I take my car this morning

first time after lots of modifications

I put 4 pistons AP racing


I drive for 10 km (very cool and did not brake a lot)

and after a braking, the car start to slow ....

I finish the car was immobilised, impossible to move from 1 meter
4 wheels where bloqued

I've been lucky and after 30 min same I can drive slowly, I come back to home using only hanbrake

I do some check :
- fuid level is good
- connectors are good
- I check from brake to see a bloqued piston (everything is ok)

and I find a problem :

- I can push pistons on a caliper (when 1 go inside, an other one move ouside) but if I block the 3 pistons and try after to push the last one

it's impossible

so brake fluid can go from brake unit to caliper, but something is wrong and fluid can not go back

I suppose my master cylinder is dead and I need to change the brake unit

I did not find post about that

do you think it's the brake unit whitch is dead ???

 

Easy way to see if it's the master cyl(which I doubt) is clamp the brake pipe flexi, then open bleed nipple and try to push the piston back.
tabetha

 

I open the bleed nipple

brake fluid go out

and piston go back

whitch "malfunction" inside the brake unit can do this problem :
brake fluid can not go back in the brake fluid tank when I push on the piston ??

 

It sounds like a problem with your abs valve block, did you renew all the fluid by flushing through till new fluid came through ?
tabetha

 

yes I do it

I found a new brake unit

will change it next week

hope it will solve the problem


is it possible to rebuilt the master cylinder ?

 

Bonjour Florent

For some people who have trapped air in the system it shows this problem.

The fluid can not push the air back up to the tank.

Are you sure no air in the brakes or abs ?

Tony

 

not sure
but I think I do it correctly

as I say before , I can push pistons on a caliper (when 1 go inside, an other one move ouside) but if I block the 3 pistons and try after to push the last one

it was really impossible
I use I big multi grip pliers
and really unable to push back the last piston 1mm back

so I suppose if I had air in the system, I can push back the piston
no ?

 

Can you push piston back with brake pedal down past half way ?
Master cylinder 'open'
(even just a little ?)

1 side of car or both ?

Fronts and rear both locked ?

 

yes

front and rear was blocked