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 <[email protected]>, [email protected] 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, >><BR><BR>

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
<[email protected]> 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" <[email protected]> wrote in message
news:[email protected]...
> "Fallaces sunt rerum species." - Seneca On Wed, 26 Nov 2003 12:08:12 -0500, dvt
> <[email protected]> wrote:
>
> >On Sun, 23 Nov 2003 21:24:00 -0500, John Dacey
<[email protected]>
> >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" <[email protected]re> wrote in message
news:[email protected]...
> 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 <[email protected]> wrote:

>In article <[email protected]>, [email protected] 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