E92 M3 Brakes

[REP1KRR]

Originally Posted by ImOntheWater

Hi Steve,

IIRC you were one of the first on BM3W to put AP's on your CSL, and didn't you weigh the old calipers when changing over? Aren't the AP's a lot lighter than the standard BMW parts too, therefore reducing unsprung weight? That and the fact that they look awesome.

Unsprung weight would include the rotors, not the calipers. Rotors spin, calipers don't.

[ImOntheWater]

Originally Posted by REP1KRR

Unsprung weight would include the rotors, not the calipers. Rotors spin, calipers don't.

I think you'll find that the calipers are mounted within the wheels, to the hub carriers, and therefore count as unpsrung weight.

"Unsprung Weight
In a ground vehicle with a suspension, the unsprung weight (or, more properly, the unsprung mass) is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them, rather than supported by the suspension. (The mass of the body and other components supported by the suspension is the sprung mass.) Unsprung weight includes the mass of components such as the wheel spindles, wheel bearings, tires, and a portion of the weight of driveshafts, springs, shock absorbers, and suspension links. If the vehicle's brakes are mounted outboard (i.e., within the wheel), their weight is also part of the unsprung weight."

http://en.wikipedia.org/wiki/Unsprung_weight

[Woms]

Originally Posted by REP1KRR

Unsprung weight would include the rotors, not the calipers. Rotors spin, calipers don't.

Oh dear.

[bullitt5897]

I was about to say something about that hehe
the only things I can see that you could lower unsprung weight in would be the rotors, rims, and tires. and if you are really worried about unsprung weight that much go spend about 12grand on some good dymag rims, and another 3-6grand on carbon composite rotors. that out to cut some weight. anyway I think BMW has got some brains and put in 6 pot and 4 pot brakes WOOHOO. if I miss counted I will proudly wear my DUNCE CAP!!!

[E90Fleet]

Originally Posted by bullitt5897

I was about to say something about that hehe
the only things I can see that you could lower unsprung weight in would be the rotors, rims, and tires. and if you are really worried about unsprung weight that much go spend about 12grand on some good dymag rims, and another 3-6grand on carbon composite rotors. that out to cut some weight. anyway I think BMW has got some brains and put in 6 pot and 4 pot brakes WOOHOO. if I miss counted I will proudly wear my DUNCE CAP!!!

Miscounted, compare to M5/M6 brakes

[bullitt5897]

the brakes appear to be the same 6 front 4 rear

[bullitt5897]

its just placement and picture size that makes them look off. If you compare rotor to calipers they cover about the same area.

[E90Fleet]

Originally Posted by bullitt5897

the brakes appear to be the same 6 front 4 rear

So you say they look the same

But the M5 and M6 only have 2 pots up front and 1 in the rear

[E90Fleet]

The M5 2 pot front caliper

[bullitt5897]

ok I see thanx for clarifying lol *puts on cap and sits in corner*

[ksfrogman]

I too have wondered why BMW uses single-piston calipers. I have no experience driving other models, but that brake unit on my E90 was very touchy, and difficult to apply even pressure linearly to stop. I had to compensate by applying not-so-linear brake pressure with my foot.

EDIT: just read Fleet's post. I'm curious to know what the M3 will get.

[REP1KRR]

Originally Posted by ImOntheWater

I think you'll find that the calipers are mounted within the wheels, to the hub carriers, and therefore count as unpsrung weight.

"Unsprung Weight
In a ground vehicle with a suspension, the unsprung weight (or, more properly, the unsprung mass) is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them, rather than supported by the suspension. (The mass of the body and other components supported by the suspension is the sprung mass.) Unsprung weight includes the mass of components such as the wheel spindles, wheel bearings, tires, and a portion of the weight of driveshafts, springs, shock absorbers, and suspension links. If the vehicle's brakes are mounted outboard (i.e., within the wheel), their weight is also part of the unsprung weight."

http://en.wikipedia.org/wiki/Unsprung_weight

What about...but are you supposed to...well think about... Oh, never mind!

Sorry for screwing that up - true on the Wiki def. But, isn't the real concern with reducing unsprung weight, the concern of reducing rotating mass?? So, rotors, wheels, tires, yes? What good would lightening your calipers do, besides just overall weight reduction of the vehicle?

I'm confused.

[bullitt5897]

lighter calipers just reduce vehicle weight over all. the new materials and composites dissapate heat better and can be stronger. Unsprung weight allows for more torque and power can truely be delivered to the wheels by lightening the weight/mass it has to turn to get going. it also allows for the brakes to be more effective as well limiting the amount of mass/weight it has to slow down to stop. just recently in the motorcycle field have we discovered counter rotating rotors and the affect they have. this was to determine if they would have an effect on turn in ability and come to find out they stop the bikes in half of the distance due to the speed at which they counter rotate. its scary how fast they stop. Ill see if i can find the article online and let you guys read about unsprung weight and the possible technology of counter rotating rotors!!! They are SCARY!!! how fast they stop a bike!!!

[bullitt5897]

here is the company's website.
http://www.reverserotatingrotors.com/

I saw this thing first hand at the track and wow they can brake so much later than me going into the turns and I brake really late (usually at the 1 marker right before the turn in point) they stop alot faster too. I couldnt find the original article that talked about unsprung weight but I can find a good article for yall on it. brb

[bullitt5897]

http://victorylibrary.com/brit/M-sprung-c.htm

[T Bone]

The thing I really hate about floating calipers is you cannot change the pads easily at the track.

In my old Porsche, take a clip off, compress the pistons and pull out the pads. 5 minutes / corner.

[E90Fleet]

Incase you guys didnt know, BMW's M5/M6 brake calipers are made by Continental, under their Continental Teves subsidiary

[enigma]

Originally Posted by T Bone

The thing I really hate about floating calipers is you cannot change the pads easily at the track.

In my old Porsche, take a clip off, compress the pistons and pull out the pads. 5 minutes / corner.

I would echo this. Proper fixed calipers are much nicer to work with. They can be a PITA to bleed though.

[Epacy]

Surely some of you have seen that BMW again included single piston calipers on the new M3. Kinda puzzled....

[ase2dais]

I undrestand that sinlge piston are better, any truth to that matter ?

[swamp2]

I'm sure the M3 will have identical or similar to the M5 dual pot brakes on the front. The english pdf spec sheet however looks to be in error and lists a single piston.

[Epacy]

Originally Posted by swamp2

I'm sure the M3 will have identical or similar to the M5 dual pot brakes on the front. The english pdf spec sheet however looks to be in error and lists a single piston.

So you are saying the official press release is a misquote and you are right? What supporting information do you have?
Just asking.