Why not multi-piston brakes?

[ArtPE]

Bosch Automotive Handbook
Compared to fixed calipers the advantage of floating:
-modest space requirements
-reduced thermal stress on fluids

constructive measures efectively alleviate any inherent disadvantage of the floating:
-rattle & squeak
-uneven wear of friction material
-corrosion in moving parts, pins, guides, etc.

they seem to infer that the floating, if designed/constructed properly, is a better solution

a major advantage being since the caliper floats, it will absorb radial run-out and brake smoother, and maintain better contact between friction surfaces with more consistent/uniform pressure...

so should BMW use a less effective system for marketing advantages? brand names and fancy colors/looks?
that's not the BMW I've known for 30 years...
they'll take the heat (pun intended) and stand by engineering, NOT marketing, based decisions...

btw: they are not inherently cheaper to design/build...the floating components add cost to offset the additional pistons...

[T Bone]

Originally Posted by lurks

The latest Road & Track test figures show the M3 out-stopping (from both 60 to 0 and 80 to 0) all but 2 Porsches - the GT1 (not a real road car ) and the Cayman. Both of which weigh almost 1,000 lbs less. As for fade - no fog light option so that the huge holes in the front air dam below the headlights direct massive amounts of air to the brakes to reduce fade. I too would like the option of six pot calipers etc for aesthetics but BMW knows what it is about and they seem to like the challenge of pushing simple technology beyond where most thought it could go. Look at how long they have stuck with normally aspirated engines of the M cars!!!! long after ALL the competition has gone forced induction.

These tests are BS.....like the skidpad, they measure the tire as much as anything else. These tests are also greatly influenced by environmental conditions.

Tests that need to be eliminated....as they give wrong data.

0-60, skidpad, 60-0 braking.....

Imagine what happens when the GT1 brakes actually heat up a bit to get the pads working properly??

[footie]

Originally Posted by lurks

The latest Road & Track test figures show the M3 out-stopping (from both 60 to 0 and 80 to 0) all but 2 Porsches - the GT1 (not a real road car ) and the Cayman. Both of which weigh almost 1,000 lbs less. As for fade - no fog light option so that the huge holes in the front air dam below the headlights direct massive amounts of air to the brakes to reduce fade. I too would like the option of six pot calipers etc for aesthetics but BMW knows what it is about and they seem to like the challenge of pushing simple technology beyond where most thought it could go. Look at how long they have stuck with normally aspirated engines of the M cars!!!! long after ALL the competition has gone forced induction.

Don't mistake stopping distance with durability as they are totally different, another thing, when you have very little weight over the front, stopping is more difficult, also weight has less effect on stopping times than a lot of people think.

As for sticking with N/A engines on their M cars, just look how many other manufacturers still do the same. It's a policy and belief, not something shockingly amazing. What is truly amazing is when a main stream manufacturers pushes the limits and gets 120hp+ per litre from a N/A engine, especially if it's a V8 of the capacity that we are talking about, then I will have the same excitement.

[home7271]

Once again, this thread has turned into debates about the technical aspects of single vs. multi, fixed vs. floating.

I think we can all agree smart engineering CAN beat out smart designs on paper; like fitting a square peg in a round hole sort of speak, take a rear-biased car and turn it into world class sports car, making struts working as well as double a-arms, etc....

Man...I just wished the M3 had a brake system that caused no debates then it's the end of story!

[!Xoible]

idk why people think more pistons = better stopping ability and less fade!

take for instance 335 and G37. G37 has 4 piston, what can it do?! and it's close to 335's weight

[jaiman]

Originally Posted by home7271

Once again, this thread has turned into debates about the technical aspects of single vs. multi, fixed vs. floating.

I think we can all agree smart engineering CAN beat out smart designs on paper; like fitting a square peg in a round hole sort of speak, take a rear-biased car and turn it into world class sports car, making struts working as well as double a-arms, etc....

Man...I just wished the M3 had a brake system that caused no debates then it's the end of story!

I think this has gone down the technical road as several people here can offer insight into the various trade offs involved, but no-one has any deep insight into BMW's marketing decisions.

edit: What's top level for post count? will manits's title one day be POTUS?

[!Xoible]

lol what's or who's POTUS?

[sayemthree]

pres of the US. you apperantly have read or watched Tom Clancy!

[tifosi360]

Most of us don't have the skills to explore the limits of our "M" cars. If you track it, change the pads, which should not take that long. For spirited street use, the car with standard pads will hang with any sports car Germany or Italy has to offer.

[swamp2]

Good discussion guys.

@T-Bone: Excellent addition/supplement to my post in your comments about fixed vs. floating.

@T-Bone and footie: You are both right. Fade is highly dependent on BOTH pad compound and temperature (and fluid boiling if it occurs). Temperature gets too high for a given implementation when pushed too hard, has improper/inadequate cooling, has an inadequate basic brake design (rotor radius, swept area, rotor/caliper mass) which includes too heavy of a car for the design and speeds.

jaiman: Yup, old school back in the day, AMP. I did a lot of design work, CAD, prototyping, testing, manufacturing engineering, etc. for their cable actuated, hydraulic brake system we brought out. Compound floating rotor, novel closed hydraulic chamber with spring loaded expansion compensation, dual ceramic pistons, novel spring based anti-rubbing spring, etc. It would have been waaaay more robust if I had my way with everything but cost was given too much emphasis.

[e36jakeo]

I have an E36 M3 that I use only as my track car. Even with R-compound tires providing even more of a workout for the brakes, my stock braking system armed with Performance Friction 01 pads, super blue fluid, and no dust shields work excellent and stop as well as any of my competitors cars, lap after lap.

I, too, replaced the stock rotors with the Euro-M3 spec floating rotors (direct replacement)in order to prevent warping and reduce unsprung weight. This inexpensive replaceent part (available from BMW) is excellent.

Given that the new M3 will have optional race pads from BMW and huge, cross-drilled floating rotors all around, and large (potential) brake ducting in the stock front air dam, I am hopefuly this thing will stop just fine.

Has anyone confirmed that the air-ducting actually channels a lot of air to the brakes?