Juddery Brakes??

[claytow]

Sorry to post again,
On my S6 4.2 V8 tip/Auto car which I have had for a month now and loving it..
I am discovering these little things through driving it and wondering if they are normal.. already posted about my gearbox but this is about the brakes.

They seem to work fine, stop well, abs works and there are no lights on and no ECU errors. However if I am stopped with my foot on the brake, and lift my foot up to creep along very slightly i.e. foot half on the brake and not completely off.
the car seems to judder, this is a high speed judder like the ABS cutting in, thought of a warped disc etc but this is far too quick for the speed I am doing the judder is noticeable by me and under my brake foot.

Any Ideas anyone? if you get what I mean...

 

[n0m1secnerwal]

Perhaps it is actually the ABS? After all you have your foot on the brake, well mostly /ubbthreads/images/graemlins/shocked.gif, and the wheels are moving!

Might be wide of the mark here, but it was just a thought. /ubbthreads/images/graemlins/smile.gif

 

[claytow]

I did think that but at normal speeds under normal braking its fine.. its just a snails pace I get this phenomenon /ubbthreads/images/graemlins/smile.gif

 

[Rev-head]

have you checked transmission fluid?
If you read this link it will give you an insite into the working of your AUTO box and possible answers to your problem

http://www.audiworld.com/news/99/multitronic/content.shtml

To me sounds like fluid low or sensor fault

Cheers

 

[claytow]

Thanks for the article rev-head, unfortunately mines not multi tronic. Aud do recommend an oil change every 40,000 miles on a multitronic but mine is not one of those and thats why they dont recommend it.
Although they wont say when it should be done

 

[Whiz_kid_uk]

I too have this problem, I have not got to the bottom of it yet.. These are the things I have checked.
ABS - REmoved fuse - Problem does not occur.
Checked ECU using VAG com, no faults.
Blead brakes (1 lt or brak fluid. Using vag com to kick of the bleed program)

New pads and discs.
Calipers work perfectly.
Cleaned all eletrical connectors and re-assembled.
Recalibrated abs ( http://wiki.ross-tech.com/index.php/01486)
Verified ABS sensors on wheels detect moovement at high and low speeds

All that is left I would imagine is the abs pump / Control unit.

What do the rest of you guys think ?
J

 

[Whiz_kid_uk]

OK Guys, This was a very weird one, I worked out using VAG com that the Front left wheel was showing a slower speed (Just before the stop). It was only about 2Kms slower.
Turned the Sensor by 3 degrees, and all apears good. Will advise after a longer run !.