[Flying_Squad]

Originally Posted by addy27

One thing im unable to locate is the spec sheet for the E60 M5 rear brakes (which are also 370x24) but the hat geometry is what I dont know of, or the width of the face that contacts the brake pads. Zimmerman might have it but no one else shows the dimensions (Since brembo it seems did not make them for BMW, VNE did)

UPDATE: Yeah those won't fit either and neither would the E65 ones:
https://shop.peninsulabm.com/product...e-rear-e65-e66

Thanks for checking this avenue too Addy.

[DT_10]

Ok sounds good, thank you for taking the time to do that !

Just curious how you came up with those rankings, they all seem so close in % and brake torque.

[Unspec]

Originally Posted by Blue Angel

DT_10, if you go with the F01 760 rotors + G11 calipers in front your braking torque will increase by (392/381)= 3% and your balance will shift from 64/36 to 65/35. Total braking torque will increase by (605/593)= 2%

This assumes the same brake pad coefficient of friction front and rear.

Four piston G11 calipers have slightly less effective piston area (40mm+44mm) than the single piston (60mm) calipers used on F10 and F01 models. It's only a 1.8% decrease, but it diminishes the 4.8% increase in rotor effective diameter.

Wouldn't a more proper comparison for piston area be with G11 calipers at 40+40+44+44, and given that the single piston is a floating caliper, the single piston surface clamping is more like 60mm + whatever the floating "fingers" surface area is

[DT_10]

That was my understanding as well. I was under the impression that bias would be fairly dramatically shifted forward with a mod like this. I also thought fluid had something to do with it, as you can get proportioning valves to adjust bias (via fluid). You usually wouldnt have that on a street car, it just gave me the idea that fluid or fluid capacity of a caliper had something to do with it.

But my understanding is limited at this point, more learning to do.

Unspec I'm going to be running the same wheels as you as well. I see you mentioned possibly machining that corner on the caliper for wheel clearance. What was your thought on how to go about that exactly ? Just sort of taking that corner off at a 45 or ? I would be open to doing it, but would still want it to look close to factory after its painted.

And with that 8mm (i think it was) spacer youre running, hows the fit ? any rubbing etc ? I also see youre running taller tires, I was able to grab the size off the photos for the rear, but what size are you running in front ? Potholes are bad where I live, and having more tire for rim protection would definitely be a plus.

Last thing, has anyone been able to source a 760 rotor thats drilled ? I really want the subtle look the zimmermanns offer, but would prefer not to trim the pads.

[DT_10]

Is there any reason E60 M5 rotors wont work with the G30 caliper ? They are are 374x36mm, drilled, and a 2 piece which is nice from a weight perspective. Im assuming the main issues will be hat size and offset ?

I saw these brought up earlier in the thread but it doesn't look like anyone's attempted to use these rotors.

[Blue Angel]

Pressurized fluid exerts an even amount of force per unit area. The more area you have, the more force for a given fluid pressure. The larger area of the 60mm piston calipers versus the slightly smaller area of the G11 callipers does reduce their clamping force slightly, but not much.

Opposing pistons do not offer any more clamping force than single pistons in sliding calipers. Well, maybe a small advantage if you consider the friction from the sliding pins in the sliding calipers, but this is going to be very slight.

Assumptions:

1. No break biasing valves. A car company wouldn't bother with brake biasing valves when they could just use larger or smaller pistons in the rear callipers. Look at the 42 mm pistons in the X5M rear callipers, for example, compared to the 44mm pistons in the F car rear calipers.

2. Pistons in the middle of the brake pads. I am assuming the pistons are acting directly in the middle of the brake pads, and the brake pads effective area is centred on the middle of the braking surface of the rotor. I'm basing this on drawings of brake pads and their spring clips I found on the Brembo website. If I'm off it can't be by much, so I'm assuming directly in the middle for all to keep it consistent.

3. The same brake pad material front and rear. This means an equal coefficient of friction between the rotor and the pad front to rear.

I put this together out of curiosity, and to be honest I was surprised at the results when I saw them. After thinking about it though, it makes perfect sense. All of the factory brake setups are within a couple percent of each other. There's only about 10% difference in braking torque from the smallest to the largest setup.

The real difference is in thermal capacity, as in how many times you can stop from speed before overheating the brakes. The larger rotors in the bigger systems have far more thermal capacity and could handle repeated stops or stops from higher speeds much better than the smaller systems could.

[Blue Angel]

I should add that the M5 is the only F10 with a unique master cylinder. If I had to guess, I would say it's probably got a higher displacement due to having front callipers with larger pistons, but that really is just a guess given the rear callipers have a 44 mm pistons just like the regular F car brakes do.

