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[bkorven]

Buying second hand ,genuine knuckles with genuine ABS sensors would be a way back to working ABS
not cheap though as you'd have to fit them, then get an alignment 

what happened to the original sensors 

I purchased low mile Omega B2 hubs/sensors  as spares when i had omega As (Vauxhall Carltons) years ago 

Yep! New sensors will be ordered. But I think I use the old knuckles, and use some material inbetween to increase the distance if needed.

I don't mind the fitting, as I do all the work on my car myself in my garage. Since I've replaced suspension I'll need an alignment regardless. So that's OK!

The original sensors broke as I tried removing them, while replacing suspension parts. The Haynes book stated to do so, but it would not have been necessary. All of the problems I have with the ABS is just an unlucky side effect from wanting to replace suspension parts.

If you do buy second hand knuckles, think long and hard before you attempt to remove the sensors from them. I have never, repeat NEVER, in about 10 attempts, managed to get one out in one piece. They are always 'welded' in. I suspect its dissimilar metal corrosion - the hub is cast iron, and the shell of the sensor is aluminium. Once water (and salt in the UK) get at it you're stuffed - the things will not come out in one piece if they've been in more than 5 minuites.

Haha, don't worry. I've learnt my lesson, and will never again attempt to remove wheel speed sensors unless I intend to replace them.

[bkorven]

Didn't get as far as I'd hoped today - took ages to find the old bits, and they needed quite a lot of cleaning. However, results so far...

https://ibb.co/Lkz0pzF
The Hubs are made by KOYO - both the bearings and the cast wheel flange are marked as such.

The ABS reluctor ring has 48 teeth, with an inner diameter of (about) 75mm and an outer diameter of 95mm. Each tooth is 2.5mm wide, and 2.5mm deep.

https://ibb.co/JdBJ3KT
The ABS sensors carry several markings on the wiring side, but these just look like date codes to me. I'll put it under the microscope at work (tomorrow) to see if I can get anything off it.

The sensor tip side looks like this...
https://ibb.co/VvTLPn7

The 'blade' of the sensor is 2mm wide, and 9mm long. It stands 5mm proud of the steering knuckle. The blade is aligned to point towards the hub axle axis. The body/barrel of the sensor is (about) 17mm diameter, and stands about 1.5mm proud of the steering knuckle.

The next step is to assemble the bearing onto the steering knuckle and measure the clearance from the tip of the sensor to the reuctor ring. Unfortunatley I can't do that at home - the surface rust on the knuckle doesn't let the bearing slide on, and I don't have the tools here to 'force it on'. So tomorrow I'll polish up the knuckle/bearing surface and measure it, and then take some 'scope readings of the signal generated by the sensor at various RPM's.

Thank you so much for taking your time to look all that up!

The sensor looks different from the one installed on Omega B.

[LC0112G]

For the earlier Carlton/Senators, it looks like the 'current' part numbers are...

VX-90510208, OP-5-30-409, BOSCH 0265001220.

Given that the hubs and knuckles are the same on Omega B, I suspect these will fit and work just fine. Might be worth a google to see if you can get these.

Interestingly, on Rock Auto the seem to list 4 or 5 aftermarket sensors for the 2001 Cadilac Catera. The pictures show these as having plastic bodies. I wonder if these are less prone to "rusting in"

[Doctor Gollum]

Was that a genuine question?

You've potentially modified your current hubs to the point that even a genuine sensor won't fit correctly and you need replacement sensors.

It's the quickest cost effective solution to resolve your original issue.

[LC0112G]

And....just been looking at your oscilloscope shots.

The frequency readout say 116Hz, 77Hz and 91Hz. There are 48 teeth on the reluctor ring, so the actual wheel speeds will be one forty eighth of this - 2.41Hz (145 RPM), 1.60Hz (96 RPM) and 1.90Hz (114 RPM)

Do you really mean you were testing at 2 RPM - or two revs per second (i.e. 2Hz = 120 RPM)?

[dave the builder]

right side clicky

left side clicky

not sure what postage to USA would be though 

[bkorven]

And....just been looking at your oscilloscope shots.

The frequency readout say 116Hz, 77Hz and 91Hz. There are 48 teeth on the reluctor ring, so the actual wheel speeds will be one forty eighth of this - 2.41Hz (145 RPM), 1.60Hz (96 RPM) and 1.90Hz (114 RPM)

Do you really mean you were testing at 2 RPM - or two revs per second (i.e. 2Hz = 120 RPM)?

Should be revs per second, ofcourse! My bad.

The frequency I'm referring to is for the signal, i.e. the passing of teeth. 96 Hz = 120 RPM (or 2 rev/s)

[bkorven]

Was that a genuine question?

