A recent outing on My 1985 Colnago Master highlighted a problem in that when freewheeling downhill the rear derailleur was “picking up”. This annoying fault indicated a problem in the hub which is part of the Shimano 600 x 6 speed gearing, and in particular the Regina Free Hub.
The first job was to remove the spindle and then a Park Tool FR4 block tool to remove screw on block and free wheel hub from the wheel.
Once the free hub was removed from the wheel hub the individual sprockets could be removed, the outside three are threaded to each other and these needed unscrewing, this is achieved using two chain whips or in this case 1 whip and a length of old chain gripped in a vice. The larger three sprockets then lifted off with spacers between.
The free hub can then be opened, the cover is a left hand thread and needed to be shifted with a punch before a pin spanner or straight circlip pliers, this exposed the top race and the 32 x 1/8’’ ball bearings removed. the outer case is then lifted to show the bottom race and pawls and it became clear we were short of ball bearings, research suggested there should be 39 but with only 35 present this would have caused the hub to stick and lift the derailleur, the balls were still in good shape so I can only assume the shortfall were as a result of a previous repair.
The hub and bearings were all cleaned with solvent and ball bearings checked for size and shape, then began the process of greasing the races and replacing all the balls with tweezers, the pawls were lubricated and all reassembled. The cogs cleaned and refitted and then the unit screwed onto the wheel hub,
I also took the opportunity to take out, clean, and regrease the cone and cup wheel hub bearings.
Assembly is easy but final adjustment is a bit trickier. Because the quick-release mechanism compresses the axle slightly when it is tightened. If you adjust the cones so that they feel just right off the bike, they will bind when you tighten the wheel with the quick release. You must set the cones carefully so that there is the smallest amount of play when the hub is off the bike so when the wheel is installed with the compression of quick release it takes up this adjustment.
A quick test ride and all working as it should, I enjoy repairing these bikes almost as much as riding them.