Thread: Hard brake pedal on 2a

Blockage? if it's been sitting for a while the lines may have rusted internally. Brake fluid can attract an alarming amount of moisture just from the air.

I would guess a master cylinder fault, probably from sitting for a long time. It won't be the hoses, I wouldn't think. When the pedal goes hard, are the brakes locked on? If not, the problem is probably the pedal pivot binding, or possibly the piston in the master cylinder sticking.

John

Originally Posted by JDNSW

I would guess a master cylinder fault, probably from sitting for a long time. It won't be the hoses, I wouldn't think. When the pedal goes hard, are the brakes locked on? If not, the problem is probably the pedal pivot binding, or possibly the piston in the master cylinder sticking.

John

x2. Pull the MC apart and inspect. If the bore and piston are OK you can just put a seal kit through it.

It's actually part of the reason it is parked up. Did it early on, not only recently.
Will check to see if the brakes are locked on or not.

I can see the pushrod going in and out of the master and it feels like the piston is coming back with the pedal. The lines would be full of air as I have just put a new solid one on from junction to front left wheel. So lots of air. Yet if I pump the pedal it slowly builds pressure and then goes hard. So in other words the pressure isn't being released when the pedal retracts.

Originally Posted by the big fist

It's actually part of the reason it is parked up. Did it early on, not only recently.
Will check to see if the brakes are locked on or not.

I can see the pushrod going in and out of the master and it feels like the piston is coming back with the pedal. The lines would be full of air as I have just put a new solid one on from junction to front left wheel. So lots of air. Yet if I pump the pedal it slowly builds pressure and then goes hard. So in other words the pressure isn't being released when the pedal retracts.

This indicates the piston is not coming back far enough or the passage that allows fluid back into the reservoir when the pedal is released is blocked. Possibly the piston is sticking due to rust in the bore as it gets to the end of its stroke and the spring pressure is less, or due to the seals being swollen by contamination with oil (even dirty hands will do it!).

Master cylinder out, strip and examine, I am afraid, unless the piston rod is incorrectly adjusted.

John

Hi John,
do you have any information on how to adjust the piston rod ?
This cured it before but I cant find any information on it.

I was planning on doing a little testing tonight by cracking brake lines in certain spots to see where the pressure build up is.

Cheers,

Peter

OK, did a little bit of diagnosing tonight.
I got the pedal hard then cracked the line coming out of the master cylinder.
Fluid came out and pedal went soft. When pumping the pedal more fluid came out and I could hear it hissing on the pedal up stroke. My assumption is that the MC is ok as it is trying to suck the fluid back.

So, got the pedal hard again and went to the bottom slave on the front wheel and cracked the bleed nipple. Fluid came out...a little bit. Pedal still hard. Tried to pump, but still hard and no more fluid from bleed.

So I work backwards to the top of the flexible line and crack that where the tube joins. Lots of fluid under pressure. Pedal soft again. Pump the pedal and out squirts lots of fluid.

So I am assuming that its the flexbile lines that are dodgey. I have all new slaves and shoes and springs. Even if the springs were on wrong I would think that the pedal would go hard, maybe just hard to push. I also noticed the flexible line looked oily like the fluid was coming out through it.

Whats other peoples thoughts on this. Would it be likely all the flexibles are dodgey ?

cheers,

Peter

Yes, it sounds as if the hoses have collapsed internally - replace all three and any other dodgy looking pipes whilst you are at it,

Cheers Charlie