F80 M3 / F82 M4 Brake Caliper/Rotor Retrofit Guide to E9x M3 - Using OEM Parts

Great information all around. Thx

I finally had a chance to perform this task. I kept asking friend to borrow a solder iron but finally someone has it. It work perfectly. After i did my brake upgrade, i had to align it but since i was off a little and i didn't have the tool to check whether is balance or not. During down shift the car feel jerky. Now with this, downshift smooth. Thanks again.

tdott wrote

Yes it's only two wires.

Quick question for those who did the swap, with the F8X retrofit, do you still need to remove/cut the dust shield like other BBKs? I don't think anyone mentioned it here, so I assume you don't need to touch the dust shields?

W12x wrote

Quick question for those who did the swap, with the F8X retrofit, do you still need to remove/cut the dust shield like other BBKs? I don't think anyone mentioned it here, so I assume you don't need to touch the dust shields?

It's in the first post.

F8x dust shields or you can cut trim the e9x ones.

tdott wrote

It's in the first post.

For some reason I didn't see that part...my bad

About to carry this mod in coming week. In regards to the ABS wheel sensors, splicing the cable. I assume there's no polarity to follow any which way soldered/heatshrink works?

I found this thread with interest, as I have been doing lots of research into doing a properly matched BBK retrofit, with calipers that have as close to stock piston area and front/rear bias as possible.

My first consideration was of course this F8X setup as it would seem a no brainer, however despite the relatively simple fitment, I've realised that the M4 has a 10% smaller total piston area than the E92 M3, which means a 10% firmer pedal with 10% less modulation, and 10% less torque at the piston.

Here are the caliper stats side by side:

E92 M3 calipers
Stock M3 piston area front 60mm - 2826 x 2
Stock M3 piston area rear 46mm - 1661 x 2
Stock M3 total area 4487
Stock front bias 63%

M4 calipers
F8X M3/M4 front BB-43 (40/40x30mm) - 2512 x 2
F8X M3/M4 rear BB-22 (44x24mm) - 1520 x 2
Total 4032 - 10% firmer - Stock bias 62%

Ideally you want to find calipers that maintain the total piston area to match the capacity of the master cylinder. If you compare the E92 specs with even the Stoptech setup, we can see that even they deliberately only differ total piston area by 1% and shift the bias slightly rearward:

Stoptech BBK
Stoptech non Trophy st60 front = 36/36/30 - 2741 x2
Stoptech Trophy ST60 32/34/36mm = 2729 x 2
Stoptech st40 355 back = 34mm 32mm - 1711 x 2
Total 4452 or 4440 x2 / 1% harder 61.5 front bias

To keep as close to stock piston area, ideally you need to find a combination of front and rear calipers with the following piston configurations:

Front 6 Pot
32/34/38mm - 2845 x 2
30/34/38mm - 2748 x 2
30/36/36mm - 2741 x 2
32/34/36mm - 2729 x 2

Rear 4 Pot
34/32mm - 1711 x 2
30/34mm - 1614 x 2
32/32mm - 1608 x 2

Definitely not poo-pooing this setup, especially as I haven't tried it, but wanted to be transparent with my findings so that ppl can make an informed decision.

Mart.

Captain Caveman wrote

E92 M3 calipers
Stock M3 piston area front 60mm - 2826 x 2
Stock M3 piston area rear 46mm - 1661 x 2
Stock M3 total area 4487
Stock front bias 63%

M4 calipers
F8X M3/M4 front BB-43 (40/40x30mm) - 2512 x 2
F8X M3/M4 rear BB-22 (44x24mm) - 1520 x 2
Total 4032 - 10% firmer - Stock bias 62%

Definitely not poo-pooing this setup, especially as I haven't tried it, but wanted to be transparent with my findings so that ppl can make an informed decision.

Looks like those numbers match what was posted earlier in this thread, brake bias is within 1%. Perhaps it is the slightly more rear bias, or it could be the fixed calipers, but high speed braking is improved and much more stable than stock brakes when heavy braking from high speeds.

Captain Caveman wrote

10% smaller total piston area than the E92 M3, which means a 10% firmer pedal with 10% less modulation, and 10% less torque at the piston.

I am no expert in the math, can't really say I understand it. But how come only the area of two pistons are used for the front caliper? When there is 4 pistons, and torque being applied from both sides vs 1 side on the stock caliper.

Shouldn't that have an effect on torque applied, since it is from both sides? It certainly doesn't feel like less torque is being applied to braking. Either way I am very happy with the upgrade especially at the prices I paid, as the prices on these parts have taken a jump recently, probably due to increased demand.

I just began the conversion here. Very straight forward. My biggest dilemma...

Do I change the colour of my caliper?!?!?

FMLYSDN wrote

I just began the conversion here. Very straight forward. My biggest dilemma...

Do I change the colour of my caliper?!?!?

If you track, you'll want to.

Big fan of black calipers on the E9X as it's aligned with the GTS and is generation correct.

