Rear Brakes - Do Not Be Afraid! Disc Replacement

[PICASSOCONVERT]

Full story below but does anyone know the minimum front/rear brake disc thicknesses on a 2003 2.2HDi C5 estate, please?

 

Fuelled by my success at replacing my rear tailgate struts, I decided to tackle the squealing rear brake problem. With grateful thanks to the author of the pinned thread I made a start with great fear and trepidation.

 

I was very lucky that all four caliper bolts came loose and could be removed individually without too much difficulty - I didn't have to use WD40, drill out broken bolts or make a sacrifice to the relevant gallic powers. I loosened the pad retaining bolts and removed the protective covers for rust removal and repainting. I even took some photos which I will attempt to load up once the job is complete. I put everything back together as I did not have any copper slip.

 

This morning, armed with copper slip and a piece of plastic I intended to carry on. However, I sheared the pad-retaining bolt (it had been sprayed with WD40 earlier). I have ordered new pads and retaining bolts which should arrive on Tuesday.

 

However, looking at the rear discs this morning I wondered if they should be changed? I can't see the minimum disc thickness in my Revue Control Technique manual but mine are approximately 12mm, excluding the small lip around the edge of the disc. The discs have some concentric marks and the car has done 90,000 miles.

 

Is disc removal and replacement as simple as the manual says - remove the caliper, remove 2 screws, gently remove the disc and replace? If it is I will fit new discs.

 

Thank you in advance for any help.

 

David

 

 

[Johndouglas]

Mimimum thickness of rear discs is 12mm.   On some Citroens it's possible to get the disc off without removing the calliper but not on the C5.   However if you've got the two calliper bolts running, then the battle is over.   Clean up the arm mating faces at the same time.   My C5 maintenance record shows that I fitted new pads at 40K miles and new discs and pads at 86K miles.   Two of the four set screws had to be drilled out because they lost their grip and the near side disc needed some heavy clouts before coming away.

[citrophile]

Hi David

 

Haven't done rear discs but I changed my front vented discs and pads a couple of weeks ago and it was actually really easy to change the discs. And yes it is as simple as removing the two small screws, pulling off the old discs and slotting the new one's on. It's actually the wheel nuts that provide the mechanical connection of the disc to the hub.

 

Good luck

 

Rob.

[paul.h]

The 2.2 hdi has larger front discs than the other engines.

 

-  front discs diameter 288 mm, thickness new 28 mm, min 26 mm. Brake pad friction material 12 mm new, min 2.5 mm. Disc max runout 0.05 mm. Caliper bolt 120 Nm, caliper pivot bolt 30 Nm. Disc screw 10 Nm. Left piston rotate clockwise to wind in, right one anti clockwise (I prefer with the bleed nipple open to release the fluid). Pump the brake pedal to push the pads against the disc before fitting the handbrake cable back. The plastic guide for the pad wear cable at the bottom of the caliper is brittle but has 2 lugs to push in before it will pull out of the caliper.

 

- rear discs diameter 276 mm, thickness new 14 mm, min 12 mm. Pad friction material 12 mm new, min 3 mm (I have found due to the shims only covering half the pad back plates, the pads wear slightly thinner at one edge). Disc max runout 0.05 mm. Caliper bolt 16 mm AF, 70 Nm, pad cover bolt 3.5 Nm (so do not do too tight). Disc screw 10 Nm (if seized, an impact driver may help, or if new ones are available knock round with a chisel).

[PICASSOCONVERT]

Gentlemen, thank you very much for your very helpful replies.

 

I have now removed the two pairs of screws retaining the rear discs to check they were not seized. New discs/pads front and rear and the filters for a service are now on order from Citroen Letchworth (thought less risk of problems if I used Citroen parts) who were very helpful - asked if I had got the caliper bolts loose, did I know about the corrosion problem etc, etc.

 

I don't think I will attempt the front discs myself as the RTA manual refers to "...desacouppler la canalisation hydraulique..........", which is "uncouple the brake pipe". I don't think I am competent enought to bleed the brakes on a C5 (used to do it on the old Morris Minor, though, with my mother pressing the brake pedal), particularly as one appears to need a "Luro" or similar device and a Lexia for the secondary circuit. Also, the 2 man approach is not recommended except in an emergency when its effectiveness cannot be guaranteed.

 

I will report back on how I get on, but it probably won't be until the end of November as I'm away for most of the next month.

 

David

[paul.h]

It will pay to get a copy of Haynes, whilst it does not cover the 2.2 hdi engine, the rest of it is relevant. To replace the front discs you do not need to undo the brake pipe, just move the caliper to one side, so no need to bleed the brakes afterwards.

 

If the new discs are premium ones painted silver instead of grease for corrosion protecton, the paint should not need removing before fitting but you may still want to wipe them with a brake cleaner.

 

It may be preferable to replace the front and back pads/discs on separate dates with some driving in between since they take time to bed in and the brakes will not be that effective to start with, so better to have 2 poorer brakes at a time rather than 4 - just my experience.

 

As for bleeding the brakes or just the 2 yearly brake/clutch fluid change, I use a Mityvac brake bleeder (model 6820 which can also give pressure as well as vacuum and has been used to set up a turbo) which sucks the fluid out of the bleed screws and is a one person job. It is particularly effective on the clutch slave cylinder since here pedal pumping is not that good. Bleeding by vacuum is better since any bubbles get larger but under pressure they get smaller so harder to remove. I have previously used a Gunsons one that used pressure from a tyre but prefer the Mityvac being much quicker and less bother. The standard Mityvac fluid receiver is a bit small, about 100 ml and needs frequent emptying, a larger one is available from the US but with shipping is expensive so I made a 300 ml one from a screw capped plastic container by fitting 2 bleed screws to the top. They also tend to fall over but putting it in a cup with a heavy old bearing in the bottom stops that. I have also tried a vacuum one that uses a compressed air supply but found it needed a higher air flow than my compressor could provide. The Lexia would only be needed if air got into the abs unit so it can be actuated.

[PICASSOCONVERT]

Thanks again for the reply paul.h. I have the RTA manual which is broadly similar to a Haynes manual and my French is just about up to the job of understanding it. Once I have got the rear brakes sorted (and bedded in - thanks for the tip) I will look at the front and might have a go if it's not necessary to undo the brake pipe, as you say.

 

David

[paul.h]

I have the RTA ones as well as the Haynes and the Citroen dvds so find it useful to compare. The RTA ones have good photos and line drawings and the RTA wiring diagrams are the Citroen ones and are better quality paper than Haynes but the Haynes procedures seem more detailed, are based on them taking a car apart and rebuilding it .

 

The Citroen procedures also do not undo the brake pipes for the front brakes. Maybe the confusion from the RTA procedure on the front brakes comes from the disc procedure refering you to the caliper removal procedure. Also no need to disconnect the battery as in the RTA procedures - just do one brake at a time with the suspension at max height before jacking up that corner, use an axle stand, use chocks on a rear wheel so the car will not move (handbrake and gears both on the front and you will need the handbrake off and in neutral) and take the key out of the ignition, except once the wheel is removed, for access, it is useful to turn the steering so the front of the disc points out and then remove the key again (steering lock).

 

If you have not replaced discs before, once the old has been removed, clean the hub face with a file to make sure the face is flat and check that the hub contact part at the back of the disc is also flat, fit the disc to the hub with the 2 screws and the 4 wheel bolts (spacers from washers/nuts needed) and check the disc runout - if you do not have a dial guage, rotate the disc while holding a pointer fastened to something (such as another axle stand base) and touching the outer part of the disc - if an excessive gap appears then it may reduce if the disc is rotated 180 degrees. If all is ok continue putting everything back.

