F10 520d brake disc replacement - how many miles?

[Calypso-E34]

My 520d is coming up to 48000 miles now, and is still on its original brake discs.  OBC says I will need to replace the front pad soon - in 4400 miles - and the rear pads in 20000 miles.  Can anyone tell me roughly when I will need to look at replacing the discs?  Everything seems to be working fine, and I'm not hard on brakes generally.

[Steve84N]

Forget the onboard computer and go and look at the discs & pads. 

Discs can have a small lip but if it's anywhere near 1mm deep then they're due for replacement.

Pads should trigger a warning when the wear sensor burns through. Try and eyeball the remaining thickness, although bear in mind the inside pads may be thinner than the outside (visible) ones. If they are down to 3mm or less get organised to replace them. 

If you're light on brakes you may have some time yet, but if you're near the above limits it's time to think about it. 

Edited October 11, 2023 by Steve84N

[Calypso-E34]

21 minutes ago, Steve84N said:

Forget the onboard computer and go and look at the discs & pads. 

Discs can have a small lip but if it's anywhere near 1mm deep then they're due for replacement.

 

There's a lip on the fronts, and yes, I'd say about 1mm or close. Rears have no lip at all.

[Steve84N]

What do the pads look like, can you take a picture through the wheel spokes? 

[Calypso-E34]

Just now, Steve84N said:

What do the pads look like, can you take a picture through the wheel spokes? 

I can't really see them, but the wear indicator must be still intact or I'm sure the car would tell me!  Car will be due to go for its MOT and an oil change mid January, so I'm hoping to get away with it until then.  I'm averaging 550 ish miles per month at the moment.

[Steve84N]

Sounds like you might be OK until then but expect to replace discs with the pads. 

[Andrew]

Rear pads wear out after 30-35k. Mine are due a second set of rear pads but will also need discs too.

I got 48k out of front discs and pads, inboard front pads were more worn than the outside visible ones. 
 

At 62k my rears are on my to do list but after 14k miles the front discs are still like new with no lip. 

[Calypso-E34]

So the consensus seems to be that the front discs and pads wear at about the same rate - meaning you have to replace both every time?  Still - I suppose almost 50000 miles is not too bad  

My tears look brand new still. 

[Steve84N]

My rear discs are a mess on the inside where the caliper isn't sliding smoothly. In other words, it pays to inspect the inside too. 

[dj123]

Get yourself a micrometer to check the disc thickness. Then you know if the next replacement is disc & pads, or pads only. Most set ups these days will be a 2 x pad replacements to 1 disc replacement. Of course, this will depend on how hard you are on the Brakes, how often TCS/ESP activates, brakes wearing evenly etc. 

[Calypso-E34]

I’ll budget for discs and pads in January I think. 
 

4 new tyres next week. Fairly even wear front and rear.  Not quite on the wear indicators, but they feel pretty shabby now. 

[Andrew]

Remember on this chassis the cruise uses the rear brakes to slow the car down when you manually adjust (slow) the speed down using the cruise control buttons.

You can feel it’s backside drop when doing this rather than it’s nose. 

If you use cruise lots the rears will wear out sooner than you think. 

[Calypso-E34]

18 minutes ago, Andrew said:

If you use cruise lots the rears will wear out sooner than you think. 

On my once a year trip from Inverness to Dublin!

[Steve84N]

1 hour ago, Andrew said:

Remember on this chassis the cruise uses the rear brakes to slow the car down. 

That's my something new learnt for today. Makes sense now you mention it, in terms of how it feels. I use cruise a lot on the motorway but rarely decrease speed, usually just deactivate it in time to coast down where necessary. Gives me something to do when sat there bored, still concentrating on traffic. 

It's annoying that the limit function doesn't use the brakes, my C63 did and it was so handy to know you wouldn't sneak over 30mph in town on a downhill. That car also had monumental engine braking so the brakes lasted ages. 

