35I brake upgrade

stijohnny · Post by **stijohnny** » Tue Mar 16, 2021 11:31 pm

I have acquired a set of M4 calipers and have ordered a pair of 370mm Performance discs.
Can anyone tell me what else I need? What about backplates? Assuming the standards are too small now, do I order a set to fit 370mm ones? Is there anything else I need before I get the axle stands out???
Thanks in anticipation

richg · Post by **richg** » Wed Mar 17, 2021 7:52 pm

I went down the same route earlier this year. I went for the textar slotted and dimpled disc, plus textar pad as they were OE supplier I believe.

Textar Disc: 92265425 / OEM 34106797603
https://textar.com/wp-content/uploads/2 ... sc_ENG.pdf

I'll dig out the pad part numbers later.

I bought a new fitting kit and the garage bought the wear sensor. The wear sensor might have been different fitting for the caliper, I can't recall. The fitting kit for an M4 works. You might be able to re use what came with the calipers.

Brake line on my 35iS was fine.

I went with MTEC slotted and dimpled rear discs to match with textar pads - mine needed replaced at the time. This I would do differently, the rear pads is not chamfered and you can just hear it against slot in discs with roof down and windows up. Windows down you can definitely hear it. I'd get chamfered pads if they exist, plain rear discs or dimpled rear discs.

There is no noise from front as the pads I bought were chamfered.

Hope this helps.

Rich

stijohnny · Post by **stijohnny** » Thu Mar 18, 2021 9:06 pm

richg wrote: ↑Wed Mar 17, 2021 7:52 pm fitting kit for an M4

Thanks Rich, this is great info, I'll bare all this in mind. I ordered standard discs, ie not dimpled/grooved. I have a set of pads with the calipers and they are low miles so I'll give them a go before upgrading them.
Did the brake fitting kit include back plates? Did you need to swap them?
Thanks

richg · Post by **richg** » Fri Mar 19, 2021 10:01 am

I seem to recall the fitting kit was a retaining clip and two pins per caliper.

From memory the pads came with backing plates perhaps.

I got both the front pads and fitting kit from eurocarparts. The 435d gran coupe comes with those calipers and 370mm discs so I used that as the vehicle to search for parts using - with either plain or slotted and dimpled discs. The M4 comes with 380mm and, I think, a different pad.

Pbondar · Post by **Pbondar** » Fri Mar 19, 2021 11:56 am

Are you going to code the DCS to let it know about the BBK?

richg · Post by **richg** » Fri Mar 19, 2021 2:06 pm

I'm not without conclusive evidence that it's necessary. I'd also want to understand exactly the impact of the change would have on the software if not a normal BMW change.

The discussion on the German Z4 forum was not conclusive for me. They do it for F series. Welcome to more information if it's available now.

The actual balance shift is not huge - 2.05 vs 2.17 F/R. When you consider the factors that influence the system I'm not convinced the system can't already cope with this change. Factors at each wheel: surface, tyre, environmental, and brake pad/disc. Each wheel can experience significantly different levels of grip.

I think the sampling rate of the sensors will be key to the effectiveness of the system.

I tried to upload the spreadsheet that calculates brake bias but I can't so screen shot attached. I found it on another forum.

Rich

Pbondar · Post by **Pbondar** » Fri Mar 19, 2021 2:55 pm

richg wrote: ↑Fri Mar 19, 2021 2:06 pm I'm not without conclusive evidence that it's necessary. I'd also want to understand exactly the impact of the change would have on the software if not a normal BMW change.

The discussion on the German Z4 forum was not conclusive for me. They do it for F series. Welcome to more information if it's available now.

The actual balance shift is not huge - 2.05 vs 2.17 F/R. When you consider the factors that influence the system I'm not convinced the system can't already cope with this change. Factors at each wheel: surface, tyre, environmental, and brake pad/disc. Each wheel can experience significantly different levels of grip.

