Bigger Rear brakes? - BMW 3-Series (E90 E92) Forum

Nick10923 · 06-29-2005, 10:44 PM

Hey everyone my name is Nick as my sn implies. Anyway after going to the BMW Ultimate Driving experience and getting a chance to drive the new 330i I was looking at it a noticed that the rear brakes were bigger, sure enough I checked and the rear brakes are 13.2" while the fronts are 13.0", as compared to lasts years model with 12.8" up front and 12.6" in the back.
My question is why, I mean sure I have a few ideas why, but so far nobody at BMW has been able to tell me, I even went as far as to call BMW headquaters in Munich, Bavaria.
http://www.bmwusa.com/vehicles/3/20...an/techdata.htm

onesixeight · 06-29-2005, 10:57 PM

I'm not exactly sure why...but I noticed the same thing when reading the product literature...

With the E90's brake system able to change brake bias to each of the individual wheels, my best guess is that maybe BMW uses more brake bias to the rear in an attempt to balance out the weight during hard braking. Another note, although the rear rotor maybe larger than the front, the front caliper is still larger than the rear. Maybe during R&D testing, BMW found the rear rotors overheating more than the front???

scottz5 · 06-29-2005, 11:19 PM

I know the back pads wear fast on e46's compared to almost all other cars. I am thinking same as above.

visor · 06-29-2005, 11:37 PM

I think the rear brakes have been increased significantly in size due to the more extensive functions in DSC+, chiefly Start-off Assistant, DTC, and ASC+T. All these features use the rear brakes solely to reduce slipping of the driving wheels in slippery conditions, in addition to reducing engine output.

Nick10923 · 06-30-2005, 12:12 AM

Thanks for your input guys, I was thinking of the same things for the most part. It seems weird that they would need more mechanical advantage on the rear brakes. Usually the rear pads would wear out more because of their small size (at least thats how it is on my Accord). Anyway I'm going out of the country till July 20 so I probably won't be able to reply back for a while.

E90Fleet · 06-30-2005, 06:34 AM

The rear brakes have a bigger diameter but the front ones are thicker to absorb more heat

This isnt new the E46 M3 had a similar situation and the E60 and E65 have just about the same size ones all round

CC 330i · 06-30-2005, 01:20 PM

It's true that most cars have larger front brakes than the rear, and the e90 seems to be one of the few exceptions. (the only one I know about). It could be because of the near 50/50 weight distribution and the possibility that under constant hard driving, the DTS may be using the rear brakes a lot to keep someone on the road... If the rears were small and get used too much, they might lose effectiveness.

I was just reading some specs on the Fort GT (the new GT40) and it has the same sized rear rotors as the E90 330i. (13.2 inches.). The front rotors on the Ford GT are 14 inch though.

Pretty cool that our 330i has the same diameter rear rotors as a supercar! (but they are not crossdrilled like the GT though).

stressdoc · 06-30-2005, 02:08 PM

Another reason for the larger rear rotors is having to deal with the heavier wheels (wider) with zsp. But then I suppose it would make more sense to have the brakes linked to zsp.

CC 330i · 06-30-2005, 02:20 PM

Quote:

Originally Posted by stressdoc

Another reason for the larger rear rotors is having to deal with the heavier wheels (wider) with zsp. But then I suppose it would make more sense to have the brakes linked to zsp.

I am sure that this has something to do with it, but ALL 330i cars come with the bigger brakes, not just the ZSP equipped ones. And the standard 330i comes with 17 inch wheels and tires.

Dave C. '06 330i · 06-30-2005, 03:08 PM

I think it probably has something to do with the DSC.

I know the Corvette Z06 guys (I traded one on this BMW and was on alot of the Z06 performance forums) have to replace the rear pads very frequently when using the Active Handling (Corvette's stability control) when racing the car on a road course. The rear Corvette pads are smaller than the fronts.

-Dave C. '06 330i

stack · 06-30-2005, 03:35 PM

What is ZSP?

stack

CC 330i · 06-30-2005, 04:51 PM

Quote:

Originally Posted by stack

What is ZSP?

stack

It's the code for Sport Package. Not sure what the "Z" stands for.

scottz5 · 06-30-2005, 08:31 PM

Quote:

Originally Posted by Dave C. '06 330i

I think it probably has something to do with the DSC.

I know the Corvette Z06 guys (I traded one on this BMW and was on alot of the Z06 performance forums) have to replace the rear pads very frequently when using the Active Handling (Corvette's stability control) when racing the car on a road course. The rear Corvette pads are smaller than the fronts.

-Dave C. '06 330i

That is also true as a former Z06 owner, but those pads were small for the HP of the car. That car stopped so fast it hurt your neck.

