We have a single reservoir master cylinder with sunny struts and discs etc on front. We had to reconnect rear brake lines and we bled the brakes but the brake pedal still needs to be pumped a couple of times to work. Any solution to this ? We were thinking maybe still air in the line as the reservoir blows bubbles when we pump the brake pedal. Help ??

Hey Andy, No Fancy plumbing, no leaks, no silicone fluid? Bleed master again then re-bleed from longest line P/S rear working around D/S rear, P/S front and D/S front last. If still having a fade off the master cylinder must be bypassing between the cups or pulling air through a slave rubber(you would see a leak or moisture). Check all vacume points. I know you know all all of this? But if all is right I am not sure where to look either

adjust rear brakes???

check the adjustment of the rear brakes and adjust accordingly,thats if there no leaks or anything to suggest such.


edit: tommo beat me to it!!!!!
damn u tommo!LOL

yep peter is write. if u do how he is saying ur system should be perfectly working.

Clamp each of the brake hoses and see if any one hose or just the front 2 get your pedal up. Carefully use a G clamp/vice grips if you do not have the correct tool. It does not need to be clamped very tight at all. If this does not improve the pedal AND the system is correctly bled you most likely have a MC problem as the man said.
In any case it will point you in the right direction.

Quote:
Are you using a single resevoir master cylinder or a single circuit master cylinder. If single circuit, then, ... Why?

If you have bubbles coming up into the resevoir when you pump the pedal, then you must have air inside the master cylinder, since the bubbles are surely made of air.
In all fairness, that wasn't too hard to figure out.

Theoretically, the master cylinder will eventually expel all the air through the resevoir but far better to bleed the master cylinder first.Quote:

Oh Dodgeman, AKA MONK, You make people feel so good about themselves. We bought the car as it is. All i have done is replace the rear brake line from the junction on the fire wall to the rubber hose at the rear junction on diff and was bitten by a red back in the process. The master cylinder has only one reservoir and the one line going to the junction on the firewall. Why ?? Well as i said its how i bought it. The back line was cut off at the firewall junction and at the diff. We figure its a good idea to put it back for rego. We have bled the brakes again and the pedal is improving which tells me the problem was just air in the lines still. Thanks people for your help.

I think that you will find that for registration with a disc/drum combination a dual circuit master cylinder will be required.

You also keep refering to a single resevoir, but some dual circuit master cylinders use a combined single resevoir & some use two separate resevoirs, which is why I asked about that. The number of resevoirs, in this case means diddly squat.

Disc brakes, as are fitted to the front of this car, require no residual pressure in the brake line when the brake is released so that the caliper can release all brake pressure on the rotor, but drum brakes require a small amount of residual pressure in the line to ensure that the cups in the wheel cylinders remain in contact with the walls of the cylinder at all times to prevent the entry of air. The strong springs on the brake shoes will ensure that the brakes are fully released.
With a single circuit cylinder you will either have residual line pressure, which is bad for discs, or no residual line pressure, which is bad for drums, both of which this car has.

That's why a dual circuit master cylinder is required. That's why every manufacturer that uses a disc drum system, even before the ADR's required it, utilised dual circuit master cylinders, yet you say that you will front for a blue slip & registration with a single circuit one.

Good old Professor Julias Sumner Miller unknowingly passed to me the best gift I ever received, ..... a question.
Whenever you see something that you have not seen before, like this for example, or when pressing a spongy brake pedal while watching air bubbles rise in the resevoir, just ask yourself 'why is it so?' There will always be a reason, we all just need to figure it out.

O.k Well How do i tell if its a dual circuit master cylinder. Also wouldn't the fact that the brake pedal is getting harder and doesn't require pumping up tell you that it is doing the job ??Oh i know. Will contact the guy i got it off and ask if he knows whether its single or dual as he said it was replaced and it looks New.