7 replies to this topic

[mozzo1]

going to bleed brakes as just nenewed all pipe work but the nipples have been trashed in the past. how do i remove these as mould grips just slip off and i want to mot it soon and iv spent to much lately on it and really dont want to have to bye new calipers

[phil_clubman]

going to bleed brakes as just nenewed all pipe work but the nipples have been trashed in the past. how do i remove these as mould grips just slip off and i want to mot it soon and iv spent to much lately on it and really dont want to have to bye new calipers

could you file two flats on to it and get an adjustable spanner on?

phil

[maddogmcg]

there are a few ways to get them out , depends on how rusted in they are


get a crescent wrench ( the type that get tighter as you apply more pressure )


drill them out with a left handed drill ,this will get a grip on the nipple and sometimes can unscrew them


drill them out with a drill about 1 mm smaller than the nipple thread and re tap the hole once its all out ,you must be careful not to drill too deep and damage the seating face . run the drill at a slowish speed as nipples are slightly hardened ( this is why they break off ) and spray wd 40 on it as you drill

the best way is tale the caliper off the car ,clean out the brake fluid and get some heat into the nipple with a blow torch , when its hot too touch stand back and spray it with wd 40 ,this will smoke a lot and any gap opened up by heating will soak in the wd40 and free things off a bit wait until cool and try mole grips again ,try to tighten it a bit first then un tighten ,back an forth and it should free off easier

then buy some new bleed nipples and fit them with copper grease , make sure when youve bled the brakes to clean up and fluid around the nipple and slap a bit more grease over the nipple

[dklawson]

I agree with the above. Heat and quench the nipples with penetrating oil so it will wick into the threads. Do this several times and after each quenching, strike the top of the nipple with a hammer (gentle blows) like you're driving a nail. The shock from the blow will help get the oil into the threads.

Big wrenches will give you more leverage... but I'd still avoid a crescent wrench. Their jaws spring and are likely to round the nipple off again. It's also a bit harder to feel with things are failing if you use a big wrench. I'd stick with a big pair of vise-grips (mole grips) as they will bite into the nipple.

[mozzo1]

well i gave it ago and f***ed it up as i snapped the top off so goint to have to try drilling and tapping (god dammit)

[mozzo1]

and if i f**k that up aswell where is best place to get another caliper from, im guessing ebay

[dklawson]

This is not the end of the world. There have been several threads on broken bleed nipples... perhaps we need to post a summary thread in the FAQ section sometime.

Regardless, start by taking the caliper off. I would certainly start with what was suggested by Maddogmcg and use progressively larger LEFT-HAND drill bits to drill down through the center of the broken nipple. Left-hand is important. There's a very good chance with the LH bits that towards the end, enough material will have been removed to relieve stress on the threads, the bit will "catch" and the broken part will back out on its own.

I strongly encourage you to try to avoid re-tapping the caliper if possible. If you must re-tap it, use only a very sharp bottoming tap. You don't want to enlarge the threads at all and you don't want to damage the seat in the bottom of the hole.

Once you do have the broken part out, there is a fix that was recommended to me that I have posted on every one of the broken bleed nipple threads. With the broken nipple out of the caliper, look at the hole in the bottom of the caliper. Find a steel ball from a ball bearing that is about twice (2 times) the diameter of the hole in the bottom of the nipple seat. Buy a new bleed nipple. Take the new bleed nipple and grind its point away until it has a completely flat face. Drop the ball down into the bleed nipple hole and follow it with the flat faced nipple. The flat faced nipple will drive the ball into the seat and close it. Loosening the nipple will allow the ball to lift up for normal brake bleeding.

The ball bearing fix will become important to you if you re-tap the caliper. The seat is machined concentric with the threads and the fit of the threads to the nipple is important. If you get slop in the threads or if the threads are off center... the conical point on the nipple will not close off the seat. The ball will.

[mozzo1]

makes good sense thanks and i ordered a new one anyway as the one i screwed up i used as a doner as i wanted an old one to grind through to the internal fluid canals to see how far i could go untill i find em as then i will know how far to grind so i can put my 10 inch wheels over the discs but if anyone else was to do stuff like this i highly recomend getting the caliper presure tested before fitting it to any road go car