06-29-2005, 10:44 PM	#1
Nick10923 2001 Honda Accord Concept sedan Drives: 2001 Honda Accord Join Date: Jun 2005 Location: Long Beach CA Posts: 4 iTrader: (0)	Bigger Rear brakes? Hey everyone my name is Nick as my sn implies. Anyway after going to the BMW Ultimate Driving experience and getting a chance to drive the new 330i I was looking at it a noticed that the rear brakes were bigger, sure enough I checked and the rear brakes are 13.2" while the fronts are 13.0", as compared to lasts years model with 12.8" up front and 12.6" in the back. My question is why, I mean sure I have a few ideas why, but so far nobody at BMW has been able to tell me, I even went as far as to call BMW headquaters in Munich, Bavaria. http://www.bmwusa.com/vehicles/3/20...an/techdata.htm
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06-29-2005, 11:19 PM	#3
scottz5 Major Drives: 11 F10 535i Join Date: May 2005 Location: Jersey Shore Posts: 1,228 iTrader: (0) View scottz5's Garage	I know the back pads wear fast on e46's compared to almost all other cars. I am thinking same as above. __________________ 11 F10 535i AW/Cin Brown/Anthracite Headliner/Dark Wood, ZPP, ZP2, ZSP, 775, 2TB 06 E90 330i Sold 01 E46 325i Sold

06-29-2005, 10:57 PM	#2
onesixeight First Lieutenant Drives: E92 M3 Join Date: May 2005 Location: Seattle, WA Posts: 322 iTrader: (0)	I'm not exactly sure why...but I noticed the same thing when reading the product literature... With the E90's brake system able to change brake bias to each of the individual wheels, my best guess is that maybe BMW uses more brake bias to the rear in an attempt to balance out the weight during hard braking. Another note, although the rear rotor maybe larger than the front, the front caliper is still larger than the rear. Maybe during R&D testing, BMW found the rear rotors overheating more than the front???

06-29-2005, 11:37 PM	#4
visor BMW, can I have some LSD please? Drives: '08 E90 335i Join Date: Jun 2005 Location: Vancouver, Canada Posts: 1,486 iTrader: (0)	I think the rear brakes have been increased significantly in size due to the more extensive functions in DSC+, chiefly Start-off Assistant, DTC, and ASC+T. All these features use the rear brakes solely to reduce slipping of the driving wheels in slippery conditions, in addition to reducing engine output.

06-30-2005, 12:12 AM	#5
Nick10923 2001 Honda Accord Concept sedan Drives: 2001 Honda Accord Join Date: Jun 2005 Location: Long Beach CA Posts: 4 iTrader: (0)	Thanks for your input guys, I was thinking of the same things for the most part. It seems weird that they would need more mechanical advantage on the rear brakes. Usually the rear pads would wear out more because of their small size (at least thats how it is on my Accord). Anyway I'm going out of the country till July 20 so I probably won't be able to reply back for a while.

06-30-2005, 06:34 AM	#6
E90Fleet Major General Drives: BMW Join Date: Apr 2005 Location: South Africa Posts: 6,515 iTrader: (0)	The rear brakes have a bigger diameter but the front ones are thicker to absorb more heat This isnt new the E46 M3 had a similar situation and the E60 and E65 have just about the same size ones all round

06-30-2005, 01:20 PM	#7
CC 330i Captain Drives: 330i SG/Blk/Alum Join Date: May 2005 Location: Orange County, CA Posts: 714 iTrader: (0)	It's true that most cars have larger front brakes than the rear, and the e90 seems to be one of the few exceptions. (the only one I know about). It could be because of the near 50/50 weight distribution and the possibility that under constant hard driving, the DTS may be using the rear brakes a lot to keep someone on the road... If the rears were small and get used too much, they might lose effectiveness. I was just reading some specs on the Fort GT (the new GT40) and it has the same sized rear rotors as the E90 330i. (13.2 inches.). The front rotors on the Ford GT are 14 inch though. Pretty cool that our 330i has the same diameter rear rotors as a supercar! (but they are not crossdrilled like the GT though).

06-30-2005, 02:08 PM	#8
stressdoc Moderator Drives: 335 E90 ZSP+ Join Date: Jun 2005 Location: MO Posts: 8,820 iTrader: (0)	Another reason for the larger rear rotors is having to deal with the heavier wheels (wider) with zsp. But then I suppose it would make more sense to have the brakes linked to zsp.

06-30-2005, 03:08 PM	#10
Dave C. '06 330i Private First Class Drives: Saphire Black 330i Join Date: Jun 2005 Location: Florida Posts: 71 iTrader: (0)	I think it probably has something to do with the DSC. I know the Corvette Z06 guys (I traded one on this BMW and was on alot of the Z06 performance forums) have to replace the rear pads very frequently when using the Active Handling (Corvette's stability control) when racing the car on a road course. The rear Corvette pads are smaller than the fronts. -Dave C. '06 330i

06-30-2005, 03:35 PM	#11
stack Private Drives: 06 325i Join Date: Jun 2005 Location: Rochester, NY Posts: 54 iTrader: (0)	What is ZSP? stack