Are these winter projects or you want on road testing these soon 😃

Epoustouflant wrote

FMLYSDN wrote

I just began the conversion here. Very straight forward. My biggest dilemma...

Do I change the colour of my caliper?!?!?

If you track, you'll want to.

Big fan of black calipers on the E9X as it's aligned with the GTS and is generation correct.

Are these winter projects or you want on road testing these soon 😃

No plans to track this car. That was a former activity. A dedicated track car would be in order. I simply wanted an upgrade to the stock brakes with OEM parts. Mostly a cosmetic upgrade as the stock setup is drab.

No road testing till the spring 😠

FMLYSDN wrote

Epoustouflant wrote

FMLYSDN wrote

I just began the conversion here. Very straight forward. My biggest dilemma...

Do I change the colour of my caliper?!?!?

If you track, you'll want to.

Big fan of black calipers on the E9X as it's aligned with the GTS and is generation correct.

Are these winter projects or you want on road testing these soon 😃

No plans to track this car. That was a former activity. A dedicated track car would be in order. I simply wanted an upgrade to the stock brakes with OEM parts. Mostly a cosmetic upgrade as the stock setup is drab.

No road testing till the spring 😠

Looks great! There are definitely performance & longevity gains I'm sure.

Did you opt for new spindles or did you have a custom bracket made?

Curious to hear total conversion costs.

Epoustouflant wrote

FMLYSDN wrote

Epoustouflant wrote

FMLYSDN wrote

I just began the conversion here. Very straight forward. My biggest dilemma...

Do I change the colour of my caliper?!?!?

If you track, you'll want to.

Big fan of black calipers on the E9X as it's aligned with the GTS and is generation correct.

Are these winter projects or you want on road testing these soon 😃

No plans to track this car. That was a former activity. A dedicated track car would be in order. I simply wanted an upgrade to the stock brakes with OEM parts. Mostly a cosmetic upgrade as the stock setup is drab.

No road testing till the spring 😠

Looks great! There are definitely performance & longevity gains I'm sure.

Did you opt for new spindles or did you have a custom bracket made?

Curious to hear total conversion costs.

I went for the whole meal deal on this one.

Spindles, hardware and F80 ABS sensors...

As for the cost, I'm sure I could tally that up. There's a complete setup including spindles on Ebay right now for $1800 USD.

Has anyone tried this with f30 calipers and 370f/345r rotors?

I know the rear should bolt on easily just not sure about the front. Would I need f30 spindles instead?

krazi3azn wrote

Has anyone tried this with f30 calipers and 370f/345r rotors?

The calipers are the same, you need f8x spindles and f8x rotors to use them.

No idea what f30 spindles does to the geometry, the offset of the 370mm rotors are different, not sure if they would work. Can't help there. Not even sure if it would even be worth it to try.

tdott wrote

krazi3azn wrote

Has anyone tried this with f30 calipers and 370f/345r rotors?

The calipers are the same, you need f8x spindles and f8x rotors to use them.

No idea what f30 spindles does to the geometry, the offset of the 370mm rotors are different, not sure if they would work. Can't help there. Not even sure if it would even be worth it to try.

I currently have a 360 front bbk. Stock is rear, I was hoping to fit the f30 rear with 345 instead of the 370. Has anyone tried this before since it doesn't require the spindle in the rear

krazi3azn wrote

I currently have a 360 front bbk. Stock is rear, I was hoping to fit the f30 rear with 345 instead of the 370. Has anyone tried this before since it doesn't require the spindle in the rear

The rear is bolt on with some washers. The caliper is not positioned for a 345mm rotor, you'll need to figure out a custom solution.

No idea if a f30 rear rotor will even work with the parking brake.

is the bolt pattern for E92 dust shield the same as F80's? I'm trying to see if I can retro fit E92's brake cooling backing plate onto a F8x.

jim1013yyf wrote

is the bolt pattern for E92 dust shield the same as F80's? I'm trying to see if I can retro fit E92's brake cooling backing plate onto a F8x.

Fronts are the same. Direct fitment. The rears don't.

jim1013yyf wrote

is the bolt pattern for E92 dust shield the same as F80's? I'm trying to see if I can retro fit E92's brake cooling backing plate onto a F8x.

If memory serves me right, I think the E9x dust shield on the F80 spindle had 1 hole that didn't line up, so I think only 2 bolts were used to hold it down.

I went ahead and installed f8x dust shields on both sides so im not 100% sure.

FMLYSDN wrote

Fronts are the same. Direct fitment. The rears don't.

Thanks! I just ordered a E92 Brake cooling backing plate to test out on F82!

tdott wrote

If memory serves me right, I think the E9x dust shield on the F80 spindle had 1 hole that didn't line up, so I think only 2 bolts were used to hold it down.

I went ahead and installed f8x dust shields on both sides so im not 100% sure.

Thanks! I just ordered a E92 Brake cooling backing plate to test out on F82 (this one - http://www.hardmotorsport.com/hard-motorsport-aluminum-brake-cooling-backing-plates-bmw-e9x-m3/) in the worst case - I will drill a new hole for the bolt