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MG MGB Technical - Noise from New Master Cylinder?

Hello-

Here's a weird one for all you armchair gurus... I replaced my 68 'B MC with a new one (not rebuilt). I bled it three times and have a firm pedal that does not sink under pressure. However, each time I apply the brakes a metallic ticking/clinking noise happens about halfway down pedal travel. I had my wife push the pedal down and I could feel a definite 'tap' in the brake lines that go from the MC to the pressure switch. The sound is similar to tapping the metal brake line with a screwdriver and feels the same way if you put your hand on the brake line when the brakes are being applied. The brake pedal is not ovaled out, the bushes and spacers are new.

Any thoughts/experiences appreciated!
Thanks,
Sam Sullivan
Samuel Sullivan

Sam, Could it be the return spring - what happens if you disconnect that for a test ?
Miles Banister

Worn clevis pins?

Dry and/or worn pedal arm bushings?
Daniel Wong

I checked the return spring, it doesn't make any noise and the clevis pin is new. The noise appears to be coming from inside the cylinder-maybe the piston spring is doing it? The noise happens twice on each push so maybe each chamber, when pressurized, causes the clicking noise?
Sam

I believe that '68 was the first year for dual master cylinders in our cars. They have two pistons (on the same axis, one each for the front and rear). If the rear brakes are not adjusted up tight and proper, you may be hearing/feeling the two pistons hitting one another as the pedal is depressed. Just try adjusting the rear brakes and see if it helps.

Wayne
Wayne Pearson

Wayne-
Thanks for the tip but the brakes are adjusted as close as possible.

Sam
Sam

This thread was discussed between 08/09/2001 and 12/09/2001

MG MGB Technical index

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