FAQ : 50 : Change the front Brake Pads and Disks on a C4 - C4

FAQ

FAQ #50

	Change the front Brake Pads and Disks on a C4
	How to change the front disc brake pads and Disks in less than 1 hour with a few hand tools - this is based on a Citroën C4 1.6 110 bhp VTR+ The process may vary on other models in the range but the principle will be the same. If you are in any any doubt - leave it to your dealer or a trained mechanic Changing the front brake pads and disks on a Citroën C4 This is a simple process which anyone with basic mechanical skills can carry out in under 1 hour All you require is a suitable jack, a screwdriver and 13mm spanner (preferably a 'ring' type spanner or socket) for the pad change only. To change the disks you will also need a T30 and a T55 torq (star) wrench Top Tip: Remember that Brake Dust is hard to remove from wheels - so apply 'Barrier Cream' to your hands before starting or it will takes as long to clean your hands as replacing the brake pads!! For a bigger picture simply click on any of the images! With the car on a level surface, with the handbrake on and jacked up and a suitable axle stand or wood block placed under the car in case the jack fails, remove the wheel. (never work on a car supported by a jack alone) [shadowbox=images/c4/large/brake2.jpg\|Brake Assembly\|\|right][/shadowbox] With the wheel removed you will see the brake disk and caliper assembly: The caliper has 1 side fixed and the other side sliding. Brake pressure is applied via a large piston in the sliding half operated by hydraulic pressure from the foot-brake. The inner pad is pushed against the revolving disk first and when it can travel no further the other side of the caliper is pulled in applying pressure to both sides of the disk. (see the image above) This means that due to varying braking pressure the inner pads will wear down first and these are the hardest to see. [shadowbox=images/c4/large/brake1.jpg\|Tailgate Lock\|\|left][/shadowbox] What you are looking to replace are the 2 brake pads and 4 spring retaining clips on each brake assembly To remove the pads and retaining clips you first have to split the calliper by removing the retaining bolts but first using your screwdriver between the inner pad and the piston gently ease the piston back as you will need the additional room as the new pads will be thicker than those removed. WARNING: Before splitting the calliper see if the sliding pad moves freely and that there is no sign of any brake fluid leaking. If the caliper won't move or there is signs of fluid then put the wheel back and seek specialist advice form your Citroën Dealer The first time you change the pads the disks should be OK. However if there is any signs of 'crazing' on the disk surface or the wear looks excessive you may need to replace the disks themselves (at 43,000 mine had worn down by circa 0.5mm - 1mm per side and may need replacing next time the pads are) [shadowbox=images/c4/large/brake5.jpg\|Brake Assembly\|\|right][/shadowbox] Important: The minimum thickness for the disks is 20 millimetres which has to be checked using a micrometer or similar tool. The C4 also has a [shadowbox=images/c4/service/wear.jpg\|C4 Brake Disk Wear Indicators\|\|]disk wear indicator[/shadowbox] via 2 slots milled into the outside edge of the disk which show how much wear there has been. Although the minimum thickness is 20mm the grooves are a better indication of actual wear. If the edge looks 'Sharp' it's time to change the disks. Assuming everything looks OK split the calliper by removing the 2 retaining bolts (see first image for location) using a 13 mm spanner. The bolts are standard right hand thread with no locking devices. Assuming everything is still OK remove the old pads and spring clips by simply levering it out with the screwdriver. Clean the assemblies down with a soft brush or a fine wire suede brush being careful not to breathe any of the dust in and keeping everything clean and free of grease or any other contaminants - then fit the new ones [shadowbox=images/c4/service/brake_schematic.jpg\|C4 front Brake Schematics\|\|right][/shadowbox] If the disks are to be changed then you will require a T55h and T30h Torq spanner. Basically these are 'Star' shaped socket wrenches which are similar to the hexagonal ones you get with flat pack furniture. However they are designed to be used with power tools for fast assembly on the production line. As the calliper is already split all you have to do is remove the 2 bolts holding the fixed caliper section. They are at the back and are tight! - You may need to use a lump hammer to get them to move initially. Once removed, take the caliper section off and remove the 2 countersunk screws holding the disk in place with a T30 spanner and remove the disk. Once