Changing the rear disks and pads on a Citroen C4

Alex Lynne, 08 March 2009

Citroen C4 – Rear Brake pad and disc replacement (Bosch Type)

Tools required (for pad and disc removal):

Wheel removal tools.

13mm Socket – for removal of floating caliper screws x2

T50 Torx head – for removal of fixed caliper screws x2 (Motorworld £10 for set)

Piston pushing tool – for pushing and turning of pistons back into calliper (Halfords £21)

32mm Socket – for removing hub nut (Halfords £6.30)

Extendable socket wrench – if you’re puny like me, always useful to keep in the car for when you’re changing a wheel by the roadside and the wrench in the spare wheel is just not long enough. Also, highly recommended for removal of the hub nut

Chisel and hammer – for removal of the hub nut cover

Claw hammer – for removal of the ABS ring

Important: I am not a mechanic, having only basic car skills. Therefore, some procedures noted below are best performed using proper tools. I can in no way be held responsible for any damage occurring to either you or your vehicle should you decide to follow this guide. As always, a common sense approach should always be taken.

It is recommended that FAQ#50 (replacing the front brake pads and discs) is read first. It goes into details about how brakes work, and the process of changing the pads alone is almost identical, save for the rear brakes having a handbrake cable.

I would imagine the Lucas assembly is very similar. The discs are the same, but the pads are different, so be careful when ordering parts.
Steps marked D. need only be performed if changing the discs.

To start:

Take a drive around the block, use the brakes as little as possible. Check the warmth of the discs. They should be pretty cool. This gives you an indication of any problems when you repeat the process after changing the discs/pads.

When jacking the car, replace the jack with an axle stand or similar. Never work under a car using just the jack. Also, ensure that all wheels on the ground have chocs around them. You will need to release the handbrake to change the brakes.

Also, when the car is jacked up, give the wheels a spin by hand, and see how easy they are to turn. Another sign of binding will be if the wheels do not turn well after working on the brakes.

Repeat this process on the discs after the wheels have been removed.


[shadowbox=|C4 Rear Brake Assembly::||right][/shadowbox]They say that you should use brake cleaner to clean off the brakes. I just used a small wire brush and a toothbrush to clean most of the crud off. I put on a face mask, as although they’re not made of asbestos any more, the dust is still pretty nasty.

People also recommend using a barrier cream on the hands to make it easier to clean them after. I didn’t, but 5 days on from the job, they’re pretty clean.

1. Remove floating calliper – simple task of removing the two screws behind the assembly. It may make it easier to unclip the handbrake cable. When removed, do not let the assembly hang by the hydraulic tubes.

The image shows the location of the two screws (circled), the handbrake cable that can be unclipped (arrowed), and the impression of the branding on the caliper.

[shadowbox=|C4 Rear Brake Assembly::||right][/shadowbox] Image shows the released floating caliper. Note that the head of the piston has two notches in it. This is for the piston tool to locate on.

2. (If you are just replacing the pads, do this step. If you are also replacing the disc, perform steps 3&4 first)

Push in the piston. Remove the brake reservoir cap in the engine bay. Keep an eye on the fluid levels, as pushing the pistons in will raise the level. Keep something handy to siphon off any excess. This fluid is corrosive, so you don’t want it spilling!

When pushing the pistons in, they also have to be wound. Because of this, it is very sensible to have a correct tool, as without it may be difficult

The nearside piston must be wound Clockwise.

The offside piston must be wound Anticlockwise.

They should be near impossible to turn in the opposite direction.

I strongly recommend winding the pistons in, then letting them out a couple of times, to ensure nothing is sticking. In this way, on the second or third repeat, it should get easier to wind the piston in.

[shadowbox=|C4 Rear Brake Assembly::||right][/shadowbox] ’Laser’ brand piston tool. Winding the screw pushes apart the head that is in contact with the piston away from the back-plate. In this photo, steps 3&4 have already been completed.

3. Remove old pads and clips. Keep the clips safe!

4. (D) Remove the fixed part of the caliper, using the T50 Torx head. These are quite tough.

5. (D) Remove the hub nut cover. I used a chisel, gently tapping around it. After a while, it will come off. The edges can be tidied up when placing it back on after the job is complete.

6. (D) Remove the hub nut. For obvious reasons, this is on tight. Remove the old disc.

7. (D) Depending on where you got your new discs, they may or may not have an ABS ring on them (example, EBC never supply discs with ABS rings). This is a metallic ring with embedded magnets that ABS sensors pick up on to measure the speed and pulse the brakes accordingly when ABS is active. If you compare the new and old discs, you will easily tell if the new ones have them or not. If not, either get a new set, or remove them from the old discs.

I took the dangerous (and therefore not recommended) approach of easing them off using a claw hammer. Put one claw under the ring, using the disc to rest the pivoting part of the hammer. Gently tap the hammer head with another hammer, and circle the ABS ring. It will eventually come off. To attach to new disc, use a flat piece of wood over the ring to gently put it in place. Also remember to clean off the new discs with white spirit or similar.

[shadowbox=|C4 Rear Brake Assembly::||right][/shadowbox] Location of ABS ring on old disc. When covered with grime, it is hard to see the ring. However on comparison with the new disc, it is obvious that the profiles of the two are different if the new disc doesn’t have them attached.

8. (D) Put new disc on, replace hub nut and cover.

9. Assemble calliper brace, clips and new pads.

10. Assemble calliper.

11. Pump the brakes a few times to push the piston onto pads. Check that you can still turn the discs by hand.

12. Replace the wheel, and give that a good spin. If it does 2 or more revolutions, then it should be OK.

13. Replace brake reservoir cap! Drop the car, start up, and give a quick test up and down the road/driveway. This is to check a. that the brakes appear to work, and b. to check that the ABS ring is correctly in place (if it isn’t the dashboard will light up like a disco, warning of ABS and ESP faults).

14. Repeat process for other wheel.

[shadowbox=|C4 Rear Brake Assembly::||right][/shadowbox] Test drive – firstly take car for short spin (2-3 miles), using brakes as little as possible. Check first that the wheels themselves aren’t getting warm, then check the discs. My advice is to first perform the spit test before touching. If the spit vapourises, then the discs are getting too hot. You should expect them to be a bit warmer than the check performed before doing the work.

If they are getting hot, the most likely cause (in my experience) is that the pistons are sticking a bit and therefore the pads are remaining pushed against the discs. Take the calliper out, and repeat step 2.
For the actual wearing in of the pads, there are plenty of opinions on the best way to do this. I found that the brakes were pretty good straight from the set-off.

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