[BMW DIY Guy]

**edit* rewriting my question as I checked other info.

My 14 F32 has the "grey" brakes.. brembo double piston fronts, on single piston rears and 340mm rotors all around.

Does anyone know if it is possible to retrofit the front double piston brembo calipers onto the back brakes? My guess is maybe? I see the M Performance kits have double pistons but smaller in the back, which makes me thing the bolt holes from the fronts wouldnt match up to the back, and would be too big. The thought would be take a set of grey fronts and put them on the rears, if they fit.. rotor size wouldnt be an issue.

I was pondering the idea if anyone had tried this if possible, essentially a home grown BBK, but the holes would have to match up.

[johnung]

Originally Posted by BMW DIY Guy

Hey all!

Crazy idea of the day and thought I would get some input.. my car is "M-sport" brakes, which means the double pistol brembo fronts but the standard single piston in the rears.

The M Performance brakes, are brembo front and rears and available for my car, so that makes me assume the carrier bolt positions for the rears are the in the same place for the brembo style calipers. M Sport rotors are 340 front and rear, so the rear rotor size is fine.

Since the M Performance kit is essentially the other half of my brake setup.. would it be possible to just get a set of brembo fronts and put them on the rears, and thusly have the full "performance" kit?

Thoughts? Anyone tried this?

Definitely qualifies as a crazy idea. You don't say what car but if they are blue and the front rotors are 340mm x 30mm then it can't be a 335 because they would be grey. So I'm guessing a 328?

The rear 1-piston Bosch calipers are over 330mm x 20mm rotors. The rear upgrade would be a 2-piston Brembo over a 345mm x 24mm rotor.

Remember that the rear rotors are different than front rotors in that they have an integral 185mm (or 160mm) parking brake.

Even if you ditched the parking brake and somehow got all the hardware to mount the biggest problem would be that the front to rear brake bias would be completely off. If you had 4-piston Brembos on front and rear I doubt that you could even code that in the car as a workable brake bias.

During hard braking the weight shifts forward so the front brakes are doing most of the work, hence front brakes are bigger than rear brakes. And the bias in the BMW F30 braking system is set for this. It's physics! If you look at big brake upgrades for the F30 from BMW, Brembo, and StopTech they all are designed with larger front and smaller rear.

You can upgrade the rears to the 2-piston Brembo over 345mm x 24mm rotors which I have done while leaving my front 4-piston Brembos over 340mm x 30mm rotors. There is a big difference. The stock system tends to nosedive under hard braking. With the larger rear brakes added the car will instead stop in a more level and controllable "squat".

At the same time as the rear brakes I upgraded to Hawk 5.0 pads and StopTech stainless steel brake lines (only $106/set). Pads had greater bite with less dust and steel lines made brake pedal more solid.

Hope this helps!

[BMW DIY Guy]

Originally Posted by johnung

Definitely qualifies as a crazy idea. You don't say what car but if they are blue and the front rotors are 340mm x 30mm then it can't be a 335 because they would be grey. So I'm guessing a 328?

The rear 1-piston Bosch calipers are over 330mm x 20mm rotors. The rear upgrade would be a 2-piston Brembo over a 345mm x 24mm rotor.

Remember that the rear rotors are different than front rotors in that they have an integral 185mm (or 160mm) parking brake.

Even if you ditched the parking brake and somehow got all the hardware to mount the biggest problem would be that the front to rear brake bias would be completely off. If you had 4-piston Brembos on front and rear I doubt that you could even code that in the car as a workable brake bias.

During hard braking the weight shifts forward so the front brakes are doing most of the work, hence front brakes are bigger than rear brakes. And the bias in the BMW F30 braking system is set for this. It's physics! If you look at big brake upgrades for the F30 from BMW, Brembo, and StopTech they all are designed with larger front and smaller rear.

You can upgrade the rears to the 2-piston Brembo over 345mm x 24mm rotors which I have done while leaving my front 4-piston Brembos over 340mm x 30mm rotors. There is a big difference. The stock system tends to nosedive under hard braking. With the larger rear brakes added the car will instead stop in a more level and controllable "squat".

At the same time as the rear brakes I upgraded to Hawk 5.0 pads and StopTech stainless steel brake lines (only $106/set). Pads had greater bite with less dust and steel lines made brake pedal more solid.

