Sheared brake bleed nipple

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Bonwit

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The front brake on my ‘74 Commando locked up and over heated. When I disassembled the caliper, I could see damage to the cylinder wall. I have another caliper on hand that looks to be in good shape, except its bleed nipple is sheared off flush. Backing out this tiny screw without damaging the threads appears daunting. Is this something a machine shop can tackle?
 
I would think it easy to extract with an EZ Out.. But for sure any machine shop could remove it.
 
Its small in diameter and so the wall is thin, difficult to get out but I did many years ago. so long ago I have forgotten how. A correctly sized drill down the central hole will leave a spiral in the threaded hole you can remove with a fresh and sharp tap.
 
Fairly common issue in the automotive industry. Any decent auto or motorcycle shop could handle this and I'm sure they'd appreciate you bringing them a caliper off the bike.
 
Bonwit said:
The front brake on my ‘74 Commando locked up and over heated. When I disassembled the caliper, I could see damage to the cylinder wall. I have another caliper on hand that looks to be in good shape, except its bleed nipple is sheared off flush. Backing out this tiny screw without damaging the threads appears daunting. Is this something a machine shop can tackle?
Click to expand...
A left-hand drill bit a little bigger than the central hole might take it out and if not, an EZ Out out should. Just be absolutely sure not to drill to the seat. In either case, heat it first.
 
Just be very careful you don't damage the countersink at the bottom of the hole
 
I had same issue , local machinist removed it while I waited , $20 … painless fix …. easy-outs have been hit and miss for me over the yrs …..
 
And replace with SS bleed nipple and some anti-seize. I prefer nickel but others may work. YMMV as usual. Good luck
 
This is what I have done in the past. If it doesn't work you'll still be able to take it to a machine shop.

Find a Torx key bit like the one pictured which is slightly* larger than the hole in the nipple then hammer it in (ideally until it gets to the end of the flutes). Heat up the caliper ( I boil them in an old saucepan), apply some releasing fluid such as 50 /50 ATF acetone mix, then using an M7 spanner or socket try to slowly undo the broken nipple.


* Too small and it will simply slip, too large and it will expand the remainder of the nipple and make it harder to remove.


Sheared brake bleed nipple


Hope it helps.
 
Bonwit said:
Great ideas all. I think I’ll give the Torx bit method a go.

Thanks!
Click to expand...
One other thing I omitted to say. It's best to touch the tip of the Torx key on a grinder so it has nice sharp corners on the edge of each flute that will cut into the nipple as you drive it in, rather than expand it.
 
HEAT the alloy caliper, EZ out the bleeder. Or pay a talented professional to do it. Listen for: "no problem, I can get that out, no problem."
 
Using a propane torch, carefully heat the caliper with the frozen bleed screw until it will sizzle penetrating oil when it is sprayed on. ( I like PB Blaster, but any penetrating oil will do) With the "straw" in the spray nozzle, spray into the hole in the center of the broken bleeder screw. The rapid cooling will draw the penetrating oil into the threads. Use an E Z- out to extract the broken bleeder. This method has never failed me.
 
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