it's off give the boss on the end of the drive shaft a quick clean and also use some thinners to clean any protective coating off the new disks and then fit the new disk and the 2 retaining screws. Then refit the fixed calliper ensuring the bolts are TIGHT! After that it's a case of refitting the sliding caliper and new pads. Don't re use the old pads with new disks. Fit new ones as your life depends on the brakes on your car. [shadowbox=images/c4/large/brake4.jpg\|Brake Assembly\|\|right][/shadowbox] Before you re-assemble the caliper make sure the piston is back flush with the housing so it can clear the new pads when you try and put it back on. It may require some (but not excessive) pressure to press it back flush. Next fit the new spring clips first with the side with the central 'Lug' pointing out from the disk Then slide the pads into place. Then re-fit the calliper and make sure the bolts are tight. Do not apply any grease or other 'release agents' as they can lead to failure of the brakes! You could apply a 'sparing' coat of Copper slip or a similar High Pressure/Temp Copper Based Grease to the piston end to reduce potential 'squeal' but be very careful!!! Once you've done that replace the wheel (Torque setting 9nm - 75lb/ft) and press the brake pedal to ensure everything is seated correctly (moving the pistons back will mean the brake pedal feels soft initially which is why you should press it several times before attempting to drive the car Then check the brake fluid levels are OK and if necessary top up with the a fluid to manufacturers specifications You may find that initially the brakes don't feel as effective as they did before. That's because the disks will have some wear and the pads need to bed into the shape of the disks so drive carefully for a while and apply gentle pressure onto the bakes at regular intervals to bed the new pads in Just to show how easy it is and for a few more images look at this from BigJohnD BigJohnD wrote ... Job done! I got home early today, and replaced the front disc pads (at about 46,000 miles). New pad kit - 4 pads, 8 (4 top, 4 bottom) retaining springs and 2 calliper bolts: It took under an hour, most time probably being taken up making sure the car was secure on an axle stand in the drive, and afterwards trying to get the first bolt through a heavy wheel (bring back studs!) It was remarkably straight forward, and everything was in good order. It took a fairly long and firm push to put the piston back into the cylinder to open up the gap for the new unworn pads, but I've known worse. It's not easy to see the rear pad, but after doing the front one, it's exactly the same. I should mention that it's essential to replace both pads on both front discs. Hopefully that's self evident, even if the pictures only show the nearside. Loosen wheel bolts, jack up the car, make secure with axle stand and remove wheel bolts and wheel. Use a 13mm ring spanner to loosen both retaining bolts - top shown. Slacken top bolt, ease back pads carefully to loosen, avoiding levering against the disc. Completely remove top bolt (new one provided in the kit) and pull forward to expose pad. Pull out and remove pad. Push piston (arrowed) back into cylinder Flip out retaining spring clips, noting top and bottom are a mirrored pair, one bag of four in the kit being the top, the other the bottom. Push in new spring clips, making sure they're fully home. Fit new pad. Do the same with the other pad, which is more difficult to see, but exactly the same. Slide the calliper back over the pads, and fit and tighten retaining bolts. I couldn't see any manufacturer's name in the discs, but the callipers are definitely Bosch. Refitting the wheel takes a bit of strength, but I could clearly see the flange which centres the wheel (arrowed). I took the photo because I recall an owner having tremendous vibration problems because a set of after-market alloys had a larger diameter centre aperture and didn't sit absolutely concentrically. I digress. It seemed to take a lot of pumping of the pedal on the drive to get it firm but eventually it seemed it was there. It took over 20 stops from about 20 mph and lots of braking going down Grange Hill (yes, the one whose name Phil Redmond pinched) before anything like normal returned, and I expect it'll be some time before they're fully bedded in. There were no nasty noises, which was good! Here's what the old pads looked like - well used after 46K miles, and if I hadn't been going to France in a little over a week, I'd have left them on. Compare with a new one: And thanks to C4O for the big discount. The whole job cost well under £50.
Views	43630 (Unique 36158)
Member Rating :	9.8 - 22 votes
FAQ Posted by	Dave_Retired.
Info	Created: 24 July 2008 Last Updated: 18 June 2010