The crankshaft looked in a shocking state and he asked me if I knew anyone who could take it on. All bearings were locked solid and it didn't look recoverable.
I made a start and pulled it apart, not expecting much.
Although the big ends would not rotate on their pins, they did come apart.
The rollers were stuck in the big end cages and had to be physically pushed out after soaking in a hot ultrasonic bath.
I realised, eventually that this thing was stuck together with old Cartrol R vegetable oil which was popular back in those days.
Multiple visits to the bead blaster and ultrasonic cleaner were required to get it cleaned up, but all bearing surfaces wre perfect. As usual with these cranks, the sludge traps in the big end pins and the centrifuges which feed oil to the big ends wre clogged with dirt which had to be drilled and scraped out.
This stuff will eventually reduce or even block the feed to the bearings so it needs to be removed.
After several hours of cleaning, I could get ready to re-assemble.
The centre-section, in particular, needs careful alighment so I used the fixture I made for my own CB72 crank to keep all of the parts lined up.
With that done, pressing the outer webs on is just a matter of lining them up as closely as possible before final truing up.
It's necessary to get the outer shafts trued to within 0.001" and I do this by sitting the crank, without outer bearings in a set of crank cases and checking runout with a good dial gauge. Corrections are made with a good 'dead blow' mallet.
This one went together without any new parts. Everything was in spec with no visible damage.
A good day in the office..... :-)
G
