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New C4 Front Brake Pad Clean Or Replacement


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#1 paul.h

paul.h

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Posted 16 May 2014 - 01:44 PM

A few notes to help anyone wanting to clean the front brakes or replace the brake pads.

 

The new C4 from 2010 front brakes are similar to the previous model which is covered by a Haynes manual. There are 2 types fitted, TRW and TEVES. The TRW caliper is held to the carrier by bolts (possibly needing a torx socket) 35 Nm. The TEVES caliper is held by bolts needing a 7 mm allen hex bit to undo 27 Nm, plus there is a large spring clipping the caliper to the carrier which can be seen through the wheel spokes. Both carriers are held on the hub by bolts needing an E16 torx socket 90 Nm plus a further 45 degrees (except where 340mm discs are fitted, the bolt looks as if a torx bit is needed and tightened to 35 Nm plus a further 35 degrees and the caliper bolts are to 35 Nm). The wheel bolt torque is 100 Nm for alloy wheels and 90 Nm for steel wheels.

 

Our car has the TEVES brakes so these notes are based on cleaning those. The TRW ones will be similar except the spring is not used, only the lower caliper bolt need be undone so the caliper can be pivoted up, the piston side pad is not clipped to the piston, the caliper bolts have a different torque setting. The procedures say the removed caliper bolt should be renewed each time (no reason is given) but it may be just if it has loctite on it - if so, as a minimum it should be checked for re-use and fresh loctite used.

 

- apply the handbrake, chock the rear wheels, jack up the relevant corner of the car and support on an axle stand.

- remove the wheel (use the yellow plastic tool to pull off the wheel bolt plastic chrome covers).

- check the brake disc thickness - if worn below its limit then new discs are needed. Our car discs were 26 mm new, minimum 24 mm but other cars may be different with new possibilities of 28/26/24/22 mm but all minimum of 2 mm less.

- check the brake pad friction material thickness - if less than about 4 mm new pads are needed.

- turn the steering so the brake disc points out at the front.

- use a screwdriver to lever out the large spring from the caliper holes.

- at the back of the caliper prise off the plastic covers hiding the caliper bolts.

- use a 7 mm hex bit to undo the caliper bolts.

- push the caliper piston in a bit so the pads can clear the lip on the brake disc.

- remove the caliper including the brake pad at the piston side which is held to the piston by clips on the back of the pad. Suspend the caliper from the suspension coil spring using wire/string/a welding rod or similar.

- remove the brake pads from the caliper piston and carrier.

- clean everything up (pads, caliper, carrier, bolts, spring), remove the glaze from the disc using such as 180 grit emery paper, scrape off any loose rust from the disc edge, wipe the disc with brake cleaner, place emery paper on a flat surface and then rub the brake pad friction side on it to remove any glaze.

- push the caliper piston in, even if the old pads are being used again. It may be better to release the excess brake fluid via the bleed screw rather than push it back in to the braking system. Make sure the brake fluid reservoir does not overflow.

- apply a smear of copper grease to the pad/caliper/carrier contact faces but not on the pad friction material or disc - a bit of card held between the carrier and disc should stop any going on the cleaned disc whilst doing this. The pads have a rubber type backing but a bit of copper grease will also help prevent squeal.

- fit the pads to the carrier and caliper piston and put the caliper back in place, making sure the brake hose has not been twisted - also check its condition.

- apply a bit of copper grease to the caliper holes for the spring to prevent corrosion.

- fit one end of the spring to the caliper, wearing gloves hold the other end of the spring in its hole with a thumb and then with difficulty, use the other hand to fit it over the carrier. Check the spring is pushed fully in place. Trying to fit the spring without first pushing the piston back and with the caliper bolts in place does not work.

- fit the caliper bolts 27 Nm and fit the plastic covers.

- use the brake pedal in short strokes until the pedal goes hard to push the piston out so the pads contact the disc.

- check the spring is still fully in place - if not push it further on to the carrier.

- turn the steering back to the front.

- clean up the hub and wheel contact faces and apply a smear of copper grease to prevent corrosion/wheel sticking to the hub.

- check the tyre for nails/etc and then fit the wheel 100 Nm alloy or 90 Nm steel wheels.

- remove the axle stand, lower the car, remove the jack, check the wheel bolts are torqued up and then fit the bolt plastic chrome covers.

- if new pads are installed then these will take a few miles to bed in. Before then the brakes will not be fully effective.