38 replies to this topic

[Doodle]

Do the maths - they may serve as exchange units if you buy refurbed ones. I reckon Metro calipers are far worse for sheared nipples 'n I put that down to them being over torqued because the hex head is bigger.

yeah, if i can get them on exhange then i should be able to get a decent price, i'm just not sure after i've bought the pistons, seals and nipples, plus spent the hours working on them i'd save that much if any at all

dya reckon i'll get them on exchange through my local parts place

[dklawson]

As you noticed in my exchange with Terry, while I've used the nipple repair kits, I'm not a big fan of them. As you probably read, the tapered thread of the pipe bushing insert squeezes down such that the nipple is difficult to turn IF you aren't very observant when torquing the nipples in place.

The nipple repair kit I used did not use a 1/4 NPT tap as the ones Terry mentioned. The parts I used required tapping the calipers 1/8 NPT. This smaller part/tap meant that the nipple was correspondingly smaller. As I mentioned, this was on my VW and it used 6mm or 7mm nipples. The nipple in the repair kit was the common U.S. Ford size, 1/4 UNF. That's really a bit small when compared to most Lockheed brake nipples I've seen used on the majority of British cars. The nipple doesn't have to be large to do its job... but these small nipples are hard to put bleed tubing on and they just seem a bit fragile.

If you have the option of using these calipers for cores and if the shop gives you a decent amount of credit for turning them in... great. Why not let someone else fix the bleed nipple problem? However, if the value of these calipers as a core is low... why not have a go at them yourself using one of the methods mentioned above? Careful work with a set of left-hand drill bits, a pick, and a set of new nipples may be all you need. I guess it really comes down to how much effort you want to put into these calipers and what your time is worth.

[nicksuth]

Well bloody hell, after reading all of these exellent recommendations and taking great care while removing mine (lots of penetrating oil, a little bit of heat, more pentrating oil etc. etc.) one out of the six decided to shear off! That bloody one between the bolt heads (why do they put a nipple their where its so difficult to get hold of?). Anyway, I can now try my recommendation of using the easyout (carefully!).

[nicksuth]

Update

Tried the easyout method but the broken nipple was so tight it wouldn't budge (easyout felt like it was going to snap so stopped). 10/10 for dklawson!!!

Took calliper to workshop and tried drilling out with progressively larger drils but the bloody thing still wouldn't come out!

Ordered a M7 (fine) tap to see if it will clear the remainder of the nipple or as a last resort I bought some M10 bleed nipples (Mini Spares sell them for their alloy callipers) with the idea of drilling out and re-tapping?

Has anyone tried this as an alternative to the 1/4" NPT repair socket/nipple another member posted earlier?

One last question - are ALL Metro 4 Pot Callipers fitted with METRIC bleen nipples?

[dklawson]

I'm glad you didn't break the easy-out. Nasty things.

When you used the progressively larger drill bits, were you using left-hand drill bits as I suggested? The reason I suggest LH bits is that when and if they catch in the part being drilled out, they will back-out what's left of the broken part. Penetrating oil is still required with this method.

You asked if there was another fix than the one mentioned with the NPT pipe bushing repair kits. Yes. I posted a lengthy description of a ball bearing method in my first or second reply to this thread. Rather than repeat it here, flip back to those earlier pages.

[nicksuth]

Successfully extracted the sheared bleed nipple.

Put progressively larger drill bits down until we lost our nerve, then waited for the M7x1 tap to arrive. I read somewhere that it was an M7 "fine" thread, it is not, it is actually a standard M7x1 "course" thread!!!

With some carefull running through of the tap it all celaned up and with no damage to the seat at the bottom. The new nipple still fits snug in the thread the same as the others.

PS - if anyone wants to buy an M7x0.75mm pitch "fine" plug tap I have one going!!!!!

[dklawson]

I'm glad you got this sorted but sorry you invested in a twice-odd tap.

I have only seen M7 fasteners in one other place in my life. We had a VW Rabbit (Mk1 Golf to you guys). The front suspension arms leave the factory with 7mm rivets holding the ball joints in place. When you drill the rivets out to replace the ball joints you're supposed to use 7mm bolts to secure the new parts. The problem for us over here is NOTHING and NO ONE has 7mm bolts, not even the VW dealer. I sent my wife on an all-day bolt shopping trip which eventually located the six bolts and nuts we needed.

[Ethel]

No 7mm over here either, I think it's something the Germans made up to get their own back

Metro calipers are tapped M10x1, I'm pretty sure.

[nicksuth]

The lugs were to locate Metro wheels, any other wheel apart from these will require the removal of these lugs. The flanges we make have these removed already

They are definately M7 x 1.0mm pitch, trust me, I've just re-tapped them. I thought, as you did, that they were M10 and actually bought a set of 6 replacement bleed nipples ready for the overhaul, then removed one!!! = M7 = Buggar.
I'm sure MiniSpares advertised them as M10 and yes they did, BUT they are for the MiniSpares Alloy Callipers not the original Metro ones.

http://www.minispare....aspx?pid=34124

http://www.minispare....aspx?pid=33116