Hi there

I'm still having an on going problem with my STi 4 pots.

The pedal is always fading and have to pump the pedal to get the pressure to stay up.

Stuff I've tryed:

Replaced master cylinder today with a brand new shiny one.
Bled the system again..
Checked calipers, clamped off brake hoses individually one at a time, road tested same problem everytime apart from when I clamped off near side front and the problem solved, no brake fade.

The fault seems to lie with the near side front caliper... the thing is?! All of the pistons in that caliper come out and go back in without any problem, no sign of seizure or leakage..
Anyone have any ideas?! because I'm all out...!!

Thanks

Marco

 

the caliper must have an leak somewhere that is allowing it to draw air into the system as this is the problem you seem to be experiencing..................

couple of things to look at;
is the bleed nipple sealing properly after bleeding the system
any fluid around the banjo bolt, is this weeping at all
finally if its not obvious externally then i would suggest that one of the internal piston seal is worn and pulling air back past the piston


after bleeding so that yoy have no air in the system, get a mate to hold the pressure on the pedal whilst you inspect all round the caliper/hose area that is causing the problem and check for leaks...........if it is this area you should see something??

alyn

 

Could be a failing wheel bearing causing pad knock-off. Does the pedal get 'longer' after a couple of corners?

Mike

 

Yes if you have no leaks you cannot have it drawing in air , under pressure any leak will show up , I'd be more inclined to look at the wheel bearing , if this has play it will allow the disc to push the pistons back into the calipers
Jake it up , grab the top and bottom of the wheel and see if there is any movement , if there is its the bearing