Stuck plastic bottom bracket adaptor

I'm working on a $10 1990's fixer-upperer with an English threaded Shimano
LP20 cartridge BB. I thought it peculiar that this one goes in from the
non-drive side and the plastic adaptor left-hand threads in on the drive
side. However, Google assures me that this configuration is not unknown
although I've never seen it before. Anyhow, the cartridge came out with a
little persuasion, penetrating oil and hot air gun. The plastic adaptor has
totally chewed out internal splines, probably from some previous Fred trying
to unscrew it counterclockwise.

I know that the subject of stuck plastic cup has been touched on quite
recently in RBT but I cannot now find it, even with Google. At the risk of
being boring, can I ask for favourite strategems for dealing with such a
problem? I was thinking of making careful axial cuts with a hacksaw blade in
the hope that I can crack out sectors of the circle with a flat punch one at
a time until the remnants just fall out. I also thought of recutting the
splines deeper with a Dremel rotary burr using the visible nubs of the
splines as a guide and then trying the heat, penetrant and Shimano tool
again. Anyone got any different ideas?

PH

"Peter Howard" wrote in message
...

I know that the subject of stuck plastic cup has been touched on quite
recently in RBT but I cannot now find it, even with Google. At the risk of
being boring, can I ask for favourite strategems for dealing with such a
problem? I was thinking of making careful axial cuts with a hacksaw blade
in the hope that I can crack out sectors of the circle with a flat punch
one at a time until the remnants just fall out.

Pretty much it. I got an Al one out that way - it turned out to be quite
easy (cut, cold chisel to shift what's been cut). Threads needed to be
chased afterwards, but that's not hard if you've got a friendly LBS. Plastic
will be even easier. You only need to get a few mm out and the rest follows
pretty much instantly.

I also thought of recutting the splines deeper with a Dremel rotary burr
using the visible nubs of the splines as a guide and then trying the heat,
penetrant and Shimano tool again. Anyone got any different ideas?

Don't bother with that - just cut the thing out.

cheers,
clive

On Aug 18, 10:32*am, "Clive George" wrote:
"Peter Howard" wrote in message

...

I know that the subject of stuck plastic cup has been touched on quite
recently in RBT but I cannot now find it, even with Google. At the risk of
being boring, can I ask for favourite strategems for dealing with such a
problem? I was thinking of making careful axial cuts with a hacksaw blade
in the hope that I can crack out sectors of the circle with a flat punch
one at a time until the remnants just fall out.

Pretty much it. I got an Al one out that way - it turned out to be quite
easy (cut, cold chisel to shift what's been cut). Threads needed to be
chased afterwards, but that's not hard if you've got a friendly LBS. Plastic
will be even easier. You only need to get a few mm out and the rest follows
pretty much instantly.

I also thought of recutting the splines deeper with a Dremel rotary burr
using the visible nubs of the splines as a guide and then trying the heat,
penetrant and Shimano tool again. Anyone got any different ideas?

Don't bother with that - just cut the thing out.

cheers,
clive

I cut too,and found it to be the easiest way,anything else and you
will start going a bit nuts.

On Aug 17, 2:02 pm, "Peter Howard"
wrote:
I'm working on a $10 1990's fixer-upperer with an English threaded Shimano
LP20 cartridge BB. I thought it peculiar that this one goes in from the
non-drive side and the plastic adaptor left-hand threads in on the drive
side. However, Google assures me that this configuration is not unknown
although I've never seen it before. Anyhow, the cartridge came out with a
little persuasion, penetrating oil and hot air gun. The plastic adaptor has
totally chewed out internal splines, probably from some previous Fred trying
to unscrew it counterclockwise.

I know that the subject of stuck plastic cup has been touched on quite
recently in RBT but I cannot now find it, even with Google. At the risk of
being boring, can I ask for favourite strategems for dealing with such a
problem? I was thinking of making careful axial cuts with a hacksaw blade in
the hope that I can crack out sectors of the circle with a flat punch one at
a time until the remnants just fall out. I also thought of recutting the
splines deeper with a Dremel rotary burr using the visible nubs of the
splines as a guide and then trying the heat, penetrant and Shimano tool
again. Anyone got any different ideas?

PH

soldering gun, hot knife? no thread damage at all then. Pat

"Clive George" wrote in message
et...
"Peter Howard" wrote in message
...

I know that the subject of stuck plastic cup has been touched on quite
recently in RBT but I cannot now find it, even with Google. At the risk
of being boring, can I ask for favourite strategems for dealing with such
a problem? I was thinking of making careful axial cuts with a hacksaw
blade in the hope that I can crack out sectors of the circle with a flat
punch one at a time until the remnants just fall out.

Pretty much it. I got an Al one out that way - it turned out to be quite
easy (cut, cold chisel to shift what's been cut). Threads needed to be
chased afterwards, but that's not hard if you've got a friendly LBS.
Plastic will be even easier. You only need to get a few mm out and the
rest follows pretty much instantly.

I also thought of recutting the splines deeper with a Dremel rotary burr
using the visible nubs of the splines as a guide and then trying the
heat, penetrant and Shimano tool again. Anyone got any different ideas?

Don't bother with that - just cut the thing out.

cheers,
clive


It's out. Many thanks to all respondents. It succumbed quickly to the
hacksaw treatment. Two cuts not quite down to the threads seemed to relax
the tension or something and the mangled cup moved, then backed out quite
easily. No thread damage at all. If Mark Cavendish's Giant is a Ten and an
Xmart BSO is a One then this Diamondback is about a Three. Despite its
lowliness, I know someone who will be happy to have this bike when I've
finished tarting it up.

PH