Varying brake feel

[Rene_Z4MC]

I notice with some spirited driving that the biting point of the brakes seems more aggressive then when going at regular speeds.
I've read somewhere that there is clever stuff going on with the brakes on the ///M, like pads keeping the disc dry when its raining and automatic hill-assist.
Is this also a known feature?

 

[beanie]

I seem to remember reading about a brake boosting feature that happens when you come off a heavy throttle and on to the brakes really quickly. Not sure if its a physical (vacuum?) or a coded thing though.

Ive had it happen a few times and it's quite annoying really.

 

[srhutch]

Drying the pads/discs and hill assist is standard on all Z4's at least from facelift, not just ///M's

 

[Bing]

This isn't specific to the M - and I think it applies to both pre and post facelifts. Certainly my last (facelift) Z had them.

With auto wipers on the rain sensor for the wipers also informs whatever controls the brakes and periodically sits the pads just off the discs to dry them. The wetter it is the more often it does it. However you shouldn't notice it happening. I'm not sure if this feature comes on cars without auto wipers because of course they have no rain sensor. Think all Ms have auto wipers though.

The priming of the brakes happens as beanie says when you accelerate hard and lift off sharply - the pedal feel is much firmer with much less travel to full application of the brakes. It's anticipating a need to stop quickly - fair enough really - and is effectively supplementing your reaction time with some of its own. I found it quite intrusive - and scary - when I got my first Z, but in my experience you do get used to it and tend to subconsciously anticipate it when you behave in a way that provokes it.

The hill assist feature kicks in when you sit on an incline with your foot on the brakes - when you take it off the car will hold the brakes on for 3 or 4 secs, and they release as you engage the clutch. If you do nothing with the clutch depressed you will of course roll backwards after 3/4 secs

 

[simonlpearce]

On a side note, if you haven't had your fluid changed for a while and are running some aggressive pads, you could be boiling your fluid which will naturally go spongy after some spirited driving.

Interesting stuff though about the adaptive brakes, never knew that.

 

[JimmiVW]

I have to admit I find it a little 'odd' to have a variable brake feel under different conditions... Makes it harder to modulate your human inputs!
- the hill assist thing is nice, but I still find myself using the handbrake a lot, I guess old habits die hard

Does anyone know if swapping to a Big Brake Kit (new callipers etc) removes these functions or is it all electrically controlled before the callipers (i.e. increasing pressure in the system)? From inspection I can't see any level of 'control' at the callipers, which would suggest it's controlled elsewhere through hydraulic pressure.

 

[Rene_Z4MC]

I seem to remember reading about a brake boosting feature that happens when you come off a heavy throttle and on to the brakes really quickly. Not sure if its a physical (vacuum?) or a coded thing though.

Ive had it happen a few times and it's quite annoying really.

This matches exactly with my experience. Nice to know that it is not specific for my car, thanks for the feedback.

 

[Rene_Z4MC]

Drying the pads/discs and hill assist is standard on all Z4's at least from facelift, not just ///M's

Ok, didn't know that.
Do the non-Ms also suffer from the effect that I described?

 

[Rene_Z4MC]

On a side note, if you haven't had your fluid changed for a while and are running some aggressive pads, you could be boiling your fluid which will naturally go spongy after some spirited driving.

This is certainly not the case, also the effect I experience is quite the opposite; not spongy but suddenly a bit harder/more direct.

 

[Bing]

Drying the pads/discs and hill assist is standard on all Z4's at least from facelift, not just ///M's

Ok, didn't know that.
Do the non-Ms also suffer from the effect that I described?

My facelift auto did.

 

[mad4slalom]

hmmm , yes , I just thought the M's were over braked at the top of the pedal. I too have found this annoying , as you come off the throttle quickly to just "cover " the brake pedal and it actually brakes Really sharply and passengers think you have panicked or over reacted. I didnt realise either that this is designed in to the system, ....maybe the same person that figured the cdv was a good idea. one more thing that adds to the "drivers car" thing, they certainly didnt make them easy to drive,... still love it though :thumbsdown:

 

[Rene_Z4MC]

I didnt realise either that this is designed in to the system, ....maybe the same person that figured the cdv was a good idea. one more thing that adds to the "drivers car" thing, they certainly didnt make them easy to drive,... still love it though :thumbsdown:

I'm a bit disappointed that this 'analogue ///M' has quite a few of these annoying quircks.
Most are easy to solve though. How about this brake thing, is there a known work-around?