A4 spongy brake pedal

**fellow** · 12-06-2010,05:42 AM

Help!!!!!!!i have a 1995 audi A 1.8 petrol. the brake pedal seems to travel when you first apply it and then when you apply it for the second time it feels firmer. i have had 2 new calipers on the rear and a new brake master cylinder and still the travel - it has been bled by a Audi/VW specialist and still no joy!!! they have suggested the ABS pump might be to blame??? i have queried the Servo but they suggest the pump might be to blame??
any ideas from anyone who has had the same problem?before i source an ABS pump?

**BrandonA4** · 12-06-2010,05:56 AM

Hi, are you losing any break fluid??? if not then i would think the ABS might be to blame. I wonder if a brake specialist can pressure test it for leaking seals, might be easier to get one from a wrecker.
Keep us posted.

**zollaf** · 12-06-2010,07:19 AM

sounds like the servo to me. try this. start engine, run for a few seconds then turn off. press brake pedal then release. press again etc.. how many presses before it goes hard ? hold pedal down and start engine. does the pedal immediately go soft ?

**fellow** · 14-06-2010,11:17 PM

Thanks for that........i started the engine and then turned it off, pumped the brake pedal bout 2 or 3 times and it went rock hard. i then started the engine and the pedal went soft quite quickly but again a fair bit of travel.
today i slammed on the brakes whilst travelling down a slip road and there was a bit of travel, but almost immediately i took my foot off the brake pedal and slammed on again and the brakes were very sharp ( made sure that no one was behind obviously!! ) . it really is spoiling what is otherwise a really good car that still drives well. as i said, i've just replaced the brake master cylinder with no joy.
any more ideas?

**zollaf** · 14-06-2010,11:24 PM

i think you either have a faulty servo, or a vacuum leak somewhere. with the engine running, can you hear any hissing, especially when you wiggle the servo vacuum pipe, or any pipes connected to it

**bvisser** · 28-09-2010,10:32 AM

I have the same car and the same feeling. The brake pedal feels very soft and travels quite a bit. But I does brake

My vacuum is 100%, I say that because I still have some vacuum assist left (1 maybe 2 pedal depressions) in the morning before I start the car from the nights driving before the pedal becomes hard.

My concern is why if I stand at a traffic light and keep the pressure firmly(hard) on the pedal it continues to go deeper and deeper until about 1.5inch from the floor? I've (replaced the old and) bled the system and don't lose a drop fluid!

Is this normal? Is it air in the system? Is the master cylinder leaking? help?

**Alan02** · 28-09-2010,07:49 PM

Possibly faulty Servo.

**deryl** · 13-02-2011,10:29 PM

[QUOTE=bvisser;562917]I have the same car and the same feeling. The brake pedal feels very soft and travels quite a bit. But I does brake

My vacuum is 100%, I say that because I still have some vacuum assist left (1 maybe 2 pedal depressions) in the morning before I start the car from the nights driving before the pedal becomes hard.

My concern is why if I stand at a traffic light and keep the pressure firmly(hard) on the pedal it continues to go deeper and deeper until about 1.5inch from the floor? I've (replaced the old and) bled the system and don't lose a drop fluid!

Is this normal? Is it air in the system? Is the master cylinder leaking? help?[

I HAVE EXACTLY THE SAME PROBLEM WITH MY 2003 POLO 1.9 TDI SPORT

DID YOU GET ANYWHERE WITH IT?

BEST WISHES

Deryl

**BrandonA4** · 13-02-2011,11:19 PM

Sounds like your master break cylinder is passing you wont be loosing any fluid. You will need to have it serviced ... re kitted the piston and sleeve have become worn and break fluid is passing and not holding pressure.

**bvisser** · 14-02-2011,07:13 AM

Hi Deryl & BrandonA4

I still have the exactly the same symptoms and the brakes work fine. Have also checked the ABS on loos gravel so ensure all the wheels brake and on tar to see if its pulling to a side. (so there is nothing else wrong with my brakes except the slow leaking MSB).

From my mechanical understanding of the system (got the ETKA diagrams of the net) BrandonA4 is correct its the MBS. So in my opinion its not critical and when it worsens I will replace it.