weeping nipples :-0

Originally Posted by flymo_racer

The other side of this is that I think PTFE tape (or this mystery compound that I cant identify) can be useful to prevent fluid ****ing all over the place when bleeding the calipers.

"Bung in the overflow" is exactly right. When bleeding, as you know, fluid comes out the hole in the centre of the nipple. But to do this, the nipple has to be loosened, and the PTFE stops the creep (or gush, as it may be) up the threads (as mentioned).

If you're leaking when the nipples are tight, I'd agree culprit is the seals, or new nipples themselves (if they've been mistreated for example).

How far are you undoing the nipples when you bleed them?? You only need ~1/4 -1/2 turn and it really is a very small weep nothing to worry about …

You say ‘seals’ .. it sound like it is something you can replace, like a rubber seal. But a nipple is solid metal, as is the calliper side, it is the shape of the end of the nipple and the recess that makes the seal (and the seat deforming very slightly). If the calliper nipple seat is damaged, then it is new calliper time … I’d investigate this sooner rather than later

Its probably just a bit of **** on the conical bit that can simply be washed free

[flymo]

Originally Posted by Blue_SV650S

Its probably just a bit of **** on the conical bit that can simply be washed free

Thats exactly what I'm thinking. The calipers have been fully stripped and cleaned and there was no obvious damage to either the caliper or the nipple side of the 'seal' ....yes I was referring to the conical surface.

strange though as I did give 'em a good blast of compressed air during cleaning. I small peice of crap could always have got in there though.

No worries, I've got to strip 'em again anyway so I'll take a closer look at the surfaces.

Originally Posted by flymo_racer

I like the PTFE idea

thangyow

Matt

People keep saying 'Nipples'...










... tee hee hee.

liquid ptfe is called swak its made by swagelok, i dont know if its what your looking for but it sounds like it is. not very easy to get hold of unless your in industry

This is all far too complicated!!!

When you bleed the brakes fluid comes through the centre of the bleed nipple, the bottom of the bleed nipple has a taper which seals in a seat when tightened, when you loosen the bleed nipple fluid also weeps up the threads, because the taper is at the bottom, when its tight its sealed...
There will still be a residue of fluid in the nipple and in the threads, you can soak some of the fluid from the centre with a tissue, but there will still be fluid in the threads.
When you put the dust cap on the nipple it will pressurise the remaining fluid in the nipple which in turn forces it out of the threads, no leak just excess fluid.

Leave the dust covers off, wash the calipers with water (still attached to bike dont go mad just rinse) use the bike to get calipers hot, then replace dust covers.

Originally Posted by K

People keep saying 'Nipples'...











... tee hee hee.

I perfer to play with my misses nipples

Did you ever fix your nips mate?? Mine are weeping

[flymo]

Originally Posted by jumjum_0214

Did you ever fix your nips mate?? Mine are weeping

Yes I did. There are two seperate conditions though;

The nipples were weeping during bleeding due to the fluid seeping up the thread each time the nipple was loosened off. This is generally normal but just a little messy. The solution to this that I found works really well was to put a couple of turns of PTFE tape around the nipple thread (same stuff as used in water plumbing).

The other problem on one of the nipples was very slight weeping when the nipple was tightened. This should not happen and the PTFE should not be used to 'solve' this. In my case it was simply down to a build up of material on the coned sealing section of the nipple itself. This cone must be clean and a good seal against the bottom of the nipple hole in the caliper. I gently polished the coned section with a brass wire brush tool on my dremel and refitted. Sorted it out perfectly.

If the coned section of the nipple or the hole it goes into is badly damaged then either the caliper or the nipple must be replaced.

What ever you do dont overtighten the nipples to compensate as you'll strip the threads in the caliper.

Also, I found that ProBolt sell replacement brake nipples in stainless steel. Worth it for a few quid. Nice and shiny too!