts. I was hoping to get on to the silver pieces but they will have to wait for the next warm spell.

frame in blue by graham.curtis, on Flickr

Another interesting (to me at least) detail on the '61 frame is that it is missing the two locations for the single seat / carrier just behind that rear cross-member. Later CB72s and 77s have those two threaded bosses in a larger cross member and the rectifier bracket has extra stiffening pressed in.

Once everything had had a little time to dry. I couldn't resist a little 'trial assembly'.

Here are the fork sliders with their freshly chromed seal holders....

fork legs by graham.curtis, on Flickr

And here are the headlamp ears and stanchion covers with their mating chrome ribs.

fork covers by graham.curtis, on Flickr

Finally those difficult-to-find aluminium rear shock covers and their paper-thin anodise aluminium lowers.

Suspension covers by graham.curtis, on Flickr

Looking at the later pictures it looks like I painted the parts three different shades of blue! The first picture shows the color best....

It's been a long day.....

G