[Jon TDI]

I’m due to replace the front discs at some point this year, and I have the blue M Sport (Brembo) calipers with the M Sport 340mm discs.
This has probably been asked before but will the 370mm discs fit without changing anything else?
I run 19” wheels (both summer & winters) so I know they will fit over 370mm discs.
However (& I think I know the answer) but will the discs fit the caliper spacing or will it need new caliper carriers?

I really do like the look of Vagbremtechnic discs:-
https://performancem.co.uk/choose-yo...msport-brakes/

[danb1979]

No

The 340mm calipers will only take the 340mm discs

You need the 370/380mm calipers to up the disc size

Re wheels - every 18" wheel for the F3x range fits over the 370/345mm brakes. So your 19s won't have any issues

[Jon TDI]

Originally Posted by danb1979

No

The 340mm calipers will only take the 340mm discs

You need the 370/380mm calipers to up the disc size

Re wheels - every 18" wheel for the F3x range fits over the 370/345mm brakes. So your 19s won't have any issues

As I suspected. Just wanted to check

[danb1979]

Originally Posted by Jon TDI

As I suspected. Just wanted to check

No worries

You could always go for something like these:

https://www.darksidedevelopments.co....&isp_ref_pos=3

I run the dimpled/slotted OEM BMW discs on my F31 with the 370/345mm brake set up and find them to be very good indeed (OEM pads also)

Just wish I'd seen this time last year when I was getting them all together that the M3/M4 pads were a decent upgrade if sticking with OEM BMW etc

Would a full upgrade to the 370mm calipers be an option?

[Jon TDI]

Originally Posted by danb1979

No worries

You could always go for something like these:

https://www.darksidedevelopments.co....&isp_ref_pos=3

I run the dimpled/slotted OEM BMW discs on my F31 with the 370/345mm brake set up and find them to be very good indeed (OEM pads also)

Just wish I'd seen this time last year when I was getting them all together that the M3/M4 pads were a decent upgrade if sticking with OEM BMW etc

Would a full upgrade to the 370mm calipers be an option?

I’ll have a look at the Darkside stuff. This maybe an option.

Full 370mm upgrade may well blow the budget if new calipers are required. Plus there is nothing wrong with the current calipers. Just discs & pads for now.

[ade555]

I honestly don't see any benefit of having drilled /groved disks for daily driving.

[Jon TDI]

Originally Posted by ade555

I honestly don't see any benefit of having drilled /groved disks for daily driving.

I can see your point but the same can be said for having a hot hatch for a daily driver.
A mind numbing bland hatchback would do the same job…….but what’s the fun in that?

[danb1979]

Originally Posted by Jon TDI

I can see your point but the same can be said for having a hot hatch for a daily driver.
A mind numbing bland hatchback would do the same job…….but what’s the fun in that?

Drilled discs I get; but dimpled/grooved are spot o for road use; never had any issues at all

And IMO; they look good with the blue Brembo brakes and aid in keeping the pad faces that bit less glazed than they can do with blank discs etc

[Jon TDI]

Originally Posted by danb1979

Drilled discs I get; but dimpled/grooved are spot o for road use; never had any issues at all

And IMO; they look good with the blue Brembo brakes and aid in keeping the pad faces that bit less glazed than they can do with blank discs etc

I’ve never liked drilled discs ever since I had an incident with them on my Corrado many moons ago.
They took a hammering during a track day session at Donnigton.
Brakes felt really rough after that & after inspection, they had started to crack in a few areas from the drilled holes.

Never bought drilled discs after that.
Dimpled or grooved are fine though.

[Ennoch]

Originally Posted by ade555

I honestly don't see any benefit of having drilled /groved disks for daily driving.

Yep, agreed. Some love them but my experience for a daily is that they get corrosion creeping in under the braking surface more easily, make more noise, and wear pads more rapidly. Any slight benefits are offset by those downsides, or at least they are to me.

[blau3er]

You could buy some adapters that allow the 340mm calipers to work with the full fat 380mm ///M discs from the F8x cars.

[Jon TDI]

Originally Posted by blau3er

You could buy some adapters that allow the 340mm calipers to work with the full fat 380mm ///M discs from the F8x cars.

