M4 Front Brake Caliper Retrofit

[Nictrix]

With the calipers from the M4 and as said normally a 380mm disc, what pads are used with the 370mm disc?
Or do the pads hang off the edge of the disc?

When I looked on realoem there were two different part numbers for the M4 pad and the 440i pad at first however closer inspection showed that one supersedes the other and there's other part numbers that supersede that. In terms of size and shape, they are both the same though and both correlate to the same numbers from manufactures such as TRW and Brembo.

Just in my head if the pads are attached to the caliper and they are made for 380mm discs when you go down to 370mm discs surely there will be 5mm of pad hanging over the edge of the disc.

 

[john-e89]

Very interesting read on the M3 parts Player...something I’ll definately be doing.

I also wondered about using the line lock from PB brakes for fitting the whole M4 brake kit if the rears will fit too.

Good to hear! If you do it and any questions pop up, just give me a shout and I'll be happy to help

I did look into the rear brakes and I don't think there's anything that's going to swap over from other cars without fabricating adaptor brackets. If it wasn't for the electric handbrake it'd be a lot easier!

Are you on standard springs and adaptive shocks Player? I don’t really want mine lowered and want to keep the ride comfort, but at the same time take out some of the ‘jelliness’ and tighten it up as much as possible. Sounds like you’re of a similar thinking no?

 

[Nictrix]

With the calipers from the M4 and as said normally a 380mm disc, what pads are used with the 370mm disc?
Or do the pads hang off the edge of the disc?

When I looked on realoem there were two different part numbers for the M4 pad and the 440i pad at first however closer inspection showed that one supersedes the other and there's other part numbers that supersede that. In terms of size and shape, they are both the same though and both correlate to the same numbers from manufactures such as TRW and Brembo.

Just in my head if the pads are attached to the caliper and they are made for 380mm discs when you go down to 370mm discs surely there will be 5mm of pad hanging over the edge of the disc.

Nobody have any opinions on this?
If I am right, after these have been fitted for thousands of miles the overhanging pad will eventually come into contact with the overhanging pad on the other side of the disc and then you will have no brakes.

 

[john-e89]

5mm could be neatly ground off the outside pad edge if need be, no different to them being worn down.

 

[Nictrix]

5mm could be neatly ground off the outside pad edge if need be, no different to them being worn down.

Yep thats fair enough. This could be done but has it? They could also be ground down later if they are getting close to contact but this would need to be remembered.
It does beg the question though, why not just use 440 calipers that are made for 370mm discs.
They look the same to me, are there any performance differences?

 

[john-e89]

5mm could be neatly ground off the outside pad edge if need be, no different to them being worn down.

Yep thats fair enough. This could be done but has it? They could also be ground down later if they are getting close to contact but this would need to be remembered.
It does beg the question though, why not just use 440 calipers that are made for 370mm discs.
They look the same to me, are there any performance differences?

You should be able to yes, it’s just in Players case he had calipers off an M4 so used the part number for those.

 

[Player 1]

5mm could be neatly ground off the outside pad edge if need be, no different to them being worn down.

Yep thats fair enough. This could be done but has it? They could also be ground down later if they are getting close to contact but this would need to be remembered.
It does beg the question though, why not just use 440 calipers that are made for 370mm discs.
They look the same to me, are there any performance differences?

I'm not really sure what else to say other than they don't overlap the disc?
I've just gone to take a look and there's definitely no overlap, I couldn't get the camera to focus between the wheel and caliper but could feel where the pad meets disc and did take a photo of the disc itself and as you can see there's a line just at the edge of the disc where the pads end.

EDIT: Thinking about this some more, I imagine the difference between the M cars and standard isn't in the caliper or pad but in the wheel carrier and how it mounts the caliper further away from the centre point of the wheel.

 

[Player 1]

Are you on standard springs and adaptive shocks Player? I don’t really want mine lowered and want to keep the ride comfort, but at the same time take out some of the ‘jelliness’ and tighten it up as much as possible. Sounds like you’re of a similar thinking no?

I'm on standard springs and passive dampers. I completely agree with you re lowering, been there, done that and it's more hassle than it's worth! :lol:
I fitted the anti roll bars before the M3 bits, they do exactly what they say on the tin and really help with confidence more than anything. They have a minor effect on the ride over really bad surfaces but 99% of the time you won't tell.
The M3 suspension bits have no noticeable impact on ride quality at all, if anything it's better because you've just replaced worn bushes with new.

 

[Nictrix]

5mm could be neatly ground off the outside pad edge if need be, no different to them being worn down.