I think the sampling rate of the sensors will be key to the effectiveness of the system.

I tried to upload the spreadsheet that calculates brake bias but I can't so screen shot attached. I found it on another forum.

Rich

The BBK coding is done in the VO / as 'retrofit sports brakes' factory option in Protool?

That toggles various DSC options on like soft start /soft stop/ e-diff etc plus actual parameters in the pressures etc

Had quite a marked effect on pedal sensitivity and other behaviour..

if you can give me the link to the other forum that would be great.

richg · Post by **richg** » Fri Mar 19, 2021 7:34 pm

Thanks for that info

Sounds like the understanding has moved on since I last looked into it. I'll look into that software.

Are you running the 370mm setup Pbondar? With lockdown I've not had much cause to drive and even less in a spirited fashion.

The kit sat for 6 months before I had it fitted then we hit second lockdown.

richg · Post by **richg** » Fri Mar 19, 2021 7:50 pm

https://www.zroadster.com/forum/

Pbondar · Post by **Pbondar** » Fri Mar 19, 2021 10:59 pm

I fitted the E90 M3 official BMW BBK to my non 35 Z4 and then retrofitted the Z4 35is rear brake as well

viewtopic.php?f=46&t=123860&start=30

viewtopic.php?f=23&t=126288

Also a Quaife LSD

So pondered a lot about the DSC implications

TomK · Post by **TomK** » Sat Mar 20, 2021 12:54 am

Pbondar wrote: ↑Fri Mar 19, 2021 10:59 pm I fitted the E90 M3 official BMW BBK

I'd say that's difficult given no such thing exists.

richg · Post by **richg** » Sat Mar 20, 2021 8:15 am

OK, would be interesting to see brake bias calculation for your specific setup.

I found the brake bias spreadsheet online but can't find original source to link. PM me with email address and I can email over.

Rich

MACK · Post by **MACK** » Sat Mar 20, 2021 8:50 am

Pbondar wrote: ↑Fri Mar 19, 2021 10:59 pm I fitted the E90 M3 official BMW BBK to my non 35 Z4 and then retrofitted the Z4 35is rear brake as well

viewtopic.php?f=46&t=123860&start=30

viewtopic.php?f=23&t=126288

Also a Quaife LSD

So pondered a lot about the DSC implications

That must have made one hell of a difference over the 300/300mm combo on the 20i as standard

Pbondar · Post by **Pbondar** » Sat Mar 20, 2021 10:24 am

TomK wrote: ↑Sat Mar 20, 2021 12:54 am
Pbondar wrote: ↑Fri Mar 19, 2021 10:59 pm I fitted the E90 M3 official BMW BBK
I'd say that's difficult given no such thing exists.

There is always one...

It’s a BMW kit that gives you M3 brakes to be retrofitted to E90 versions...

https://www.bimmerworld.com/Brakes/Big- ... 44738.html

Pbondar · Post by **Pbondar** » Sat Mar 20, 2021 10:28 am

MACK wrote: ↑Sat Mar 20, 2021 8:50 am
Pbondar wrote: ↑Fri Mar 19, 2021 10:59 pm I fitted the E90 M3 official BMW BBK to my non 35 Z4 and then retrofitted the Z4 35is rear brake as well

viewtopic.php?f=46&t=123860&start=30

viewtopic.php?f=23&t=126288

Also a Quaife LSD

So pondered a lot about the DSC implications
That must have made one hell of a difference over the 300/300mm combo on the 20i as standard

Hi yes the rears less so but the fronts were a bit vicious until I applied the DSC parameters...

Without it they were too grabby and over powerful...on the last runs we did last year in the Borders the ABS kept kicking in as it was difficult to modulate it on greasy roads.

After applying the software fix the pedal pressure required is heavier and less initial grab...still very powerful, especially noticeable from very naughty speeds trying to scrub speed for low speed corners...

Z4-forum.com

Z4-forum.com