thread size

[DaveyBoy]

Morning all,

I've been through a bit of a palaver with a rear brake caliper on my plus 2 recently. Essentially the sequence of events went - seized brake nipple - sheared brake nipple - sheared Easyout - blunt drill - spark erosion. Anyway, the end is now in sight. However, although the thread has been mantained within the bore, I need to run a tap down it to clear out some debris. So, does anyone have a clue what the specification of the thread is? It's just the standard Girling rear caliper as far as I know.

Thanks

Dave

[garyeanderson]

I believe that it is 3/8" 24 tpi, nothing to special about it. I could be wrong so let a few others chime in and see if there is a concencous. If I run into difficulty with opening bleaders, I stop. Split the calipers and pull out the square in section O-ring and then start working on it, a torch
(oxi-accetene) and heat the area surounding the nipple to a dull glowing red, then drive in an easy out(break) and it will usually come right out. If not, repeat the heating and try again. Thats for the broken off nipples, much simpler if you have the 7/16" hex head still on the bleader. If you are having problems opening the bleader, stop before you break it, much easier to remove and split and reassemble. Yes I have broken off a few before I learned "Heat is your friend".

Gary

[nebogipfel]

Pretty sure it's 3/8" UNF

I totally agree about using heat. Another good method if you have access to oxy-acetylene is to heat the nipple itself (red) and then allow it to cool. Often this will do the trick without having to strip the caliper.

[Dave-M]

3/8 UNF for sure. Just done two sets.
Easyouts are SH*T don't use them.
Plenty of heat initially and use a flat drive socket supported at the socket end of the ratchet so as not to put any bending load on the nipple and you should be OK.
If you are not splitting the caliper you must bear in mind that the thread must be tapped/cleaned out upside down or bits of swarfe will find there way into the piston/seal area.
Best of luck
Regards
dave