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Brake Bias
- eyup
- Member
- Posts: 374
- Joined: Sat Jun 07, 2008 6:17 pm
- Location: East Riding of Yorkshire
Brake Bias
Morning all,
Simply because I don't know and a quick search did not reveal the answer. What is, if there is any, the foot brake bias front/rear on the z4 coupe?
Thank you
Simply because I don't know and a quick search did not reveal the answer. What is, if there is any, the foot brake bias front/rear on the z4 coupe?
Thank you
Coupe - Montego Blue. 108's, simplest mod - second medical box
The journey so far;
i) 1998 Ford Focus 1.8 Litre
ii) The Z
iii) what else is needed?
The journey so far;
i) 1998 Ford Focus 1.8 Litre
ii) The Z
iii) what else is needed?
- Ewazix
- Lifer
- Posts: 4721
- Joined: Sun May 02, 2010 5:30 pm
- Location: Somerset
Brake Bias
The ABS DSC/traction modules continuously optimise braking forces, the underlying braking potential of the front with bigger discs and multiple pots probably gives a ratio of about 60/40 but in use the dynamic bias isn't fixed.
I always wonder if people are getting the best out of the system when they only upgrade their front brakes but assume serious track guys with modded set-ups will have discovered the advantages, and limits
I always wonder if people are getting the best out of the system when they only upgrade their front brakes but assume serious track guys with modded set-ups will have discovered the advantages, and limits
2003 2.5 SE, low miles, Sterling Grey, 108's & Eagles, no stubby here! Unmolested.
2018 Cooper S Countryman
Fiesta Ecoboost
2018 Cooper S Countryman
Fiesta Ecoboost
- eyup
- Member
- Posts: 374
- Joined: Sat Jun 07, 2008 6:17 pm
- Location: East Riding of Yorkshire
Brake Bias
Great. Thank you
Coupe - Montego Blue. 108's, simplest mod - second medical box
The journey so far;
i) 1998 Ford Focus 1.8 Litre
ii) The Z
iii) what else is needed?
The journey so far;
i) 1998 Ford Focus 1.8 Litre
ii) The Z
iii) what else is needed?
- Steve84N
- Senior Member
- Posts: 1828
- Joined: Tue Jul 21, 2015 1:00 pm
Brake Bias
All Z4s have single pot calipers.
I have felt the difference of upgrading brakes back on my old Fiesta Mk4.
- Started with 240mm solid and drums
- Changed front for 260mm vented (pretty big jump but not amazing)
- Changed rears to solid discs (definitely noticeable but drums are pants)
- Changed fronts to 280mm vented (amazing stopping power)
It was only a 1.25 with no ABS but it ended up with very good braking. You can get away with less extreme front only upgrades but improving the rear helps too.
You will probably find that your rear brakes are doing less than 30% of the braking when under load.
www.stoptech.com/technical-support/tech ... ce-matters
I have felt the difference of upgrading brakes back on my old Fiesta Mk4.
- Started with 240mm solid and drums
- Changed front for 260mm vented (pretty big jump but not amazing)
- Changed rears to solid discs (definitely noticeable but drums are pants)
- Changed fronts to 280mm vented (amazing stopping power)
It was only a 1.25 with no ABS but it ended up with very good braking. You can get away with less extreme front only upgrades but improving the rear helps too.
You will probably find that your rear brakes are doing less than 30% of the braking when under load.
www.stoptech.com/technical-support/tech ... ce-matters
C63 AMG Estate 6208cc
- Ewazix
- Lifer
- Posts: 4721
- Joined: Sun May 02, 2010 5:30 pm
- Location: Somerset
Brake Bias
Your experience with the rear upgrades makes sense, I guess the benefit of upgrading rears with the front would be even more noticeable on the Z4 with 50/50 weight bias as opposed to a typical FWD like your Fiesta with about a 60F/40R weight distribution.Steve84N wrote: ↑Sun Oct 14, 2018 7:59 am All Z4s have single pot calipers.
I have felt the difference of upgrading brakes back on my old Fiesta Mk4.
- Started with 240mm solid and drums
- Changed front for 260mm vented (pretty big jump but not amazing)
- Changed rears to solid discs (definitely noticeable but drums are pants)
- Changed fronts to 280mm vented (amazing stopping power)
It was only a 1.25 with no ABS but it ended up with very good braking. You can get away with less extreme front only upgrades but improving the rear helps too.
You will probably find that your rear brakes are doing less than 30% of the braking when under load.
brakebias_5.jpg
www.stoptech.com/technical-support/tech ... ce-matters
2003 2.5 SE, low miles, Sterling Grey, 108's & Eagles, no stubby here! Unmolested.
2018 Cooper S Countryman
Fiesta Ecoboost
2018 Cooper S Countryman
Fiesta Ecoboost
- Steve84N
- Senior Member
- Posts: 1828
- Joined: Tue Jul 21, 2015 1:00 pm
Brake Bias
Depends how you drive it.
