E89 BBK for rear wheels..part deux

[B21]

The subject is BMW Z4 E89 rear brake upgrades.

The key point is that the E89 was one of the first BMWs to use the TRW integrated electrically operated parking brake which is part of what otherwise is an unremarkable sliding pin single piston rear caliper.

Because of this, its very difficult to find carry over solutions from other cars, like the E90s that carried on using a conventional handbrake.

One option for non 35is owners and for non-european 35i owners is to swap the basic 300mm x 20mm vented disc and caliper for a 324mm x 20mm 35is disc and its caliper. Pad size remains the same.

The only aftermarket rear brake solutions for EMF-based cars (including for the E89 Z4) is made by the Taiwanese firm, PB Brakes and Hong Kong based Ceika..typically at around £2,400 for a 348 mm disc..

From my view the style of their calipers is a bit gauche and really you'd need the front and rears to match which pushes it into a £5k-£6k solution.

There was one well documented US attempt at this by using later G series calipers, its fair to say it turned into an engineering nightmare requiring for example hand cut brake pads to make it work!

There were several cars that used broadly the same system and used 324mm or bigger discs.

The actual emf motor part is common to all these, so although some later cars use a different EMF ECU the motor is still the same..so it should work.

Group (A): F10 550i-x / F06 F11 F12 F13 640/650
Group (B): F06 640 / 650 M-sport
Group (C): G30 530e/i/iX 540i/iX/dX / M550iX / G11 750iX / G12 740i/iX 750i/iX

Group (A) and Group (B) share the same rotor 345mm x 24mm (p/n 34216775289). Basically the rear caliper and brackets are the same across both Group A & B, though B is powder coated black.
TRW.jpg
TRW.jpg (64.32 KiB) Viewed 82 times
Group (C): when coupled with the S2NHA (m-sport) package, has rear caliper (p/n 34216881295) and brackets (p/n 34206891915).

The US attempt was based on Group C calipers and turned into an engineering Vietnam!

However, on another forum I saw a Lithuanian had used a Group A/B caliper together with a different 345mn x 24mm disc from a F 5 series BMW with a different offset and some home made brackets.

The details were scant and the OP now long gone.

I've decided to resurrect this and have a go myself.

So Autodoc have my order now..

Carrier, brake caliper
£59.60
Article №: BDA1027 incl. 20% VAT
Quantity : 1
£59.60

Brake caliper
£125.52
Article №: BHS1190E incl. 20% VAT
Quantity : 1
£125.52

Brake caliper
£110.82
Article №: BHS1191E incl. 20% VAT
Quantity : 1
£110.82

Brake pad set
£56.24
Article №: 2470301 incl. 20% VAT
Quantity : 1
£56.24

Brake disc
£106.55
Article №: 150.3461.52 incl. 20% VAT
Quantity : 2
£213.10

Order total: £629

Brake caliper and caliper carrier are TRW and the discs are Zimmerman coated and drilled. Pads are Textar. One caliper carrier is missing so I've bought a 3rd party one and hope it works out OK.

[DozerPDX]

Really looking forward to seeing results. I'm based in the U.S. and there is so little information on brake fitment/upgrades on this model.

Would love to see pictures once they're on too!

Cheers!

[B21]

Originally Posted by DozerPDX

Really looking forward to seeing results. I'm based in the U.S. and there is so little information on brake fitment/upgrades on this model.

Would love to see pictures once they're on too!

Cheers!

I’ll do some updates as I get to it..parts dispatched from Germany this morning..

[B21]

So most of the parts arrived for the ‘small’ BBK for the rear..

F10 series calipers and E60 series disks…these rears are bigger than my current 6 pot Brembo front disks..

The F10 series caliper just looks like an upscaled copy of the E89 version.

Done a first paper mock up of a possible bracket to join these to the E89 chassis.

Not only is the disk much bigger 345 vs 300 or 324 for non 35is / 35is but the depth of the swept area is bigger..pic shows an E89 rear pad (same pad on both 300mm and 324mm rear discs) vs the E60 pad..

Autodoc do a cute trick with TRW ..they sell a ‘remanufactured’ real caliper for about a 1/5 of the price of an E89 caliper..

One caliper bracket wasn’t available in TRW OE supplier so bought a pattern part..interesting to see the myriad of differences…hopefully it will work ok..

[KennyP]

If this experiment proves to be successful... would you consider selling those custom brackets to others? Im sure there are some who are interested...

[B21]

Originally Posted by KennyP

If this experiment proves to be successful... would you consider selling those custom brackets to others? Im sure there are some who are interested...

I’ve asked for a quote for 10k..

[B21]

My quest to create a wide range of lower cost big brake upgrades for the E89 continues…this is looking at the more tricky rears..