You've potentially modified your current hubs to the point that even a genuine sensor won't fit correctly and you need replacement sensors.

It's the quickest cost effective solution to resolve your original issue.

I actually don't believe my current steering knuckles will pose a problem with genuine sensors.

[bkorven]

right side clicky

left side clicky

not sure what postage to USA would be though 

Thanks for the links. I noticed that the sensors do not have the GM-label on them, as the sensor in my link has.

Could it be that they come from factory both with and without the label, perhaps depending on production date or something else? Or could there be a risk that the sensors are not genuine?

[Doctor Gollum]

They came from a working car, just fit them as they are.

[bkorven]

I have ordered the two steering knuckles that Dave suggested. Thank you! They'll arrive in 2-3 weeks.

Fingers crossed!

[dave the builder]

right side clicky

left side clicky

not sure what postage to USA would be though 

Thanks for the links. I noticed that the sensors do not have the GM-label on them, as the sensor in my link has.

Could it be that they come from factory both with and without the label, perhaps depending on production date or something else? Or could there be a risk that the sensors are not genuine?

It's Ebay, if the parts don't work, claim a refund 
though I've rarely had problems buying from ebay ,others may disagree
I've TRIED to find you a cost effective way out of the hole you've dug 

just fit them, reset the fault codes, get your alignment and inspection and drive it 

sincerely the best of luck moving forwards with your project   

Oh , and book lots of chiropractor appointments  for when your back is aching after fitting coilovers 

[bkorven]

right side clicky

left side clicky

not sure what postage to USA would be though 

Thanks for the links. I noticed that the sensors do not have the GM-label on them, as the sensor in my link has.

Could it be that they come from factory both with and without the label, perhaps depending on production date or something else? Or could there be a risk that the sensors are not genuine?

It's Ebay, if the parts don't work, claim a refund 
though I've rarely had problems buying from ebay ,others may disagree
I've TRIED to find you a cost effective way out of the hole you've dug 

just fit them, reset the fault codes, get your alignment and inspection and drive it 

sincerely the best of luck moving forwards with your project   

Oh , and book lots of chiropractor appointments  for when your back is aching after fitting coilovers 

Your suggestion to buy steering knuckles complete with used sensors was brilliant  In addition to being cost effective, it eliminates the risk of something being wrong with my steering knuckles.

Haha, I might need some recovery after this all is over. Physically as well as mentally 

[LC0112G]

Todays results from the Somerset 'elf-n-safety' conscious test labs....

The Markings on the sensor are 0265 001 220, which is the Bosch part number. The word Bosch is also molded into the rubber boot on the sensor.

I polished up the knuckle, and mounted the hub. Not torqued up to 300Nm, but tight enough for this. Then mounted it in the bench mill, with a bodged up drive assembly, and got it as centered as I could.


Then fired up the feeler gauges to measure the clearance...


The 0.8mm gauge goes in fine, the 0.9mm is snug, and the 1.0mm will not go in. So I'd say the installed clearance from sensor tip to reluctor ring is +/- 0.9mm (ish). I wouldn't argue or be worried about any value in the 0.8mm-1.0mm range though.

Then fire up the bench mill, and record the sensor waveforms on a cheap USB scope. The setup wasn't very well balanced, so I lost my bottle at 700Hz as the thing was shaking the desk and threatening to tip my cup of coffee over. Anyway...Scope traces at 100Hz, 200Hz, 400Hz and 700Hz.






Assuming standard tyres (235R45-17) with a rolling radius of 79.57 inches (2021mm), then these sensor frequencies equate to...

100Hz = 2.08 Rev/s = 165.5 inches/sec = 9.4 MPH
200Hz = 4.17 Rev/s = 331.0 inches/sec = 18.8 MPH
400Hz = 8.33 Rev/s = 662.0 inches/sec = 37.6 MPH
700Hz = 14.16 Rev/s = 1158.5 inches/sec = 65.8 MPH

As you can see, the sensor signal grows from about 140mV ptp at 100Hz (9.4MPH) to 630mV ptp at 700Hz (65 MPH). I'll leave you to extrapolate what happens at other speeds. The point is the output from the sensor is probably supposed to be of the order 100mV ptp at 5MPH, up to perhaps 1V ptp at 100MPH.

There will be quite a large tolerance in the ABS system to cope with mechanical and sensor variations - but these are the figures I can demonstrate.

Remember this is all Carlton gear. There is a possibility the Omega B is different. However, your "Holstein" sensors are producing significantly less signal voltage than these Bosch ones do (even at your reduced clearance), and I strongly suspect they are the cause of your issues.

[STEMO]

Once you get the bit between your teeth, Malcolm.........