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      07-29-2017, 01:05 PM   #1
raolc
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z4m using blue m4 brakes?

what do i need to fit the blue m4 brakes to my 06 z4m?
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      07-31-2017, 10:51 AM   #2
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I can't tell you what you'll need, but I can tell you where the hurdles are.

1. Size of Brake Master Cylinder: If the size of the master brake cylinder isn't a near perfect match, you will be chasing a soft or stiff pedal AND lack of performance from the swap. If this hurdle can't be cleared, no amount of "hacking" you do to the system will make one work with the other. This is going to determine, no DICTATE the ratio of master cylinder to slave (piston size on the calipers) size. If this doesn't work, forget it.

2. Size of slave (Piston Surface Area) cylinders: See number 1. IF the master cylinder size match, which most of the time on a BMW, it does between certain trims (i.e. master cylinder size is the same despite different part numbers between E36 M3, E46 M3, Z3 M, and Z4 M, but not between the M and the non-M variant...i.e. the E36 325, 328, and E46 323, 325, 328, and 330 all use the same size master cylinder, but not the same as the M3/Z3M/Z4M master cylinder), then you have to see if the slave (caliper pistons) match as well. If it doesn't, then things become complicated, but not impossible. If the size of brake caliper piston area is within 10% of each other, and if the new caliper piston area is SMALLER than the OE size, you can still POTENTIALLY have a working system. All it does is effectively shift brake bias one way or another by the percentage difference between the two piston areas. This can be remedied either by using a more aggressive pad on the end that the bias shifted from, or going to a larger diameter rotor.

On a side note, the E46 M3 has 2 different brake parts, one for the run of the mill M3, and the other for the ZCP (competition package) equipped M3. The competition package equipped M3 has larger rear caliper piston, but also larger front rotor to effectively equalize the shift in rear brake bias due to the change in piston diameter. I believe the master cylinder area remained the same between the two trim levels. The Z4 M runs the same setup as the E46 M3 ZCP, but speaking with a few brake industry veterans, most production car tend to have too much brake bias toward the front brake, because, well, the front does the most work regardless of how the car's laid out. A better, more performance oriented brake system would want to spread that load a little bit more evenly. A lot of aftermarket high performance brake suppliers make kits that shift the hydraulic fluid brake bias on our BMWs to the rear by 5-10% on purpose.

3. Caliper radial and axial mount location: Once you've determined that the master brake cylinder size is the same, and the caliper piston area to be equivalent AND keeps hydraulic fluid bias within a small range, the "fun" part begins. Because you're swapping from a sliding caliper design to a fixed caliper design, first you must figure out if the caliper's radial mount accommodates the size of rotor you wish to run. For example, most calipers have a range of overall radius/diameter of rotors they can accommodate, the 4 piston RacingBrake caliper I run up front works for a rotor as small as 340mm to a 365mm rotor. Then you MUST determine HOW to make the central axis of the caliper (the centerline between the retracted pistons) align perfectly with the axial centerline of the rotor.

This means, first having to determine how the caliper is mounted to the kingpin. If it's an axial mount, meaning the bolt holding the caliper to the kingpin is parallel to the axle, your options, based on the determination above (axial and radial clearance) would be to have a spacer bracket to move the caliper in a way that it's centered axially and have the pad sweeping area match the outer diameter of the rotor. HOWEVER. If the caliper's mount creates an axial center closer to the car than the rotor's axial center, this won't work. You will have to shave off parts of the fixed caliper's mount to accommodate, which weakens the structure rigidity of the caliper. Or if the rotor is significantly smaller than what the caliper is originally designed for, this won't work either. Or if the rotor is significantly larger than what the caliper is designed for, it won't work. If the caliper you're using is radially mounted, then it gives you some flexibility because you can build a bracket that mounts axially to the kingpin, then have the caliper radially mounted to the bracket. The bracket can be milled to a specific thickness and height to make sure the caliper is mounted axially centered to the rotor and radially sweeps all the way to the outer edge of the rotor (the top of the pad meets the top of the rotor). With a radially mounted caliper, as long as the rotor falls within the range that the caliper is designed for, you can machine/make a bracket to fit it.

