BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   ZPOST > BMW Z4 Roadster and Coupe > Z4 DIY (Do It Yourself) Articles

Post Reply
Thread Tools Search this Thread
      09-28-2012, 07:52 AM   #1
Some say...
GuidoK's Avatar
Drives: Z4 3.0i ESS TS2+
Join Date: Jul 2012
Location: Netherlands

Posts: 349
iTrader: (0)

DIY custom OEM Rear BBK

After installing the ECS front OEM big brake kit for the E85 Z4 (non /m), I also wanted a matching BBK for the rear of course..

When I bought the ECS kit they also had this crazy sale for matching rear calipers (135i performance calipers in phoenix yellow) for only $99 /piece, so I took advantage of that

This is how I designed my BBK:

initial fitting on the stock rotor and stock mounting points showed that this had potential:

You can clearly see that the caliper was designed for much lager rotors.

Offset would require some adaptation:

Lots of room between caliper and rotor on the inside

Not so much room between caliper and rotor on the outside

In -c-'s thread about Z4, 2.5, 3.0 easy cheap brake upgrade's I already wrote that E46 330i rotors would never fit and that the best options would be an E90 rotor (320i) which is roughly the same size or an X3 rotor if you like a challenge. The X3 rotor is 320mm (vs. stock 297mm), so much larger, and in combination with the ECS front BBK a well used combination size wise (front 325mm rear 320mm; eg. used in a 330i etc).
Also the x3 rotors are thicker, so overall they can handle more forces and dissipate more heat.

But the X3 uses a larger diameter e-brake than the stock z4 (185mm vs. 160mm). But I decided to go for the x3 rotors after all

First of all the x3 rotors have a ridge on the inside which had to be removed with a lathe:

About 9mm has to be taken of.

Then I had to fit and measure the offset from the rotors compared to the calipers. Between the caliper and caliper mounting points on the suspensionarm aluminium bushes can be fitted to place the caliper more outwards. After fitting some testbushes and measuring the space between caliper and rotor with some feeler gages I found that the bushes should be 7,65mm thick:

So the final size of the aluminium bushes I made on the lathe is 7,65x30mm and the hole is m10 (a bit over 10mm).

To fit the calipers you need longer bolts:

I used the same blots as the rear bolts from the underside pullrods. (M10X35-10.9ZNS3 part nr.: 31 10 6 772 199).
Be sure to use 10.9 bolts in this application

After that came the adaptation of the e-brake, protection plate etc.
I used the protection plate from the e46 330i (34 21 1 166 107 and 34 21 1 166 108) which had to be modified to fit the larger calipers and different z4 hub:

The red lines & holes is where I cut the plate and drilled some holes. The holes are for mounting an 'elevation' mountingplate to fit the e-brake shoes. These brake shoes cannot be fitted directly on the protection plate because they will then touch the brake caliper and they will not fit properly in the brake rotor. The mountingplate for the brake shoes is fitted with m6 bolts where the elevation is done by a washer and a nut between protection plate and mounting plate (washer and nut obviously on the m6 bolts)

The yellow area on the plate is where you have to bend it a little.

Next the mounting plate for the brake shoes. For that I used the "Supporting ring brake shoe" as bmw call it from the 130i (34 21 6 771 430). (the e60 has a similar construction but these mounting plates are too fragile and narrow to modify for fitting on the protection plate as I experienced).
This is how the final brake shoe mounting plate looks like:

The red lines indicate where I cut/drilled the plate, and the yellow corner indicates where I bent the plate a little bit upwards to support the brake shoe on that spot.

Next is fittng the protection plate:

Fitting the caliper:

Fitting the brake shoe mounting plate:

The brake shoes themselves also have to be modified.
I used brake shoes from the e46 330i. (185mmx20mm)
I chose to adapt only the side where the expanding lock is located:

I cut away a piece on the expanding lock side and welded the corresponding piece of metal from the original brake shoes in place.
3 area's should be aligned to the original z4 e-brake (all on the expanding lock side):
1. The holes where the spring fits. (use the original spring; it fits between the expanding lock and the bearinghousing)
2. The little slot where the expanding lock fits into
3. The 'pins' which push against the metal piece form the suspension arm which lock the brake shoes in place.

When all is fitted it looks like this:

Final results....
Front original:


Rear original:

Rear custom OEM BBK:

The only thing now on the list is fitting some decent brake lines. The rear calipers have a mounting point for the lines which is coming straight out of the cilinder and the original brake lines come out on the underside, so regular kits dont fit. I have a temporary piece of copper line flaired on the caliper and hose (in a 90 degree angle) but that is a bit flimsy. I probably need to use a banjo bolt and an an3 to m10 adapter or someting like that.
GuidoK is online now   Netherlands
Reply With Quote
      09-28-2012, 08:44 AM   #2
Major General
Drives: VT2-500 M Roadster
Join Date: Jun 2008
Location: Delray Beach, FL

Posts: 7,111
iTrader: (3)

ZStig is offline  
Reply With Quote
      09-28-2012, 08:45 AM   #3
Drives: E86 3.0si
Join Date: Apr 2010
Location: Boston

Posts: 494
iTrader: (0)

that looks awesome. I wish I had this on my car.
CJW2OO4 is offline   United_States
Reply With Quote
      09-28-2012, 10:26 AM   #4
Major General
inTgr8r's Avatar
Drives: 07 M Coupe
Join Date: Mar 2006
Location: Toronto

Posts: 7,751
iTrader: (7)

