Rear ABS Sensor Replacement on 1.0E w Drums - aaarghh..
Posted: Wed May 18, 2011 1:06 pm
Just had to share this one..
So, the manual says remove the roadwheel, remove the bolt holding the sensor to the backplate, unplug from under the rear seats, then pull out sensor. Assembly is the reverse of the disassembly process.
What actually happened;
Jack up, remove road wheel and put the car on an axle stand. Safety first. It's all a bit rusty under here, but lets carry on.
-Attempt to remove the bolt holding the speed sensor in place, but the star-bit splines shear inside the rusty bolt head and fingers hit the suspension arm. Curse.
-Try to use mole-grips to remove the bolt. Head shears off. Hit fingers again. 'Piffle' I say.
-What next? Now the plan is to remove the stub axle and attack the sheared off bolt.
-Manual says undo the screw and pull off the drum. The screw comes undone, but the drum won't shift. Ahh.. release the handbrake, dimwit (after chocking front wheels). Still won't shift.
-So, remove the centre nut on the bearing and try pull of the drum and hub complete. Drum now loose, but still won't come off. Firkle in the wheel bolt hole with a screwdriver to release the brake shoe adjusting wedge. Success, drum and hub off.
-Lay the drum on the bench and re-insert the wheel bolts and apply light use of a 2lb copper faced mallet to the bolts to release the hub from the drum. Put the hub in a sandwich bag to keep the wheel bearing clean.
-Clean up the drum and paint it a nice silver colour. Aahh..
-Remove the brake shoes; Remove the hold-down springs, then retrieve one from across the driveway where it pinged out of the pliers. Mental note to buy the right tool for the job. Start at the bottom of the shoes, lever out the bottom of the left shoe, curse a bit, and remove the spring. Then remove the top of the shoes from the wheel cylinder. Note that the cylinder pistons will pop out if not held in place with a strong elastic band or a cable tie. Another mental note; make sure next time that the cable tie is in reach, and not over there in top of the bench. Piffle, put the top of the shoes back in and go get the cable tie. Remove the brake shoes and put the cable tie round the wheel cyilnder.
-Shoes now dangling on the handbrake cable. So move the semi-siezed handbrake lever on the shoe so that the handbrake cable can be removed. More cursing and effort required as the spring on the handbrake cable is quite srong, and in the way. Anyway succeeded in removing the brake shoes. Take a photo to show where all the bits go beforehand! Oops, forgot.
-Now remove the hydraulic pipe to the wheel cylinder and cap it off using the cover for the bleed nipple. Hey, that went easy, nothing siezed.
-Just the four bolts holding the backplate on to remove and then the stub axle, with speed sensor, along with the backplate can be removed. All came undone, these bolts were just about loose, but rust seems to make them difficult to unwind.
-Take the stub axle to the open vice on the bench. The aforementioned 2lb copper faced mallet then comes in very useful to beat the living daylights out of the old speed sensor to remove it from the hole where it's rusted itself well and truly in. Satisfying, but at this stage there is no going back. Watch the magnetic bits, they have a habit of adhering to the bearing surfaces of the stub axle, which will not do the bearing any good at all.
-Turn the stub axle over and clamp the sheared off bolt thread in the vice. Try to turn it. More shearing occures. 'Piffle' gets used again.
-So centre-punch the middle of the bolt, and drill it out in small steps to 5mm. Make sure its drilled straight and central. I used a pillar drill that happens to be on the bench.
-Obtain the correct tap,and re-cut the thread so that a new bolt can be used. Cut off a spare bolt to the right length and tidy up the cut end with a file.
-The, reassembly is a reversal of the dismantling process, except of course that every part is cleaned painted and appropriately lubricated before it goes back on. And I did remember to bleed the brakes.
It makes the brakes work more smoothly if the plastic bearing surfaces for the shoes in the brake backplate are rotated so that the shoes can move freely, as they get worn and stop the shoes moving.
There y'go. How one person replaced a rear wheel ABS speed sensor on a 6N2 Polo in under 3 hours. Looks nicer under there now.
