Brake Caliper Type 14 Bleed Nipple Extraction

[GrayFox]

Wondering if anyone has a magic solution to a brake caliper problem with my "free" (ha ha) Herald 13 60.  
I got the n/s caliper off without major trauma, replaced the piston and seals and refitted it successfully.  However, on the nearside front caliper the bleed nipple has snapped off and I wonder if there is a way to get it out.  

[beefertoo]

soak the whole lot in diesel for a couple of days or a bit of heat maybe?  depends on how tight it was in the first place, could try drilling most of it out then a screw extractor. if taken gently you should ''feel'' when the drill breaks through the sealing taper,that then should relieve pressure on the threads........good luck

craig

[junkuser]

A tricky job Gray Fox but there may well be someone who has a reliable method.
My approach would be to first try to free the bond between the threads on the nipple and the caliper before attempting to unscrew it.
Heating and cooling may be best first.
One trick is to use an oxy torch directly on the centre of the broken of nipple to bring it to red heat and then let it cool before attempting any mechanical means of unscrewing.
The principle is that the nipple tries to expand but can't because the surrounding metal has not so in effect it is crushed. On cooling it will shrink away from the surrounding metal.
Possibly one of those chilling products would help if necessary.
Some penetrating oil at this stage and possibly a firm tap on the end of the broken nipple with a hammer using a drift whose diameter is just less than the root diameter of the thread.
The idea behind the tapping trick is that the nipple was tightened so the upper surfaces of the thread are in contact, Tapping it hopefully compresses the tip a bit to break the threads clear.

This is submitted for your consideration pending the posting of better ideas.
An "Easy Out" type tool could then be tried but only gently as they lill tend to expand the nipple.

Sorry Beefer, your reply came in while I was composing,

[GT6 M]

Yes you can try some heat around the out side o the caliper,
best to use ..local heat..
the way i got the MX ones out, and a lot of other things  is as follows,

1, get a carbon rod from inside a a type battery,
2, put one end of this to your jump leads,the other end o jumper to  battery,
3, put the other lead from bat earth to what ever you working on,
4, touch carbon rod onto caliper, around the nipple break, it will glow white hot, but will heat the local area up
5, get either a ..allen key, or a torx / spline, knock it in the end o the bleed nipple, and then unscrew, back and forads, a little at a time, this to break the seal,  TIGHTENING first, as this nearly alwys works.

drilling out can work, but if you get any dedris in the piston, then you will have to strip it doon to make shooa its clean/free, or you will get a leak sooner or later. :-/

it will come out, honest,
Marcus

[andycon67]

You can also try a left handed drill,these can heat up the nipple and often snags and unscrews the nipple. :)

Andy

[GrayFox]

Success!!!!!!!!!!!!!!!!!!!!!!!!!!!  Thanks for all the advice.  Like the carbon rod idea and will save that for the next suitable problem.

I managed to do it by drilling it with a pillar drill.  I took the caliper off and split it - intend to put new pistons and seals in.  Drilled down with an undersized drill and collapsed the threads in on themselves without doing any damage to the thread.  I then ran a tap down to make sure it was clean, cleaned out the seat of the casing with my drimmel and a small wire brush.  Took about five hours but it does mean the caliper will go again.

Good advice from all concerned.  Just need to be patient and eventually you get there.

[junkuser]

Great effort Grey Fox.
I was hesitant to mention the drilling method as it takes a bit of skill, which obviously you have and not so sure I have, to not run out and damage the female thread.

Marcus's heating method sounds a good idea, not relying on specialised equipment.