Sounds like your ABS is over sensitive and is activating even though the brakes are not locking up.
Check this by removing the ABS fuse and take the car for a short drive.
Dont worry, your brakes will still work as normal, you just wont have the anti-lock function.
Removing the fuse is a test procedure, NOT a repair!!!
If the juddering is still there then you probably have one or more warped discs. Remember discs must be replaced as axle pairs.
If the juddering has gone away with the fuse removed then you have an ABS problem, probably with one of the wheel sensors or reluctor rings.
You could have a look at them, make sure the sensors are firmly fitted and clean, check the rings for looseness, cracks, or missing teeth, give the ring a clean to make sure rust has not filled the gaps between the teeth.
Unplug and re-connect the sensors.
If you are not mechanically experienced it would be best to get a garage to check this for you, brakes are not the best part of a car to practice on.
doofer
September 2009
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.