How to Replace Rear Brake Discs and Pads.
How to Replace Rear Brake Discs and Pads
First, please may I start with a bit of preamble…
Listen to your car!
Try and find a bit of road with high side garden walls or similar. Open all your windows and cruise up and down this bit of road, preferably when it is quite or not much other traffic around. Listen to the sounds your car makes. These sounds will bounce or echo of the walls and will be amplified slightly through the open windows. You will hear lots of things happening that perhaps you were not aware of before hand. Do this with the radio off, then with the air/con on and off, try changing gears or kick down if an automatic, try the brakes slowly or if safe give em a stab, apply the handbrake gently and if safe vigorously. Just listen to your car and how it responds to all these options!
Now I suggest that you do this about 4 times a year, once every 3 months. Your car is talking to you and it uses a language that is foreign until you get used to it. Get to know its nuances and make a mental note of how well it is running. Then when it is feeling a bit sick; and more often than not this starts happening very slowly, you will distinguish these sounds from when it is well. It could save you a lot of money and heartache.
Why I say this is because I didn’t practice what I have just preached as you will see in a moment. I always jump into the car the radio comes on when I start her up and I’m off. It’s not loud but it does distract from listening to my car.
Last week I took her into to get the Automatic Gear box fixed and when I went to pick it up the guys told be that there was a grinding noise and I should check the brake pads etc. So on the way home I did listen using the method above and sure enough there was a slight grinding noise. Half the beauty of these cars is the nice quite smooth ride. I like to be taken from A to B and not have to drive there but as I don’t have a chauffeur so I have to do it myself.
Anyway enough of that. When I got home I took a look at all the wheels and on peering through the alloy spokey-e-dokey’s, on the nearside rear I saw something horrible. I took the car round to a local mechanic and he said it would cost me about £160 for him to change the disks and pads. I decided; out of sheer cussedness, to do it myself. The following is what transpired…
I bought the Mintex discs and pads from eBay and a warning sensor wire too. Little did I realize I was going to need some additional bits as well, more on this later. These cost me about £60 all together. I saving of about £100.
First I couldn’t get the wheels off, they had become stuck; I now believe, because the discs had rusted and gripped the alloy wheels. I had to use a piece of wood and a hammer to knock each side of the wheel also at top and bottom to get it to let go.
Some say that a rubber mallet should be used. That is probably a good idea, but as I didn’t have one I used a bit of 3X2 and hit it with the hammer. Don’t hit the tyre wall as this could weaken it and cause a probable blowout some where down the track. Also don’t hit the rim with the hammer direct as this will damage it (the wheel not the hammer). It should only need a few gentle taps and that should break the rust binding to the alloy. Eventually it did and I was presented with this extraordinary view.
I imagine the pads had been worn out for some time, but because I was listening to the radio and not the car, I was unaware of what could have been a potential danger to myself and others. I noticed when the guys at the auto transmission place jumped in to test drive the old girl, the first thing they did was turn the radio and air/con off. So live and learn from my experience. Listen to your car.
The above picture was taken just after I had done a 35 mile round trip to the auto transmit guys. One positive thing to come out of this… Our cars are well insulated against outside noise aren’t they! Or; more likely, I am just dim and deaf (don’t respond to that).
Now this picture below is not the best as I couldn’t get my camera and my head in under the wheel arch at the same time. But it does show how tight a fit this area is. You have to get a spanner down inside the back of the caliper to undo the circled bolt and one below this to remove the caliper.
Now this brings me to something I wasn’t prepared for. I could not get my socket set into this area to get a firm fit on the bolt head so I could turn it. Fortunately my wife has her own car so I was able to pop out to buy an appropriate tool. Unfortunately the only place near enough to where I live is Halfords in Telford another 35 mile round trip. After looking at a few options they had I decided to get myself a set of these.
Quite expensive but has to be the best tool I have purchased for a long while now. They come with a lifetime guarantee; you break one and they will replace it for free; or so the man said. To be honest it was the only tools that would fit into the area behind the caliper where the two bolts are that have to be undone. I had tried an open ended spanner but it was going to do more damage to the bolt head and then I would have had some serious problems getting them out. Believe me I tried very hard but decided that discretion was the better part than stuffing it up. Be warned! These bolts are very tight and difficult to undo.
Don’t be tempted to hammer the top of the spanner after attaching it to the bolt to jolt it loose. You will do more damage to bolts and or surrounding areas and probably not get the spanner replaced if it is abused this way Use copious amounts of WD40 or equivalent. After much effort I did get them undone using brute forces and gloves to protect my hands. If anyone can suggest a better way then by all means do so.
