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Massive Braking Issue



BIFCAIDS

ClioSport Club Member
  340i M-Sport & 182
Afternoon kids,

Ok, so where to start? On the 14th we were at Snetterton for a track day, brakes were on form for the first half of the day and after lunch rapidly went down hill. I'm sure as most of you will know Snetterton has some big braking sections and I was finding the pedal would go through half of its travel before we got some retardation but if you had a second bite at the cherry they were ON!

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So into the garage, check fluid and bleed brakes. We bled the brakes as you would furthest from the cylinder first etc, the pedal felt great nice and solid. once we dropped the car down pedal was still quite spongy so I took the car down the paddock and my foot went straight to the floor before I could hear pad on disc action. Back into the garage and bleed the brakes again maybe we're not bleeding enough out of them, so we bled them some more with more pumps of the pedal. The pedal felt great and again dropped the car down but the pedal felt better this time but still not great so as the track was dead we decided to go out to see if we could try and get "something" from the brakes. Again 2 bites of the cherry and we get some braking power only the rear is waving like and excited dogs arse. Again after a lap bled them again nothing, not air in the system it would seem, so with it being an hour from the end we called it a day.

All the way home you had to brake way way in advance (probably not the safest or best idea), but the pedal got no better.

What I would like to know is if anybody has any theories/ideas and or solutions for this I would really appreciate it.

Brake set up for those interested.
Standard Calipers with new everything (big red seal and piston kit etc)
CL RC5+ Pads up front
Brembo Discs front and rear
Brembo Pads rear
Goodridge braided lines front and rear
Motul 5.1 fluid.
 
As above check the servo vacuum pipe, they can melt if the engine is left long enough idling.

The rear locking up sounds like the ABS system has a fault as it reverts to 50/50 leading to the rears locking under hard braking, but you'd probably get a load of dash lights if so.
 

BIFCAIDS

ClioSport Club Member
  340i M-Sport & 182
No dash lights Im afraid, but the servo vacuum pipe sound like a cause.

Oh to mention I also have a make-shift head sheild between the engine and the master cylinder. As for it melting christ surely you'd have to have it running on idle for days not minutes.
 
No dash lights Im afraid, but the servo vacuum pipe sound like a cause.

Oh to mention I also have a make-shift head sheild between the engine and the master cylinder. As for it melting christ surely you'd have to have it running on idle for days not minutes.
Not necessarily, especially with a makeshift heat shield.
 

BIFCAIDS

ClioSport Club Member
  340i M-Sport & 182
split servo hose should give you hard crap pedal. you had it on brake roller at all?

No we've not, the pedal is only hard when its not running and you pump it otherwise its straight to the floor.
 


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