Torpedo Duomatic "sudden brake", then heavy to get loose
 

Hello again guys,

today there was a guy with a Torpedo Duomatic
and I recall I've seen his problem before, also
on a Duomatic.

When you brake, instead of getting a modular
effect, at some point the break virtually looks
the wheel - if the bike is upside down, this
happens all but instantly!

After this, the wheel stays like that unless
considerable effort from the crank will get it
loose and one can start pedaling
normally again.

Here is an explosion of the Duomatic
rear hub [1]. It is in German but I suppose the
world of mechanics has a language of its own.
The brake shell is part 11, right?

Anyone knows what to do/replace?

TIA

[1] http://user.it.uu.se/~embe8573/bike/duomatic.png

--
underground experts united
http://user.it.uu.se/~embe8573

Torpedo Duomatic "sudden brake", then heavy to get loose
 

On 4/13/2018 12:58 PM, Emanuel Berg wrote:
Hello again guys,

today there was a guy with a Torpedo Duomatic
and I recall I've seen his problem before, also
on a Duomatic.

When you brake, instead of getting a modular
effect, at some point the break virtually looks
the wheel - if the bike is upside down, this
happens all but instantly!

After this, the wheel stays like that unless
considerable effort from the crank will get it
loose and one can start pedaling
normally again.

Here is an explosion of the Duomatic
rear hub [1]. It is in German but I suppose the
world of mechanics has a language of its own.
The brake shell is part 11, right?

Anyone knows what to do/replace?

TIA

[1] http://user.it.uu.se/~embe8573/bike/duomatic.png


Bearing is set too loose and/or locknut(s) are not tight.

Adjust bearing to a slight trace of play at the rim. This
is usually done with axle in vise, holding upper end of axle
in one hand and rim in the other.

If hub feels sticky, add oil or open clean and refresh
lubricant.

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

Torpedo Duomatic "sudden brake", then heavy to get loose
 

AMuzi wrote:

Bearing is set too loose and/or locknut(s)
are not tight.

So the problem is the break-arm piece cannot
reach the brake shell?

OK, great, will try that, thanks.

Adjust bearing to a slight trace of play at
the rim. This is usually done with axle in
vise, holding upper end of axle in one hand
and rim in the other.

Hm, I've done this a couple of times by now (in
a vice) but I don't remember any trick or
method. It is done just like the cone and nut
on a front wheel, right? (Or the bottom bracket
I suppose.) Back and forth a few times until
just right? What end of the axle do I put into
the vice, the one that doesn't have the
brake arm?

--
underground experts united
http://user.it.uu.se/~embe8573

Torpedo Duomatic "sudden brake", then heavy to get loose
 

On 4/13/2018 4:32 PM, Emanuel Berg wrote:
AMuzi wrote:

Bearing is set too loose and/or locknut(s)
are not tight.

So the problem is the break-arm piece cannot
reach the brake shell?

OK, great, will try that, thanks.

Adjust bearing to a slight trace of play at
the rim. This is usually done with axle in
vise, holding upper end of axle in one hand
and rim in the other.

Hm, I've done this a couple of times by now (in
a vice) but I don't remember any trick or
method. It is done just like the cone and nut
on a front wheel, right? (Or the bottom bracket
I suppose.) Back and forth a few times until
just right? What end of the axle do I put into
the vice, the one that doesn't have the
brake arm?


Duomatic only adjusts on the left side so left side up.

I shouldn't have to say this but use an axle vise or clamp
on an axle nut, not directly on the axle itself.

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

Torpedo Duomatic "sudden brake", then heavy to get loose
 

AMuzi wrote:

I shouldn't have to say this but use an axle
vise or clamp on an axle nut, not directly on
the axle itself.

The atmosphere here sure hasn't changed...

--
underground experts united
http://user.it.uu.se/~embe8573

Torpedo Duomatic "sudden brake", then heavy to get loose
 

On Friday, April 13, 2018 at 8:37:37 PM UTC-4, Emanuel Berg wrote:
AMuzi wrote:

I shouldn't have to say this but use an axle
vise or clamp on an axle nut, not directly on
the axle itself.

The atmosphere here sure hasn't changed...

???

Seems to me you got good information. You don't seem grateful.

- Frank Krygowski