Disk pads replacement and spungy, weak break pedal?

jsosic

Registered User
Hi guys

I've taken my Audi to the stealers and they've replaced my disk pads (both fronts and rears). Since I bought the car, brake pedal was always biting at the top, and was biting pretty hard straight on, but now, after the stealers replaced break pads, break pedal feels "spungy" and I need to press it really deep - like 2-3 inches, to achieve hard breaking.

Another thing I noticed is - if I pump it (press it 2-3 times hard while stationary) - correct biting point and hardness is achieved, but it fades out after couple of seconds.

Also, if I press the break hard while stationary, I kinda feel my leg slowly diving in, like the pedal isn't completely stationary...

I don't think this is normal, but, since the official dealer did the work, it's hard for me to imagine that the service guys can't swap the break pads on A3 8P from 2009 without screwing everything?! This is my first replacement since the car was new, I'm now at 9 years and 70k miles... and breaks were perfect from the first day I bought the car till today.

Since I also drive a mountain bike, I know that when I push the calipers pistons back in - it only takes 2-3 pulls of the lever for the brake to level of and start biting at correct point and become really "hard". Why is it different with a car? Did they mess my brakes up? :(
 

Jezza16v

Registered User
Sounds like you could have a couple of issues, the spongy feel will be air in the hydraulic lines and the pedal dropping slowly could be fluid leaking past the master cylinder seals (or the air in the system dissolving in the fluid under the pressure). How far down does the pedal go when you keep the pressure on it?
You shouldn't have to bleed the brakes when you change the pads (unless one of the pistons popped out of the calipers). If the fluid was old and contaminated then when they pushed the pistons back it may have forced some crud back up the pipes into the master cylinder and reservoir causing damage to the seals?
 

jsosic

Registered User
Fluid was probably ~20k miles old. I don't know what they did when they replaced them and what procedure they used, it is an official dealer so I guess they use the correct procedure :(

I will test it tomorrow, maybe even record it and share it here.

I've searched online for the symptoms and have seen the possibility of old oil contaminating and damaging master cylinder. If they did that, that's really ****** amateur work... I mean, if I was working in a repair shop, that could have happened to me first time I did the job, but then I would learn and never repeat that mistake - like - never AGAIN...

How long after the replacement of the pads should the brakes get back to the original feel ?
 

samuelh_888

Registered User
...
it's hard for me to imagine that the service guys can't swap the break pads on A3 8P from 2009 without screwing everything?!

It’s not hard for me to imagine!

It’s probably worth a fluid change but nevertheless you wouldn’t expect it to come back worse than when you took the car in.

Have you spoken to the dealer about the issue?
 

Retroman

Audi A3 2010 Sportback 2.0 TDI 170 (CBBB engine)
I changed by discs, pads and fluid myself in 2016 at 78K. The discs & pads were in a poor state and yet I always thought they felt good. Like you, I was not happy with the feel immediately afterwards despite bleeding through (twice) a fair bit of top quality Castrol (React Performance) DOT 4 brake fluid. It took around 300 miles for the brakes to feel as good (if not slightly better) again. I've never known a car to take so long for a so called "bedding in" process.
 

Jezza16v

Registered User
The pedal 'feel' should come back straight away but it can take up to 500mls for the pads to bed into the old discs so that the braking efficiency is back to 100%. You may have got used to a 'false' firmness of 'feel' if the old pads were seized on their sliders, they are unseized as a matter of course when new pads are installed. If, as you say, this was the first pad change in 70k (a miracle in itself) then the pads may well have been seized in a bit, 70k!! Surely they must at least have changed the front discs as well? If your pads are lasting 70k you must be older than me...:suspicion: ?
 

Retroman

Audi A3 2010 Sportback 2.0 TDI 170 (CBBB engine)
Changing brake discs and pads will be "everyday bread 'n butter" work for mechanics and so extremely unlikely that they "messed up". Furthermore, main dealer OE stuff will be top quality. As I said above, I have never before experienced new disc brakes take so long to "bed in" after changing as the ones on my A3 and assume it must be some sort of sensation/characteristic of the servo assisted brakes on the 8P A3, which for the status of car, seem very sharp and need very little pressure on the brake pedal - a slight change therefore, being more noticeable.
 

nluk100

Registered User
Rear calipers are notorious for seizing and may need replacing / refurbishing - check if the pads are either binding or are lose (rattling) once you've done a few hundred miles.
 
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