Retro (un)fitting ABS

[Linegeist]

It occurred to me, following on from the reliability thread, that one of the achilles heels of our cars is the ABS system. It's hard to get ABS specific parts like sensors and it's yet another complicated thing to go wrong.

As a lover of engineering simplicity, I was wondering ........... assuming one had a pre-ABS donor car, how easy would it be to remove the ABS completely along with its associated plumbing, and revert to une systéme ordinaire?

[Stinkwheel]

easy enough i expect.

the only issue is say a 1992 BX is on the MOT testers computer as having ABS and that the ABS dash light should do such and such at startup etc, when it doesnt then MOT man he say no new test for you.

Thats the only issue i can see personally

[mat_fenwick]

A simple timer circuit would get round that problem...

[Linegeist]

But ABS (AFAIK) isn't a legal requirement so, like rear washers/wipers and foglamps, if it ain't fitted, then it ain't part of the test surely?

[MULLEY]

I wouldn't have thought that the mot tester would have the options list of every bx configuration according to year & spec model, mine doesnt have abs, i suspect that they'll probably need to spot that it's an abs model & therefore they'll check that, if abs was removed then its not got it & therefore that element doesnt need checking?

[docchevron]

AFAIK if the car left the factory with ABS, it MUST have it to pass an MoT.
Since computerised MoT's have been around for a while can't see an easy way round it really..
Unless you have a very friendly / corruptable tester.

The ABS system itself is quite reliable, but sensors are expensive and hard to get, and rear wheel bearings are almost impossible to get now..
As are ABS Driveshafts come to think of it..
Have to say, since I've got one with ABS and one without, I'd take the non ABS car everytime.

[citro-geoff]

I bought a CX Safari a few years ago with ABS,but found that the rear o/s sensor had been cut and joined together with a rubber pipe.The previous owner had wired the dash bulb to the oil pressure light.It was never picked up at all in the 3 mot's I had done on it.I only found it when I had to do the arm bearings!! Still plenty of cowboys out there.

[Linegeist]

I bought a CX Safari a few years ago with ABS,but found that the rear o/s sensor had been cut and joined together with a rubber pipe.The previous owner had wired the dash bulb to the oil pressure light.It was never picked up at all in the 3 mot's I had done on it.I only found it when I had to do the arm bearings!! Still plenty of cowboys out there.

Hell's teeth!

Surely the tester would have felt the difference on the rolling road?????

And wouldn't the rear brakes have thrown up an imbalance because they locked up in different ways ....... ie locked vs 'cadence' effect?

Scary!

[docchevron]

It's not that uncommon, we;ve had the odd Xantia before now in for MoT, not badged as ABS, and since the hydrovalve block is fairly well hidden they've passed with inop ABS as the tester didn't realise it actually had ABS (the bulb had long since snuffed it..)
This was in the days before computerised MoT's though...

[Kevin B]

Surely the tester would have felt the difference on the rolling road?????

Not so as the ABS does not come into operation until the car is going faster than 20MPH, well that is what is the case for an ABS equiped BX.

And wouldn't the rear brakes have thrown up an imbalance because they locked up in different ways ....... ie locked vs 'cadence' effect?

Not the case, because when the ABS ECU detects a fault, it allows the braking system to behave as if it were a car without ABS fitted.

rear wheel bearings are almost impossible to get now

Do you not mean rear hub?, as there would be no need for the bearing to be different?.

rear wheel bearings are almost impossible to get now..
As are ABS Driveshafts come to think of it

Agreed, but it is not possible to remove the ABS ring from the old driveshaft, machine an interferance fit register on the non ABS driveshaft, and swap the ABS ring over?

If you think that any of the above items are tricky to locate, you should try finding rear ABS sensors for a Citroen BX 4x4 GTI. I ended up modifying some from a peugeot GL4x4, that I was lucky enough to find in a scrapyard.

[docchevron]

The rear wheel bearing on a BX )non 4x4) is the hub.
Hence the issue.
With genuine ABS shafts you can usually get the ABS ring off without destroying it, but a lot of after market / recon shafts have silly CV joints with the ABS ring as part of the casting sadly..
Both of my cars have said shafts, even though the TD doesn't have ABS, but oddly enough at the time I needed shafts I could only get ABS shafts! Oh how the times have changed..