1961 CB72 Project

[G-Man]

Greg

Email and picture sent....

G

How close did we get with the CYB 5 speed with the list I provided?

Greg

[G-Man]

Although the obvious thing to be doing this weekend was getting the engine finished, I realised that I needed to get some parts off to the chome platers. They do excellent work but that means that their turnaround time is in excess of two months. With the amount of travelling that I do it is necessary to plan ahead. I had one or two small bits ready to go but, before I could pay them a visit, I wanted to get some early damper bodies cleaned up.

The correct rear units for these bikes are the ones with aluminum covers top and bottom, but these are not very durable. I have restored a set but they will be kept for 'best'. If I am using the bike I will fit some slightly later rear shock absorbers. I picked up a rusty set with my '62 project and Alan Curtis had a set which needed restoring also. These 'not so early' ones are still not the mainstream type that Honda fitted later. The top covers are steel and the bottom clevis is similar to the very early ones - cast into the body, rather than welded on.

Unfortunately the other 'not-so clever' feature that Honda included was an aluminum screw which holds the damper rod in. All the others are steel and relatively easy to remove with tools that I have made. These aluminum ones were all already butchered by previous owners and to compound the crime that had all been nastily punched at the top to secure the screws.

I did manage to find a spare set on eBay for just $9.99 but they were just as bad as the ones I had. The chrome was a little better but that was the only consolation.



You can see the battered steel upper covers and here you can see the lower clevis..



Because the ends were damaged from the punch marks and the threads were all a mess I thought about cleaning up the threads in my lathe by screwcutting them but that is a risky business requiring careful set up and perfect alignment.



Then, I was idly searching eBay and came up with this: A giant 27mm x 1mm pitch tap from a supplier in China. I couldn't believe my luck. It was cheap and came pretty quick, too.....



Armed with this I was able to set the shock bodies up in the lathe in a fixture that I had made for dealing with CL77 dampers a while back.



Each body had to be individually trued up for running in the lathe but that was a minor problem now that I had the ability to clean them up nicely.



First job was to use that new tool to clean up the nasty threads.



Then I was able to clean up the end of the bodies by shortening them slightly. This involved removing around 3mm of the worst damage so that I could get them nice and square.



It's good doing multiple parts as most of the time is spent working out the method and getting things set up. I now have 3 sets of bodies. One for Alan. a spare set for my '61 bike and a set for my '62 CB72 which I am collecting parts for. They are now cleaned up sufficiently for Prestige Electroplating to do their magic.



The best bit for me is that I have managed to sort out all of that horrible thread damage. I still have to get 6 sets of innards ready for when the parts come back but I can take my time over that....



It will be nice if I can get them to look as good as the last two sets which are the type with alloy covers .......



G

[Waveblaster]

Nice work Graham

I am very jealous of the fact you have a lathe at your disposal.

regards

Greg

[G-Man]

Greg

It's one of the best purchases you can make for a home workshop. But, it doesn't matter which lathe you buy, it's always too small.... With a bit of ingenuity, you can get by.

The great thing is you get your investment back x10 by repairing parts the you's otherwise have to buy new or pay someone else to repair. Being able to make special tools is also a godsend.

I've had this one for 20 years. Bought secondhand, it is now worth 10 times what I paid. I wish the bikes were such a great investment...... :-)

G

[Steverino]

G Man
I don't know the first thing about metal lathes but your metal working posts make me want to learn. My father in law was a machinist for Boeing and he has a lathe in his shop he hasn't used in thirty five years. I wonder... I can just image how many parts I could ruin. I break enough stuff with the tools I have now.
Steve

[G-Man]

Steve

It's extremely satisfying doing this stuff. Your father-in-law will have developed some very special skills at Boeing. Derby, where I live, is the home of Rolls Royce (cars and planes) and there have been some pretty special metal magicians here.

It doesn't matter what you do with the lathe but you will find it amazingly satisfying if you persevere. Just being able to shorten a bolt nicely or to make a bush is just such great therapy.

I bet that you father-inl-law has some pretty special tools in his collection as well as the lathe.

G

[sixtiescycle]

Greg

It's one of the best purchases you can make for a home workshop. But, it doesn't matter which lathe you buy, it's always too small.... With a bit of ingenuity, you can get by.

The great thing is you get your investment back x10 by repairing parts the you's otherwise have to buy new or pay someone else to repair. Being able to make special tools is also a godsend.

I've had this one for 20 years. Bought secondhand, it is now worth 10 times what I paid. I wish the bikes were such a great investment...... :-)

G

I'll second that! I don't use mine enough but it is handy to have when you need it. My quick change gearbox spit some gear teeth a while back so I bought a second lathe. Box was an A/M addition and obsolete. Found one on ebay years later and it's back up and running, then sold the other one for a profit..................well not really, it paid for the quick change box!