How to change your brake discs - W210

[Parrot of Doom]

Tools required:

2 new discs
Trolley jack or Mercedes jack, 2 tonne axle stands
Wheel brace
16mm ring spanner and 16mm ratchet
Big lump hammer
Pair of adjustable grips/pliers with at least 2 inches clearance
Wire brush and sharp chisel
Copperslip grease
Degreaser
Paper towel
Swear filter

If you've ever changed a wheel, this job isn't that much more difficult than that. Its a pretty simple job, and just requires a bit of brute physical strength.


1) Park the car on level ground, apply the handbrake, put the car in P, turn off the ignition

2) Get your wheel brace out and loosen the bolts to finger-tight levels.

3) Jack the rear of the car up on one side, and put your axle-stand underneath the large rubber jacking point. Let the jack down slightly, and let the axle stand take the strain.

4) Remove the 5 bolts from the wheel, and put the wheel to one side.

5) The first thing we have to do now is remove the calipers. The calipers hold the brake pads in position, and are bolted onto the rear of the wheel hub.

At this point, just double check the car is securely raised, since from now on your head is going to be under the vehicle.

Here are the bolts, on the inside of the disc.

There isn't a lot of room in there, so you'll either need a short socket, or a ring spanner. Either way, the bolts are 16mm. What I do is get my ratchet on the bolts and use that to remove most of the tension. Once they're coming loose, I change over to the spanner as my sockets are too long to unscrew the bolt all the way out.

You might find it easier with a 11/16ths spanner once the bolt is loose, it makes it easier locating the bolt and helping free it. After a few turns you should be able to unscrew it with your finger and thumb.

Now to remove the caliper from the disc. The bolts are out, but the caliper is stuck fast to the disc. This is where my friend Mr Hammer comes into use:

Don't go whacking hell out of it, just a few light taps to help it free. Once it moves a little, grab hold of the caliper and work it free. Tap it a few more times if necessary.

When the caliper is free of the disc, wedge it somewhere in the suspension behind the hub, or if you can't find a place, just get a tin of paint or something tall, and rest it on that. Try not to let it hang via the brake line.

6) Now to remove the disc.

In normal use, the disc is held on the hub by the wheel bolts. Theres a little allen screw that stops the disc from falling off and breaking your foot. Thats all its there to do, it doesn't have any other function. It won't be tight, so unscrew it and put it to one side.

 

[Parrot of Doom]

At this stage, please be wary of errant cats exploring and scratching your bodywork

Once that screw is off, you'd expect the disc to fall off. Except it won't. It'll be hanging for dear life, and this is where Mr Hammer comes back into play.

At this stage, take the handbrake off - or the disc won't budge.

I had to belt hell out of mine to get them off, they were stuck fast. You might want ear defenders for this bit. Seriously, you really have to whack the hell out of them before they'll shift. Be prepared to spend a good few minutes doing this.

7) Once the disc is off, this is what you'll see:

Thats the parking brake mechanism. You can clearly see the shoes, they press against the inside of the disc to hold the car while applied.

Before we put the new disc on, we need to clean all the crap off the surface of the hub:

Give it a right good going over, use the chisel on the stubborn bits near the hub centre. Get every last bit of grime off the surface, and you'll end up with this:

 

[Parrot of Doom]

Get your copperslip out, and spray/smear a thin layer on the surface:

This will help prevent the disc from sticking to the hub, and will help make it easier to remove the next time you have to do this job.

8) Now to put the new disc on. The new discs will arrive with a thin layer of either paint, or grease. This is to stop them corroding when on the shelves. We need to remove this.

If its paint, just use the wire brush to scrub it off. If, like mine, its grease, get some degreaser (I used Isopropyl Alcohol spray), and wipe the grease off.

Get the allen bolt, and find the smaller hole with the thread (there are 2 small holes, only one is threaded). Then put the new disc onto the hub, line up the holes, and tighten the allen bolt into place. Not too tight, its only to hold the disc in place while the calipers and wheel bolts are off.

9) Now the new disc is on, we need to reconnect the calipers. Unfortunately as the old discs were thinner, the calipers won't fit back on, so we need to compress them.

I haven't enough hands to show this and take the picture, but basically you get your pliers, get one set of teeth on the caliper body, the other set of teeth on a brake pad, and gently squeeze the pad back into the caliper. Use some paper tissue to cover the brake pad so you don't break any material off.