Again, as long as the first two parameters fit (master and caliper piston sizes match within a range).

4. Pad sweep area: Typically, a multi-piston fixed caliper have a bunch of smaller pistons vs. a sliding, single (or double) piston setup. The result is pads for multi-piston fixed calipers are usually a lot shorter and longer, while single or double piston sliding calipers have pads that are much taller or more square shaped. IF you're using your stock rotors and just swapping over the calipers, you have to look at the actual sweep area of the new pads and see if it covers about the same general surface area as your OE setup, as well as the height of the pad to see if it cover the same sweep. Because the size of the sweep surface also determines frictional force, therefore the same piston (or roughly the same) surface applied to different sweep area will alter the brake bias calculation. If the new surface area is much larger (or smaller) you can always use different pad compounds to re-adjust the brake bias.

The other factor is mostly aesthetics. If your new pad surface area is roughly the same, but with the mult-piston setup the pad is longer but shorter, it will leave a portion of your OE rotor uncovered and since that part will never get scrubbed by the pads, it will be covered by rust very quickly.

5. Rotor selection: Thus far we've only assumed that you're only swapping the calipers, not the rotors. Once you take rotors into consideration the equation becomes complicated AGAIN. You have to figure out where the rotor's axial center is, how the rotor's hub depth and size affect other various mounting points, the dust shield, the location of the steering knuckle and tie-rods, and other suspension hardware. Even assuming that a BMW rotor SHOULD fit a BMW hub (5x120mm w/ a 72.6mm hub), there's no guarantee that the rotor won't interfere with one or more of the components listed above.

Now, having said all that. Typically, fixed calipers are designed in a way to fit a specific subset or parameters, and variation in master cylinder sizes usually, again, fall within a specific range or quanta given the same manufacturer (i.e. see 3 series example above). So a lot of times, people have good luck fitting, say, a Porsche Boxster Brembo caliper to a BMW E30 M3. It's not to say that the M4 caliper to Z4 M would be a monumental task. But I certainly wouldn't assume that it'll be as easy as just building a custom bracket to fit either. The least I would do, is to figure out how the parameters fit within 1-3 above before I would ask "how."

And in all reality, unless you're getting the M4 calipers on the dirt cheap, the entire process of research and fabrication to make it fit may end up costing you more time, money, and headaches than to just buy, say, a RacingBrake (although they don't sell just the calipers alone, even though there are simple ways such as shim kits to make it work) or a StopTECH or any of the reputable brake vendor's kit that offers better performance for less cost.
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      07-31-2017, 11:21 AM   #3
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Hack's response is top notch and the only thing that is worth adding is that this was covered before and based on the OPs final response, it did not work well.

BMW M Performance BBK RETROFIT:
"In short, the hat of the new rotors is so deep that even without a dust shield the disc itself would make contact with the control arm/tie rod end. With different rotors I am convinced the kit would still work, but I am not really interested in going down that road."
http://www.zpost.com/forums/showthre...ght=f80+brakes

Before you search for it, the "BMW M Performance BBK" utilizes the same calipers as base F80 M3/M4 but with slightly smaller rotors. See more info here:
http://f80.bimmerpost.com/forums/sho....php?t=1064542

Hope this helps!
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      07-31-2017, 11:38 AM   #4
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The problem with the blue m3 brake calipers (the stock ones) and the 435 style calipers (both M brake calipers and stock calipers) is that the mounting lugs are fixed.
So radial and axial offset is very difficult to alter. That means that only a certain disc with a certain offset and certain diameter is going to work.
Only the 6 piston M3/4 carbon brake calipers have a bracket, for which you could mill a new, custom one. That way you have control over what radial/axial offset you want to use for your planned rotor.
But those calipers are gold, not blue
That type of bracket that is used on the 6 piston carbon brake calipers is similar (not the same) as for instance is used on the 135i 6 piston brembo calipers. For those last calipers there are multiple aftermarket bracket manufacturers to fit them on say a z4 or z4m.

