When I bought my used 2000 Audi A6 about 2 months ago the brakes were totaly shot . ( one of the reasons I got it so cheap ) the car has 350,000km on it .

So i proceeded to replace 4 rotors , four sets of pads and rebuilt the front right caliper . I also replaced the master cylinder thinking i am going this far and put 4 new flexible brake lines on it . I removed and cleaned out the brake reservior also .
After putting it back together the brakes felt to me a little soft but the P.O I bought it from felt it was normal . I did a complete flush with super blue by the way with the old fashioned pump method s i felt this would be fine with a brand new master and fresh fluid .... now the problem ..
I was backing into the garage yesterday after very limites driving with this car ( about 1ookm max as i never needed it ) and my foot went right to the floor on the brake .. I panicked and pressed harder and the car stopped . I then put it in park hit the brake peddle a couple of times and it cam right back up .
Today was the first real chance I had to drive it so i drove to the city to borrow a motive power bleder and payed particular attention to the brake s ... I noticed that whenever I press the brakes it stops fine but if i press on the highway for example it goes a ceratin distance before it gets hard , I press again and it only goes half the distance , third time it brakes right at the top . I have no idea if this is somewhat normal.
My questions are multiple .
1. is this indicitive of air in the lines ?
2. is this indicitive of a bad master cylinder which is BRAND NEW .
3. If these is air in teABS module for example would this cause it ? and if so how would I go about getting it out ?
4. Is it worth bleeding again with the power bleeder or is this good money after bad and I need to replace the M/c again ?
5. does the power bleeder really do anything pump bleeding doesn't do ?

Any feedback would be appreciated ..

My personal feeling is that if there was air in lines would it not be soft all the time and not pump up or is my thinking wrong .

Thanks for any input . I will cross post this to Audi world also .

 

sounds to me like you have air in the lines. A power bleeder doesn't do anything the pump method wont, just does it faster and without 2 people. Just keep bleeding all 4 of those brakes, there is air in there somewhere.

 

There is a method in the Bently manual for proper brake bleeding. It tells you in which sequence they should be done, and how to bleed the abs pump. Unfortunately I can't help you out any more than that, as me and my manual are in different countries right now.

 

well that is intereting . I wonder if i missed something. I don't have vag com so i hope it doesn't involve that,but i guess i could go buy it . as a rule you always start with the farthest caliper from the reservoir and work back . ie passenger rear, drivers rear, passenger front . drivers front.
I am thinking i may have air in their . A porsche guy I was talkingto was telling me he had my exact issue . se he went out and drove it hard , he said once the ABS fired a couple of times the brake pedal was rock har d.. so there may be something to this.
If anyone has an idea of how to accomplish this please pass it along.
I bled today again and got a few bubbles but nothing significant..

 

First, bed your brakes. It COULD be that your brake pads need to warm up before they act right. To bed them, drive at 60 MPH (100 klicks/hour) and stop hard. Repeat once. Now, park the car and let it sit for 24 hours. This will usually bed your pads (but racing pads may take a bit more). The small bit a non-fit between the pads and the rotors, bacause both are new and haven't broken into each other yet, can cause the calipers to back out a bit more than they will when everything is bedded nice causing just your symptoms.

Good luck,

Bob