So reflecting on the various issues I bit the bullet and bought a couple of old rear hubs and bits with a view to being a lot easy to faff around with bits off the car rather than on..

A few head scratching hours playing with the old bits and my new bits…plus lots of washers, spacers, bolts..

As Meatloaf would say 2 out 3 ain’t bad..however in this case you need all 3 things to work for it to be a viable solution..

These parts are for a 345 mm disc with a 44mm piston sliding caliper solution..roughly based on a 5 series non M

I’ve got a set of M5 rear calipers coming with the option of a 370mm or 380mm rear disc….

New disc is 345mm vs an old E89 300mm disc from the non 35i/35is E89s…

[B21]

First trial fit of the 345mm E60 discs with F series 5 caliper and my first attempt at a bracket ..looks pretty ok.

[KennyP]

Looking good...and quite straight forward with that adaptor plate, doesnt it?

[B21]

Originally Posted by KennyP

Looking good...and quite straight forward with that adaptor plate, doesnt it?

Yes after about 7 hours of messing with endless combinations of bolts, spacers, washers etc..needs the inside edge of the caliper carrier trimming in a couple of places…can’t see how to avoid that with out other structural compromises ..


Planning to make a kit for sale..

What do you think people would prefer ..basic bracket and bolts..

That plus modified caliper carrier

That plus whole caliper

That plus discs

Thoughts ?

[KennyP]

Braket, bolts and anything that needs to be modified being already modified(carrier?) is my guess... basically make it pure bolt on affair...
Calipers and discs(unmodified parts): ...well each customer can search by partnumber for the cheapest place to buy those locally...I wouldnt want to ship heavy discs to another side of the world,pay import duty on them and so on... but a bracket, bolts and modded carrier... that would be ok... some may even go to a breakers yard and get used calipers from there to really make it on a budget... im sure you can find some e60 bmw-s there to rob some calipers off of.. no?

or give buyer the option... like with n54 downpipes... buy just the downpipes or add gaskets, clamps and so on if they wish.

[B21]

So for many reasons the M5 caliper route is not as viable as the non M5 caliper route on F 5 series..

I tried but I’ve abandoned it..

370mm F 7 series looks do-able so investigating that next ..using the 5 series calipers

[B21]

The F01 7 series rear discs arrived..

Found a UK company selling high carbon content drilled discs to match my 380mm M2 M4 fronts..

So it turns out for the 370 rear disc two options exist..

Either you can use my 345mm caliper carrier bracket adapter with a F series M5 caliper carrier OR…await the second 370mm specfic bracket ..that uses the F series 5 550i carrier bracket…

In both cases the caliper bracket needs machining..not that the required machining is difficult to be done at home.

The rear caliper in all cases is the F series 5 550i caliper..

I’ll fit the 370mm rears to match my 380 M2/M4 discs mated to the Ford Mustang GT350 Brembo 6 pot calipers…this will keep the front / rear brake ratios in the correct area..

Price for 345mm or 370mm discs are around £150 for a pair…caliper carriers are around £50 ish and calipers can be had for £50.these are all new prices..so a rear brake kit kit for £350 plus the price of my brackets..

Pics show stock rear Z4 300mm disc and 345 mm and 370mm disc options..

[B21]

Reference my lost cost rear big brake upgrade..

Trying to get pad alignment on the discs perfect..getting hard work cutting these brackets out in steel so went for 3D printing purely for alignment purposes…

So the good news is that the 345mm version is now perfect with the pad sat nicely on the disc using all the pad and most of the disc..previously the top of the pad was just fractionally past the top flat part of the disc..

The 370mm version needs one more iteration as the front of the pad is siting fractionally lower than the rear..2mm adjustment on the front caliper bracket hole should see it..

Then ready to hand them over to the laser / water cutter boys to fab a few..

Interesting to see how much disc the original 300mm rear disc pad missed..

[B21]

One of the things I’ve always disliked with E89 rear calipers is the unfinished look caused by them using a casting process using steel…this ends up with a pebble dash look that no amount of paint hides..-plus the remnants of the cast flash lines etc..

I bought a pair of F series M5 rear calipers for developmental purposes for my rear E89 big brake kit..

I discovered that the caliper itself (not the carrier) is in fact the same as the F series 5 50i caliper I’m using for production of the BBKs.

So I decided to refurbish these and re-use them.

I’ve never liked the blue that is now so popular on BMW calipers ..

So..a belt sander, conventional sander, flap wheel in the 4.5 angle grinder and a dremel later..

Voila..polished caliper ready (subject to final finish) for treating and spraying in your preferred colour..

Pics show blue and silver calipers pre process and calipers on their way to final polish before painting..