Rear Brakes replacement

[PatBoySlimUK]

Rear brake disk/Pad replacement

Its been a few years since I replaced a set of pads and disk on a car,but did the fronts yesterday and all went well (apart from the 2 locating screws needing to be chiseled out,is this a common problem ?) and now its time for the rears.
Last car I changed the rears had Drums ! I'm told the rear is different as it has a set of shoes for the handbrake,but someone else has said there a cable to the calper.

Can anyone send me a link to a servive manual or pictures(been sent links to service manuals for HID buld replacement and filler cap motor) or give me advice ? and there must be an easier way to get that torx screw out right ?

[davelowe]

According to my Haynes manual the rear callipers pads and discs are very similar to the front ones. There is no need to bother with the handbrake cable unless you plan to remove the callipers from the car. There are no shoes.

[markren2004]

to do the rears i think you need need a special tool to wind back the piston into the caliper whilst at the same time opening the bleed nipple.
if you wind back the piston without bleeding at the same time there is a possibility of popping the seal on the master cyclinder.

[PatBoySlimUK]

Yes I own one of the clamps,I used it on the fronts yesterday.

[AlexB]

Myths, myths...

Reading the factory manual (from our Links). There is nothing there about bleeding while winding back the rear pistons. So, every time I replaced the rear pads I just opened the brake fluid reservoir under the bonnet and wound back the pistons. There is no danger of damaging the master cylinder and there should be no danger of damaging anything with dirt coming from the wheel cylinders if the fluid is changed every two years -- there will be no dirt then.

To do the job I use a combination spanner, I think 16mm, with a short bar put through the ring. The open part of the spanner is used as a "screwdriver" to rotate the piston and push it hard in the same time. On both sides the pistons are wound back clockwise. In the very beginning you may need to rotate the piston both ways just to loosen it. Then proceed clockwise.

If the brake fluid was topped up before, then the reservoir may overflow in the process. Beware of that.

A couple of bonus hints. I use GreenStuff pads and replace discs when they are worn. Read the manual for the torque values and use Loctite threadlock where it should be used. Clean all rust and paint the surfaces prone to rust (including any visible brake pipes) with Hammerite. Use absolute minimum of ceramic antiseize. If you decide to bleed the brakes, never exceed the rated torque for the bleed screws (RTM). Never use clamps (for squeezing the flexible brake lines) -- they damage brake hose, especially the braided Teflon (typical performance upgrade).

[davelowe]

Myths, myths...

Exactly! I'll book mark this one for when I have a go at mine. Cheers for clarifying + the additional info about corrosion.

[markren2004]

Myths, myths...

Reading the factory manual (from our Links). There is nothing there about bleeding while winding back the rear pistons.

Theres a warning in the haynes manual about popping the master cylinder seal if you don't bleed at the same time ( so it must be true ) - i'll dig out the exact text.

[AlexB]

What's the point, Markren? One wouldn't be able to create such a force by hand, which is needed to damage the master cylinder. Furthermore, the master cylinder is designed to bypass the fluid when the pedal is released. I wouldn't trust Haynes too much, and there is no point really, as the factory manual is available. What I explained is safe. Please trust me -- I did it three times on this car. Everything went smoothly and no excessive force was ever involved.

What they probably meant was to stop the monkeys from "inflating" the brake fluid reservoir when its lid is not open. Just open it...

...Theres a warning in the haynes manual about popping the master cylinder seal if you don't bleed at the same time ( so it must be true ) - i'll dig out the exact text.

[markren2004]

The Haynes says...
"Caution: Pushing back the piston causes a reverse flow of brake fluid which has been known to "flip" the master cylinder rubber seals, resulting in a total loss of braking.To avoid this clamp the flexible hose and open the bleed screw......close the screw just before the piston is pushed fully back to ensure no air enters the system."

[AlexB]

Using clamps may damage (and frequently does!) the hose and it is completely unacceptable with modern stainless steel braided Teflon flexible lines (people use them as they don't expand thus making brakes more responsive, take much higher pressures and serve longer).

The Renault factory manual does not suggest using clamps. Their procedure of changing the brake pads is much simpler -- read the factory manual in our Links (MR364MEGANE3.pdf).

You may also look in the section describing replacing the calliper. In order to prevent the fluid loss Renault suggests to press the brake pedal slightly with a special tool. Then the master cylinder stops bypassing the fluid from/to the reservoir. Otherwise, when the pedal is free, the brake lines communicate freely with the reservoir. I never used this pedal trick, to be honest. It seemed to be easier to just unscrew the brake hose and quickly plug the open end with a special cap (supplied with performance brake lines).