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Difference between revisions of "Brake Pads - Changing Front"
Latest revision as of 16:11, 22 April 2011
|Difficulty?||Low to Medium – but can be dirty & requires some exertion|
|How long does this take?||3-4 hours|
Mk3 Mondeo: Changing Front Discs
Your brakes are the only thing other than solid objects (like trees) and other vehicles (like trucks) that stop your car.
This also requires lifting the car – get that wrong and it’ll really put a dent in your day – not to mention your head.
So basically, if in doubt, don’t do it.
Sorry, no pictures – I did something boneheaded with my camera ... I forgot to take any pictures :(
Things you’ll need:
Trolley jack, Axle stands, bits of wood for support & wheel chocking
Wheelnut brace, 17mm open ended spanner, half inch drive 12mm, 13mm, 14mm & 15mm sockets, Ratchet driver & extension bar/pipe for leverage.
Rubber mallet, possibly also a big heavy metal lump hammer too.
A short length of metal tube (say 15mm diameter by about 125mm long) will help enormously with getting the wheels back on.
You may need low ramps of some sort – I find there’s not quite enough room to get my trolley jack underneath, so I use a couple of short lengths of roof joist, cut at a 30 degree angle one end to gain a couple of inches.
Dustmask(s), Wire brushes, old screwdrivers etc for derusting, smaller brushes for the dust, some sort of air source (can, compressor, even a bicycle pump) & possibly a small syringe for extracting excess brake fluid, grease (I prefer Copperslip myself), rags, vinyl gloves, torque wrench, small & medium flat bladed screwdrivers.
Length of cord or wire, Large G-clamp, small length of thin dense wood (or similar)
I’d also recommend that you replace the calliper carrier to Hub/knuckle bolts (which I believe are FINIS code 1447853, £6.72 for four (March 2011)).
New discs & pads (I used Brembo parts from Nextdaybrakes.com, £86 posted)
1 - Park somewhere safe, flat & level, chock both sides of both rear wheels, loosen the wheelnuts on the side you want to start on, it makes no odds but I prefer the NS (left), as despite popular myth, I always find cars to be slightly less rusty that side & therefore easier to work on.
2 - Jack your preferred corner up (I have a gravel drive so always put a thick bit of plywood underneath to spread the load, and another smaller bit to spread the load on the jacking point (just inboard of the scissor jack notch on the sill), then support at a suitable point with axle stands I tend to use the front subframe, with wood either side, lowering the jack just enough to begin to take the weight. Undo the wheelnuts, clean them up & apply a bit of grease, then put somewhere safe. Clean up the inside face of the wheel & lightly grease that too. Compare your new parts with what’s already on the car.
3 - Put on your dustmask at this point, and scrape/wire brush the two bolts that hold the calliper to the carrier, and the two bolts that hold the carrier to the hub/knuckle, avoiding the CV joint boot and the calliper slider pin boots.
4 - Undo the bolts that hold the calliper to the carrier (mine were 13mm) – this may need a lot of leverage – I used an 18” long tube over the end of a ratchet driver - which is not a good thing to do to it, but a regular bar won’t give the angle you need. This is a 2 person job – one needs to hold the socket square on the bolts and hold a 17mm (I think) spanner on the flats on the end of the calliper to carrier slide mechanism(s). Compare the bolts that come out to the ones with your new pads & discard the old ones.
5 - Slide the calliper off, and support it with a bit of cord or wire on one of the spring coils. Remove the old brake pads from the carrier – an old flat bladed screwdriver should help unlatch the springs at each end.
6 - Remove the two calliper carrier to steering knuckle bolts – these are nominally 15mm, but if they have rusted badly, once you get the rust off they may be smaller – so use a socket that fits without too much hammering. Again, a lot of force will be needed to undo these bolts.
7 - Clean up the carrier with a wire brush, paying particular attention to the dimples where the brake pad ends are retained. If the calliper slide pins more freely they don’t need to be removed, but if they are difficult to move in and out they need stripping, cleaning carefully, regreasing & reassembling.
8 - Carefully clean the area around the protruding end of the piston and its seal with soft brushes & air. Wind the piston back into the calliper by using a small bit of wood across its end, with a 6” G-clamp. The Brake fluid level will rise in the reservoir as you do this, but don’t remove any unless it looks like it’s going to spill over. Lightly grease the end of the piston.
9 - If your brake disk is held on by washers (it may not be), use a small screwdriver to get them started & wind them off the stud threads. With luck your old disk will lift straight off, or just need a few taps with a mallet... if not, use a bigger hammer. Hit the old disk on the inside & then turn a bit, repeat until it comes off, using gradually more force if it doesn’t co-operate. Don’t worry about damaging the old disk. The pitch of the ringing noise made when you hit it should change when it’s beginning to move.
10 - Once it’s off, clean the end of the hub & apply a little grease to the mating surfaces (for both disc & wheel).
11 - Wash your hands, thoroughly degrease the new disc, and fit on to the car, refitting the special washers if applicable.
12 - Refit the carrier to the steering knuckle using new bolts, torque up to 96 lb-ft (130 NM). That’s very tight - more than you can do by hand & guesswork with a regular socket set.
13 - Lightly grease the ends of the new pads (being careful not to touch the surface of the pad) & install ... there is a bit of a knack to it – the pads need to go in square & can be a problem unless you get it just right.
14 - Untie the calliper, and refit over the disc. Fit the new pin bolts that came with the brake pads (mine were 12mm head rather than the 13mm that came off the car), tighten using a 17mm spanner on the slide pins to stop them rotating. Torque required is 22 lb-ft (30 NM), which is easily doable with a regular ratchet, but as you’ve got the torque wrench handy ...
15 - Refit the wheel & nuts, give the wheel a good twirl to check nothing is rubbing/binding. I really struggled getting the wheels back on – there really is nothing for them to locate positively on until the nuts are seated. I found using a short length of metal tube really helpful – approximately 15mm diameter by 125mm long. Before putting the wheel on, rotate the hub so one stud is at the top, rotate the wheel too, so a hole is at the top – and a gap through the “spokes”. Slip your tube half way into the top most hole, then aim that for the top stud. The wheel should just hang on enough to let you locate it on the other studs, and get a couple of nuts started.
16 - Jack up the car enough to take the weight off the axle stands, remove them & let the car down off the jack, torque the wheelnuts up correctly. Remember that nothing will happen the first time you press the brake pedal – you need to pump the piston back out – be very aware of this if you need to move the car to do the other side.
Repeat steps 1-16 for the other side. DO NOT DRIVE the car only half done – a car that doesn’t brake evenly is not safe.
Pump the brakes until the pedal feels normal (should be 2-3 presses max). Check the brake fluid reservoir & remove any fluid over the “max” line.
Give the car a quick road test & listen out for odd noises, check that the car pulls up in a straight line too. Remember that the brakes will not be as effective until they are bedded in – a couple of hundred miles of gentle use should do it.
Don’t work the brakes extra hard thinking it’ll bed them in faster – it might, but it’s more likely to do damage (like warping the discs) due to the extra heat. Two weeks or two hundred miles is the usual recommendation.