Then again if you're buying new rotors, new calipers and new brackets, something like a D2 racing BBK is just as expensive.

Fitting rear calipers gives even more complications
Took me about 2 weeks to fabricate a custom rear brembo caliper/rotor brake setup in the evenings and weekends....
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      07-31-2017, 12:12 PM   #5
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Quote:
Originally Posted by raolc View Post
what do i need to fit the blue m4 brakes to my 06 z4m?
You've got a pretty good brake set there with the standard Z4M package. With some judicious pad selection you can make it even better without all the work of modding in a custom setup. Are you planning on doing some serious track usage where you think you'll need more heat capacity or do you just like the blue calipers?
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      07-31-2017, 01:03 PM   #6
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Quote:
Originally Posted by dc_wright View Post
You've got a pretty good brake set there with the standard Z4M package. With some judicious pad selection you can make it even better without all the work of modding in a custom setup. Are you planning on doing some serious track usage where you think you'll need more heat capacity or do you just like the blue calipers?
1) i saw lightly used sets on ebay for under $2,000
2) they seemed like great brakes to have for the track
but most importantly for me:
3) my car is blue, wheels are black, so the giant blue calipers with M badges would look stunning
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      07-31-2017, 03:54 PM   #7
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Hack, Azeka1, and GuidoK

thank you so much for the responses

if this was about certain brackets or adapters to make it work then i'd go for it but it seems like it's far more complicated.

i guess i'll settle for powder coating my brakes.

thanks again!
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      07-31-2017, 05:44 PM   #8
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Quote:
Originally Posted by raolc View Post
Hack, Azeka1, and GuidoK

thank you so much for the responses

if this was about certain brackets or adapters to make it work then i'd go for it but it seems like it's far more complicated.

i guess i'll settle for powder coating my brakes.

thanks again!
You're welcome! You might also want to consider this upgrade if you are really set on upgrading calipers. Retains the stock floating rotor, too.

Rallyroad Porsche caliper conversion
http://www.zpost.com/forums/showthread.php?t=711529
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      07-31-2017, 06:19 PM   #9
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Or get some 135i 6 piston Brembo calipers and a pair of aftermarket brackets.
Similar pricepoint I think.
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      08-01-2017, 04:59 AM   #10
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oh wow. i love both of these responses!!! i think that is even cheaper than what i was considering. i can take the porsche calipers, powder coat them blue, and slap the M sticker on the caliper. if i get the 135i ones i might keep it gold but i can't find the bracket for that one. anyway I had an 07 cayman S and i already know those brakes are awesome so this sounds like a dream come true!!
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      08-01-2017, 08:27 AM   #11
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Quote:
Originally Posted by raolc View Post
if i get the 135i ones i might keep it gold but i can't find the bracket for that one.
I think https://www.epytec.de/ do them and also maybe MS raceline on facebook:
https://www.facebook.com/MSRaceline-506685679373515/
(also do porsche brackets/custom work).
I think these do them too:
https://burkhart-engineering.com

All in Germany.

I think any e46 m3 adapter will work on the z4m because the z4m has the same stock calipers/caliper carriers as the e46m3 and csl (and of course the same csl rotor) but you can always check with the supplier.
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      08-01-2017, 12:52 PM   #12
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i have previously fitted the blue 435is front brake calipers to my Z4m coupe. they bolt right on with the use of the stock 345mm z4M rotors. the 435 disc's have incorrect offset's that cant be made to work. here is a link with some pics: http://www.zpost.com/forums/showthread.php?t=1309755
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      08-01-2017, 01:00 PM   #13
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the stock sized brake pads will also have to modified at the bottom edges to clear the rotor hats. the rears will not fit. overall my personal opinion on the braking "feel" and stopping capabilities were an improvement. HACK has some very good points above about braking system modifications that should be observed. I feel the braking bias shift to the rear suites my driving style. the firmer brake pedal is also a bonus for me. this was a cheap/ somewhat effective upgrade for track day fun time. brake fade is still an issue on the local track I play at.
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      08-01-2017, 01:18 PM   #14
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latest brake upgrades