The M5 rotor sizes are almost the same front to rear (a constraint based on wheel size?), so it could be necessary for more piston area in the front callipers to maintain enough braking torque advantage in the front. Once again, this is just a complete guess since I have no idea what the piston sizes are in those calipers. If someone can find out I will gladly add the M5 braking system to the chart!

[Unspec]

Originally Posted by DT_10

That was my understanding as well. I was under the impression that bias would be fairly dramatically shifted forward with a mod like this. I also thought fluid had something to do with it, as you can get proportioning valves to adjust bias (via fluid). You usually wouldnt have that on a street car, it just gave me the idea that fluid or fluid capacity of a caliper had something to do with it.

But my understanding is limited at this point, more learning to do.

Unspec I'm going to be running the same wheels as you as well. I see you mentioned possibly machining that corner on the caliper for wheel clearance. What was your thought on how to go about that exactly ? Just sort of taking that corner off at a 45 or ? I would be open to doing it, but would still want it to look close to factory after its painted.

And with that 8mm (i think it was) spacer youre running, hows the fit ? any rubbing etc ? I also see youre running taller tires, I was able to grab the size off the photos for the rear, but what size are you running in front ? Potholes are bad where I live, and having more tire for rim protection would definitely be a plus.

Last thing, has anyone been able to source a 760 rotor thats drilled ? I really want the subtle look the zimmermanns offer, but would prefer not to trim the pads.

For machining, it's more of a speculative thing and it is a spitball idea, I have not nor do I know of anyone who has tried it. I would machine it back 2-3mm, and even then I am unsure if that is enough to let you get away with 3mm or no spacers. In my head, I would just take a file and file it back at a 45 degree angle, and then bevel/round off the corners to give it a OE like finish.

No rubbing issues with the 7.5mm spacer. I am running 245/40/20 F and 275/35/20 R. I don't have rubbing issues, but I also have more front camber than factory spec since I am lowered on KW v3's.

Also, for drilled rotors, my recommendation is to find dimpled rotors. Offer similar off gassing benefits, without compromising the structural integrity of the rotor as much.

[Blue Angel]

Here's my 408m with the G11 caliper, NO SPACERS. They clear with about 1mm to spare. Unspec, is this about what you saw with your 343m as well?

So with 4-5mm spacers on the caliper I would plan to machine about a 5.5mm (7/32) x 45 degree chamfer if you don't plan to use wheel spacers. From what I can see on the caliper this should be ok, but as usual "do at your own risk".

BTW, I have no doubt there are 18" wheels that will clear these calipers, there's tons of room on these 19s and the caliper seems shaped specifically to clear smaller wheels.

[Unspec]

Originally Posted by Blue Angel

Here's my 408m with the G11 caliper, NO SPACERS. They clear with about 1mm to spare. Unspec, is this about what you saw with your 343m as well?

So with 4-5mm spacers on the caliper I would plan to machine about a 5.5mm (7/32) x 45 degree chamfer if you don't plan to use wheel spacers. From what I can see on the caliper this should be ok, but as usual "do at your own risk".

BTW, I have no doubt there are 18" wheels that will clear these calipers, there's tons of room on these 19s and the caliper seems shaped specifically to clear smaller wheels.

Yup, pretty much what I saw with the 343M's. Me and spielnicht played around with spacers. 10mm will work but if you're lowered can cause poke, and we are both currently running the 7.5mm spacers with VAC hub extenders.

[Nenad4884]

Hi everyone,

So, i did manage to find time and do a retrofit to G calipers.

As u can See on first pic, clerance is measured in 0.0xx mm, I'm not sure if i have 1 mm space between Rim - caliper. 9x20 et15

On the other Hand, my 19" fıt perfect ( m351).

I did looked how can i get more space to fit my 20" Rim, and only answer is New Rim with another et specs.

Yes, m409 would be also a fit, but I'm just trying to fit my wheels what i already have

Any Suggestions?

[Blue Angel]

409m wheels likely have a spoke profile the same as the 343m (tested by Unspec) and the 408m (tested by me above). They are all wheels made specifically for the F10 M5, the 408m and 409m specifically as winter wheels.

The 343m and 408m will not clear the medium size (374x36) G11 caliper. I'm looking into machining the caliper, but this is not something to take lightly and is a "do at your own risk" option.

[Nenad4884]

Originally Posted by Blue Angel

409m wheels likely have a spoke profile the same as the 343m (tested by Unspec) and the 408m (tested by me above). They are all wheels made specifically for the F10 M5, the 408m and 409m specifically as winter wheels.