Again, that would blow the budget replacing the discs & pads.

[TurboWeasel]

Originally Posted by Jon TDI

I’ve never liked drilled discs ever since I had an incident with them on my Corrado many moons ago.
They took a hammering during a track day session at Donnigton.
Brakes felt really rough after that & after inspection, they had started to crack in a few areas from the drilled holes.

Never bought drilled discs after that.
Dimpled or grooved are fine though.

Funnily enough, I ran them on my old Corrado as well and binned them off not long after fitment. Cheap old Zimmerman ones though, so probably not a surprise they were rubbish. They started cracking just from normal road use.

Drilling holes in a large metal disc that is subjected to 1000s of heat cycles is a dumb idea as it just creates loads of stress risers. Even the Porsche ones - which allegedly have cast holes - crack.

OEM drilled/cast holed rotors last considerably longer than aftermarket ones though to be fair.

[Jon TDI]

Originally Posted by TurboWeasel

Funnily enough, I ran them on my old Corrado as well and binned them off not long after fitment. Cheap old Zimmerman ones though, so probably not a surprise they were rubbish. They started cracking just from normal road use.

Drilling holes in a large metal disc that is subjected to 1000s of heat cycles is a dumb idea as it just creates loads of stress risers. Even the Porsche ones - which allegedly have cast holes - crack.

OEM drilled/cast holed rotors last considerably longer than aftermarket ones though to be fair.

Yep mine were Zimmerman discs!

[danb1979]

Originally Posted by TurboWeasel

Drilling holes in a large metal disc that is subjected to 1000s of heat cycles is a dumb idea as it just creates loads of stress risers. Even the Porsche ones - which allegedly have cast holes - crack.

Watched this happen live on Anglesey Circuit many moons ago; watching a Porsche fly round and then a loud pop/bang and limped back to the pits with the front brakes literally in pieces

Crazy really and it seems that Porsche love to use them on their cars...!

I've never had any issues running dimpled/grooved discs on many cars; some J hook discs are good too (they're a lot louder than grooved discs IMO)

But drilled discs are just not required due to the above

The OEM BMW discs & pads I run are very quiet indeed; never once have I thought them to be loud. You only really hear them if you're driving in a built up area/past fences at low speeds and even then it's more of a light clicking...

Nor are there any issues with corrosion, whatsoever...

[blau3er]

Originally Posted by Jon TDI

Again, that would blow the budget replacing the discs & pads.

You best stick to the 340mm then!

[sensible]

Mine is a 420i GC M-Sport with M-Sport brakes. Will mine be the 340mm too?

[danb1979]

Originally Posted by sensible

Mine is a 420i GC M-Sport with M-Sport brakes. Will mine be the 340mm too?

Not necessarily; could be the 370/345mm

Best way to check is take the wheel off and look on the back of the caliper; it'll say 340 or 370/380

You'll know which brakes you have then...

My F31 325D has the 370/345mm brakes - it's all down to what was spec'd from factory etc

[sensible]

Originally Posted by danb1979

Not necessarily; could be the 370/345mm

Best way to check is take the wheel off and look on the back of the caliper; it'll say 340 or 370/380

You'll know which brakes you have then...

My F31 325D has the 370/345mm brakes - it's all down to what was spec'd from factory etc

Thanks. I am taking my winter wheels/tyres off this Sunday, so will have look then.

[blau3er]

20i will 100% be 340mm.

Front caliper size is directly linked to the engine variant.

In the case of M Sport brakes

20d and below get 340mm
20i and below get 340mm

25d and above get 370mm
28i and above get 370mm

30e gets 340mm

[danb1979]

Originally Posted by blau3er

20i will 100% be 340mm.

Front caliper size is directly linked to the engine variant.

In the case of M Sport brakes

20d and below get 340mm
20i and below get 340mm

25d and above get 370mm
28i and above get 370mm

30e gets 340mm

Never knew that! Thanks

[Jon TDI]

Originally Posted by blau3er

20i will 100% be 340mm.

Front caliper size is directly linked to the engine variant.

In the case of M Sport brakes

20d and below get 340mm
20i and below get 340mm

25d and above get 370mm
28i and above get 370mm

30e gets 340mm

And 35d?