Yet another (relatively) low cost BBK for the E89

[B21]

The general feedback from most folks is that the stock brakes on the E89 are 'adequate'..that is no one complains about the brakes, certainly for everyday use..

However they are not the prettiest and if you start to push things harder then some of the limitations of the stock systems appear.

Of course twiddling with pads does have some effects, but there's no free lunch..pad design is a trade off between cost, wear rates, performance envelope and wear and tear on the discs.

One option for the 18i,20i and 23i is to swap the front discs and calipers from 300 x 24 mm to 330 mm x 20..rears are 300 mm by 20 mm for all non 35i/35is E89s.

You can even go to the 35is (35i in some markets) 348 mm x 30 front and 324 x20 mm rear as all brakes are fully interchange-able on the E89 range.

All these brakes are single sliding calipers...effective but not exactly sexy.

The E89 shares more or less the same front suspension as E90s..

A simple and cost effective brake kit is BMW's own 'Performance Brake' option, this is two 6 pot Brembos in a fetching gold colour with 338 by 26 mm discs ..retails in the UK for around £1,200..and its almost pure plug n play bar a brake pad sensor change..

https://www.schmiedmann.com/en/bmw-e90/ ... 9133826BBK

This has been used by a few E89s owners with no reported issues.

In my case I went with a 330 mm BMW 28i/30i caliper / discs upgrade to my 20i following its jump to 300 BHP and then used the Performance Brake...

I later transferred this same brake system to my 35i after I started tuning it.

Although everything works fine I had this nagging issue as I approached 550 BHP about maybe revisiting this issue.

To get one thing out of the way, its close to impossible to upgrade the rear brake beyond the 324 mm x 20 mm rear from a 35is (Euro 35i)..only one recorded attempt was made and it was a major effort.

The electronic parking brake is the issue..very difficult to retain that function and upgrade the calipers /discs..

The only known solution is to usw PB company in Taiwan which starts at £2,400 plus VAT and import duties.

https://www.pbbrakes.com/bmw-z4-e89-09- ... JOU8Hoxn3E

So having covered the basics and groundwork attention then moves to other options.

There are no shortage of BBK kits for the E89 from various suppliers, prices start at around £2,000 for something that may be an improvement over BMW's own Performance Brake kit..and quickly gets into the £3k area.

With the F series BMW started offfering as both standard fit and as an option a range of brake options based on the Brembo/BMW 4 pot design that addorns many F and G series cars.

Normally blue colour with a distinct 2 obvious externally facing pistons and mounted vertically.

The key point is that these calipers can bolt on to E89 and E90s pretty easily as well as their sister brake rotors.

What’s not so clear is there are two versions of this caliper (excluding colour choices) and 3 sizes of disks..

So that’s a 340 mm caliper , a 370/380 mm caliper and 340mm/370/380 mm discs..

By default on F series its a 340mm caliper with 340 mm by 30 disc or a 370/380 caliper with a 370 mm by 30 mm disc.

If you have an M series car you would have the 370/380 caliper with a 380 mm by 30 mm disc (different offset from 370 mm disc)

If you have the M series you can have a carbon ceramic disc n pads instead of steel..but since the pads and discs retail for around £10k we will skip that one.

In addition various third parties have made adapter brackets to allow various options..

I have the much cheaper 340mm caliper (which is identical to the 370/380 caliper apart from mounting location) and some adapter plates that allow the M4 380 mm discs to be bolted on an E89…

I sourced the calipers from Autodoc..I used ABS whose business is refurbed parts and used Zimmerman 380 mm by 30mm two piece rotors with stock Textar pads.

The calipers came in bare metal as do BMW's OE parts as an option..so I've used a rattle can and sprayed them phoenix gold to match the rears..and the outgoing Performance Brake.

A few pictures to break this post up!

First pick is rear 35is brake pad vs new F series front pad..

[axelleveau]

I will keep an eye on this as I have been toying with the idea of doing this on my E86 (when time and money is no problem...), which will be a path no one seem to have taken (and I am not happy with what I have seen on E46s). My hope is to manage to go for 363*32mm front (Land Rover discs) and 345xXX rear (E65).
B21 for your curiosity or anyone who might wonder how those 4 pots calipers compare to the E85 and the famous 6pot performance:

F30 vs E85.PNG (285.32 KiB) Viewed 2371 times

F30 vs 6pot.PNG (306 KiB) Viewed 2371 times

[B21]

I will keep an eye on this as I have been toying with the idea of doing this on my E86 (when time and money is no problem...), which will be a path no one seem to have taken (and I am not happy with what I have seen on E46s). My hope is to manage to go for 363*32mm front (Land Rover discs) and 345xXX rear (E65).
B21 for your curiosity or anyone who might wonder how those 4 pots calipers compare to the E85 and the famous 6pot performance:
F30 vs E85.PNG
F30 vs 6pot.PNG

Not an expert on E85 systems so can't really say....