Having more rear braking power on a FWD is actually very noticeable if you're still on the brakes into a corner as it can give you less understeer (explained in that article above).
Having more rear braking power on a FWD is actually very noticeable if you're still on the brakes into a corner as it can give you less understeer (explained in that article above).
C63 AMG Estate 6208cc
-
- Member
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- Joined: Wed Jul 26, 2017 12:32 pm
- Location: Newbury, Berks UK
Brake Bias
Differences in static weight distribution are largely irrelevant, as it’s all about weight transfer forward under braking. The rear brakes are always limited in what they can add to the overall braking as weight is transferred to the front during braking and the last thing you want is the rears locking up and causing instability in the car.
I would assume that the lower down centre of gravity and relatively stiff suspension on a sports car like a Z4 will result in less weight transfer forward than say a typical rolly polly FWD hatchback so you probably can make more use of the rear brakes before risk of locking occurs (or the ABD system reduces rear brake prsssure before this happens).
Chris
I would assume that the lower down centre of gravity and relatively stiff suspension on a sports car like a Z4 will result in less weight transfer forward than say a typical rolly polly FWD hatchback so you probably can make more use of the rear brakes before risk of locking occurs (or the ABD system reduces rear brake prsssure before this happens).
Chris
08 Z4 3.0si Sport Coupe in Montego Blue
- Steve84N
- Senior Member
- Posts: 1828
- Joined: Tue Jul 21, 2015 1:00 pm
Brake Bias
Strangely, you get more rear brake bias with less load on the rear and a higher centre of gravity.
Probably why FWD cars have smaller rear brakes as they want to keep the bias down for benign handling whereas RWD cars have bigger rear brakes relatively speaking.
Probably why FWD cars have smaller rear brakes as they want to keep the bias down for benign handling whereas RWD cars have bigger rear brakes relatively speaking.
C63 AMG Estate 6208cc
- MrPT
- Lifer
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- Location: Bucks/Oxon
Brake Bias
The E46 M3 community has put a lot of time into static bias calculations. I was trying to understand them (and mostly failed) when I upgraded my front brakes and came away with the impression that they are still useful as a reference point once you start modifying components, mixing pads etc.
The range of values being talked about for the M3 runs between about 1.5:1 and 2.25:1, so between 60/40 and 69/31 F:R. Stock is about 66/34. This is at the axle, so takes into account the whole braking system but not the tyres and their interaction with the road.
The range of values being talked about for the M3 runs between about 1.5:1 and 2.25:1, so between 60/40 and 69/31 F:R. Stock is about 66/34. This is at the axle, so takes into account the whole braking system but not the tyres and their interaction with the road.
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone
2006 Z4 2.5si: gone
- BMWZ4MC
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Brake Bias
I'll second this, as evidenced when I changed from Eibachs with OEM dampers to KW Clubsports. The reduced pitching under braking led to a marked reduction in braking distances in track driving.rally-chris wrote: ↑Sun Oct 14, 2018 8:28 am Differences in static weight distribution are largely irrelevant, as it’s all about weight transfer forward under braking. The rear brakes are always limited in what they can add to the overall braking as weight is transferred to the front during braking and the last thing you want is the rears locking up and causing instability in the car.
I would assume that the lower down centre of gravity and relatively stiff suspension on a sports car like a Z4 will result in less weight transfer forward than say a typical rolly polly FWD hatchback so you probably can make more use of the rear brakes before risk of locking occurs (or the ABD system reduces rear brake prsssure before this happens).
Chris
Z4MC - heavily fettled for track use
Lotus Exige - sensible daily driver on the mods slippery slope
Westfield SEiW - in hibernation
Modified RS4 Avant - back in Blighty
S2000 GT - gone
- Jembo
- Lifer
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- Joined: Sat Jun 25, 2011 11:59 pm
- Location: 1066 Country
Brake Bias
I experienced this on my old 3.0 when upgraded front from 300mm to 325mmEwazix wrote: ↑Thu Oct 11, 2018 8:34 am The ABS DSC/traction modules continuously optimise braking forces, the underlying braking potential of the front with bigger discs and multiple pots probably gives a ratio of about 60/40 but in use the dynamic bias isn't fixed.
I always wonder if people are getting the best out of the system when they only upgrade their front brakes but assume serious track guys with modded set-ups will have discovered the advantages, and limits
In the dry in summer, real noticeable difference though balanced.... in the winter especially when wet, if you ever really needed to slam on the anchors hard, the front ABS sometimes kicked in & you felt as if there was nothing there at the rear.
My stock //M brakes are more than adequate for me...
Joined the dark side with a ///M Hell Bronze Sepang Coupe
Ex Aug 2005 Maldives Blue 3 litre cruizer, lots of toyz,
Lifer 54
Ex Aug 2005 Maldives Blue 3 litre cruizer, lots of toyz,
Lifer 54