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MG Midget and Sprite Technical - Dual Master cylinder assembly

Can anyone point me in the direcion of an accurate drawing or assembly sequence for the seals and internals of a 3/4" dual master cylinder.

I have the MK1 Sprite manual and also an illustration in an article by J E Davies (photo attached) but they differ slightly. I am inclined to trust John's drawing over the manual

I have a kit of replacement seals from AH-Spares. This has one white nylon 3-legged item that looks a bit like part 9 in the drawing, but as there is only 1 it may actually be the brake pressure retaining valve item - part 7 in that same drawing although it seems a different shape.

In the archives there is also mention of a square section rubber washer that I think goes down the bottom of the brake cylinder bore. But the kit I have doesn't have that and it may have been superceded by the nylon 3 legged item?





GuyW

Guy
Have a look at MGA Guru HT204(304?)
Alan
Alan Anstead

Thanks Alan,
I have now assembled it. Page HT204 photos confirm that I am doing the right thing although the residual pressure valve I have differs in form though hopefully not in function. Time will tell when I get to bleed and test run the brakes on the road, but that is a long way off in time! At least I made a photo record of what I have and how I assembled it.
GuyW

Guy

The three legged thing is the restrictor valve: http://www.gerardsgarage.com/Garage/Tech/DbrakeUg.htm

Cheers
Mike
M Wood

Brilliant Mike!
That is the missing clue. What I have is the (correct for my 3/4" m/c) RESTRICTOR valve, not a RESIDUAL pressure valve. I had read that before but forgot where I had seen it.

Abstract from that site:

In the case of these tandem master cylinder Sprites and midgets, the early 7/8" MC for drum applications uses a residual valve, while the 3/4" disc brake master cylinders use a restrictor valve. A residual valve left in place on a disc brake application will maintain too much pressure for the disc brakes and will keep the pads in contact with the rotors. This will cause heat build up and premature wear of the pads.

Photo is just like the one I have, to go with my disc brakes.

(Acknowledgement to Gerards garage.com, with thanks)



GuyW

This thread was discussed on 29/12/2017

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.