ABS kicking in just before car stops!??!

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stormduck

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Alright all, finally got the car back on the road but only just passed mot due to poor braking results on the rollers. Weird thing is i didn't touch the brakes while the car was off the road! They were rusted up due to sitting there for 6 weeks so i took her for many 70mph to 0 foot heavy on the brakes to try and clear before the MOt but obviously didn't work. The strangest thing i'm getting is kickback in the pedal from the abs coming on at about 5mph as i'm coming to a stop under light braking...very strange.

Its in the garage today and they've been driving it while plugged in to the diagnostics and its showing no faults even while its doing it. They're a bit confused like me, the only thing i changed in that area is the passenger driveshaft, and removed the front hubs to replace the bearings, didn't touch the brakes in any way. And there's no dash lights on either.

Any one experienced this strange witchcraft before?
 
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stormduck

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He's been spinning each wheel and reading the wheel speed off the laptop...the two back wheels register very quickly and accurately, whereas the two front wheels only show up a reading at 5kph and the reading fluctuates...but the front pair match and the rear pair match, one wheel doesn't stand out as being different.

The abs ring on the drivers side is the thin version and was changed last year without a problem...the passenger side has only just been changed, and as the other abs ring, being thin had no problems, i didn't see a problem with changing the passenger side to match. That is only difference....but the sensors are working and picking up both rings, and there hasn't been a problem before. ARGH!

He's checked all the rings for slipping, cracking, missing teeth and all are fine. He's bled the whole brake system, taken off both hub nuts and checked the hubs are fitted in where they should be and re-torqued the nuts.

I can slam the brakes on at 70 and the car pulls up faultlessly and hard. But pull up slowly to a junction and at 5mph-ish grrrrrrrrrrrrrrrrrrrrr. Very confused.
 
Carbon Chaos

Carbon Chaos

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May be as you said the front pair only start to register road speed at 5mph or so the abs computer is seeing a difference in road speed front to rear at low speeds.

I.E it thinks the fronts are locked? therefore applies the abs pump?

just a thought.
 
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stormduck

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yeah i think your right mate, after the confusion cleared it's becoming more apparent that there's no fault in the system, it's the reading the sensors are picking up, and like you say, no reading below 5mph makes it think they've locked up....i think i'm gona have to replace both driveshafts for the wider ringed versions. yeehar.
 
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