front abs sensor and trigger ring Galaxy 1999 mK 1

[biker01]

Was told some time ago that the front offside trigger ring was cracked but as this did not trip the abs warning light and the car continued to pass mot, I did nothing.
Now warning light has come on and am told by garage that the nearside sensor has failed.
They say that they need to replace both and the price is ott.

questions:
re ring?
does the drive shaft have to be removed to replace the trigger ring?
would a cracked ring necessarily fail to trigger the warning light?
re sensor
I'm informed the sensor can be replaced by removing wheel, brake caliper and a torx bolt holding the sensor.
How easy / difficult is it to remove the brake caliper?
all thoughts and hints gratefully received.

[insanitybeard]

Yes, the driveshaft has to be removed from the wheel knuckle and hub (and possibly removed entirely from the vehicle to make the job easier) in order to remove and refit the ABS reluctor ring from the outer CV joint casing. The sensor is possibly removable without removing the brake disc and caliper from the knuckle but access is certainly much better with them removed- depends on how tough it is to shift when you try to remove it!

It relates to a Mk2 model instead of a Mk1 but the general layout and procedure should be similar, this procedure shows what's involved removing the brake disc and caliper, the driveshaft from the hub, the sensor from the wheel knuckle and the location of the reluctor ring-which is probably best shown in image 8 on the end of the outer CV joint.

If anything I would expect a badly split/sprung reluctor ring to cause a fault in the ABS system and cause the warning lamp to come on as it would cause an irregular signal/sinusoidal wave pattern from the sensor as the gap in the 'teeth' of the ring would be wider at the point where it is broken, giving rise to an incorrect wheel speed reading for that wheel,  but it does depend on how bad the split was. If the ring has sprung open it could also be contacting the sensor, causing damage. Do you mean the garage is telling you both the sensor and reluctor ring require renewal? If the ring has damaged the sensor then I would say that was entirely plausible.