I have recently changed out the 435is caliper mods for a more serious set of brakes hopefully now the brakes can last the entire HPDE session before the brakes fade to mush again. those front rotors are 35mm thick!
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      08-01-2017, 01:27 PM   #15
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that AMG six pot caliper was just kicking around. wanted to compare the differences between a factory option AMG/Brembo to what AP had to offer. BTW, for all who would like to do some brake piston area calculations. the caliper piston sizes are: 28mm, 32mm, 36mm
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      08-01-2017, 01:51 PM   #16
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Brake piston area calculations are meaningless unless you take pad area and the specific pad friction coefficient/gradient into account.
A large pad brakes very differently compared to a small pad with the same overall pressure applied. That makes it very very difficult to calculate because you need a tonne of data.

The 135i front brembo calipers for instance have huge pads: ~165x74mm
Compare that to the stock z4m pad area: ~112x55mm (total pad height is of course also dependant on what radius the pad grabs).

A bigger pad usually needs less pressure to get the same brakeforce because the pressure/friction ratio usually isnt 100% directly proportional, but to make matter really complicated, these ratio's also change with disc speed....


So in the end imho it all comes down to building it and test it in person on a quite road.
If it doesnt give the expected result, go and change something or build something new
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      08-02-2017, 05:28 PM   #17
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very true GuidoK! I agree with you. many factors need to be accounted for. in my link to when I first mounted up those 435is calipers to my Z4M. I felt blasted for even attempting the mod based on solely on piston area calculations. overall it wasn't dangerously biased to the rear nor did it negatively affect the vehicles braking balance. just wanted to share an easy/inexpensive brake modification that also improves the look inside the wheels. a $4500 dollar AP brake upgrade is not for everyone nor does everyone need that kind of upgrade.
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      08-02-2017, 09:43 PM   #18
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Or... do what I did. Not sure if this will fit a Z4M (I have a 3.0si), but I "upgraded" to the 335i front caliper, and Z4M rotor:



There is a thread here with all the details. The Z4M caliper weighs roughly 15lbs (w/pads), the 335i caliper is mostly aluminum and weighs 14lbs (w/pads). Bigger pad area, visually.

I ran this setup at a few HPDEs on Stoptech Sport pads, and with some custom brake cooling ducts, had no fade ever.
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      08-03-2017, 12:33 PM   #19
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very nice dre99gsx! great to see people trying different things! I think the 4 piston m sport calipers I previously used were just under 8 lbs loaded with pads and hardware. what pads are you using at te track?
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      08-03-2017, 03:38 PM   #20
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The 335i caliper is aluminum, but the caliper bracket that attaches to the hub is 'heavy' steel, which adds to the weight for certain.

I'm running Stoptech Sport pads.
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      09-23-2017, 05:09 AM   #21
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Quote:
Originally Posted by dre99gsx View Post
Or... do what I did. Not sure if this will fit a Z4M (I have a 3.0si), but I "upgraded" to the 335i front caliper, and Z4M rotor:



There is a thread here with all the details. The Z4M caliper weighs roughly 15lbs (w/pads), the 335i caliper is mostly aluminum and weighs 14lbs (w/pads). Bigger pad area, visually.

I ran this setup at a few HPDEs on Stoptech Sport pads, and with some custom brake cooling ducts, had no fade ever.


Awesome dude!

First time I see that somebody bring to life that idea - 335 calipers + M3 CSL rotors!
Looks perfectly and im sure working so!
Take please actual photo of your brakes.

I want to do that setup some time ago on e36, but price on CSL rotors are too much, and I sold the car soon.
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