If you use the 340mm calipers then its a very low cost starting point !

As I stated the E89s never felt badly braked..the 6 pot Performance Brake had a lovely feel to it and was easy to modulate the braking without needing the ABS to help...ironically the stock system seemed a bit 'snatchier'..

[B21]

The economic case is interesting..

340mm calipers are cheaper AND you can buy non OE alternatives new at lower costs..

Second hand 370/380mm calipers go for £500-£800 in average condition..new ones are around £1,600 a pair (they are handed)

Two new 340 mm calipers from ABS were £270

370 mm discs (Zimmerman, drilled and vented, two piece) are £360

380 discs are £500

You can't make a 340 mm to 370 mm adapter for space reasons..but for around £120 you can easily do a 340 mm to 380 mm M disc adapter..

So a 380 mm kit based on new ABS calipers and adapter brackets and 380 mm x 30 mm discs works out at around £1,000 with all the faff and paint..

A used 370mm caliper kit will cost about the same.

You can get an adapter to allow the 370 caliper to use 380 mm M disks for around £100..

Either way for £1,000 big stopping power...

[axelleveau]

Not an expert on E85 systems so can't really say....

If you use the 340mm calipers then its a very low cost starting point !

As I stated the E89s never felt badly braked..the 6 pot Performance Brake had a lovely feel to it and was easy to modulate the braking without needing the ABS to help...ironically the stock system seemed a bit 'snatchier'..

The issue is that those 340mm discs have a big offset difference with the E85 ones, also the jump from 325 to 340mm does not seem as interesting at pushing to 370mm or close to it hence going for 363mm Land Rover ones which are dirt cheap and should fit alongside caliper adapters.

Oh my comparison between the 6 Pot Performance and F30 4 pots was not to claim one is better than the other, more that the pad swept area is very similar

[B21]

Not an expert on E85 systems so can't really say....

If you use the 340mm calipers then its a very low cost starting point !

As I stated the E89s never felt badly braked..the 6 pot Performance Brake had a lovely feel to it and was easy to modulate the braking without needing the ABS to help...ironically the stock system seemed a bit 'snatchier'..

The issue is that those 340mm discs have a big offset difference with the E85 ones, also the jump from 325 to 340mm does not seem as interesting at pushing to 370mm or close to it hence going for 363mm Land Rover ones which are dirt cheap and should fit alongside caliper adapters.

Oh my comparison between the 6 Pot Performance and F30 4 pots was not to claim one is better than the other, more that the pad swept area is very similar

Hello…I’m not able to comment on E85s as I’ve not really driven them or twiddled with them..so you are on your own!

I’m not suggesting you were making a claim or not…until you’ve tried it almost back to back it’s difficult to predict..

Certainly for me having 380mm 30mm wide is going to help cooling when compared to 338 at 26mm..

I’m sure there will be plenty of E85 owners interested in your path..

[B21]

Pic of F series 340mm caliper vs 370/380mm caliper ..as stated mechanically identical bar extended casting for bigger spacing on 370/380 caliper..

[B21]

380 MM bad boy M4 discs arrived..Zimmerman's finest 2 piece..trial fit of caliper..

The caliper in isolation looked big..more of a pimple on that boy!

[B21]

A few pictures of a 338 x 27 Brembo E90 series 6 pot disc vs a F30 series 370mm x 30 disc from Zimmerman and a 380 x 30 mm M4 disc again from Zimmerman.

Note the weights and the relative small change is actual size of the discs as you change.

The OE 35is disc was a 348 x 30

Note the 380mm disc has a lower height of the hat compared to the others..this is what allows easily a bracket to be fitted to allow a 340mm F caliper to work with the 380 mm M disc...something you can't do with a 370 mm disc as its not possible to devise a bracket that works in the situation..

The conclusion is that the 380mm disc, with bracket works very cost effectively with the 340 F series caliper!

[B21]

Disc top hat height 370 vs 380

[B21]

Relative disc sizes overlaid

338 vs 370 and 370 vs 380

[B21]

Pics of discs..

[axelleveau]

Hi B21, could you by any chance tell me what screw diameter you adapter kit uses to go into the caliper and into the adapter itself?

[B21]

Hi B21, could you by any chance tell me what screw diameter you adapter kit uses to go into the caliper and into the adapter itself?

I’ll take some pics shortly

The bracket replaces the existing caliper inserts with new inserts and then provides its own bracket to caliper bolt!

[axelleveau]

Brilliant, thansk very much for the pictures! I am a bit surprised they provided a new bushing despite being M12, I guess that might be due to thread pitch availability on countersunk screw rather than to downsize the diameter or take advantage of an eccentric

Those pictures gave me the idea of using eccentric bushes offered for E9X rears adapters as the combination of eccentric and moving down to M10 would give more clearance between screws as with my plan on E85/6 to go from 340mm to 363mm the spacing between the screws is too small. If only I had time and money to go forward with it