ABS Reluctor Ring Replacement (aka ABS brake pedal judder)

[steve_earwig]

That's the kiddy

[Archangel]

so , if it appears to be not working , reluctor rings could be the problem ?

[OdinEidolon]

This juddes happens only when the ABS kicks in or even with small braking?

[highlander]

Normal braking, you won't get the juddering. It only occurs when the car detects that the wheels are not spinning while the car is still moving - the juddering is the brakes going on/off/on/off/on/off (etc) so that the car slows down without the wheels locking up.

The best way to simulate this is to go about 40 MPH and then absolutely stand on the brakes - you should feel the pedal pulsing as the ABS goes bananas.

[Archangel]

That's the kiddy

Thats another thing that this car has that I didn`t know about ,just finding what an older car should have or not is interesting

[OdinEidolon]

Normal braking, you won't get the juddering. It only occurs when the car detects that the wheels are not spinning while the car is still moving - the juddering is the brakes going on/off/on/off/on/off (etc) so that the car slows down without the wheels locking up.

The best way to simulate this is to go about 40 MPH and then absolutely stand on the brakes - you should feel the pedal pulsing as the ABS goes bananas.

Yes, but then the juddering is normal, isn't it?

[highlander]

It's perfectly normal - it's how ABS works.

If the brakes are applied hard (at speed), and the wheels lock up, then you're just going to keep moving forward (regardless which way you turn the steering wheel), buggering your tyres up pretty badly, leaving a big long trail of burnt rubber in your wake.

The ABS works by not allowing the wheels to lock up - but it still needs to stop the car - so the brakes cycle between on and off very quickly, allowing the wheels to keep turning. This therefore affords you some directional control, as you can't steer if your wheels aren't rotating.

The pulsing you feel through the pedal is the pressure from the ABS braking system. It's very distinctive, but it's just a sign the ABS system is doing its job.

If you get the juddering when you're not braking hard (like, "emergency stop" from high speed) then there may be another problem.

[OdinEidolon]

It's perfectly normal - it's how ABS works.

If the brakes are applied hard (at speed), and the wheels lock up, then you're just going to keep moving forward (regardless which way you turn the steering wheel), buggering your tyres up pretty badly, leaving a big long trail of burnt rubber in your wake.

The ABS works by not allowing the wheels to lock up - but it still needs to stop the car - so the brakes cycle between on and off very quickly, allowing the wheels to keep turning. This therefore affords you some directional control, as you can't steer if your wheels aren't rotating.

The pulsing you feel through the pedal is the pressure from the ABS braking system. It's very distinctive, but it's just a sign the ABS system is doing its job.

If you get the juddering when you're not braking hard (like, "emergency stop" from high speed) then there may be another problem.

Ok, I understand how ABS works. It's just that when I bought my 406 I road tested one that didn't judder when heavy breaking, even if the ABS was working. The braking was very smooth and strong I was starting to think there was smth wrong with my car!
Thanks.

[pgascoyne]

The judder effect you get when your reluctor rings are worn/broken teeth/not aligned is complete loss of braking control.
Basically it skips the mini braking effect as described by Highlander and you feel for a short moment like your brakes have failed, thus forcing you to ram your foot on the brake.
So in effect it increases the time that the brakes are actually cycling on/off because it looses sync.
Certainly puts your heart in your mouth when you're coasting towards a car say at a junction/lights and just when you need to brake it starts skipping!