kfk Posted December 30, 2008 Posted December 30, 2008 Full edit - paul.h 17/12/2013. Raise the suspension to max height.Loosen the 4 wheel nuts.Jack up the relevant corner of the car and support it on axle stands - this is a must (if a height sensor is caught the car suspension could drop to a low level).Chock the rear wheels so the car will not move.Remove the wheel nuts and the wheel.Turn the steering wheel so the hub points out at the front to give better access. Check that the brake disc is not worn too thin so that it needs replacing - if so, put the wheel back, buy new discs and pads and start again at a later date. Also check the pads have sufficient friction material left if planning to re-use them - if not, put the wheel back and buy new pads.Release the handbrake (as this operates on the front of a C5) and put the gear lever to neutral. Check the car is still secure on the axle stands and the jack.Unhook the end of the handbrake cable from the handbrake pivot on the brake caliper.Slide the handbrake cable out through its hole in the caliper (to prevent damage to the cable when you pivot the caliper)The caliper is held in place by 2 bolts fitted from the inboard side of the caliper. Undo and remove the lower bolt.Pull apart the wear sensor wire connectors at the top.Note the wear sensor wire routing and unclip the lower wire white sleeve from the caliper bracket - it has 2 tangs that need to be pushed in a bit to allow it to move but it is brittle and may break. Then pull out the wire from the bracket, leaving the end in the brake pad.Pivot the caliper upwards from the bottom and use something such as wire or a bent welding rod hooked to the strut to hold it up.Remove the brake pads complete with the wires for the pad wear sensors, paying attention to the route the wires take.If fitting new pads, You need to screw the caliper piston back (to give a pad clearance of 1 mm max) or the new pads will not fit. This requires a special tool because you need to push it and screw it at the same time, but you can try levering the piston back with the handle of a hammer and using a screwdriver in the notches of the piston to screw it, it is just quite awkward this way. The slots in the piston need to line up to a mark on the caliper, opposite the slot in the caliper for the lugs on the back of the pads. It is recommended to clean the caliper and piston first and whilst winding the piston in to let the brake fluid out of the bleed screw (using a pipe/container to collect it whilst holding the caliper so the bleed screw is at the highest point so air does not get in and then tighten the bleed screw whilst still pushing the piston) as opposed to the brake fluid going back into the brake system with possible damage to the master cylinder seals and dirt in to the abs sysem. Whilst winding in the pistons, make sure the master cylinder reservoir does not overflow.The pistons on either side of a C5 have different threads, so one will screw back clockwise (left one, UK nearside) while the other will screw anti-clockwise (right one, UK offside) - there may be a direction arrow on the caliper. Do not screw them too far the wrong way or they will come out. So screw them back and check you are screwing them the right way before you go too far.Scrape/Sand clean the surfaces of the caliper that the pads sat in. If using the old pads, clean them up and rub the friction face on emery paper (such as 180 grit size) on a flat surface to remove the glazing then wipe the pad to remove any dust/emery from it. Similarly clean the face of the disc, consider removing the wear ridge/rust around the disc and wipe the disc with brake cleaner.Grease these cleaned surfaces on the caliper with a smear of copper grease, (a piece of card between the caliper bracket and the disc will keep grease off the disc) and grease the metal end edges of the pads and the backs of the pads with copper grease. (if you don't your brakes will start to bind soon due to build up of rust and brake dust.)Fit the pad wear wires back to the pads and then fit the new/old pads.Close the caliper and fasten with the lower bolt (30 Nm). Correctly route the pad wear wires and fasten the connectors at the top.Pump the brake pedal to adjust the caliper piston, then refit the handbrake cable to the caliper lever. Check the handbrake comes on fully by 4 clicks but when released the caliper lever should be against the stop. Now is a good time to check that the bleed screw can be easily undone if the old pads have been refitted. Put the steering back to the straight ahead position.Clean the hub face with a file to remove any rust and apply a thin smear of copper grease if you have alloy wheels to prevent it rusting on. Clean the wheel hub contact face, apply also a smear of copper grease, check the tyre for damage/stones/nails/etc and fit to the car. Continue in reverse order to removal and check the brake fluid level in the master cylinder is between max and min.New pads take time to 'bed' in and for the first few miles the brakes will feel slightly softer until the pads bed in properly so allow a greater stopping distance. Do not brake too hard (unless an emergency) to allow the pads to bed in properly - forced bedding in can result in a poor brake feel.
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