Pass the brandy.
So, the manual says remove the roadwheel, remove the bolt holding the sensor to the backplate, unplug from under the rear seats, then pull out sensor. Assembly is the reverse of the disassembly process.
What actually happened;
Jack up, remove road wheel and put the car on an axle stand. Safety first. It's all a bit rusty under here, but lets carry on.
-Attempt to remove the bolt holding the speed sensor in place, but the star-bit splines shear inside the rusty bolt head and fingers hit the suspension arm. Curse.
-Try to use mole-grips to remove the bolt. Head shears off. Hit fingers again. 'Piffle' I say.
-What next? Now the plan is to remove the stub axle and attack the sheared off bolt.
-Manual says undo the screw and pull off the drum. The screw comes undone, but the drum won't shift. Ahh.. release the handbrake, dimwit (after chocking front wheels). Still won't shift.
-So, remove the centre nut on the bearing and try pull of the drum and hub complete. Drum now loose, but still won't come off. Firkle in the wheel bolt hole with a screwdriver to release the brake shoe adjusting wedge. Success, drum and hub off.
-Lay the drum on the bench and re-insert the wheel bolts and apply light use of a 2lb copper faced mallet to the bolts to release the hub from the drum. Put the hub in a sandwich bag to keep the wheel bearing clean.
-Clean up the drum and paint it a nice silver colour. Aahh..
-Remove the brake shoes; Remove the hold-down springs, then retrieve one from across the driveway where it pinged out of the pliers. Mental note to buy the right tool for the job. Start at the bottom of the shoes, lever out the bottom of the left shoe, curse a bit, and remove the spring. Then remove the top of the shoes from the wheel cylinder. Note that the cylinder pistons will pop out if not held in place with a strong elastic band or a cable tie. Another mental note; make sure next time that the cable tie is in reach, and not over there in top of the bench. Piffle, put the top of the shoes back in and go get the cable tie. Remove the brake shoes and put the cable tie round the wheel cyilnder.
-Shoes now dangling on the handbrake cable. So move the semi-siezed handbrake lever on the shoe so that the handbrake cable can be removed. More cursing and effort required as the spring on the handbrake cable is quite srong, and in the way. Anyway succeeded in removing the brake shoes. Take a photo to show where all the bits go beforehand! Oops, forgot.
-Now remove the hydraulic pipe to the wheel cylinder and cap it off using the cover for the bleed nipple. Hey, that went easy, nothing siezed.
-Just the four bolts holding the backplate on to remove and then the stub axle, with speed sensor, along with the backplate can be removed. All came undone, these bolts were just about loose, but rust seems to make them difficult to unwind.
-Take the stub axle to the open vice on the bench. The aforementioned 2lb copper faced mallet then comes in very useful to beat the living daylights out of the old speed sensor to remove it from the hole where it's rusted itself well and truly in. Satisfying, but at this stage there is no going back. Watch the magnetic bits, they have a habit of adhering to the bearing surfaces of the stub axle, which will not do the bearing any good at all.
-Turn the stub axle over and clamp the sheared off bolt thread in the vice. Try to turn it. More shearing occures. 'Piffle' gets used again.
-So centre-punch the middle of the bolt, and drill it out in small steps to 5mm. Make sure its drilled straight and central. I used a pillar drill that happens to be on the bench.
-Obtain the correct tap,and re-cut the thread so that a new bolt can be used. Cut off a spare bolt to the right length and tidy up the cut end with a file.
-The, reassembly is a reversal of the dismantling process, except of course that every part is cleaned painted and appropriately lubricated before it goes back on. And I did remember to bleed the brakes.
It makes the brakes work more smoothly if the plastic bearing surfaces for the shoes in the brake backplate are rotated so that the shoes can move freely, as they get worn and stop the shoes moving.
There y'go. How one person replaced a rear wheel ABS speed sensor on a 6N2 Polo in under 3 hours. Looks nicer under there now.
Pass the brandy.