What's inside a shimano sealed bottom bracket?

I've searched the web for a picture or drawing without success.

My UN-72 has developed a metallic double clicking sound, twice per revolution,
It feels OK when turned by hand, and there's no side to side play. I've already
taken it out of the frame and the threaded cups and shell look entirely normal.

Does this sound indicate a pending terminal failure, or is it simply a loose
race inside the shell?. Should I be worried?

Mike

In article ,
where says...
I've searched the web for a picture or drawing without success.
My UN-72 has developed a metallic double clicking sound, twice per revolution,
It feels OK when turned by hand, and there's no side to side play. I've
already
taken it out of the frame and the threaded cups and shell look entirely
normal.
Does this sound indicate a pending terminal failure, or is it simply a loose
race inside the shell?. Should I be worried?

I would check the crank and the pedals too. They could be the source
of your noise. Especially since you said the BB feels smooth when you
turn it by hand.
---------------
Alex

Mike- My UN-72 has developed a metallic double clicking sound, BRBR

Make sure you tap the right cup off, lube in there and then tap it on. Lube in
the left cup and the BB shell..all tight.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

On Mon, 01 Mar 2004 19:09:18 +0800, Mike Buckler
may have said:

I've searched the web for a picture or drawing without success.

My UN-72 has developed a metallic double clicking sound, twice per revolution,
It feels OK when turned by hand, and there's no side to side play. I've already
taken it out of the frame and the threaded cups and shell look entirely normal.

Does this sound indicate a pending terminal failure, or is it simply a loose
race inside the shell?. Should I be worried?

The last time I had a noise like that, the left retainer wasn't tight
enough. Check your pedals, too.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

A prior posting by John Dacey (who made the effort to crush a 6500 just to
see) on this topic:

"John Dacey" wrote in message
...
"Fallaces sunt rerum species." - Seneca
On Wed, 26 Nov 2003 12:08:12 -0500, dvt wrote:

On Sun, 23 Nov 2003 21:24:00 -0500, John Dacey

wrote:

A full complement of 1/4" balls surrounding a spindle of this
dimension seems not possible with the space constraints.

Is it possible that the spindle has a smaller OD inside the cartridge? I
haven't looked at this newfangled fancy stuff, but it's possible that the
spindle is only 26.7mm on the visible portion of the BB.

Curious, I crushed the left sided of a worn 6500 cartidge yesterday to
see what lay within. The interior section of the spindle normally
obscured from view _is_ stepped down somewhat from the Ø of its
visible ends, and the race upon which the balls orbit is cut even
further into the spindle. The bearing complement on the left side was
seven 7/32" balls.

Thanks for the input on this. I actually bought / installed the 6500
yesterday. It took 2min to install. Compared to the 45min I spent trying to
get the old original 7700 to spin smoothly, it was a dream.


"Mike Buckler" wrote in message
...
I've searched the web for a picture or drawing without success.

My UN-72 has developed a metallic double clicking sound, twice per
revolution,
It feels OK when turned by hand, and there's no side to side play. I've
already
taken it out of the frame and the threaded cups and shell look entirely
normal.

Does this sound indicate a pending terminal failure, or is it simply a
loose
race inside the shell?. Should I be worried?

Mike

A mechanic's stethescope at less than ten dollars will do a lot toward
intuiting the source of the click. Try different cup torque settings, see if it
gets worse the harder you fix the cups. (Retainers....)



My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter

On Mon, 01 Mar 2004 07:44:08 -0500, Alex Rodriguez wrote:

In article ,
says...
I've searched the web for a picture or drawing without success.
My UN-72 has developed a metallic double clicking sound, twice per revolution,
It feels OK when turned by hand, and there's no side to side play. I've
already
taken it out of the frame and the threaded cups and shell look entirely
normal.
Does this sound indicate a pending terminal failure, or is it simply a loose
race inside the shell?. Should I be worried?

I would check the crank and the pedals too. They could be the source
of your noise. Especially since you said the BB feels smooth when you
turn it by hand.

I changed the pedals, cranks, wheels and the bottom bracket, none of which made
the slightest difference.

It turned out to be the aluminium mudguard rubbing against the rear carrier when
the frame flexed under load. The actual source of the sound was way back over
the rear wheel, but it was traveling along the mudguard and being broadcast near
the bottom bracket !

Mike