DIY Car Mechanics Explained - Changing Brake Pads & Discs

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Okay, just a simple guide as it's a regular topic that comes up for discussion - how to save yourself rather a lot of labour charges by doing a simple job like changing discs and pads yourself. You need a jack, axle stands and a basic tool kit. Your caliper may well be held on with a special allen-key style socket. No, a normal allen key will not really do the job, not enough leverage.
A caliper winding tool is also useful, but not essential.

Please not all cars are different and may have different methods for holding the pads in (pins, bars, etc) - but with a little common sense the theory is basically the same.

I accept no responsibility for you damaging yourself or your car, this post is for interest value only!

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One car. Jack it up and take off the wheel....

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To reveal a truly rogered brake disc. Ignore the rust, that is of no consequence - but check out the scoring on the disc face! Not good. This is what happens if you don't change your pads the moment they begin to get noisy.

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So, remove the anti vibration clips (these hold the caliper and slider apart at the right angle)

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Then using a power bar, crack off the two nuts (usually allen-head sockets) that hold the caliper to the caliper carrier. These may be VERY tight! Then undo them with a socket. Sometimes both need to come out, sometimes just the top one and then let the caliper swing down. On the Mondeo, both need to come out.

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At this stage, pop the lid off the brake fluid reservoir, or you will have a mighty struggle to push the pistons back into the caliper.
 
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Now get a bar and lever the caliper gently away from the carrier..

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Like so. Pop out the pads (they just fall out on most sliding caliper designs) and support the caliper to save damaging the brake hoses.

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Well and truly rogered.

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Now, peer behind the disc and you can see the carrier (the large metal bracket that goes round the disc) is held in by two big bolts. Undo, and remove the caliper carrier.

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Now you are free to remove the disc. Some have a retaining screw which will need removing or drilling out first. On the Mondeo, a hammer comes in handy as they tend to stick onto the hub. I had to belt seven shades out of these before they came off.
 
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After a lot of frenzied banging (hur hur) the disc should come off. Make sure you clean up the hub thoroughly or you'll get the notorious "warped disc" sensation.

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New discs. Shiny shiny, clean them with brake cleaner first as they tend to be covered in an oily film

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Refit the carrier..do it up....tight.

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Now this is a caliper winding tool. What a brilliant device.

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It lets you push the piston back into the caliper relatively easily - a job that otherwise requires herculean effort, a crowbar, and lots of swearing and stuff. When it's wound right back you can put in the new pads.
 
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Now the caliper is fully rewound, you can place the new pads in both the carrier....
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And into the caliper - these are held in with sprung metal clips and can be tricky to get in so use a screwdriver to wedge them in if you're struggling.

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Be careful here! Bolt the caliper back to the carrier - it's hard to get them straight on some cars, and I ended up cross threading the bolt, badly damaging both bolt and carrier! I got a whole caliper which I used for parts from a scrappy for £20 - put it down to experience and you'll not make the same mistake again.

Brakes19.jpg

After replacing the clips (the ones I removed at the start of the job) you can bolt the wheel back on and remove the car from axle stands. Put the cap back on the brake fluid reservoir (if you've been topping it up, it will now have oozed out everywhere :p) and drive gingerly down the road, press the brakes a few times to get the pedal feel back, it may be spongey at first.

Job done! Drive carefully for the first few hundred miles, and avoid hard braking over long periods. Or just follow the pad manufacturers instructions for bedding in.
Hope this was of some use.
 
Excellent thread! I've done it before with much swearing, knuckle brusing, and depression on my mondeo... however I did it and it felt wonderful after having spent half a day :o doing it. However from now on I'll just stick to changing the pads rather than the discs - too much effort without the right tools!
 
Agreed! There should be more posts like this. If I'd have thought about it, I could have done one about doing an oil change last week :D

Anyway, my discs are warped and need changing soon, so I might have to borrow that winding tool off Gordon if he'd be so kind ;) :p
 
Lostkat said:
Anyway, my discs are warped and need changing soon, so I might have to borrow that winding tool off Gordon if he'd be so kind ;) :p
Show him some cleavage and he'll do anything you want.
I have another guide coming soon, will start stickying this sort of thing. If anyone else has pictoral guides that they want to write, or have already made,(for ICE, mechanical stuff, bodywork, GPS installation and so on) then RTM the thread or mail me and we can get them added to the sticky.
 
3 Things...

1) Do you not use copper grease on the back face of the pads?

2) If you dont have a winding tool a mint G-cramp is ideal

3) I would always reccoment pumping the pedal a few times BEFORE driving off to get back the feel!
 
Brilliant! There seems to be quite a shortage of well written and described guides (especially ones that are easy to find).

Might this be the beginning to the 'Numpty's Guide to Cars' by Lopez?
 
Threads like this should be archived instead of being allowed to fade away. A nice archive of threads like this would be good for new users and current users alike. Perhaps Lopez's other guide on how to melt away your tyres can be left out? ;) :p
 
I would use a bit of Copper Grease on the backs of the pads to prevent any squealing, and on the hub to stop the discs sticking in future.

Slime mentioned using a G-Cramp instead of a winding tool - this is fine but only if the handbrake doesn't operate on that caliper. On most cars its the back but several do have handbrakes that act on the front, notably Citroens with HP suspension but others do as well. Most handbrake mechanisms require that the pistion be wound rather than pushed back in as they use a threaded bar to take up that slack as the pads wear.
 
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