brake bleed nipple: sheared off

if it doesn't leak when you press the brake pedal (engine running) then it is quite safe to drive. very few garages have any engineering skills these days, almost every one will just fit a new pair of calipers (which are very cheap in any case now)

removal of the broken bit would likely require removal and dismantling of the caliper, careful drilling down the bore of the broken bit (without breaking through) insertion of a grooved screw extractor (not a taper one) heating of the area and hopefully it would undo. rebuild the caliper and bob's etc. trouble is that the average place would have to charge more labour than a new caliper.

I have sheared nipples on both front wheels and have had for some years. If I need to bleed the brakes I just slacken the union of the flexipipe into the back of the top wheel cylinder and get the air out that way. Always works. (Drum brakes) I think whether it will work for you will depend on how high up the union is into the caliper. Nothing lost trying, though (just a bit of brake fluid).

But why are you doing this? If you are just trying to replace all the fluid rather than trying to expel the air then I'm sure you'll be OK.

Rob Graham

I've always got them out with a cordless with a left hand bit or a steep taper tapered extractor

I would not recommend it as a job for someone without skills in that direction, just in case (and if the OP was skilled he probably would not be asking here). Depending on the vehicle the nipple thread can vary from about 6 mm to 10mm, French stuff is usually fairly small, making the job harder.

I was attempting to change the brake fluid because it was due a change (hoping this won't start a fierce debate about whether it needs changing every two years or not!).

I stood on the pedal a few times with the engine off and nothing happened. I will try with the engine on but I am sure that if it was going to leak it would have done so by now.

I see. Thanks.

Thanks. I've never used one but when they've been mentioned here and elsewhere on the 'net, people never say nice things about them.

If I were skilled, I wouldn't have broken it off! ;)

if the fluid gets changed every couple of years (as it should) then the nipples don't get seized, so yes you were trying to do the right thing. You can still change the fluid without touching the nipple. You will need to release the caliper from its mounting bolts (having slackened the brake hose first) then loosen the hose a bit more and press in the caliper piston, fluid should come out of the loosened joint, keep the piston pressed in and pump through fresh fluid, with the pedal pressed down tighten the hose, refit the caliper and final tighten the hose, press the pedal a few times to push the piston back out.

Oh never bet on that :-)

They're not guaranteed to work. If the original failed because it's rusted in place then the bit you apply them too after you've drilled it is even weaker. In order to stand a chance of working they're "glass hard" so if you knock them or bend them sideways whilst using them they snap & then they're far harder than the original bolt so drilling them out involves a solid carbide drill, snap that (which is even easier) & it gets really dull. Left hand drill bits are more reliable for most things, in my experience, bleed nipples are the odd one out as the tend to have a weak point between the threaded bit & the hex.

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Stephen saying something like:

Don't be so sure - it happens to everyone.