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Shimano 333 hub problem



 
 
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  #1  
Old January 7th 19, 03:23 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 6,970
Default Shimano 333 hub problem

I built up a lovely kids bike with a Shimano 333 coaster brake 3 speed
hub. The young lad rode it on the ride we took today.

There's been a consistent problem keeping gear #2 adjusted. It acts as
if an internal spring responsible for pulling the hub into 2nd gear is
somehow weak. That is, the little circle with the letter N doesn't
settle down in its target hole. As a kludge, I used a bit of inner tube
as a rubber band on the bellcrank to help pull the hub into 2nd, but
that rubber decayed and I didn't have a spare. In any case, I've
readjusted it several times in the past couple months.

I'd suspect a dragging cable, except the hub shifts into the other gears
just fine. 3rd gear requires the hub to retract the cable even more, and
shows no problems. Of course, I lubricated the cable during
installation. I even spent time grinding away part of the kickstand
mount to give the straightest possible cable routing.

Unfortunately, the bike is an hour away and I normally see it at most
once per week; so some things are difficult to check, other things may
be difficult to remember. But are these hubs extra sensitive to cable
friction? Instead of the full housing, should I consider scrounging
parts to run bare cable over pulleys, etc?

But if anyone has tips, I'd be grateful.

--
- Frank Krygowski
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  #2  
Old January 7th 19, 10:06 AM posted to rec.bicycles.tech
news18
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Posts: 307
Default Shimano 333 hub problem

On Sun, 06 Jan 2019 22:23:58 -0500, Frank Krygowski wrote:

I built up a lovely kids bike with a Shimano 333 coaster brake 3 speed
hub. The young lad rode it on the ride we took today.

There's been a consistent problem keeping gear #2 adjusted. It acts as
if an internal spring responsible for pulling the hub into 2nd gear is
somehow weak. That is, the little circle with the letter N doesn't
settle down in its target hole. As a kludge, I used a bit of inner tube
as a rubber band on the bellcrank to help pull the hub into 2nd, but
that rubber decayed and I didn't have a spare. In any case, I've
readjusted it several times in the past couple months.

I'd suspect a dragging cable, except the hub shifts into the other gears
just fine. 3rd gear requires the hub to retract the cable even more, and
shows no problems. Of course, I lubricated the cable during
installation. I even spent time grinding away part of the kickstand
mount to give the straightest possible cable routing.

Unfortunately, the bike is an hour away and I normally see it at most
once per week; so some things are difficult to check, other things may
be difficult to remember. But are these hubs extra sensitive to cable
friction? Instead of the full housing, should I consider scrounging
parts to run bare cable over pulleys, etc?

But if anyone has tips, I'd be grateful.


Its a few decades snce I rode with a Sturney Archer 3 spped hub and my
understanding of how they worked was you set #2, which was direct drive
and adjusted for #1/#3.

As you mentioned, things like cable drag, etc can affect gears meshing.
How old is it? I basically wore mine out. Well, dad purchased it second
hand and it was the kids bike although it ended up being me who rode it,
every where & everyday.

Is the hand piece(?)/adjuster correct for the device? I vaguely remember
one hand piece not being suitable, aka either twist grip or thumb
shifter. They were "indexed".

  #3  
Old January 7th 19, 01:48 PM posted to rec.bicycles.tech
AMuzi
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Posts: 10,167
Default Shimano 333 hub problem

On 1/6/2019 9:23 PM, Frank Krygowski wrote:
I built up a lovely kids bike with a Shimano 333 coaster
brake 3 speed hub. The young lad rode it on the ride we took
today.

There's been a consistent problem keeping gear #2 adjusted.
It acts as if an internal spring responsible for pulling the
hub into 2nd gear is somehow weak. That is, the little
circle with the letter N doesn't settle down in its target
hole. As a kludge, I used a bit of inner tube as a rubber
band on the bellcrank to help pull the hub into 2nd, but
that rubber decayed and I didn't have a spare. In any case,
I've readjusted it several times in the past couple months.

I'd suspect a dragging cable, except the hub shifts into the
other gears just fine. 3rd gear requires the hub to retract
the cable even more, and shows no problems. Of course, I
lubricated the cable during installation. I even spent time
grinding away part of the kickstand mount to give the
straightest possible cable routing.

Unfortunately, the bike is an hour away and I normally see
it at most once per week; so some things are difficult to
check, other things may be difficult to remember. But are
these hubs extra sensitive to cable friction? Instead of the
full housing, should I consider scrounging parts to run bare
cable over pulleys, etc?

But if anyone has tips, I'd be grateful.


Generally I'd suggest open, clean, lubricate but in the case
of an F or FA gearbox, you need the Shimano ball cup tool to
do that. Next time you're there, remove the bell crank and
see if the pushrod moves easily with your thumb. If it does,
you may merely have a sticky/smashed/worn bell crank and
those are simple to reform.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #4  
Old January 15th 19, 09:17 PM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Posts: 7,127
Default Shimano 333 hub problem

Following up on the problem three speed hub:

First, I see I mislabeled the hub. It's a Shimano 3CC coaster brake
model, not a 333.

I took the bike home and spent several evenings gazing at and
pondering the hub's internals. The Shimano mechanism is much
different than Sturmey-Archer's.

Everything inside is pristine and now clean of grease and lubed with
oil, except the ball bearings, which are greased. 2nd gear drive is
via axial meshing of two members with 56 tiny crown teeth. I looked
hard at that, since 2nd gear is where the irritating slipping occurs. But I see absolutely nothing wrong.

With the guts assembled and the axle held in a vise, but with the
shell (or wheel) removed, everything seemed fine, with one
largely irrelevant detail mentioned below. Installing the shell
plus wheel also seemed fine. For that work, I was holding the
bellcrank in the various gear positions by means of a tapered
wedge. But installed on the bike in a workstand, the hub first
seemed fine, but then started the 2nd gear skip.

Seems the cable tension adjustment had somehow shifted again; and
it seems to me this hub is much less tolerant of misadjustment
than the S-A hubs I'm more used to. Late last night, I re-adjusted
yet again, and at 11 PM it seemed OK, but I remain worried.

At this point, weather will prevent test rides for maybe a week.
We'll see how things go after that.

BTW, I thought the hub felt draggy. Applying a spring scale to
a chain on the sprocket, it took about 1000 grams (2 pounds) to
turn the sprocket even with no load, or even with the wheel
overrunning. That seems to be built in to the design of this
coaster brake version. There is a sort of steel band spring in the
brake mech, wrapped about 330 degrees around a "spring guide", and
normal pedaling rotates the guide inside that spring, with sliding
contact. I thought "That can't be right," but on further thought
and computation, it wastes only about 4 Watts. It's a little
offensive to this guy used to perfectly free-running bearings, but
it's mostly an aesthetic problem.

And digging around the internet and printed sources, it seems
Shimano tried and tried again with these hubs. There are several
generations, some with bellcranks on the left, some on the right.
The internals vary as well. I don't know where my hub is in the
trial-and-error cycle. Overall, I like Sturmey-Archer better.

- Frank Krygowski
 




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