On 9/18/2018 12:03 PM, Frank Krygowski wrote:
I'm finishing up the build of a sweet kids bike, including a
NOS Shimano 3CC coaster brake hub of unknown vintage.
(Thanks again to Andrew as the source of the appropriate but
rare shifter.) The bike is a very lightweight and pretty
little antique. It also has hand brakes.

The bike is in my workstand and ready to go, but I have one
worry. When turning the cranks, there seems to be excess
resistance. It's not the bottom bracket, because I
overhauled that, plus the cranks feel very free during the
forward or backward motion until the drive or the brake
engage. It doesn't affect coasting; the rear wheel seems to
spin very freely, so the coaster brake is not dragging. The
friction seems to be in the drive motion itself.

(About five and ten years ago, I resurrected two other bikes
with Shimano three speed hubs and don't remember feeling
this resistance. But that was long ago.)

I've added lubricating oil via the axle's pushrod hole, but
so far I perceive no difference. I'm (understandably?)
reluctant to disassemble the hub, not only because I'd like
to deliver the bike in three days. Is there a reasonable
chance it will "wear in" and loosen up? Should I consider a
solvent flush and adding oil? Or I wonder if there's a
bearing adjustment that applies to the drive mechanism,
separate from the main wheel bearings?

I've gazed at the Shimano hub manual available at Sheldon's
site
https://www.sheldonbrown.com/sutherl...-5-shimano.pdf
but at least so far, I don't recognize a solution there.

Any tips?


Unusual problem these are so simple and reliable generally

1. Unlikely to be the problem but check hub bearing. Mount
the wheel in a vise adjustment side up. Hold the axle in
one hand and move the rim up and down in the other. Adjust
for a trace of play at the rim.

2. Maybe a tight spot in the chain adjustment? Easy to check
for that.

3. Possible frame ends not parallel and axle is flexing.
This would have to be extreme for a symptom.

4. Perhaps dirt/crud/rust in gearbox. Wouldn't hurt to undo
the adjustment enough to peek at the bearing. If rust shows,
these are simple assemblies don't be afraid of a
rebuild/clean/lube.

Do write back I'm curious to know what you find.
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971