5k tq ABS xshooting

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> If that doesn't do it, then looking at the sensor waveform with a
> scope could help you find a missing tooth, or low amplitude (compared
> to one of the rears, which is presumably working okay. The main cause
> of low amplitude is too large a sensor gap.

Amplitude is affected by the sensor gap, the tooth profile and speed
of hub rotation.  ABS problems generally show up first as a stutter at
very low speeds - this is because the amplitude has fallen low enough
at low speeds for the computer to think the wheel has stopped.

I've had three cases - all in cars that have been used extensively on
the east coast of Scotland - where no amount of effort would restore
ABS function after the hub was pulled.  The teeth are no longer
square and straight - they come to a point like gear teeth and they're
concave along the axis of the hub.

-- 
 Phil Payne
 UK Audi quattro Owners Club
 http://www.isham-research.freeserve.co.uk/quattro
 Phone +44 7785 302803   Fax: +44 7785 309674