MG Car Repair: 1975 MGB Master Brake Cylinder, master brake cylinder, ap lockheed

Question

Piston sleeve O-rings   I understand that '741/2 to 1975 MGB MBC's may be different from other years, in particular the differential brake pressure piston assembly and the pressure failure switch. While rebuilding, I tapped out the assembly very hard. The last items to come out were a small nylon sleeve and a small O-ring. The order is unknown. The piston is very different in shape from the Haynes manual and the one in an MBC rebuild video by John Twist. The spring is also very stiff. The placement of 2 O-rings are shown in the manual, but no mention of the plastic sleeve. A small detent exists on the end of the piston, begging for an O-ring but the sleeve will not allow placement. Placement before or over the sleeve are options. I need an assembly sketch as I cannot find pictures or a cross section diagram covering this particular design. The black pressure switch and the wedge shaped reservoir highlight the uniqueness of these two transitional years and the parts needed. Can you help and explain design differences?

Answer

MGB master cylinder le   Hi Walter.  I think I understand what you are referring to.  There was a change in the design of the MGB master cylinder during 1974.  I have a small leaflet which AP Lockheed inserted into their repair kits a few years ago.  It clearly shows two different types of piston, and one of them has a separate plastic sleeve.  I attach a photo of the leaflet.  If this doesn't answer your question, please get back to me.