I was playing with my brakes last night and noticed that there is a clicking sound when I step on my brakes. I think it's coming from the diaphragm in the vacuum servo and I've just never noticed it before. The click happens at the end of the brake motion (pedal to floor)

Is that normal or is it a sign of bad things to come?

After changing my master cylinder my brake feel (at static) has gone from
nothing nothing nothing nothing solid
to
nothing 'a bit' solid solid solid

It feels a lot better but I'm just curious about that sound. Also I wonder if I should be getting any play at the start with the brakes. I'm yet to take it out for a spin to see what it's like dynamically just because I want to be sure that it's not going to fail on me .

I've been bleeding it before starting the car - could I have missed a bubble? (so the booster may have been in a different position?)

If it feels spongy, then solid, that means air in the system.

Recommend you either:-

1. Take car to specialist if you are not sure re your mechanical competency, or
2. If you feel confident, check master cylinder first. Replace outlet pipe with bleed nipple, fully closed.
Pedal should be rock hard. If so, replace line & repeat process with booster outlet, bleed booster from top facing bleed valve. If pedal still OK, bleed lines individually starting from LH rear, then RH rear, Then LH front & finally RH front wheel.

I assume having fitted a booster you have discs at the front. If there's drums at the front, the air is often difficult to expel due to the dumb arse way the interconnecting line is routed. Other than pressure bleeding, alternative solution is to remove front shoes and clamp pistons in wheel cylinders, then complete bleeding process, using a sudden/fast pedal to move any air, then replace shoes and adjust brakes.

As for the clicking, I am not sure whether that is anything to worry about, assuming the booster is otherwise working satisfactorily. From my experience, boosters rarely give trouble, other than drawn in petrol from the inlet manifold due to faulty one-way vacuum hose valve. Remove valve from booster vacuum tank to check operation and whilst you have it off, check tank for any fluid that may have collected using piece of wire or similar as a probe.

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

As suggested above I would try bleeding. Have you bled the booster, front left and right and rear left and right individually? I sometimes get a click as well - my pedal is solid and brakes work great. but the pedal should not go to floor whatsoever. Mine doesn't even go halfway before having a heap of pressure. What type of brake fluid are you using? It can make a difference

Make sure you bleed all corners of the car and the booster as well. Also you don't need to 'start the car' for it all to work as it should.

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