Brake pedal to the floor???

[Tea]

So with only one day to go until we're supposed to be going to the rally the brakes on our 1968 saloon have gone.

They had been squealing for the past week or so and so we thought it'd be worth a check before towing a trailer tent to the national.

The shoes were down to the metal rivets on both sides on the front brakes and as we had 4 spare new shoes we decided to replace them. We also had a sticking cylinder on either side so changed all 4 to lockheed ones whilst the brakes were apart.

Once they were replaced and the brakes were bled the brake pedal started going right down to the floor. We've now bled both the front and back brakes to make sure there is no air/ bubbles in the pipes.

Before we changed the shoes the brake pedal was a good few inches from the floor and braking nicely. The master cylinder looks like it must have been replaced within the last few years. Could the master cylinder have gone and it's just a coincidence to have happened at the same time?

Has anyone got any suggestions as to what may have caused the pedal to not fully engaged the brakes?

Any help would be HUGELY appreciated.

[bmcecosse]

Adjust the brakes up properly so they are gently rubbing on the drums.......

[Tea]

We've done that, but it still goes right to the floor.

Tightened the screw right up and then one 'click' to the left (no clicks and the wheel won't move)

[Sandun]

check oill in master pump -if ur brake pedal go floor and no brack ? 1st remove filler cap of master pump check oill , it must be small gap to the top , then the pedal fush down by ur hand and look inside of the master cyilinder ,when u push pedal oil must come out from filler mouth or u can see air come up , if it is ok ur master pump work fine - 2nd check have same oil leak of connection or from bad cylinder or air leak , have some?, close it 3rd reset filler cap and do paddel up and down then look the pedal come up and tight - remember the filler cap has gascut ring check is it ok and if the cap loose not brake ur car -

[GBond]

Remember front drums have two adjusters each and also do the rears.

Otherwise I'm thinking still air in the cylinders, because of their shape even after bleeding there can still be air pockets especially in the rear brakes. Try bleeding just a little again, pumping the pedal very slowly and it should rise back up.

And do check you've tightened down everything so that there's no fluid coming out somewhere.

[kennatt]

what happens when you pump the pedal,do you now get a firm pedal or does it still go to the floor,the answer to this would give an idea as to where to go next.

[Tea]

Many thanks for all the replies. I'll be checking all these things this evening (or my partner will check them during the day as she's off work - though not very well). The pedal doesn't go to the floor after pumping it. Maybe an inch or two from the floor.

One strange thing that happened is this morning the front brake drums spin freely, even though they were tight last night. The same thing happened yesterday after tightening them and then applying the brake. A bit like applying the brake is somehow loosening them off. Also, once it's loosened itself when you turn the adjuster screw either way it tightens up...

[bmcecosse]

The master cylinder retains a low pressure to keep the shoes close to the drum surface. This falls away after a short while. You are almost certainly not adjusting the brakes correctly. At the rear - you must slacken the cables and only then - tighten the adjusters till they 'rub' gently - and then retighten the cables to put the handle where you want it. At the front - tighten them all till they 'rub' - and then go round bleeding - starting at the rear then passenger front and finally driver front. Are you sure you put the shoe springs on correctly when changing the shoes? This may sound daft...and sorry for suggesting it....but ...... if they are 8" front brakes - you haven't fitted 7" shoes by any chance?

[Tea]

Master cylinder is working fine.

Redid the brakes and still the same. Used a different set of new brake shoes and they have improved the brakes a bit, but still not good enough to be doing a trip down the motorway, or around town in case someone steps out in front of us.

With the newest brake shoes the pedal doesn't go all the way to the floor, maybe an inch or two from the floor.

I think we're admitting defeat now and borrowing a modern car for the rally.

[Tea]

also, the springs are correctly set up and we are definitely using 8" shoes. Have checked too many times and then some more to be sure

[kennatt]

from your answers.as bmc says ,the problem is highly likely to be an adjustment issue,if pumping gives a better pedal its because the shoes are being pushed out further towards the drum. also when fitting new shoes this will have the same effect as more adjustment ,since they will be thicker so nearer the drums. Is it possible to put a photo on re the inside of the brakes showing the fitment of the shoes and snail cam adjusters,just in case something is obviously amiss.what happens if you over adjust the brakes so that they are all now binding solid,whats the pedal like now,with the shoes now fully held onto the drums.

[Tea]

[frame][/frame][frame][/frame][frame][/frame][frame][/frame]

[Tea]

The springs are flipped over on the opposite side. Hopefully this shows what it needs to. Let me know if you need more photos

[bmcecosse]

Looks absolutely perfect to me!

[Tea]

I think that is what makes it so frustratingly annoying

[katy]

If the brakes are adjusted properly, and the brakes come up with pumping, that tells me that there's still air in the system.

[GBond]

I agree, either still air or the only thing I can think of is one of the rubber brake hoses being about to give up.

[kennatt]

99% of the time if pumping improves the pedal its ADJUSTMENT thats needed,If there is air in the system the pedal will be soft,if there is a lot of air all the pumping in the world will not improve the pedal.it will still go down the same, untill the air is compressed and moves the fluid,lifting the pedal just lets the air return to it's original volumn untill the pedal is repressed,etc etc. But yes it's worth re bleeding just in case,but I bet it's an adjustment issue.

[Tea]

I spoke with some of the restorers at the rally who have had similar problems with the new cylinders. Apparently the way they get them to work correctly is to tighten the brakes so that they won't turn, pump the pedal like crazy followed by keeping the pedal down and releasing the nipple just enough to let out the brake fluid and then to do the nipple up again.

After doing this it's improved the brake, but still not enough. So will give it another go and see what happens.

[bmcecosse]

It can't be anything to do with the 'new' cylinders...... Adjusting up is a good idea - although not the 'binding' point for me......