Discovery 300tdi caliper bleed nipple (1997)

I'm rebuilding a pair of rear brake calipers from a 1997 300tdi discovery. The bleed nipples were chewed up so I bought some replacements RTC1526, however these are a good bit longer and I'm not 100% sure that they are the same thread, they start to screw in then tighten up, I'm a tad worried that I bugger up the calipers if the threads wrong, hence I've not put a spanner on them. The calipers are stamped Lockheed.

photo of the new and old side by side is attached

Any advice would be appreciated!

If you clean the original nipple of all crud in the threads, then try to interdigitate the threads of old and new, this should show you if they are the same pitch, as, if they are, they will "mesh" into each other cleanly.... ( useful comparison for other things with threads on too!)

Obviously the diameter can still be wrong, but digital calipers will resolve that... a set of thread gauges is a useful addition to every tool box....

thread chasers are very useful when refurbing stuff too.... sure they available on the bay of fleas....

Just measured an old bleed nipple off my 97 D1 - 3/8* 27 and they are lockheed calipers - your calipers might be metric, though I see from the part number that the nipples you have are metric - in which case the calipers you have will be imperial !! (IIRC, imp bleed nipples part number is 556508)
All good fun eh??

The thread is metric, it seems u have an aftermarket part with RTC1526 used as a reference number, if you're happy with the extender length then use them I'm sure they will work, but for me better to get the genuine parts bleed nipples.
http://www.rimmerbros.co.uk/Item--i-RTC1526
http://www.jgs4x4.co.uk/land-rover-...ic-brake-caliper-bleed-screw-x-5-rtc1526.html

Thx guys, i'm surprised that a 97 Disco would have a unc threaded nipple, but there again given it's land rover i guess i shouldn't be. Having cleaned up the old one the thread looks the same (so metric, maybe), and they do appear to mesh together nicely, however due to my lack of competence I've not put a spanner on it yet.

I spent half an hour cleaning up the caliper threads and low and behold the metric nipples fit perfectly, although they are ridiculously long, I've ordered some shorter ones. Thx again for the all the advice & info.

mephitic said:

I spent half an hour cleaning up the caliper threads and low and behold the metric nipples fit perfectly, although they are ridiculously long, I've ordered some shorter ones. Thx again for the all the advice & info.

Click to expand...

That's good advice for any one thinking of... or having to replace the bleed nipples.