[Matthew]

You can't tell whether the discs need changing by feeling for a lip on the disc. It may give you a vague idea but the only way to make the safe and accurate decision is by measuring the thickness of the disc (or just paying for new discs and pads of course)

The front discs on your 520d are probably 330 x 24.

     If the measured thickness is no less than 22.4mm (24mm - 1.6mm) then you can just change the pads. 
     If the measured thickness is 21.6mm or less (24mm - 2.4mm) then you must change the discs and pads.

The rears are 330 x 20 and the same calculation applies so up to -1.6mm = change pads only; Over -2.4mm = change pads and discs.

[Steve84N]

Technically that's correct. However, in practice if it's already notably lipped and I'm doing pads I'd change the discs because the disc won't last the life of another set of pads and you'd then need another set of pads with the new discs. 

Also, in my experience the disc gets quite shabby and worn before the full wear limit anyway if you're not hard on brakes and they're on for a long time. 

Edited October 11, 2023 by Steve84N

[Andrew]

If you do measure the discs make sure you have the means of measuring around any lip on the disc.

As I don’t have the brake disc measuring calipers I used a normal one with two thick washers either side of the disc and zero’d the caliper so it only measured the disc

The lip was quite pronounced (made worse by the disc corrosion around its perimeter) but given the above reading technically I could have just put new pads on. 
 

Easy DIY, 7mm Allen key for caliper slide bolts on an 520d, torque to 35Nm, 

 

[Cadwell Parker]

It all depends on usage. My car cruises on A roads most of the time and does a lot more mileage than braking. The Brembo discs and pads I replaced earlier this year had covered 89000 miles. There was still plenty left on the pads but I got an MOT advisory for worn front discs (but not excessively) so I had them all replaced. I figured I'd had my moneys worth out of them by then.

[Matthew]

On 11/10/2023 at 23:03, Steve84N said:

Technically that's correct. However, in practice if it's already notably lipped and I'm doing pads I'd change the discs because the disc won't last the life of another set of pads and you'd then need another set of pads with the new discs.
 

Yes, that’s why there are 2 measurements, at -1.6mm the discs will go the distance with a new set of pads only. I won’t waste money on new discs if there’s no need, the measuring rather feel has always worked well.

 

[canman]

Rule of thumb is 2 sets of pads to a pair if discs but that also depends on driving style and usage and type of roads car used on 

[Calypso-E34]

So - a wee update on this.  Car is now on almost 55000 miles on the original front discs.  There's a bit of a lip on them, and I will be travelling 4 up to Ireland next month, so I've chickened out and booked the car in for front discs and pads.  OBC is saying I have 3100 miles to go, but it's been saying that for three months.

[Andrew]

That's not bad mileage, I was just shy of 50k miles when I needed pads and discs.

What pads and discs are you going for?

 

[Kopfjaeger]

Whose discs are recommended for F10/F07? If you want to avoid Dealer mark-ups, but not conpromise on quality? Thanks.

[Andrew]

25 minutes ago, Kopfjaeger said:

Whose discs are recommended for F10/F07? If you want to avoid Dealer mark-ups, but not conpromise on quality? Thanks.

The genuine discs are actually quite good quality and can be bought for less than you think, even more so if you have a good relationship with your local parts dealer or Cotswolds although postage will bump up as they are heavy. I paid ~£360 for my genuine front brakes back in 2019. £120 for each disc and £120 for the pads and wear sensor.

The genuine discs have no manufacturers markings so we suspect that they are actually made by BMW themselves. The pads however on the F10 are Galfer at the front and Textar at the rear.  

When I've gone aftermarket I've used ATE and febi for discs. Wifes Kuga has febi front discs and pads and are terrific so they are going on my rear axle when it stops raining and I've fixed my water pump.

[Calypso-E34]

5 hours ago, Andrew said:

 

What pads and discs are you going for?

 

Textar I think they said - something like that anyway! OEM quality. The choice was these, OEM or budget.