ABS reluctor ring

[rick28]

Hi all

Just a quick post in the hope someone with experience with the A3 8P ABS system can advise me on an issue I am having with my ABS. I have recently replaced the rear left wheel speed sensor due to a VAG code but the code still remains. I want to inspect the ABS reluctor ring to find out if its badly rusted, cracked etc. Whats the easiest way to go about this, apart from taking it to a garage..? Is the only way to get to this part by removing the caliper and disc etc?

 

[Khufu]

The ring is part of the wheel bearing, im sure its hard to see without stripping off the disc.

AFAIK if you can clear the code and it comes back on over a certain speed it could be the ring but if it wont clear at all its usually the sensor or associated wiring.

 

[rick28]

Hi

If i clear the code, it only comes back on about ten seconds after driving off, I have already swapped the sensor so i suspect that in itself is fine. The speed that this sensor reads is intermittant as compared to the other 3 wheel speed sensors, i will try and figure out how to get the caliper and disc off but I dont really want to remove the pads etc and I am not sure if there is a way to remove the caliper but keep the pads secured within it so that I can just bolt the caliper back on after without having to adjust anything

 

[Lewis583]

Just undo the carrier bolts, if you can get at them. The caliper, carrier and pads will come out as one then. Just make sure you don't press the brake pedal/ apply the handbrake

 

[rick28]

Hi

Those carrier bolts do look a little tricky to get too but hopefully i'll find something suitable in my tool kit. So basically, I need to:

Jack the car up
Chock the front wheels (bricks should do)
Remove the handbrake
Remove wheel
Remove carrier bolts
Remove caliper carrier, caliper and pads
Remove brake disc screw
Remove brake disc (any good methods to remove if its not budging or should I expect it to just fall away? Maybe tap a piece of wood against the disc?)
Hopefully I will then be able to see the ABS ring and at least inspect it, hopefully it just needs a good clean with a wire brush or I need to confirm the sensor is at the right range from the ring

 

[Lewis583]

Hi

Those carrier bolts do look a little tricky to get too but hopefully i'll find something suitable in my tool kit. So basically, I need to:

Jack the car up
Chock the front wheels (bricks should do)
Remove the handbrake I pressume disengage
Remove wheel
Remove carrier bolts
Remove caliper carrier, caliper and pads
Remove brake disc screw
Remove brake disc (any good methods to remove if its not budging or should I expect it to just fall away? Maybe tap a piece of wood against the disc?)
Hopefully I will then be able to see the ABS ring and at least inspect it, hopefully it just needs a good clean with a wire brush or I need to confirm the sensor is at the right range from the ring

The discs can sometimes be a bit tight, usually when they are i just give the area around the wheel bolt holes a good hit with a hammer (I know i'm a vandal) and they come off.

If the reluctor ring is built into the bearing assy i don't think there is much you can do. When you replaced the sensor did you fit genuine?

 

[rick28]

Yes, i think they are built into the wheel bearing but I hope to at least visually inspect the abs ring and if it looks to be busted it may have to go into a garage to replace. Funny you ask about whether the sensor was genuine, i was thinking about that being an issue, it is in fact just one a bought from Euro Car parts for £40.. I was thinking of swapping over the rear sensors to see if the fault follows but with the trouble i had removing the sensor in the first place it came out in pieces so I would have to buy a genuine one to test, but if it made no difference, i doubt I could take it back.

 

[Lewis583]

Unfortunatley not many places will allow refunds for electrical parts. I only asked as my boss had issues on his BMW with aftermarket ABS wheel speed sensors and as soon as he fitted genuine it cured it. The only definite way to check whether it's the sensor is to as you said sway it to the other side and see if the fault follows.

 

[rick28]

I didnt manage to get the caliper off the other day, those nuts are so tight its unreal! The screw that secures the brake disc in also is a bit cut up now too. I did however manage to get some light down the back of the brake disc and turn the wheel, the small ring which i assume is the reluctor ring that is about 1mm or so away from the wheel speed sensor end has a small chunk missing, probably just rusted away. Looks like I am going to have to get the full wheel bearing and hub replaced to get my abs working again :-( i wonder how much labour a garage should charge for that? The hub and bearing kit looks to be around £100-£120