E89 Z4 4-corner big brake upgrade with Brembo m-sport calipers

fmorelli

Major General
Staff member
Aug 11, 2017
3,027
Virginia
Curious the weight difference...
Me too, since I happen to have both here new. Did rears as well and will have photos of that installation this week. About a 10% weight savings on the 2-piece aluminum rotor.

Rear Z4 35i rotors are little baby things lol. These were rusty (junkyard) but like 5k use, so like new.

Filippo


F30 S2HNA Front 370mm BMW p/n 34106797603
1-piece rotor (Zimmermann p/n 150290532)

IMG_20200712_090810.jpg
F30 S2HNA Front 370mm BMW p/n 34106797603
1-piece rotor (Zimmermann p/n 150290532)

IMG_20200712_091228.jpg





BMW E89 Z4 35i Stock Rear Rotor 300x20mm
BMW p/n 34216782605


IMG_20200712_091334.jpg

BMW E46 M3/ E86 Z4 CSL Front Rotor 345x28mm
BMW p/n 34112282445

(application - E89 Z4 rear big brake conversion)​

IMG_20200712_091304.jpg
 
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Torgus

Major
Nov 6, 2016
1,636
Boston
Newb question but do they not make a 'real' BBK for the z4 like from brembro, stoptech, etc? I know it is less expensive piecing kits together don't get me wrong.

One thing I have always wondered when adding calipers not designed for the car is how do you keep the brake bias and ABS functioning 100% like it is supposed to? Once you change the number/size of the pistons in the calipers and or brake master cylinder from stock doesn't it throw everything off? Unless you have a stand alone ABS controller: http://info.3dmmotorsport.com/mk60-motorsport-abs-standalone-guide

https://www.brakes-shop.com/brakepedia/bbk/abs-and-brake-kit-fundamentals <-- A good read, a bit technical

"at STOPTECH all brake upgrade kits are designed with the characteristics of the original braking system taken into account to minimize these differences. This is the reason that when you order a STOPTECH big rotor upgrade kit the new caliper bores may actually be smaller than the units you are replacing to "balance the equation." This is just one way in which our engineers attempt to retain the original system's P-T and P-V integrity. Sure, it's not one-size-fits-all, but neither is your car…or your driving style. Why should you expect any less from your brake upgrade?"
 
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fmorelli

Major General
Staff member
Aug 11, 2017
3,027
Virginia
We worked much of today. Slow but steady progress. Ran into a few issues but no show stoppers. The G30 M-sport calipers are a millimeter shy on clamp width, so need to mill off 30 thou off each rear brake pad. I swapped the rear actuators from G30 to E89 - connectors are different. Fitting is tricky, getting clearance for how this is mounted, so the rear EMF clears both the chassis and the external controls on the TTX. Further tomfoolery is that the G30 calipers are actually front mounted (9 o'clock) on the G30, but we need them mounted at 3 o'clock. So we swap calipers left to right so we get the bleeders upright. Thankfully the EMF controllers are designed to clear mounted either up or down.

Devil is in the details ... all the research, mockup etc ... but reality is an unforgiving teacher and, sometimes, we get lucky.

@Torgus yeah only company on the planet that makes an EMF-based BBK is PB Brakes. Works great. Not cheap. In my case I wanted a factory look for a few reasons where I won't digress here.

Filippo

E89 Z4 TTX : CSL.jpg
 
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fmorelli

Major General
Staff member
Aug 11, 2017
3,027
Virginia
Alright a few more photos. We've been working fitment in the rear. This is all custom in a way that's not been done before, and bench mock up only gets so far. We missed one or two small things along the way, but we have addressed them. One of the Torx bolts I used required knocking 2mm off the ends, for clearance. Bracketry is tight, with backspacing from the EMF actuator to the Öhlins TTX lower shock body, but we believe we've got reasonable spacing now. One thing I completely missed - and I had to go back and look at photos to verify I spaced - I never tested caliper width relative to the new rear rotor setup (versus the Gen 1 F30 rear rotor). Turns out pads don't quite fit with the massive 28mm rear rotor thickness. We knocked a few mm off the pads with the mill, and all is happy. This setup is massive for the rear of the car, so no real concerns as a ton of pad is still there.

Clearance on lines and plugs are good. Amazing given we're running G30 m-sport calipers backwards with side-to-side swapped. I was able to swap the G30 actuators (different plug config vs the E89). The E89 actuators bolt right up to the G30 rear caliper. A lot of shenanigans to sort all of this out, especially when we'd found no information from anyone prior attempting any of this.

Next we'll hook up caliper lines, bleed the whole system, validate that the EMF is happy, bed this setup in and see if we have a proper working brake system.

Filippo

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fmorelli

Major General
Staff member
Aug 11, 2017
3,027
Virginia
With two initial test drives, I can attest that this system is functioning. Initial EMF-related codes cleared from changing everything out. Parking brake works great and the brakes are generally operable. I did an initial pressure bleed, but still have some air bubbles so a bleed with ISTA will take care of that.

Filippo
 

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