problems with my brakes

[Skull]

Hello.

I changed the steering rack some days ago, and now i have problems with the brakes. The thing is, i had to remove the master cilinder with the "brake amplifier" (dunno how it is in english, the black disc), and i also had to remove some brake lines from the abs. I put new brake fluid in, "ventilated" the brake sistem 4 times, one also with air pressure, and the brake pedal is still soft. I have brakes, i can stop, but the pedal goes to the bottom. If i pump it a couple of times it gets hard as it should be, but when i release it, it gets soft again.

helpe me please

[~Delta]

Sounds like you still have air in the system.

[s2dude]

Hello.

I changed the steering rack some days ago, and now i have problems with the brakes. The thing is, i had to remove the master cilinder with the "brake amplifier" (dunno how it is in english, the black disc), and i also had to remove some brake lines from the abs. I put new brake fluid in, "ventilated" the brake sistem 4 times, one also with air pressure, and the brake pedal is still soft. I have brakes, i can stop, but the pedal goes to the bottom. If i pump it a couple of times it gets hard as it should be, but when i release it, it gets soft again.

helpe me please

Hi

DId you folow this procedure for bleeding the brakes??

http://www.s2-audi.co.uk/tech_articles/brake_bleeding.htm

Also, Im guessing you bled the power steering with five full lock to lock turns?

[Skull]

I forgot to write that i changed the front calipers too, and drained all the oil out of the sistem (it was old). I cant figure out where could this air be. The abs is working fine (tested on the road).

[Skull]

Power steering? uhh err.... no?

[dan_b]

The brakes and power steering are separate hydraulic systems.

What brake fluid did you use to bleed?
Are you sure you've screwed everything back together tightly- all the bleed valves done up correctly, and the brake lines to your new calipers are on correctly? It does sound to me like you've still got air in your system -refer to the bleeding instructions given in the linked thread above - look to use at least 2 litres of brake fluid to bleed fully.

[Skull]

I used 2 liters of bosch dot4 fluid. I have bleed everything 4 times, but i can still press the pedal almost to the floor at engine on. I have absolutly no leaks. I can drive around with the car, but the brakes grab only when the pedal is 3/4 floored. Disc and pads are new btw.

[Nuvo]

[thread resurrection]How did you solve this Skull? I am having similar problems with my brake system. [/thread resurrection]

[Skull]

Well the problem back then was that i had new discs, pads and oil, and looks like the sistem needed some time to settle itself, as after something less than 2000 km, it started braking as it should.

[s2driveruk]

i think it was also possible to not fully bleed if you did it with the handbrake on too from memory

[Nuvo]

Thanks, I too have replaced all discs and pads and bled the system (with the handbrake off). I hope it settles some time soon as I have an MOT test late this afternoon.

[Skull]

Let us know how was the MOT.

[Nuvo]

Well, it failed I'm afraid. The front brakes passed thankfully, even though the brake pedal stills feels a little soft to me. I had a bad feeling that my master ctlinder had failed letting brake fluid past the seals.

It failed on handbrake braking efficiency on both sides which surprised me as I replaced all the guide pin boots as they were perforated, I replaced the carriers too (thanks Noel) as the guide pins had seized. I lubricated the guide pins with the proper grease that comes supplied with the boots.

I was genuinely surprised that it failed on this, my only criticism was that the handrake lever was setting on six clicks rather than three but it is capable of holding the car on a steep hill. I'm tempted to take the car to another garage to run on their rolling road for a second opinion.

Hand brake cables and calipers had been replaced to a good few years back in my ownership so I have no reason to suspect them. I'll start by looking at adjusting the handbrake cable first and take it from there.

[Skull]

I have the same problem on mine, but the guy at the mot let me trough...

[gedu]

As for bedding in pads and disks, you can accelerate the bedding in process quite handily. A few gentle brakings at first to bring pad and disk temperature slowly up a bit. After this start doing 60mph-10mph brakings one after another until brakes soften a bit up. Then let them cool down by cruising along and using brakes as little as possible for 10 minutes. Never ever come to stop while doing this, as this will leave imprint from pad to the disk, and you will have shaky brakes. You might need to bleed your brakes after doing this. You also might need second cycle of "heat treatment" for your brakes. For more info, read http://www.zeckhausen.com/bedding_in_brakes.htm