This now brings me to another problem I had, your situation maybe different…
I didn’t have the right size star shaped bit required to undo the screw that holds the disc onto the axle. So while at Halfords I also bought a set of these. Again quite expensive but should do me for a while now that I intend to do all my own servicing.
The discs takes some getting off if the hand brake shoes are adjusted up tight. It may require adjusting them down a bit so that the old discs come off (Check the Haynes book for details on this). I didn’t have any problems with this side but the other side was difficult, more on this later.
Once undone and discs removed I was presented with this view… Note I have supported the caliper with a length of wire attached to the spring so it doesn’t put any strain on the brake fluid hose.
I cleaned off all the surfaces in this area with an old dry rag and give it a good brush out with an old paint brush, don’t be tempted to use any DW40 or any other oily substance that will leave residue which will contaminate the brake pads and make the brakes inoperative. Also wear a mask to avoid inhaling the dust.
Clean the new discs with an appropriate liquid that doesn’t leave an oily residue on the pads. I used some white spirit some suggest Mentholated spirit. You need to get the transport rust protective oily residue off the new discs not forgetting the interior where the hand brake pads run against the drum surface. Get these surfaces as clean as you can, this will enable bedding in to be quicker.
Once you are happy with all the cleaning interior and discs, fit the new disc and screw it into position. Apply copper grease to the center axle hub and face of new disc to stop rust binding the alloy wheels again.
Apply the hand brake a few times to make sure the hand brake pads are centered inside the new drum. Release the hand brake and spin the new disc to make sure it isn’t binding and apply the hand brake again and then loosen off. If there seems to be a bit of play or you can still spin the disc while the hand brake is on you will have to adjust the knurled adjuster through a hole in the disc…
On my old cars in Australia to adjust the hand brake all you had to do was reverse and apply the handbrake gently. Apparently this adjusted them automatically. I am not sure if this applies to the MG Rover cars. Perhaps someone can inform us.
To adjust the hand brake you will need to pass a small head screwdriver through a hole so that it locks under the notches on this knurled head...
Pass it through a hole in the new disks like this... Yeah I know I am still showing the old disc here but it serves its purpose.
And lever it up or down to adjust. Check with your Haynes book about how much adjustment to make. This is a tedious job getting the blade to engage with the knurled nut and the adjustments can get confusing as to witch way; up or down, to get the hand brakes adjusted properly. Don't make them too tight but make them so that there is little travel for the pads when the hand brake is applied.
Now we get to an interesting bit…
Undo the top of the brake fluid container under the bonnet here…
Note that the fluid level is well above the MAX level of the fluid. This is because I took this image after I had done the next bit (see below). At this stage just undo the top but leave it very loose on top of the filler cup to stop any dirt getting in. There are differing opinions about doing this but in my case this method worked. Some would prefer bleeding the brakes through the fluid bleed nipple located at the brake caliper end. I didn’t undo these I undid the cap and allowed the fluid to be pushed back up into the container as I pushed the old pads back into the caliper. I did not have any problems with this at all but be aware that the fluid can overflow into the plenum area, keep an eye on this fluid level in the cup. Use an assistant to watch it while you are spreading the old pads. I have done this on many cars both here and in Australia without any problems. You do what you feel comfortable with.
Now we have to push the old brake pads apart. Unfortunately I was so engrossed in what I was doing I forgot to take any photos of this stage. I found using a large screw driver inserted between the old pads and using it as a lever and twisting and pulling from side to side did return the piston back into the caliper. Do this while the old pads are still in there, it makes for less possibility of damage to the piston and dust grommet. Do it slowly and keep checking that the fluid doesn’t overflow from the cup.
Once done I found a pair of long nose pliers helped to get the old pads out… The pads are a tight fit and in this very dry and rusting environment it is difficult to get them out. Although; I have to say, it is much easier to get the old ones out than to put the new ones in.
The Warning Sensor...
The warning sensor is fairly easy to fit, make a note of how the old one comes out and fit the new one in reverse order. Make sure you put it back in the correct orientation otherwise it will not work and you will not get a warning when it wears out. It is shaped like a key and comes with a new spring clip. It should actually only go in one way with a small raised section that will eventually come into contact with the disc when the pad wears down. This then makes a contact and a light will appear on the dashboard to let you know that you need to replace the pads again.
The wire is hooked underneath the rubber cap which is fitted over the bleed nipple to the right of the above picture.
Follow the wire to the other end which is fixed behind the wheel arch flap. It is just a plug in with a simple catch that is pressed to separate them.
Refitting the new pads and caliper...
The image below shows one of the new pads inserted into the gap and then it has
to be pushed against the piston head and seated into the recess before trying to
get the other pad in; as in the second shot.