Any consideration given to f/r bias control?????
Alpinweiss '07 M Coupe •DKF Section1•Eisenmann Sport-Ceramic Black•Fabspeed Headers•VRS Hyper-Narrow rear wing•Autosolutions SSK•APR splitter•Tekarbon headlights•StrongStrut STB•KW Clubsport•H&R ARBs c/w Turner Adj Links•Poly FCAB/RTAB•Volk Racing G2•Direzza ZII•Stoptech BBK•Vibra-Tech mtr mounts•
inTgr8r is offline   Canada
Reply With Quote
      09-28-2012, 10:40 AM   #5
Some say...
GuidoK's Avatar
Drives: Z4 3.0i ESS TS2+
Join Date: Jul 2012
Location: Netherlands

Posts: 349
iTrader: (0)

No, but that seems to be no problem (so actually yes , I've given that some consideration). These calipers also seem to swap 1:1 on 1 series as part of the performance package without bias adjustment.
ECS recommends when only fitting the front bbk set to use a more aggressive pad on the rear, but that's no issue now
I also didn't experience any premature lockup at the rear with brake tests and braking in the pads.

What might be an option for the future is a bigger master cilinder. Brake pedal travel incresed with this setup about 1cm or so, but the stock cilinder can push around enough fluid (there's easily enough travel to lock up the brakes)

I don't know if an z4m master cilinder would fit and if it is bigger.
GuidoK is online now   Netherlands
Reply With Quote
      08-02-2013, 05:27 PM   #6
Drives: Z4 3.0I, MINI cooper S, 135IS
Join Date: May 2010
Location: wheaton, Il

Posts: 789
iTrader: (4)

yea running the CSL / Z4M rotor is also possable on the front which is a tad bigger than what is on the kit that you are running, you just need to add a 5MM spacer on the carriers as i did mine, fills the wheel super nice.

the car also had shown no ill effects or further travel on the brake pedal. so im thinking this is a great cheap brake mod for the money.

you can get the 1 series brake calipers off of 1 addicts site for super cheap as they come up often.

scored a rear and front setup then all i had to buy was the rotors which can get pricey but all in all i was out 750 dollars total. but what an upgrade!

easy to swap as well.

thanks for the DIY.
-c- is offline   United_States
Reply With Quote
      08-02-2013, 08:07 PM   #7
Some say...
GuidoK's Avatar
Drives: Z4 3.0i ESS TS2+
Join Date: Jul 2012
Location: Netherlands

Posts: 349
iTrader: (0)

Yes, the increase in brake pedal travel is completely gone now. That was the new pads still needing to glaze a bit.

If I would guess the added spacer could be as thin as 3,5mm. The original caliper carriers are ment for a 338mm disc (the z4m disc is 345mm (+7mm :2=3,5mm)).
I don't know if the 338mm (1 series) disc would fit (offset etc).

It's too bad that there's no data on the bmw performance (/m) discs. Normal discs are also made by brembo etc and they have data on their site, but but that's not the case for the performance /m discs.

The rear still is a matter of making your own like I did. I don't think I've seen a manufacturer making a rear bbk for a non m Z4.
Then again on a z4m you can't have the bmw performance calipers I think (unless you make them fit of course)

My rear setup still works fine. A few weeks ago I disassembeled my complete rear axle (I've replaced all 19 bushes for poly) so I had a good look. 1 e brake pad I welded again because it bent a bit during desassembly.
Carefully tig welding (nice small weld) stops the need to grind off the weld on the pad for the spring to fit. (grinding the weld weakens the weld obviously)

Too bad that ECS is still incresing the sales price of the front bbk (I paid more than $500 less 1,5 years ago than the current price), but thats how things go.
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Custom Brembo BBK front/rear | Schrick cams | Schmiedmann headers/cats | Powerflex/strongflex PU bushings | Vibra-technics engine mounts | H&R anti rollbars

Last edited by GuidoK; 08-02-2013 at 08:14 PM.
GuidoK is online now   Netherlands
Reply With Quote
      08-03-2013, 07:33 AM   #8
Brigadier General
Drives: 2007 Z4 M roadster vt2-500
Join Date: Sep 2007
Location: UK

Posts: 3,576
iTrader: (0)

very impressive stuff
Pristine Bi-colour Ti /Bsm...z4m roadster Ess vt2-500....Perfection on wheels.
Beedub is offline   United Kingdom
Reply With Quote
      12-04-2013, 07:25 PM   #9
andrey_gta's Avatar
Drives: 130i coupé ;)
Join Date: Nov 2011
Location: Bimmerpost

Posts: 2,575
iTrader: (1)

Garage List
2008 BMW 128i  [0.00]
Originally Posted by GuidoK View Post
My rear setup still works fine.
Can you comment on the use of your idea with the 130i/135 shoe carier back plate to make the Handbrake work on 128i/125i for these rear perf brakes. Is it possible for 130i plate to be cut up and used to make 135i brake shoes fit?

The 128i shoes are smaller in diameter. Otherwise everything bolts on (caliper & rotor).
The proper fix requires 135i knuckle with 135i back plate and Hub and 135i hand brake shoes.

Some one on e90post has made e90 work using cusom expanded brake shoes instea of the whole back plate/knucle approach
128i Sport 6MT converted to Euro 130i spec, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: n54 ssk, m3 trans mnt, e36M lip Wishlist: m3 susp, n55 eng mnt, headers, LSD, finn dif e60

"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is

Last edited by andrey_gta; 12-05-2013 at 06:20 AM.
andrey_gta is offline   Canada
Reply With Quote
      12-05-2013, 05:40 PM   #10
"Midas Touch"
Drives: E86 ///M
Join Date: Aug 2007
Location: Seattle, WA

Posts: 332
iTrader: (7)

Did I see a similar conversion for the M cars up front?
R0ME0 is offline  
Reply With Quote
Post Reply


bbk, brake kit, oem

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -5. The time now is 05:34 AM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST