c5 front brakes

daviemck2006 · Post by **daviemck2006** » 12 Mar 2011, 16:49

I'm not having a good day. Decided to do the front discs and pads on the c5, since I am on hols for a week. 1st problem, locking wheel nut remover broke after taking off one nut. Oh well do that side then worry about how to get nuts off. 2nd problem trolley jack, only 3 months old decided not to work. Use cars sicissors jack. Got caliper off ok and pads out. Bolts holding the carrier on siezed solid, no way am I getting them off in the drive. I thought thats not too bad, the discs are not as bad as I thought and would go again, although pads down to 1mm so thought I'll just put in pads and keep the discs for next time. Handbrake lever and cables all seem to be in perfect condition. Tried to screw in the piston, it moves ok but will not screw in. I've never done screw in pistons before and now I'm stuck, car on stands, no locking key and no pads! I could put back in the old pads and drive to a garage to do, but goes against the grain. Could someone please help and tell me how to get the pistons in so at least I can get the new pads in? At least the droplink I replaced at the same time did not give any grief. To cap it all it's now snowing and cant even get worked outside!

dnsey · Post by **dnsey** » 12 Mar 2011, 20:53

I've never done screw in pistons before and now I'm stuck

Firstly, have you released the handbrake cables?
Next, are you turning the pistons in the correct direction? (Depends which side of the car you're working on).
Thirdly, in practice you do need to apply a bit of axial pressure whilst turning, unlike, say, a nut, which will travel along the thread as you turn.
Lastly, the C5 has quite a fine adjustment, needing a lot of turning (comparatively) to retract very far.

citronut · Post by **citronut** » 12 Mar 2011, 20:58

try clampping the flexi hose and openning the bleed kniple, and as you wind the piston push at the same time, or wind a bit them push a bit till they are fully home,

also it is best the un hook the hand brake cable from the lever on the calliper,

then once the pads are back in press the brake pedel several times to re/set the pads/pistons, before hokking the cable back on,

regards malcolm

Monkeyfeet · Post by **Monkeyfeet** » 12 Mar 2011, 23:18

At about almost nearly exactly the same time you posted this I was changing the discs and pads on my C5. Drivers side. Hope this helps:

I got the 13mm-head bolts holding the brake cylinder assembly bit off no problem. Then used a T55 torx on a 1/2 in T-bar, supported by a small trolley jack to hold it square while smacking the t-bar end with a club hammer to get off the rest of the calliper assembly (only necessary if changing the disc).

I took off the handbrake cable from the calliper and then cable tied calliper to the strut. With the end of the piston now accessible I used a strap ratchet to turn piston anticlockwise until fully home, with bleed valve open. ( I used a mityvac to suck crappy old fluid out. (makes life easier and stops muck getting into ABS I'm told). I didn't clamp the hose though.
Well, this method worked for me but don't forget, passenger side (UK RHD) screws in clockwise.
I realise that you have no trolley jack but maybe improvise a support if needed?
Pls write back how you got on.

Post by **myglaren** » 12 Mar 2011, 23:49

Shouldn't need a trolley jack - just axle stands.

Suspension on high, bung the axle stands in place on either side, suspension low, front of car rises as the rear falls.

fred1 · Post by **fred1** » 13 Mar 2011, 09:32

Hi,

1) essential to release/remove H/B from caliper.

2) dont normally need to open bleed nipple - just relese cap on the master cylinder resevoir and keep eye on level to avoid overflow. If it gets too full suck it out with a meat baster syringe.

3) you do need a means of pushing in piston while rotating it.

4) it is a different direction of rotation on each side - anticlockwise for RH caliper and clockwise for LH

5) you can try and do it with twin screw drivers as on the Xantia but the sloped sides of the piston slots makes this more difficult. I eventually invested in seperate LH and a RH piston retractors.

6) I ALWAYS use Plusgas to free the caliper mount bolts. Using a suringe and needle you can apply small amounts to head area and thread end. A lot of the intial resistance is the friction between the head and the mount (not just the threads). WD and similar are no good at all, Plusgas works like magic!

7) make sure you have a good quality, well fitting torq bit. I have broken poor quality ones on this job.

8) use a long breaker bar or large torque wrench and apply heavy sustained pressure. If that fails you can try heating up the bolt with a blow lomp.

To date plus gas and a long bar have always worked.

While you are in there dont forget to grease the HB lever on the caliper.

Good luck.

John

Post by **myglaren** » 13 Mar 2011, 09:47

fred1 wrote: 2) dont normally need to open bleed nipple - just relese cap on the master cylinder resevoir and keep eye on level to avoid overflow. If it gets too full suck it out with a meat baster syringe.

With the C5 a Lexia should be used to open an otherwise inaccessible valve to prevent contaminated brake fluid flowing back through the ABS system as this can ruin it.

Where a Lexia is unavailable it is better to open the relevant bleed nipple, attach a pipe and container to catch the fluid and allow it to drain off while pushing the pistons back in their bores. Gets rid of some dirty fluid at the same time.

citronut · Post by **citronut** » 13 Mar 2011, 10:00

on a lot of modern car it is said in the garage trade, to clamp the flexi hose and open bleed valve, this stops any back presure causeing any problems in the rest of the system,

and the calliper carrier bolts are lock tighted in, and i always use my two foot breaker bar to loosen them off,

although i have destroyed three torx bit on my freinds Picasso, one twisted one sheard and the other took a chunk out of the edge,

these bits were Kamasa and Sealey,

i finaly cracked it by buying a MAC tools bit worked a treat,

regards malcolm

daviemck2006 · Post by **daviemck2006** » 13 Mar 2011, 12:51

Thanks guys for the advice. Poor weather here and daughters 21st birthday today means I wont be out at car untill tomorrow (hangover permitting since no work either

) I will have to do something quickly though, cant see my 107 or the wifes 206 towing the caravan on wednesday! I'll let you all know how I get on.

Kowalski · Post by **Kowalski** » 13 Mar 2011, 16:11

citronut wrote:although i have destroyed three torx bit on my freinds Picasso, one twisted one sheard and the other took a chunk out of the edge,

these bits were Kamasa and Sealey,

I've got a set of Sealey torx style bits which have a lifetime guarantee (apart from T40 size) and that means that when you destroy them, you can return them and they are replaced under warranty!

citronut · Post by **citronut** » 13 Mar 2011, 20:53

Kowalski

yes i know this and it was the T40 that died

i did also phone round the local factors asking if they had or could get me a T40 especialy for brake callipers, most of them saidthey had never heard of such a tool,

its funny how a few years ago i was told by a motor factors that the T40 is not coverd by the life time warenty, as people use them to undo calliper bolts that are very tight,

regards malcolm

Monkeyfeet · Post by **Monkeyfeet** » 14 Mar 2011, 08:25

daviemck2006 - hope this won't apply to your brakes, but just in case:
I did the passenger side yesterday and have ended up with lots of brake pedal travel, except when the ( working) handbrake's on, so I'm going to check adjustment etc there. I had to take the layer of paint of the pad edges where they fit into the calliper so they could actually move a bit. I also turned the piston in with bleed valve cracked and bled afterwards. (But don't have Lexia). Now pedal goes down and I think that there wasn't enough power to bring in the ABS when hitting the brakes. Hopefully look at it this evening, but any advice could be helpful to anyone attempting this (simple?) job.
Ta!

411514 · Post by **411514** » 14 Mar 2011, 16:45

only thing i can imagine is that there is still air in the system somewhere, if i was you i would change both sides and then bleed the whole set of brakes in order, should sort the problem if not is good maintenance routine anyway. Failing that i had a semi similar problem on a vag car a few years back of very little brake pressure which turned into brakes locked on when driving, turned out that the mastercylinder had somehow become unattached from the vacuum servo (probably whilst bleeding), hope you sort it,

citronut · Post by **citronut** » 14 Mar 2011, 19:25

trouble i can see if you have the kniple open whilst windding the piston back, is you could loose more fluid ferther up the system towards the master cylinder,

this is why i would also clamp the flexi hose,

regards malcolm

daviemck2006 · Post by **daviemck2006** » 14 Mar 2011, 19:38

Hi, got the disc off on pass side and piston wound back. I had flexi hose clamped and bleed nipple cracked open while doing it and no prob. Once I got the carrier bolts cracked things were easy. However as my luck is on a bad run right now took new pads out of box to discover thet are for a 2.0, not the 2.2 that halfrauds said they are for, despite them having the reg no of the car. they are 148mm long, I need 168mm. I'll bet that everyone on here heard the swearing

Now ordered the hopefully correct pads, still need to figure out a way to get other locking nuts off. Think I'll have a puncture and call the AA out, 3 times!!!!