The 343m and 408m will not clear the medium size (374x36) G11 caliper. I'm looking into machining the caliper, but this is not something to take lightly and is a "do at your own risk" option.

Hi,

I did forgot, yesterday i purchased extra 3mm plates to clear the wheel but as u can assume, Rim will poke more Further out.

Maschining the caliper is not an Option for me, just to scare to take that risk.

With M351 19" Looks good, at least Safe.

Here is few more Angles from my 20" Rim, the wheel itself Spins with no problem but clerance is a Pain to see.

I did think about another et spec with the Same Rim but, I'm affraid that my only Option is 3mm plates between rim/caliper 😔

[Nenad4884]

Originally Posted by Blue Angel

409m wheels likely have a spoke profile the same as the 343m (tested by Unspec) and the 408m (tested by me above). They are all wheels made specifically for the F10 M5, the 408m and 409m specifically as winter wheels.

The 343m and 408m will not clear the medium size (374x36) G11 caliper. I'm looking into machining the caliper, but this is not something to take lightly and is a "do at your own risk" option.

M408 / M409 both are/have et25 Front and et32 rear, they are more concave and I'm 99% sure they will fit ( my 351m is et33 Front and fit no problem with clerance, Look Above).

You have right about wheel Design itself ( spoke Profile), on my 20" as u can See Above Design is "straight" no curve spoke at all, that's missing to clear the Rim and even if i buy the Same wheel with another et spec ( for example et25), It doesn't solve my problem.

I did saw Unspec post with m343 Rim, he have more clerance ( i have like, 0.0xx mm) but still, too little, thats why I think that M408/M409 will clear the wheel. 🙃

[Unspec]

I have M343 but I had to use a 7.5mm spacer to get that clearance. I think a clearance of less than 1mm is playing it a bit close, I personally would not be comfortable with that kind of clearance.

[Nenad4884]

Originally Posted by Unspec

I have M343 but I had to use a 7.5mm spacer to get that clearance. I think a clearance of less than 1mm is playing it a bit close, I personally would not be comfortable with that kind of clearance.

Hi,

I agree, that's why i'm staying on my 19" m351, safety first no matter.

Will put clearance plates tommorow (3 mm) and See how it looks tho I'm sure it will poke like crazy...

I did looked a little how to get more clearance without putting extra spacers but, sadly there's not much to do except buying a New Set of 20"s.

My brakes are better, main reason why i did this retrofit, cooler Looks too, but i didn't pay enough attention on my spoke Profile as i thought "perfect fit" 🙄, now i know not every 20" will fit 😄 cool right 😄

[Blue Angel]

OK, so I found the M5 front caliper piston sizes (30, 34, 36mm) and the brake rotor info from some assumptions made based on info from this page:

https://racingbrake.com/2472/

This is a steel replacement for the 410mm front ceramic rotor, but they state on the technical drawing to use the iron brake pads which are 77mm deep. This would give us a 400mm disc with a (400 - (2 x 77mm)) = 265mm ID for the braking surface. This isn't far off the other F10 braking systems so I'm going with it.

The rear M5 brakes us the same caliper and pad as the 550, just on a 396mm rotor, so I just scaled up the 550 system to 396mm.

NOTE: This chart is for US spec cars. EU spec F10s often have larger braking systems than the US cars.



Note the M5 system has the highest rear brake bias (37.1%) of all the OEM F10 braking systems. Rear brakes on most passenger cars are set up from the factory to favor understeer (front losing traction first) since it's considered safer. The M5 is set up for a more performance oriented balance and takes advantage of added rear brake torque.

The M5 has less front caliper piston area than any other option for the F10 (6.9% less than 60mm F10 calipers, and 5.2% less than the medium 40/44mm G11 caliper). It creates its braking torque advantage through its huge front discs. It uses a bespoke master cylinder, and I now wonder if it's because it requires less displacement? Not entirely sure what the difference is to the standard F10 master cylinder now...

The M5 uses the same 44mm rear caliper piston size as the rest of the F10 lineup, but pairs that with huge 396mm discs to increase rear braking torque and maintain the desired F/R bias given its front brakes.

Here's a graph showing the total braking torque of all the different models and swap upgrade options. Again, this assumes the same brake line pressure and brake pad coefficient of friction for all systems.

[Nenad4884]

Originally Posted by Blue Angel

OK, so I found the M5 front caliper piston sizes (30, 34, 36mm) and the brake rotor info from some assumptions made based on info from this page:

https://racingbrake.com/2472/" rel="nofollow" target="_blank">http://<a href="https://racingbrake.....com/2472/</a>

This is a steel replacement for the 410mm front ceramic rotor, but they state on the technical drawing to use the iron brake pads which are 77mm deep. This would give us a 400mm disc with a (400 - (2 x 77mm)) = 265mm ID for the braking surface. This isn't far off the other F10 braking systems so I'm going with it.

