Brake discs and pads

[bushy989]

Thanks I would also be interested in the process

[TeamG]

No probs, coming soon. The front discs arrived this morning, the rears and pads in a separate package tomorrow. I’ve currently got Covid and suffering a bit, but hopefully towards the end of the week I’ll give it a bash.

[TeamG]

So a bit more background before I do the actual replacement. Firstly a bit about brake component life expectancy on this car.

I’ve the 2017 XC60 with the 2.4 litre 190hp AWD. I bought it at 2yrs/20k miles and now it’s 6.5yrs/55k miles. When I bought it, it was on original discs and pads, and at the first MOT a year later there was an advisory as the rear inner pads were approaching the limit. Outer pads were fine. I replaced the rear pads only with Brembo and bought these from ECP, although the ones they sent came with the wrong spring clips (for the unvented disc, so narrower). I reused the old clips as they looked fine and were given a quick wire brush. I didn’t grease the pins on that change, as they still looked clean and greasy. I’ve checked that the new clips fit the new disc as per photos, so this must just be a ECP thing. They don’t publish the Brembo part numbers on their website, so no way to check in advance.

Now it’s on 55k miles, the front and rear pads are on 4mm and 3mm outer thickness respectively and the inner pads are all 1mm less. I believe this is due to the pistons being on the inner face, so the inner pads contact first and may be excaccerbated by my gently style of driving and braking. Discs are all getting closer to minimum thickness, so I wouldn’t want to do another pad change before replacing these too.

The parts have now all been delivered as per the photos. It’s more apparent with the parts off the car how different front and rear are, despite similar diameter discs of 324mm/302mm. The front pair weigh around 11kg each and the rear pair around 5kg each, and the pad sizes are very different. The front pads that are for my car have the single piston clip as per the photo, there is another option that has two clips per pad.

I just need a couple of days more to shake off the Covid and for the rain to stop, then they are being fitted.

[TeamG]

I have finally shaken off the Covid, and the weather gave me a brief gap to start the job today. I’ve only done the rears as I need to pick up an 11mm Allen key socket to do the fronts.

Fo those that wanted pics, I’ll include below with each of the steps. Firstly, EPB off, cracked the wheel nuts, up on the jack and popped the alloy under the suspension in case of jack failure (quicker than axle stand and I wasn’t going under it). A quick blast of WD40 on the disc retaining screw, pop a small screwdriver in the fins of the disc to hold the wheel still and crack off the screw (Torx T50).

Next, the pad carrier bolts (13mm with a 16mm on the pin), these get discarded as Brembo kindly supplied new. EPB connector off, using a small flat head screwdriver to lift the clip in the direction shown, then wiggle it off and put the pad carrier somewhere that doesn’t overly bend the hose.

To wind back the EPB, I use a 9v PP3 battery with a connector and pair of croc clips. Negative at the flat side of the connector, positive at the curved side. Keep winding it until it winds no more. The 9V is so weak, it won’t damage anything.

[TeamG]

Now push the piston all the way in to clear the new, thicker pads. The C-clamp only needs gently pressure, but make sure it’s square and not going to damage anything.

Remove the pads and old clips, remove the sliding pins, crack off the two 15mm bolts about 7 half-turns to allow you to get the old disc out. A bash with a mallet will soon free it.

[TeamG]

A good wire brush of the hub and pad carrier, insert the new disc and pad clips, clean and lube the pins, then pop them back in making sure the rubber boot is located covering the pin.

[TeamG]

Use the correct lube for the back of the pad and for the ‘ears’ that fit in the spring clips. You don’t need much. For the inner pad, a bit in the middle as shown and for the outer pad, two strips of lube where the caliper sits.

Fit the pads in the springs, fit the new bolts, tighten everything up, reconnect the EPB connector, then wheels on, drop the jack and torque the wheel nuts to 140Nm. I then work the EPB a couple of times to make sure everything works before heading off.

The fronts are a little different with a different pin configuration and a big spring clip - I’ll do those shortly.

[TeamG]

Amazon was my friend, so if the rain and wind do-one for an hour tomorrow I’ll be doing the fronts.

[TeamG]

To complete the thread, the front discs and pads were similar with a few distinct differences. First job, on the trolley jack. I’ve got a 3 tonne SGS trolley jack with a bit more lift for SUVs, which is perfect albeit very heavy. I’ve got an ice hockey puck with an 8mm slot cut in it that I use to cover the jacking points and avoid any damage.

Next, off with the T50 disc retaining screw, then a pair of mole grips to remove the spring. Next the two plastic caps on the caliper pins and the 11mm hex (that I bought especially for this) to remove the pins.

[TeamG]

Remove about 50ml of brake fluid from the reservoir before you push the pads back, then use a clamp on the one brake pad to return the piston (the piston is hollow, so you’d have to push on the rim if you remove the pad) and then remove both pads. The one on the piston side has a stiff spring clip to remove. The carrier bolts are a bastard to remove. 18mm, so an odd socket size that I didn’t have, otherwise I’d have used an impact wrench to get them off. A pair of ring spanner’s (18mm and 19mm) for leverage and got the swines off. Cleaning the threads on the bolts and carriers made them easier to get back on. Smack the disc with a mallet to loosen it off the hub, then remove the lot.