weak & strange brake effect

[Co-RS-ák]

Hi guys,

i have a problem on my A3 92kW AGN, 98' with brakes. When i bought it 2years ago, brakes was pretty sharp, literally even i just looked on brake pedal - it brakes )

Now when i push pedal about 2-3cm down, nothing happen, then it brakes "okay", BUT if i had to stop immediately and kick the pedal down, audi just slowing down very weakly, and sometime starts ABS at the end of braking about 20km/h and less. I changed rear complet brakes but nothing changed (they were bad) front are still in good condition. I tried push brake pedal down when the engine is not runnig, it became hard after 3-4times, then start engine and it get soft to half way, i guess. So brake booster should be okay.

Also i tried 30A safe (in batter place) for ABS system put off and i think i was little bit better, but rear wheels were totally blocked ( nice for drifting) ) but the brake effect was quite like i expecting all the time.

So can anyone help me please with this? Thank you guys and sorry for my english

 

[shan00ble]

Your break pedal should be really hard when the car is off. Was the system bled correctly?

 

[desertstorm]

As above I would say the car needs a brake fluid change through the whole system and all the flexible pipes checking. Also check the ABS reluctor rings on the front CV joints to make sure they haven't split.

http://www.evilution.co.uk/453

 

[Co-RS-ák]

Brake pedal is really hard after 3-4times pushing. And i didnt have the system open, so there wasnt reason for bleeding, its still same from i bought the car, but now didnt brake properly even i changed the rear discs and plates.

I forgot to say, i had car on diagnostic bosch kts 520, it did show "ABS/EDS Teves Mk20 0520 interface CAN component wrong" sorry but i dont know what does it mean.

Thats right, it hadnt been changed for minimum 2years, but im scared from the change, cause audi have abs unit and im not shure how to bleed without diagnostic. some say it doesnt matter, do it like theres no abs unit, but i dont think so, can you help me please?
I'll check the ring, thank you

 

[Co-RS-ák]

i was on the route, trying severaltimes in a sec push brake pedal and go about 100km/h and it becames very hard like no booster does his job..

 

[pj123]

Probably the brake vacuum hose between the servo and the engine/ vacuum pump

http://www.tyresmoke.net/forum/topic/126149-audi-s3-8l-210-apy-brake-vacuum-hose-repair/

 

[Erikn89nl]

Can that hose safely be replaced by silicone hose, when keeping a check valve in the line?

 

[desertstorm]

If you push the brake pedal very quickly several times this will reduce the vacuum. This is normal. You say that when the engine is running you have to push the pedal 2-3cm before it does anything and it's soft. Thats not a vacuum problem.
Get the brakes bled and the fluid replaced. If you can't do it take it to a garage who can.
I use an eezibleed on my car and it works fine.

http://www.ebay.co.uk/itm/Gunson-EE...496?pt=LH_DefaultDomain_3&hash=item1e71d94200

Karl.

 

[Co-RS-ák]

but this was extreme, 100% sure it wasnt normal. I replaced the hose from vacuum pump to engine and still the same, even the hose was broken. When engine is runnig, i tried to push 5x brake pedal and hold and i felt my leg is slowly falling down till half pedal way.. seems to be problem with brake pump or bad bled system?

 

[laprell]

Hi, I'm having the same problem, did you get it sorted?

 

[Co-RS-ák]

hi laprell,

no, i didnt. I changed damaged pipe from brake cylinder, but its still the same

 

[laprell]

Did you try bleeding the master cylinder? think mine needs replacing

 

[Co-RS-ák]

not yet...havent time.. i think it could be bad sealing inside master cylinder, but it just still guessing...

 

[laprell]

Mine has to be tested today for the MOT, hopefully it passes and I will try to bleed it again.

 

[Co-RS-ák]

what does it mean MOT?

 

[laprell]

Its the uk's safety/emissions test for cars. It passed but bad on emissions. Maybe a lambda sensor. My brakes are legal but im still not happy with them.

 

[Co-RS-ák]

i'll be probably change master cylinder, everything shows to him.. i ll have to go for MOT in 3months.. then ill get you know

 

[laprell]

I bled the master again, feels better but still not enough power.