You only need compress each pad about 1mm.

Once you've done that, slide the caliper onto the disc, stick your head behind the disc, and line the rear of the caliper up with the 2 empty bolt holes. Get your bolts, and screw them back in. It may take a moment or two to locate the holes correctly.

You should in theory use new bolts here, and a torque wrench, but I've always used the old ones if they're in good condition (mine were), and as for tightness I just make sure they're very tight. I usually check them after a few weeks to make doubly sure they aren't coming loose, they never have yet.

Now the disc is on, the calipers are on, all you need to do now is apply a thin layer of copperslip grease to the surface of the disc (not the braking surface).

And thats it. Job done, pop the wheel back on, take the car off the jack, tighten the wheel bolts diagonally (bolt 1, bolt 3, bolt 5, bolt 2, bolt 4), and do the other side.

Once you've done both sides, put your tools away and take it for a drive to test. You'll have to pump the brake pedal a few times when you start the car, but otherwise it should be fine.

The parking brake may be slightly tighter as well, I presume as the inside of the disc is less worn.

 

[television]

Many points here are not right in the way that you have gone about it and many important things and differences left out.

I will write it up better this evening.

 

[eric242340]

Excellent post, but at which stage does the swear filter come in?

 

[eric242340]

Many points here are not right in the way that you have gone about it and many important things and differences left out.

I will write it up better this evening.

Good one for DIY.

 

[eric242340]

I dont want to make any serious points on this, I think Malcolm will deal with that. But you havent mentioned the brake pad wear sensors, which should be changed wether you change the pads or not. To change the discs you will have to disturb these sensors. Small point, but a very important one.

 

[Parrot of Doom]

Ah I did forget to unscrew the brake fluid reservoir cap

Malcolm whatever I've missed please do tell me about, remember I'm only an amateur DIY'er and would appreciate the feedback.

 

[television]

Not all rear brake calipers are held on in the same way, some cars have 2 x 7mm hexagon headed bolt behind a rubber plug.

Since it is very bad practice to use the old pads on a new disc, the pistons should be pushed back either by opening the bleed nipple or by forcing back, the bleed nipple being the better way,this way the caliper would have cleared the ridge on the edge of the disc and the hammer would not be needed to remove the caliper.
It must not hang at any time on the hydraulic pipe and can be tied up or put on something of the correct height.

The parking brake adjuster should have been backed off,2 types in use, the ratchet as in photo or a screwdriver slot type, had this been done the drum/disc would come off with a few taps of the hammer. if you do not back it off, then you are forcing the drum over the wear ridge in the drum, It is better not to disturb the parking brake shoes or knock them off center.

When the new drum/disc is on and the screw fitted the ratchet should be adjusted so that the drum is locked, the parking brake should be applied a couple of times then released, and the adjuster should be backed off so that the drums turns with inly the slightest rubbing,if any.

Calipers should not be fitted with the old bolts, the new ones have a locking compound on them.

Maybe if you can edit your post Parrot, then blobcat can delete this when you are done

 

[Parrot of Doom]

Fair points Malcolm, and thanks for bringing them to my attention.

The hammer wasn't needed to remove the caliper, I just used it to get it moving - once it was loose I could pull it off quite easily (hence I said tap tap)

The discs were bonded to the surface of the hub, thats why I had to belt them to free them up. I had the same problem with the fronts when I did those. I had no problems getting the disc past the shoes, there was plenty of space.

 

[eric242340]

Excelllent attempt and im impressed, but to make this a DIY thread? It needs polishing and im glad to see you are thinking on this subject. With a little input from other people, this can become a good DIY thing. Well done.

 

[Parrot of Doom]

Thanks all. I'm happy I've done a good job, but if anybody feels I've given bad advice than I have no problem whatsoever with the thread going to the internet bin in the sky.

 

[television]

Thanks all. I'm happy I've done a good job, but if anybody feels I've given bad advice than I have no problem whatsoever with the thread going to the internet bin in the sky.

You have done 90% of the job with your super pics. I just feel that if the writing up on each pic was done it would be super and much need as i get fed up writing it all out all of the time.

I know some folk get pis-ed off with me,but it is so simple to make perfect.
I do not want any credits,its your threads, and it should stay that way.
How is the best way to go about it out of prying eyes, it could be done one pic at the time as they are all needed.
As before blob can take this all away

 

[Parrot of Doom]

Ok, could you briefly summarise what you'd like me to add, and I'll do it straight away.

