MadaboutKitcars

I had 'a little difficulty' with rusted brake nipples when trying to blead my brakes last week so I ordered a set of 4 new M7 brake nipples suitable for a BMW Z3. They arrived all shiny and new so I thought I would nip out before the sun went down and fit them.

Rear Passenger side
1) Jack up car, remove wheel, remove old bleed value with pliers are the head was knackered (easy as it had only been refitted a few days earlier)
2) Fit new nipple, bleed, refit wheel and move on to

Rear Diver side
1) Same and move on to...

Front Passenger side
1) Same and move on to...

Front Driver side
1) Jack up car, remove wheel, remove old bleed value with pliers are the head was knackered (easy as it had only been refitted a few days earlier)
2) Fit new nipple and realise it is totally the wrong size.
3) Stop trying to fit it using a spanner and simply pull it free from the hole, it was that much too small
4) Scrabble around the rapidly darkening drive looking for the old bleed nipple
5) Grinder some flat sides to the head so the pliers/spanner grips better
6) PTFE tape around the thread and refit
7) Pressure test to 20PSI and thankfully no leaks but...


Why does one calliper have the different size nipple thread?

I can't find any forums describing different thread sizes - nut sizes but not threads.

If it was drilled and re-tapped, is there a standard size it will have been re-tapped to?

Do I have to extract the old one again and find a shop selling a selection and try to find a match?

Help!

The pictures aren't that clear so not sure if they will help.

This is the front drivers side causing the grief. As you can see, it is pretty mangled but for the moment, focus on how close to the edge of the caliper the thread hole gets.
20171124_163234 by WCA!, on Flickr

This is the rear which despite the rubber cap surround, still looks (and is) a smaller thread
20171118_133819 by WCA!, on Flickr

All callipers are stamped as BMW and the numbers are something to do with calliper sizing rather than model number.
20171124_163014 by WCA!, on Flickr

I have met this before, no idea why, I just assumed that a caliper had been replaced at some time, but you can buy a pack of mixed sizes off ebay.

2xM8 and 2xM10 ordered. 2 is minimum order qty and M8 and M10 are the only larger sizes. Here's hoping one fits!