Hope this helps!

Sorry I corrected my question once I started comparing kits and realized I had mislabeled what I have on the car. I have the grey front brembos and single piston rears. Sorry for that mixup. 14 435i with grey brakes.

Yeah.. I realize its a crazy question, but just wondering.. figure the holes wont even come close to matching.

[johnung]

Originally Posted by BMW DIY Guy

**edit* rewriting my question as I checked other info.

My 14 F32 has the "grey" brakes.. brembo double piston fronts, on single piston rears and 340mm rotors all around.

Does anyone know if it is possible to retrofit the front double piston brembo calipers onto the back brakes? My guess is maybe? I see the M Performance kits have double pistons but smaller in the back, which makes me thing the bolt holes from the fronts wouldnt match up to the back, and would be too big. The thought would be take a set of grey fronts and put them on the rears, if they fit.. rotor size wouldnt be an issue.

I was pondering the idea if anyone had tried this if possible, essentially a home grown BBK, but the holes would have to match up.

In your updated posted you stated:

"My 14 F32 has the "grey" brakes.. brembo double piston fronts, on single piston rears and 340mm rotors all around"

FYI- what you are referring to as "double piston" are actually 4-piston calipers. You see two round bumps facing outward but there are also two more facing inward on the caliper.
The same goes for the Brembo rear calipers. The single round bump facing outward has a matching one facing inward, making them 2-piston calipers.

Also BMW doesn't have a 340mm rear rotor for F30 so it's more likely that you have a 300mm or 330mm rear rotor. Please see attached rotor table.

[BMW DIY Guy]

Wow sorry.. I Am all over the map today with info and my question, my sincere apologies. Crazy idea while multitasking in a work meeting. Probably should have waited until I got home and also had hands on my rotors.

You are absolutely correct.. the fronts are 4 pot, and I dont have brembo rears, the standard single piston rear. Also from a quick lookup, I should have 330mm rotors all the way around.

My apologies for multitasking.

[johnung]

Originally Posted by BMW DIY Guy

Sorry I corrected my question once I started comparing kits and realized I had mislabeled what I have on the car. I have the grey front brembos and single piston rears. Sorry for that mixup. 14 435i with grey brakes.

Yeah.. I realize its a crazy question, but just wondering.. figure the holes wont even come close to matching.

Okay, a 2014 435i with standard grey brakes are 340mm front and 330mm rear. You can upgrade the rears to 2-piston Brembo calipers with 345mm x 24mm rotors. (Only 18" road wheels fit over these brakes. 17" wheels won't fit)

It's pretty easy to find a used pair of rear blue 2-piston Brembo calipers for about $400-$600/ pair depending on condition. Add used stock rotors in great condition or new Zimmermann 345mm x24mm rotors. Add Hawk 5.0 pads, StopTech stainless steel brake lines and new brake fluid.

It's also easy to paint your calipers to match in any color with a brush right on the car. See G2USA website for 2-part epoxy like Caliper Paint that evens out as it dries for a sprayed on look. I also did the sides of my rotor hats in G2 Silver to prevent rust for an always new look. See attached photos of my previously grey front and previously blue rear calipers.

Hope this helps!

[BMW DIY Guy]

Ok.. just hustled home and you are absolutely right.

My OEM rotors are 340mm fronts, and 330 rears. Thank you so much for all of the really useful info, and my badly scattered question.

[johnung]

Originally Posted by BMW DIY Guy

Wow sorry.. I Am all over the map today with info and my question, my sincere apologies. Crazy idea while multitasking in a work meeting. Probably should have waited until I got home and also had hands on my rotors.

You are absolutely correct.. the fronts are 4 pot, and I dont have brembo rears, the standard single piston rear. Also from a quick lookup, I should have 330mm rotors all the way around.

My apologies for multitasking.

No apologies necessary. Your questions were all valid. I answered in detail figuring that others reading might have similar questions and the detail may help them too.
I was an engineer early in my career and I learned quickly that if I sent an email with a short answer then a year later someone would forward my email back asking for the detail behind my answer, and I wouldn't remember a damn thing! So I learned to include the details while they were fresh in my mind and accurate.
Hope it helps!

[BMW DIY Guy]

Thanks man.. but self answers my own questions because 340 fronts wouldnt reverse onto 330 rears.