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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - TD Master Cylinder (internals)

I am part way through overhauling the brakes on my '51 TD. The piston in my master cylinder is fitted with two 'O' ring seals. The workshop manual and all the suppliers' catalogues show one 'O' ring and one cup seal. I have managed to buy the two 'O' rings from a brake supplier at what I think is a great expense - 25 UK pounds. I've put everything together but the cylinder isn't pumping fluid into the lines. I've removed the cylinder (again!) for bench testing and despite repeated pumps no fluid comes out of the outlet. Both the holes from the reservoir to the bore are clear. I've noticed that the piston doesn't appear to the returning as far back up the bore as it could- about 1/8inch down. If I tap the casting the piston then comes up the bore and touches the large retaining washer under the circlip. When I press the piston this time fluid spurts out of the outlet but only for one stroke. The bore is in perfect condition. Is it possible that I have the wrong spring ? or does the pressure in the lines force the piston back ? Advice will be much appreciated - My garage and myself are soaked in Brake fluid.
Jan Targosz

Hi Jan,

Your comment regarding "O" Rings worries me. A replacement Kit for an original type Master Cyl. contains. A master cup and a secondary cup also a small rubber valve cup. The Piston has a groove at the pushrod end that the Secondary cup has to be stretched onto, this does not sound like your "O" ring, unless you have used the wrong terminology.

Blower manual shows on page 400 the correct layout of
parts.

If you need a copy, email me and I will send you a copy.

russell
Russell Dade

Jan, You may not have an original MG T master cylinder. A number of other period cars had very similar brake systems with the master cylinder installed under the floor (Morris Minor etc) and a previous owner may have fitted one from such a car. So you would need the exact repair kit to make it work properly - and this is difficult if you don't know where it came from (although a serial number stamped in the casting may help). So the choices seem to be - do some research, and hope the parts are still available for what you have, or throw it away and buy a new one. Since you are largely dependant upon the efficiency of master cylinder for the brakes to work properly, I would vote for a new one. T brakes are not terrific even when at their very best! I bought a new one earlier in the year for the next time my TF needs a brake overhaul..... Good luck, AB
Adrian Bennett

This thread was discussed between 21/08/2002 and 22/08/2002

MG TD TF 1500 index

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