The rear M5 brakes us the same caliper and pad as the 550, just on a 396mm rotor, so I just scaled up the 550 system to 396mm.

NOTE: This chart is for US spec cars. EU spec F10s often have larger braking systems than the US cars.

"]https://flic.kr/p/2naLBzt][/url][/URL]

Note the M5 system has the highest rear brake bias (37.1%) of all the OEM F10 braking systems. Rear brakes on most passenger cars are set up from the factory to favor understeer (front losing traction first) since it's considered safer. The M5 is set up for a more performance oriented balance and takes advantage of added rear brake torque.

The M5 has less front caliper piston area than any other option for the F10 (6.9% less than 60mm F10 calipers, and 5.2% less than the medium 40/44mm G11 caliper). It creates its braking torque advantage through its huge front discs. It uses a bespoke master cylinder, and I now wonder if it's because it requires less displacement? Not entirely sure what the difference is to the standard F10 master cylinder now...

The M5 uses the same 44mm rear caliper piston size as the rest of the F10 lineup, but pairs that with huge 396mm discs to increase rear braking torque and maintain the desired F/R bias given its front brakes.

Here's a graph showing the total braking torque of all the different models and swap upgrade options. Again, this assumes the same brake line pressure and brake pad coefficient of friction for all systems.

"]https://flic.kr/p/2naLBAF][/url][/URL]

When i See your graph i Wonder, is there any sence to retrofit Standard brakes, except for Optik and good Look.

Either way, i have done it and now is no turning back.

Maybe next week i'll do rear M5 retrofit, while parts are here and, again, Looks good.

Like i said before, i don't feel so much Brake improvement after retrofiting to Performance calipers, maybe from higher speed to Zero stop yes, but in normal use, hm..

[Blue Angel]

Based on the data, the smallest braking system from the 528 would have the same braking torque as an M5 if the brake pads on the 528 had a 15% higher coefficient of friction.

What changes is the thermal capacity (ability to stop from high speeds and/or handle repeated stops) as well as the HUGE cosmetic improvement. BMW often refers to the larger braking systems as "high-speed braking system" which tells you everything - basically suited for stops from higher speed (autobahn) type driving, something we don't generally need in North America.

Personally, the upgrade is 80/20 cosmetic/performance. I don't feel the brakes on my 535 are lacking in performance, but it would be nice if this car stopped like my Corvette does.

The F10 is such a nice looking car I feel it deserves nice looking brakes too, and the stock brakes are not what I would call "good looking".

[Nenad4884]

Originally Posted by Blue Angel

Based on the data, the smallest braking system from the 528 would have the same braking torque as an M5 if the brake pads on the 528 had a 15% higher coefficient of friction.

What changes is the thermal capacity (ability to stop from high speeds and/or handle repeated stops) as well as the HUGE cosmetic improvement. BMW often refers to the larger braking systems as "high-speed braking system" which tells you everything - basically suited for stops from higher speed (autobahn) type driving, something we don't generally need in North America.

Personally, the upgrade is 80/20 cosmetic/performance. I don't feel the brakes on my 535 are lacking in performance, but it would be nice if this car stopped like my Corvette does.

The F10 is such a nice looking car I feel it deserves nice looking brakes too, and the stock brakes are not what I would call "good looking".

You're like a bible mate with your calculations, really appreciate it as i don't Generaly Look so deep into.

You are right, F10's are so beautiful cars and they do deserve better looking brakes.

🤗

[Blue Angel]

Originally Posted by Nenad4884

You are right, F10's are so beautiful cars and they do deserve better looking brakes.

🤗

BTW, your car looks great with those wheels and the blue G11 brake upgrade! It should have come that way from the factory!

Your wheels have a nice concave face which looks fantastic, but makes clearance a little tight for big brake calipers. Looking good!

I have my own G11 upgrade coming soon, with the 750 rear brakes as well. Can't wait!

[Blue Angel]

Nenad, I just noticed you mentioned doing the M5 rear brakes. I think that might give you too much rear brake bias at 39%. You don't want too much rear brake bias, or the rear tires could lose grip before the front.

It would also make your front brakes jealous as the M5 rear brakes are 21mm larger than your 760 brakes!

I think the correct rear brakes for your car would be the 750 rears. Use the F01 750 370mm rear discs with M5 calipers and brackets.

The 550 rears may also be an upgrade if you don't already have the 345mm rear discs. If you do, all you need is the M5 brackets to upgrade to the 370mm discs.