brakes help needed

Post by **jothina** » Mon Jan 28, 2008 8:39 pm

hi
i changed the front brake cylinders at the weekend and i can't seem to get a good pedal since, when i press the pedal it goes almost to the floor, if i lift of and imediatly reapply the pedals nice and hard and stays that way for as long as i keep my foot on the pedal then next time i use it its soft again.
i've bled the system 4 times, 3 times pumping and once by gravity but no difference.
any ideas/ advice greatly apprieciated

john

Post by **bmcecosse** » Mon Jan 28, 2008 9:22 pm

Since you have bled them - it does sound like excessive shoe travel. First move is to adjust the front brakes (two adjusters in each brake) right up so they are rubbing and you can only just turn the drum by hand - and try them. That's really a wee bit too tight - but if they work well like that then you can back them off very slightly so only the lightest of rub is there - this will soon wear off! Otherwise - it must be an air bubble and only bleeding will sort it. Have you also bled the rear brakes out ? They should be done first - then move to the fronts.

Post by **jothina** » Mon Jan 28, 2008 9:38 pm

i've bled about 3 litres of fluid through the entire system, starting at the rear furthest from the master and working forwards, i'll try winding up the adjusters so the drums lock and see how that affects the pedel, i asume that if its still soft then it must still be air.

john

Post by **bmcecosse** » Mon Jan 28, 2008 9:51 pm

Fraid so! Although highley unlikely with all that bleeding - gee whiz!But likely it's the adjusters - the shoes will now be centred up nicely inside the drums and just need adjusting - I hope!

Post by **Mogwai** » Mon Jan 28, 2008 10:42 pm

Try clamping off one brake hose at a time with a brakepipe clamp & trying the pedal if it improves significantly when a particular brake is isolated then a problem is with that brake. Also I have had a similar problem to this in the past I think it was the new cylinders that point upwards not purging out the air from around the seal I tried prefilling them with fluid before fitting to the car this seemed to work

Post by **bmcecosse** » Tue Jan 29, 2008 4:02 pm

Never had any bother with cylinders not 'purging' - and clamping flexi hoses is highly likely to damage them - it may not show right away - but it is something I never do.

Post by **dunketh** » Tue Jan 29, 2008 4:41 pm

First move is to adjust the front brakes (two adjusters in each brake) right up so they are rubbing and you can only just turn the drum by hand - and try them.

I find with mine, after pumping the pedal a few times the shoes seem to 'settle' and theres even more room for adjustment.
Do the adjusters up tightly, pump the pedal, re-check adjusters, I've replaced all my cylinders and never had any trouble with them not bleeding, though I guess it can happen.

The other option is the old trick of jamming your brake pedal down over night. (bit of wood between pedal and seat works well).
Dunno how it works but it does.

Post by **Kevin** » Tue Jan 29, 2008 9:57 pm

Just a though but I seem to remember a little while ago that some shoes can be touching the drums on the leading edges when the drums have a bit of wear did you change the shoes at the same time as the cylinders if so a small chamfer on the edges may help, also I always get someone to press the pedal on and off when refitting shoes while I turn the drum to assist with the centralising.

Post by **Spag** » Wed Jan 30, 2008 7:01 am

With the pedal pumped and held pressed down a quick bash around the edge of all of the drums can help to settle the shoes in.

Also tapping the wheel cylinders (or the backplate directly behind them) can help dislodge bubbles when bleeding.

Soft faced mallet, don't damage anything and all that.

Post by **jothina** » Wed Jan 30, 2008 6:13 pm

thanks for all your ideas,
i'll get out and have another go at itand let you know how i get on.

john