Obviously I can't take any pictures (is the handbrake adjuster under the rear seat, because I can take a pic of that), but I can certainly remove one or two, and add paragraphs in here and there. Once everybody is happy with the edited version, a moderator can 'vamoosh' this post, and it'll all be fine.

 

[television]

Ok, could you briefly summarise what you'd like me to add, and I'll do it straight away.

Obviously I can't take any pictures (is the handbrake adjuster under the rear seat, because I can take a pic of that), but I can certainly remove one or two, and add paragraphs in here and there. Once everybody is happy with the edited version, a moderator can 'vamoosh' this post, and it'll all be fine.

Do you mind if I write a summary for each pic. the hand brake adjuster is shown in pic 5 its the toothed wheel. All of the pics are fine,
I can do the summary for the first few in the morning, you just say if that is OK

 

[Blobcat]

my finger is on the button

 

[television]

my finger is on the button

Thanks Blobcat, parrot has done all of the hard work, and it will turn out perfect

 

[davidsl500]

I'm not going to mention putting a dial gauge on the new disks to check for run out...................see, I didn't mention it.....

 

[television]

I'm not going to mention putting a dial gauge on the new disks to check for run out...................see, I didn't mention it.....

Good as its the kind of thing that we all have at home just sitting there waiting to be used.

 

[television]

Tools required:

2 new discs
New rear pads
Torch or lead light
2 new caliper fitting bolts or some locking compound (red)
Trolley jack or Mercedes jack, 2 tonne axle stands
Wheel brace
16mm ring spanner and 16mm ratchet
7 mm allen key dependent on the make of caliper fitted (SL)
Big lump hammer
Pair of adjustable grips/pliers with at least 2 inches clearance
Wire brush and sharp chisel
Copperslip grease or CERA TEC copper free by Mintex (new)
Degreaser
Paper towel
Swear filter

If you've ever changed a wheel, this job isn't that much more difficult than that. Its a pretty simple job, and just requires a bit of brute physical strength. The same procedure can be used on almost any make of car, with non electric parking brake


1) Park the car on level ground, apply the handbrake, put the car in P, turn off the ignition

2) Get your wheel brace out and loosen the bolts to finger-tight levels.

3) Jack the rear of the car up on one side, and put your axle-stand underneath the large rubber jacking point. Let the jack down slightly, and let the axle stand take the strain.

4) Remove the 5 bolts from the wheel, and put the wheel to one side.

5) The next thing we have to do now is remove the calipers. it is better to withdraw the pistons at this stage, otherwise the caliper will jam on the ridge on the outer edge of the disc. The calipers hold the brake pads in position, and are bolted onto the rear of the wheel hub. it is only possible to remove the pads when the caliper is off, with the exception of cars like the 211 where they have the same double pins as on the front. With this type of caliper you must remove the pads first, by knocking out the 2 pins, then withdraw the pads. To get the pistons back, the best way is to undo the bleed nipple, and using a large flat screwdriver between the pad and the disc force the piston back and tighten the bleed niple. You can just force the pistons back but the bleed nipple way is better. do keep a check on the filling tank under the bonnet so that the brake fluid does not over flow. (note that any damage to the disc or pad does not matter as they are being renewed)

At this point, just double check the car is securely raised, since from now on your head is going to be under the vehicle.

Here are the bolts, on the inside of the disc.If there are no bolts,but you have 2 stand off pillars, remove the rubber bung in the end and use the 7mm allen key to undo the bolts.

There isn't a lot of room in there, so you'll either need a short socket, or a ring spanner. Either way, the bolts are 16mm. What I do is get my ratchet on the bolts and use that to remove most of the tension. If you have the allen keys, you may need a tube or something to extend it to get leverage. Once they're coming loose, I change over to the spanner as my sockets are too long to unscrew the bolt all the way out.

You might find it easier with a 11/16ths spanner once the bolt is loose, it makes it easier locating the bolt and helping free it. After a few turns you should be able to unscrew it with your finger and thumb.

Now to remove the caliper from the disc. The bolts are out,

With the pistons withdrawn the caliper should be loose, maybe just a light tap to help it free. and it comes off complete with pads, the pads can be lifted out at this stage and discarded. You do need something to rest the caliper like a tall tin, or wire it to the suspension, as it must not hang on the hydraulic pipe.

.