Its a rear big brake kit Jim, but not as you know it!

[B21]

Great news!

Do you already have an idea, which material will be taken for the adapters? Maybe I can ask the German TUEV inspector about his view and requirements for such a solution.

Short summary:
- 345mm x 24mm (p/n 34216775289) rotors new from BMW cost about 130€ each.
- partnumbers of the rear calipers are 34216793047/34216793047? New from BMW 290€ each.
- brackets 34216793053/34216793054? New from BMW 240€ each.

Robbi..here is a DRAFT version of my buying / installation instructions…it would be helpful to have a review of this…I’ll edit it as we get closer
to production date..likely February..

https://www.dropbox.com/scl/fi/qscymxyp ... ny9m8&dl=0

The adaptor plates are oversized relative to the loads they’ll endure (they are nearly twice as thick in cross section compared to the caliper carrier..and they are in rolled steel compared to being cast like the cradle)…

There is a choice of materials that they can be made from …S355J2 cold rolled steel or 304 stainless …stainless is about 5 times more expensive..

Any thoughts on folks paying an extra £40 over the basic price for stainless..?

I’d suggest folks buy their stuff from Autodoc..

Practically buying BMW versions are unnecessarily expensive …

The calipers and discs are pretty low tech…if you’re fussy you can buy high carbon discs with / without pretty holes much cheaper elsewhere..

My doc has target pricing ..of course you can buy BMW product ..but IMHO it’s unnecessary..

I would assume even in Germany if the product is supplied by Autodoc and is for the exact BMW part number that should be OK?

I’ve bought a variety of non BMW versions of discs , calipers and cradles and can’t see any issues…

A complete solution for 345mm should be around £500-£600 and for 370mm should be around £600-£700

[RobbiZ4]

Robbi..here is a DRAFT version of my buying / installation instructions…it would be helpful to have a review of this…I’ll edit it as we get closer
to production date..likely February.

Got it, thanks.
Will have a look on it tonight.


Using original BMW parts might reduce discussion points with the TUEV inspectors.
Can you evaluate the material quality used from my material sheet I sent to you?

[B21]

Robbi..here is a DRAFT version of my buying / installation instructions…it would be helpful to have a review of this…I’ll edit it as we get closer
to production date..likely February.

Got it, thanks.
Will have a look on it tonight.


Using original BMW parts might reduce discussion points with the TUEV inspectors.
Can you evaluate the material quality used from my material sheet I sent to you?

The steel used in that bracket / data sheet is super high quality stuff normally used for con rods and pistons pins..

Not sure it’s actually relevant in this case as the bracket in ‘normal’ low carbon steel is ..the ultimate strength is about 50% of that steel..

I’m not aware of the argument of say a BMW supplied disc vs say a Brembo that Brembo says fits..

[RobbiZ4]

Well, BREMBO is OEM, i.e. Zimmermann AFAIK not. For the latter a special document is required (i.e.ABE).

[B21]

Well, BREMBO is OEM, i.e. Zimmermann AFAIK not. For the latter a special document ist required (i.e.ABE).

Well I guess then if you buy the OE supplier versions then you’re OK..your choice ..no restrictions on my part..

FWIW that steel although strong is best suited for higher temperature applications such as those in an engine ..it’s not designed to handle cold weather issues such as found on calliper brackets on a freezing day..

[B21]

Brackets for the 345mm E89 rear BBK arrived from the shop..

[B21]

The epic story continues..

Despite lots of testing on a rig, as usual the real world bits..

The slightly modified location and the different location of the feed point on the the 5 series rear calipers means extra long hydraulic pipes..

Also a pitfall of stainless braided pipes is a poor bending circle so the routings need modification…

And to emphasise the ping about subtle differences..

Why is there at least 3 ways to route a hose straight after the caliper ..the bracket mounted to the back of the caliper

Here are 3 versions..E89 right, F10 centre M5 left of a simple clip..only the E89 works for us..

[B21]

The final iteration of the 370mm rear disc caliper cradle bracket in 3D printing looks good…will press the button on the manufacture of them now..

[dumaurier7]

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..

i'll be interested in the 370mm kit for my Euro 35i!

[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..

i'll be interested in the 370mm kit for my Euro 35i!

Hopefully testing will be done in the next 3 weeks then can advise..1,000 mile road trip

[mittu]

I've seen online (cant find it now; sods law) someone retrofitting g30 m sport rear calipers with f10 345mm rear discs.
BMW also offer the same calipers unpainted as standard on some of the g30 models.
Is there any chance your adpator would fit this caliper?

I ask because this caliper uses the same spec discs as the f10 caliper in your kit (pdc & hat will differ. Ears maybe?), however is far more widely available.
Extremely common on the used market, with the added benefits of being newer, less worn, already painted blue with the m sport badge.

[B21]

I've seen online (cant find it now; sods law) someone retrofitting g30 m sport rear calipers with f10 345mm rear discs.
BMW also offer the same calipers unpainted as standard on some of the g30 models.
Is there any chance your adpator would fit this caliper?

I ask because this caliper uses the same spec discs as the f10 caliper in your kit (pdc & hat will differ. Ears maybe?), however is far more widely available.
Extremely common on the used market, with the added benefits of being newer, less worn, already painted blue with the m sport badge.

That initial version turned into a nightmare if it’s the G30 caliper..the OP used some CSL front discs ..it turned into a Vietnam with so many modifications required to pads, calipers, knuckles etc..

The F series 5 calipers are readily available both as OE and other suppliers

[B21]

I had an issue with one of my brake carrier bolts backing out…maybe caused by the stress of the uprated rear brake, maybe cause I didn’t use the old caliper cradle bmw bolt which has some primitive antilock washer fitted..maybe because I’d remounted the caliper cradle several times the loctite had worn off..

So using these fancy nord lock washers in super harden steel..arguably the best anti vibration washer…

Fresh 10.9 high tensile bolts…double locked the through bolts..

Did try the wire lock strategy but close to impossible to drill the bolt heads to allow the wire to be threaded..

Lots of medium strength loctite this time..

[B21]

Version 3 of the rear brake caliper adaptor for the 370mm rear disc conversion using a standard F series 5 caliper…

After discussions with a brake caliper bracket guru thickened the bracket from 12mm to 15mm in S355 steel…..

This will allow me to machine a mm or so off this bracket to allow it to bolt the caliper cradle up without having to use any spacer washers..plus..

This version allow for the 370mm version to machine the caliper cradle without having to machine out the entire gap between the front and rear mounts

[B21]

Things spinning out of control….now using CAD to make caliper bracket adapters…version 5 sent off for cutting..