abs sensor gap

[bmw2101]

ive got a e36 compact, one of the mods you do is fit a e30 325i diff with the lsd which ive done. the shafts then you use are e30 325i ones. Now the sensor for the abs on the compact reads a reluctor ring that is maybe 2mm thick, and i don't know the size of the shaft. the e30 one is much taller by the looks, and the sensor hits the ring unless you space it out.


any idea what the gap should be between sensor and ring?

thanks

[awoo]

they're usually just reed sensors which are magnetic switches. I don't know the answer for whatever is specified by BMW but you could probably judge it based on the size of the sensor and how much magnetism there is in the ring. I would hazard a guess at a couple mm maximum?

[Rich]

Sept 18, 2021 12:11:34 GMT awoo said:

they're usually just reed sensors which are magnetic switches. I don't know the answer for whatever is specified by BMW but you could probably judge it based on the size of the sensor and how much magnetism there is in the ring. I would hazard a guess at a couple mm maximum?

Nearly. Hall sensor. It’s a coil and usually a magnet encased in plastic that generates a waveform voltage when the teeth pass it. A few MM is usually sufficient whilst allowing a gap big enough for very small foreign bodies to pass without damaging the sensor.

[bmw2101]

right ok ill make it 2mm and see what happens.


the problem now is, the abs works fine, the sensor has been hitting the ring and the end is now damaged. But when i pull the handbrake the system gets confused, and the light comes on. When my mate does it in his car it just accepts its locked the rear wheels at like 30 mph, and dosnt mind. I wonder if its the gap. My mates car is a saloon so the sensor and shafts are factory set up.

[homersimpson]

Sept 18, 2021 19:44:13 GMT bmw2101 said:

right ok ill make it 2mm and see what happens.


the problem now is, the abs works fine, the sensor has been hitting the ring and the end is now damaged. But when i pull the handbrake the system gets confused, and the light comes on. When my mate does it in his car it just accepts its locked the rear wheels at like 30 mph, and dosnt mind. I wonder if its the gap. My mates car is a saloon so the sensor and shafts are factory set up.

Usually the system has some form of integral overide so that if one set of wheels is turning quickly and the other isn't then it prevents the systems from activating so they can test the brakes on the rollers at MOT time.

[bmw2101]

right, so ANY idea why my car is doing this?

my mates car he can pull the bar at speed and its happy. mine i cant?

[Rich]

Airgap won't matter in what you are describing. If you lock the wheels at speed and the ABS can't unlock them and can't see any pedal pressure/push it will probably have a hissy on an older car like an E36 compact.

[bmw2101]

oh i see, i forgot to say, both our cars have the e36 m3 3 channel abs, both where chipped for better map in them too by the same guy.

this was chris s car before he split it

CLICK HERE

first corner he is on the handbrake and it dosnt mind it. I cant work out why when i do it the light comes on,

[welshpug]

is the handbrake warning lamp working?

[bmw2101]

on the dash no, there isnt one on the lever !!! maybe thats it?

[Rich]

Sept 19, 2021 15:04:50 GMT bmw2101 said:

on the dash no, there isnt one on the lever !!! maybe thats it?

Car will most definitely have an ABS hissy fit if it doesn’t know you are yanking the Dori-wand to lock the wheels. Get that sorted as that may be the issue all along.

[bmw2101]

just asked chris about his car and he didnt have a sensor for the handbrake !! i didnt know but the fault code reader should still work with the car even though i have microsquirt ecu on it.


chris recons its a dodge rear sensor. ill set teh gap on my new rear arms and see what happens