BX ABS reluctor rings

[BX Bandit]

Hmmm, not sure. I'm convinced my 16v has something like 70 odd teeth, but it's a great idea if they can make the correct teeth number and they can fit on the CVJ. I thought the original ones were cast on the CVJ though?

[RxBX]

Hmmm, not sure. I'm convinced my 16v has something like 70 odd teeth, but it's a great idea if they can make the correct teeth number and they can fit on the CVJ. I thought the original ones were cast on the CVJ though?

Hi Neil,
The O/E ABS/reluctor rings were just normally pressed on the outer diameter of the CVJ (but possibly warmed up slightly during manufacture to make them easier to slip them on), are you just after the reluctor rings or a complete CVJ with them already fitted (As your posting is in the spotting section)

Heres a complete outer CVJ with a reluctor ring fitted F/S on E-bay:-



Click on photo for link, looks like they have 90 teeth

.

[JayW]

I've seen the exciter rings for sale somewhere, i'll see if i can dig the site up!

[BX Bandit]

That's interesting RX, so the original rings were indeed pressed on? I've not got issues with mine (yet) but my xm apparently had a cracked ring, making the abs ecu 'think' the car was skidding thus extending braking distances to alarming effect.
I also know the rings on the valver have suffered from corrosion enough for me to ponder how to replace them, hence my Interest and this post.
In any case, does it mean the eBay ad is wrong in listing a ring with 29 windows (30 teeth)?

[mat_fenwick]

cracked ring

There's a joke in there *somewhere*...

As the ABS system looks at wheel speed differences, I wonder whether the number of teeth is actually critical, so long as all wheels have the same number? That may open up new possibilities if the rear hub rings can be swapped. I suppose too high a frequency may be outside pre-set limits in the electronics, but I can't see any other problem - the system can't know whether it's widely spaced teeth rotating fast, or a smaller number of teeth rotating slowly.

[BX Bandit]

Ruddy good point old boy! Where are they on the rear? Are they on the brake discs? Pressed or cast?
I guess you'd have to have all 4 the same, not just axle sets?
Being as the front ones have about 1000 'teeth' then as you say, a lower number wouldn't (or shouldn't) make a difference.

edit: Just checked on Cit site, the ABS 'teeth' are on the rear hub

[citsncycles]

I suppose too high a frequency may be outside pre-set limits in the electronics,

Wasn't someone posting a few weeks back that their ABS light came on above a certain speed? - maybe they were just going too fast

[JayW]

It's my understanding that the ABS meters the "resistence" through the wheel sensor coils. This varies as the wheel rotates and the exciter ring (with it's teeth) triggers this resistence.

This has to all happen within set parameters in the ECU, so that, if there's a fault, it knows about it.

So, it's unlikely that changing the number of teeth is feasible, this would push outide the parameters and trigger a fault, even if all 4 were changed.

This is why an MOT bodge resistor has to be 1kOHM otherwise it won't match the preset static parameter.

Still trying to find that website!

[JayW]

Think i've found it, but need someone to confirm qty of teeth and bore diameter as the only ABS car i own is 250 miles away!

[Jaba]

They have always had 90 teeth. Not so sure about the id though. It measures at about 85mm but the ones on ebay atm say 86mm so that is probably the correct dimension when new.
They have been known to rust through and drop off !

[mat_fenwick]

It's my understanding that the ABS meters the "resistence" through the wheel sensor coils.

I don't think this is the case, although I'm willing to be corrected if anyone knows for certain. My understanding is that it was a Hall effect sensor (gives a voltage output depending on a changing magnetic field), and the resistor bodge was such that it had the same resistance as the sender does when stationary (no voltage output). Once moving, there is no voltage from the resistor, so the fault light is triggered.

[JayW]

I'm always happy to be corrected too!

[Mike E (uk)]

Correct Mat, they are hall effect sensors.

A reluctor ring rusted through and cracked on my 406.

The rings can be bought on ebay for the 406 (don't know about the BX) for a few £s.

You can fit them by heating the ring with a blow lamp, then slip it into place.

Or you could saw the new ring in half, and araldite it in place.

Mike