Sticky brakes...

[sam.bullen]

I have a re-occuring problem that does not seem to follow a logical pattern - the brakes are sticking sometimes. This is accompanied by a faint smell of burning brakepad (shoe). The problem is, it manifests itself at unusual times and does not seem to follow any logic. I can tell when it is happening because along with the slight smell and the car feeling very sluggish the brake pedal feels a lot harder and the travel is reduced. I have just had the brake fluid replaced and system bled after a brake line snapped causing me to loose all the fluid (and consequently the brakes!).

During a 20 minute drive today I noticed the usual feeling of the car almost 'holding back' along with the hard pedal. When I got home I each wheel, the rear 2 wheels were cool but the front 2 were hot. Not 'burn your finger' hot, but certainly warmer than I expected. Can anyone offer me any advice?

[bmcecosse]

Disc brakes fitted?? (You do say 'pad') And was the pipe that snapped - a COPPER pipe ???

[sam.bullen]

Appologies, I meant shoe (standard drums all round). Yes it was a copper pipe, just after the 3way union on the rear diff.

[sam.bullen]

One other interesting point to mention is that since the bleed and fresh fluid, when my car has been sitting for a day I have to pump the brake pedal once or twice otherwise the movement is huge, almost reaching 20mm from the carpet. Once the pedal has been pumped it feels normal again... I am quite confused by the whole problem!

[bmcecosse]

In order of importance - you MUST URGENTLY replace all the COPPER pipes with either standard steel 'bundy' or the very much better Kunifer pipes - which don't rot, and don't work harden and snap as has happened with your pipe. It's frankly criminal in my eyes that some uninformed suppliers are still selling dangerous copper pipes for brake use........ Hopefully your pipe failed where it didn't put you (and others!) in danger - but imagine running down a hill with suddenly no brakes.... If one pipe failed - the others could do so at any time....... In the morning - the hydraulic pressure has sagged away, and the springs pull the shoes back on the cylinders - because the brakes are poorly adjusted... So you pump up the pedal, and the master cylinder is cleverly designed to hold a small pressure (~ 5 psi I believe) in the pipe system - thus holding the shoes out near the drum - ready for use. So if you tighten up the adjusters - this should be much less noticeable, although always present. The dragging brakes are possibly a wrongly adjusted master cylinder push-rod - not allowing the system to drain when you release the pedal - but could also simply be a 'tight' pedal on the pivot shaft - holding the pedal forward slightly , or even just a broken return spring on the pedal -take off the small cover over the master cylinder (driver side floor) and look inside the chassis rail to see if the spring is still there - and connected. And oil the clutch and brake pedal pivots while you are in there!

[sam.bullen]

Thanks bmcecosse. The pipe snapped whilst on the A11, I only noticed it when turning off onto a sliproad and approaching a roundabout. Fairly frightening but I managed to slow the car using the handbrake and using the gears...
Where can I source the 'new' brake pipes from? Many thanks for the advice, I will take a look behind the master cylinder cover tomorrow and report my findings.

[bmcecosse]

http://www.ebay.co.uk/itm/Copper-Kunife ... 43be8db2c7

[sam.bullen]

Would this be ok?

http://www.ebay.co.uk/itm/MORRIS-MINOR- ... 5659e8f8b3

[bmcecosse]

Never heard of 'zinc aluminium' brake pipes....I use only Kunifer - bought a flaring kit many moons ago and make my own.... Bundy pipe was the traditional brake piping - zinc coated steel. Lasts a good 10 years or so - but will rust eventually. Kunifer lasts 'for ever'.

[sam.bullen]

Ok, so I took the plate off under the carpet. There is a small amount of movement in the bush where the brake pedal pivots but the spring was definitely there and seemed to be working. I removed the cap on the master cylinder and the brake fluid is not topped up to the bottom of the neck. I will buy some more fluid today and ensure this is filled up, could this have been my problem?

[bmcecosse]

No -there should always be an air gap there. Is there some 'free play' before the pedal starts to push the hydraulic master cylinder?

[MarkyB]

Slap some grease on the shaft that the brake pedal pivots on while you have the cover off.
It will improve the clutch action and should stop any tendency for the brake pedal to bind on the shaft.

[sam.bullen]

Even though it says 'fill to bottom of neck'? There is no free play before the brakes engage, in fact there is only about 1/2 an inch of movement at all! The pedal seems hard. Just had the front up and checked the 'freeness' of the wheels. The. Did the same with the back. After the brake pedal has been pressed and released the wheels are all fairly hard to rotate. Could this be the master cylinder?

[bmcecosse]

There NEEDS to be some free play at the pedal link into the master cylinder - to make sure it can return fully and release the brakes. And is the return spring in place on the pedal link?

[sam.bullen]

I understand what you are saying. Yes the return spring is there.

[bmcecosse]

So - try slackening the rod connection into the master cylinder until there a little b it of play there.

[sam.bullen]

Just checked and there is no movement before the master cylinder is depressed. How do I rectify this?

[MarkyB]

Adjust the push rod, there is a locknut and the rod is threaded, loosen the locknut and turn the rod to shorten it a bit.

[mike.perry]

Remove the brake drums one at a time and check that the wheel cylinder pistons are operating and returning when someone is pressing the brake pedal

[bmcecosse]

It seems to be all 4 wheels Mike.....ergo it's the master cylinder not retracting properly - I believe.