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MG MGB Technical - Master Cylinder Trap Valve

Hi all. Well, after rebuilding my old master cylinder and having a long list of difficulties in getting the brakes to release, I bit the bullet and decided to purchase a new Master brake cylinder for my 68B roadster. As I was changing over the back fitting from the old MC to the new one, I noticed that the new MC did not have the Body Trap Valve assembly. I looked in my Haynes manual as well as my Moss book to find a good sketch of how these bits should fit together correctly and couldn't find one. I also looked through the archives and couldn't find anything on these parts. Does someone have a clear sketch, or better skills of communicating than I do on how to correctly install these parts? As I recall, when I rebuilt the old MC, there was only the 180-225 body trap valve and spring, no 180-235 trap valve clip was installed. Sorry for the long winded post. Any help would be greatly apprecitated.

TIA
Ed
Edward Bullard

The Parts List, which looks like it has been used by Moss as its source, is slightly larger and clearer. I'll send you a scan. It shows a valve and clip, no spring.
Paul Hunt

Thanks Paul,
I have to wait until I get home tonight to access and download from AOL. Would you know what the purpose of these valves? I rebuild my front brake calipers, as well as changed the brake hoses, after I rebuilt the old MC, and it didn't make much of a differance as far as the calipers releasing. I just wonder if these valves were installed incorrectly by me. I reinstalled them the way they came out. The whole problem started out with brake fluid dripping on the new floor pan at the brake pedal.

Cheers,
Ed
Edward Bullard

I will be rebuilding the master cylinder on my 70BGT. If there is an exploded drawing of the unit I would appreciate it.
Lee Sheldon

I am about to do the same as Lee. Any help on a visual is appreciated. Thanks
Scott

I have no idea what these valves do specifically other than control flow in some way. I'll send the same scan to Lee and Scott.
Paul Hunt

This thread was discussed between 17/11/2003 and 19/11/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.