Brake problem, out of options

Level 1 User Joined: 25 Feb 2006 Posts: 28

Hi guys, fitted a new master cylinder as the brakes were shall we say dire.
Bled all four corners and pedal was solid, took her out for a run and the pedal goes right to the floor almost and feels like shes just slowing with rear brakes, rebled again solid another drive same problem pedal goes to the floor, i dont understand why it should be solid stationery but crap when driving can anyone give some ideas as to what it maybe.

Thanks in advance Graham.
PS its a clio williams 2

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

sounds like a problem I have encountered before, on a long bit of safe road, thrash it in 3rd from about 30/40 to the limiter, arund 75/80 check to see if you have smoke out the back, the brakes would have gone by then. Eventually they would come back.

If it has then the servo is pulling brake fluid in through the master.

Seen it on a white ph1 19 16V, pedal was fine at normal speeds and with vacuum on it but when the vacuum went on sustained full throtle brake fluid went into the servo and into the engine and caused the smoke.

What to do is pull off the servo vacuum pipe block the pipe fromt he inlet manifood with a cap (the ABS bendix versions used a wee cap for this if you want perfection) then drive it, the pedal will have no servo assistance so will be heavy.

If the brakes are then fine and don't lose pressure then theres either a servo or master problem.

how did you bleed the rear brakes? on the ground? jacked up? if jacked up did you tie the bias valve open?

Level 1 User Joined: 25 Feb 2006 Posts: 28

She was bled wheels down on a ramp, weird thing is i fitted a new n/s rear caliper and when you open the bleed nipple on it its a pig to push down but we did get some fluid, so im torn between either compensator or vacuum/servo issue, a friend has a 306 td and his brakes went like mine and it was a collapsed vacuum hose.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

if the nipples open and its not flowing easily then the rubber brake pipes probably collasped.

the compensator is very simple and doesn't go wrong unless it leaks.

Level 1 User Joined: 25 Feb 2006 Posts: 28

but would a collapsed pipe on one rear make the whole braking system bad?

and which hose to the inlet manifold is the vacuum one
cheers chris

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

it would if it opened up when driving, the servo provides assistance, maybe enough to let air and fluid through the dodgy pipe to make the pedal fall away to the floor.

its the fat one to the servo, also joins a metal pipe

Level 1 User Joined: 25 Feb 2006 Posts: 28

just been out and it looks like i have fluid on the o/s caliper i gues its time for a new o/s caliper and maybe some braided lines :(

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

my blue hatch needs a new os rear caliper, its leaking out into the handbrake boot then dripping out.

I actually need both calipers on the back.

Level 1 User Joined: 25 Feb 2006 Posts: 28

yeh there appears to be brake fluid all over the handbrake lever cant tell wether its coming out of the boot or wether its running down from the hose, but it must be quite a bit because its on the tyre and theres a puddle on the driveway, bloody brakes.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

sounds like mine then!

press the rubber boot and if its solid then its filled with fluid

Level 1 User Joined: 25 Feb 2006 Posts: 28

yup the rubber boot is oozing out fluid, could that be confusing the compensator into applying all the pressure to the back hence me feeling like its just slowing on the rear?

Off to gsf in a while hopefully can get it fitted later on today will let ya know if it sorts the pedal out, it cant be anything else really coz i know the compensator moves freely

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

no but it will make the pedal go to the floor

Level 1 User Joined: 25 Feb 2006 Posts: 28

oh well new caliper didnt help even though it was deffo knackered

Site Subscriber Joined: 23 Jan 2005 Posts: 502

Renault do a kit for the hand brake side of the caliper. Water gets inside the boot so corrosion gets in under the boot.

But the kit is not cheap and a bit of a pain to fit.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

did you change the pipes?

Site Subscriber Joined: 23 Jan 2005 Posts: 502

The hand break boot O rings may leak a bit into the boot. But not so mutch as to effect breaking unless the liquid level gets to low I would have thought.

Or its realy pissing out.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

hes changed the calipers mate.

mine has filled the boot and its squirting out onto the wheel

Level 1 User Joined: 25 Feb 2006 Posts: 28

both calipers are new, the fact the pedal is solid with engine off then solid when you first fire up is odd it goes to the floor as soon as you drive, now i gotta find the vacuum pipe and check that for splits or squashed, the only things left are the bias valve and the flexible hoses.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

the flexi pipes like i said earlier

and its not odd like I said earlier you then have vacuum assistance which will provide the eextra needed to floor the pedal.

Level 1 User Joined: 25 Feb 2006 Posts: 28

also ive just been looking at the dialogys exploded view of the brake calipers and it shows to copper washers that look like they should go onto where the 13mm adaptor piece screws into the caliper do i need them coz i havent fitted them?

Flexi hoses next cheers chris again

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

theres no washers fitted mate