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MG MGA - Brake pipeline unions

Just trying to confirm the thread type for the unions on the solid pipeline. I am under the belief it is BSP, want to clean up some threads. Don't want to have to change pipeline.
S P Rossetto

The captured fittings on the brake and clutch pipes are normally UNF. However, where they enter the brake slave cylinders they may be BSF (mine were!) I don't know if my slave cylinders were original or not but I replaced them with new cylinders which were UNF.
I'm not sure of the threads on the master cylinder itself.
They used BSP fittings on the fuel pipeline.............Mike
m.j. moore

In March 1957 (c)27989 for DW, and in April 1957 (c)28540 for WW, all brake fittings were standardized to 3/8-24-UNF threads. Prior to that, threads in the 3-way fitting on the rear axle for the metal pipes only were 3/8 BSF (top hole for hose was always 3/8-UNF).

Along with changing the 3-way fitting and two pipes, an "L" shape bracket (plus one bolt, lock washer and nut) was added to hold the new 3-way fitting. Illustration in the SPL shows the later style 3-way piece with bracket.

The banjo fitting at rear wheel cylinder also changed at same time from straight to "L" shape. Was earlier 3/8-BSF for the pipe fitting only. The bleed nipple was always 3/8-UNF.

Apparently the early 3-way fitting is available (for a handsome price), but I can't find a picture of it. Pretty sure the mounting bolt goes vertical instead of horizontal, possibly screwing right into the bottom leg of the fitting. Does anyone hav a picture of the early 3-way fitting?
Barney Gaylord

Additional note. In January 1957 there was a Confidential Service Memorandum

This notes a change of the rear wheel banjo fitting from straight to "L" shape at (c)22741 in November 1956. Assuming this is true, there has to be an interim part for the 90-degree banjo fitting with one BSF thread for the pipe, and one UNF thread for the bleed nipple. I have never found any record of a part number for that application.

The silver lining in all this is that if you change the earlier cars to the later 3-way fitting and later 90-degree banjo fittings you can use all UNF threads for the pipes and kiss the BSF threads goodbye. If you do this you should keep notes of the changes with the car forever for future service reference.
Barney Gaylord

Thanks everyone, don't have my gauges at home with me so was going to wait till back at work Monday to confirm but now will get on and clean up the damaged thread hope that fixes the weeping I currently am experiencing from the rear wheel cylinders.
S P Rossetto

If the leak is not related to the damaged threads it may be that the pipe flair is damaged or malformed. The pipe ends use a bubble flair which are a bit tricky to form with hand tools. Drop me an email if you need more information.


This thread was discussed between 29/06/2013 and 30/06/2013

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