Occasional brake vibration
A6 2.5TDI Multitronic 2002.
Perfect to 40k miles, then new pads. Few days later, vibration set in at 70mph. Front left hand wheel. Stopped the car, shook everything to check wheel nuts done up (!), drove off, it cleared. Over past 2 years, it has happened maybe once in very 15 - 20 main road journeys. Now 75k miles on the clock. In that time, it's had: new pads (twice), renewed caliper, new discs (rotors). Tyres have been changed too, so balance not a likely cause. Still happens. If I stop and turn the engine off, then re-start, it almost always clears and I can go straight back up to 70mph without it recurring. After most journeys, this front left wheel is quite a bit hotter than the right front - even round town or if I haven't felt the vibration on that trip. Also this side eats pads and discs faster than the other. But why?
No ABS or ESP warning lights, Audi dealer could find no problem (but eventually changed the caliper f.o.c.).
Might it be a fault in the ABS actuator/ pump (that the electronics don't sense?). Any ideas much appreciated.
thanks
Martin
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