 

The Citroen procedures have a picture of a Luro and it is a complicated version of the Gunsons pressure bleeder.

[PICASSOCONVERT]

After three weeks away from I home I had an opportunity today to replace the rear discs and fit new brake pads.

 

The pinned post on this subject was was very helpful. As in that post, I had a pair of caliper bolts which were difficult to budge once they had unscrewed from the suspension arm - I eventually got them movng and re-attached the caliper but it was a bit of a struggle and I didn't manage to get my plastic gasket in place on that side, although I had applied the copper grease.

 

Most of the corosion appears to stick to the suspension arm and I found it came off in chunks with the careful use of an old chisel. I then used a Permagrit file to clean up the surfaces before coating the mating surfaces with a smear of copper grease.

 

I made gaskets out of a piece of thin plastic sheet I had.

 

Fitting the new brake discs was actually very easy. I removed the two screws retaining the discs on the hub and the discs came off easily with a gentle pull - just as described in the RTA manual. Fitting the new ones was also straightforward. I took note of paul.h's comment about checking the discs ran true and they did - no corrosion on the surface of the hub at all and the discs fitted perfectly.

 

The new pads fitted without difficulty. It was interesting to note that the existing inner pads had been fitted (by a Citroen garage) without the metal shim - probably because there was already some corrosion at that time (April 2010 at 7 years/59,000 miles - currently 10 years/90,000 miles) moving the caliper outwards and reducing the gap between the caliper and the inner edge of the disc.

 

I was very apprehensive about doing this job with my basic tools (principally socket set, spanners, torque wrench, screwdrivers) but in the event it was fairly easy. I would recommend people to have a go using the pinned guide and start by seeing if their caliper bolts can be removed without too much trouble (try them one at a time). Once the caliper bolts are moving OK the rest seems fairly uncomplicated.

 

If anyone would find a few pictures helpful I took some photos - if you PM me I can email them.

 

Once the rear pads have bedded in I will have a go at the front discs and pads and report back.

 

David

[paul.h]

This is one of those jobs where you just need the confidence to have a go, so well done. You will probably need to clean up the corrosion again in a couple of years and has to be seen as a regular maintenance job but second time around it is a bit quicker.

 

Did you bother fitting shims behind the rear pads ? When I cleaned mine up the other week the pads had worn at an angle which I suspect is due to the shims only covering half of the back of the pads and I was tempted to not fit the shims again.

[PICASSOCONVERT]

Hello paul.h - yes I did fit the shims (simply because I didn't know any better and I was just doing what the book said!). I have just checked the old pads and there is no difference in wear between any of them - they have all worn pretty evenly. As I mentioned the inner pads did not have the shims fitted but the outer ones did, so based on the 30,000 miles these pads lasted for the presence/absence of the shims appeared to make no difference.

 

I thought I read somewhere that the corrosion problem itself might cause the pads to wear at an angle, but I imagine your car will not have any corrosion!

 

I've been out and about today and it's very pleasant not having the brake squeal every time I stop.

 

If the weather is dry tomorrow I am going to attempt the front discs/pads.

 

David

[paul.h]

I think the corrosion starts as soon as the cars are built - our first C5 we got at 2 years old, about 16k miles and that had corrosion on the calipers/arms and the second was 4½ years old 12500 miles and again had corrosion. Maybe somewhere there will be corrosion rates when steel and the alloy are put together plus a bit of rain. I tend to redo the corrosion removal/brake clean every 2 years and in that time there is a bit more corrosion, despite the copper grease and the car is kept in the garage and not used too often.

[Johndouglas]

This corrosion problem between the arms and the calipers has been an ongoing problem since the first BX left the factory.   I had it on mine.   It continued with the Xantia and in 9 years of ownership with the C5, I've cleaned them up twice.   I find a coating of copper grease keeps them reasonable well.     Being a cynic, Citroen probably doesn't solve the problem so that it become a nice little earner for the dealers.