I have a 2000 Audi TT Quattro 5-speed. I have been having an ABS or brake or axle problem that is VERY intermittent. Audi techs have been all over the car twice and have never heard or seen a problem. WHat happens is, quite often it will feel and sound as if the ABS is activating, often when just starting out in first gear and not touching the brakes. But the noise is often a “metal-on-metal” sound, really quite alarming. It never happens at highway speeds. It happens in both wet and dry conditions. It has happened with my summer tires on alloy wheels and with my snow tires on metal rims.
Does turning in either direction have any effect on the noise?
It doesn’t seem to. I say “seem” only because of the intermittent aspect of the noise. It always stops eventually when driving, and of course, the wheels are turning direction. Audi Service had replaced an ABS sensor on one wheel. I think they were just guessing (and charging for the incorrect guess). My gut is telling me it has something to do with the axle (though I am in no way mechanically savvy).
Unnecessarily complex drivetrains, while an interesting engineering tour de force, can turn into your worst nightmare when mechanical problems develope.
You might start by disconnecting the ABS / traction control system and see if that cures it. Then you will know if it’s a brake system or drivetrain problem. Good Luck!