Yep thats fair enough. This could be done but has it? They could also be ground down later if they are getting close to contact but this would need to be remembered.
It does beg the question though, why not just use 440 calipers that are made for 370mm discs.
They look the same to me, are there any performance differences?

I'm not really sure what else to say other than they don't overlap the disc?
I've just gone to take a look and there's definitely no overlap, I couldn't get the camera to focus between the wheel and caliper but could feel where the pad meets disc and did take a photo of the disc itself and as you can see there's a line just at the edge of the disc where the pads end.

EDIT: Thinking about this some more, I imagine the difference between the M cars and standard isn't in the caliper or pad but in the wheel carrier and how it mounts the caliper further away from the centre point of the wheel.

Cool. You could be right if the calipers are definately the same. I would imagine then that the 380mm discs might have fitted if the carrier was changed as well.
I only pointed this out as I wouldnt have wanted anybody to fit something that could possibly have turned out to be dangerous.

 

[Player 1]

For sure Nictrix, now I've got a couple hundred miles on them I'm pleased to say these have worked really well indeed.
The pedal feel is much more reminiscent of the 911`s and Boxster's I've driven and are a step up in terms of outright capability over the old brakes which themselves weren't bad.

 

[MrPT]

The pedal feel is much more reminiscent of the 911`s and Boxster's I've driven and are a step up in terms of outright capability over the old brakes which themselves weren't bad.

That is exactly what I ended up telling people when I switched to multi-pot fronts. No massive difference in braking force, but the feeling of more stability under braking through the ball of your foot. Porsche brakes seem to be less servo assisted, in general, which isn’t for everybody but is more in keeping with the idea of a sports car.

Pedal was a bit firmer too, but since I changed pads, hoses and re-bled at the same time I switched callipers, I can’t rule out that being due to other factors.

Just be wary of any changes to front/rear braking bias. If you are unable to figure out where you should be on paper (total piston area before/after will give you a rough idea) then a track day or some covert heavy braking will give you a clue!

 

[Player 1]

The pedal feel is much more reminiscent of the 911`s and Boxster's I've driven and are a step up in terms of outright capability over the old brakes which themselves weren't bad.

That is exactly what I ended up telling people when I switched to multi-pot fronts. No massive difference in braking force, but the feeling of more stability under braking through the ball of your foot. Porsche brakes seem to be less servo assisted, in general, which isn’t for everybody but is more in keeping with the idea of a sports car.

Pedal was a bit firmer too, but since I changed pads, hoses and re-bled at the same time I switched callipers, I can’t rule out that being due to other factors.

Just be wary of any changes to front/rear braking bias. If you are unable to figure out where you should be on paper (total piston area before/after will give you a rough idea) then a track day or some covert heavy braking will give you a clue!

Yep, that's pretty much nailed it. During normal driving I'm finding I'm having to use a lot less effort to achieve the same braking as beforehand yet the firmer pedal makes it easier to modulate too. As you say, the latter part may be subjective and that feeling might not be for everyone!
For what it's worth, I kept the standard hoses and stuck with TRW for pads as that's what I had the last time, no complaints thus far.

Messing with the brake bias was a concern for sure however as yet all seems well and I've not seen or heard anything negative from those in the states who have done this same swap either.

 

[Player 1]

When researching I when on realoem and took part numbers off of a 2016 440i. I don't think it matters what year as long as its the 370mm discs however I can attest that 2016 works.
Likewise, any year M4 or F series M3 for the calipers, I believe the are the same calipers on the 440i however the particular ones I got hold of were from an M4 so used M4 part numbers for the pads.

I'll get in contact with some of the parts suppliers and see how much I can get them to cut prices down by too

Thanks for your effort in this, some prices and lists of the correct parts to get would be great.

Cheers

I've figured out a kit price now and shall PM you shortly with details

If anyone else is interested too, it could potentially be worth getting a group buy going

 

[Jollyjoiner]

When researching I when on realoem and took part numbers off of a 2016 440i. I don't think it matters what year as long as its the 370mm discs however I can attest that 2016 works.
Likewise, any year M4 or F series M3 for the calipers, I believe the are the same calipers on the 440i however the particular ones I got hold of were from an M4 so used M4 part numbers for the pads.

I'll get in contact with some of the parts suppliers and see how much I can get them to cut prices down by too

Thanks for your effort in this, some prices and lists of the correct parts to get would be great.

Cheers

I've figured out a kit price now and shall PM you shortly with details

If anyone else is interested too, it could potentially be worth getting a group buy going

Thanks player I'll take a look