Login


08222008, 09:00 PM  #177  
Major General
132
Rep 8,034
Posts 
Quote:
__________________


Appreciate
0

08232008, 12:11 AM  #178  
Lieutenant General
282
Rep 10,348
Posts 
Quote:
Your train brake statement is very likely false. At least in terms of stopping from any typical realistic combination of speed/load/rate/pad material. The pressure required would be so large it would heat the pad so greatly that F=mxFn would not hold the pad material would melt/sluff/destroy itself. 

Appreciate
0

08232008, 09:08 AM  #179 
Veni Vidi Vici
40
Rep 2,749
Posts
Drives: '11 JB/BBe6spe90
Join Date: Jul 2008
Location: Macungie PA
iTrader: (0)
Garage List 2011 e90 M3Sold [4.25]
2003 RS6  Sold [0.00] 2009 e90 M3  Gone [0.00] 2003 M3 SOLD [0.00] old 2002 [5.00] 
"most".
__________________
Dinan compliment of stuff plus PF rotors and RG63s. Enough for now. Why, yes. I am an abrasive bastard. 
Appreciate
0

08232008, 06:51 PM  #181 
Registered
0
Rep 1
Posts 
You want to see area? this is what area looks like
You want to see area? this is what area looks like
This what a brake is supposed to look like Luckily for you stupid guys like ART in 09 BMW will come out with Brembos. 
Appreciate
0

08232008, 07:10 PM  #182  
Banned
6
Rep 471
Posts 
Quote:
just like F = ma is an 'approximation'...it's all a matter of degree... u is a constant of the material(s), and may or may not be linear... ever see the brake on an elevator? very small...very small...but the drum is very large...it's a reverse drum type, 1 shoe... the pressure would be very small if the radius were very large... lets say the pad is 1 in^2 ...makes the math easy... say it takes 10,000 lbft of stopping torque (T = r F)...to stop the load... at 100' radius it needs 100 lbs of force F...so psi = 100, not much... at 10' it needs 1000 lbs of force or 1000 psi...much more so at 1000' raduis, it would need only 10 lf F or 10 psi and so on, big enough and the pad would barely touch the disc... and since Ff ~ u F, since F is small, so is friction force... same stopping power, different pressure, hence much different friction force and heat generated... 

Appreciate
0

08232008, 07:13 PM  #183  
Banned
6
Rep 471
Posts 
Quote:
and with a idgit like you calling me stupid, it doesn't carry much weight... but I'm sure you are well aquainted with limited intellectual prowess... breathing for you is not an autoreflex, and I'm sure you do it with your mouth open, and some spittle on your lip you do realize the M3 brakes are bigger than the C63? a car that weighs >400 lbs more? F 14.2 vs 14.2 R 13.8 vs 13.0 a true genius maybe you should leave this discussion up to the big boys... 

Appreciate
0

08232008, 07:20 PM  #184 
Major General
188
Rep 7,507
Posts
Drives: ????????????
Join Date: Oct 2007
Location: BMW M3 will get a V6TT

I remember reading an article of a braking system which replaced the calipers and pads with magnets. The advantages are clear to be seen, no wear or fade but that was over 5 years ago and nothing has been heard since. Another systems which used two disc instead of the normal one, both smaller with double the calipers and pads, this too seems to have fallen by the way side.
It's amazing with all the advances being made else where that brake technology hasn't made the same jumps. 
Appreciate
0

08232008, 07:21 PM  #185  
Lieutenant General
282
Rep 10,348
Posts 
Quote:
Ff=u Fn is an enormous approximation compared to F=ma. 

Appreciate
0

08232008, 07:23 PM  #186 
Lieutenant General
282
Rep 10,348
Posts 
And look at those "beautiful" "high tech" fixed single material rotors as well . Bling bling for the AMG...

Appreciate
0

08232008, 07:29 PM  #187  
Banned
6
Rep 471
Posts 
Quote:
s = 1/2at^2 (assuming initial v and s of 0) ds/dt = v = at d2s/dt2 = dv/dt = a s = 1/2 d2s/dt2 t^2 + ds/dt t + s0 having said that, both ma and uN give the same order of approximation, assuming m, a, u and N are measured to the same degree...and over an appropriate range of observation in fact friction is generally MORE linear than acceleration edit: after thinking about it if the coordinates were (x,y,z,t) I guess you could look at it with respect to each dimension, so partial diffs would apply...but that's what vectors are for I was referencing simple linear motion in one plane... Last edited by ArtPE; 08232008 at 08:33 PM. 

Appreciate
0

08232008, 07:33 PM  #188 
Banned
6
Rep 471
Posts 

Appreciate
0

08232008, 07:37 PM  #189 
Major General
132
Rep 8,034
Posts 
Thank you for registering just to make this valuable contribution. You sure taught us all something.
__________________

Appreciate
0

08242008, 03:27 AM  #191 
Lieutenant General
282
Rep 10,348
Posts 
Some AMG cars may have floaters but those on the C63 sure are not. They are 1 piece cast iron. Hey at least they are cross drilled.
On friction vs. Newton, I'll vehemently disagree. Yes many system can be written as ordinary 2nd order differential equations. However sometimes when you write equations for classical systems, equivalent to constructing them by F=ma, using variational principles in the form of Largange's or Hamilton's equations you definitely get PDEs. Whether or not friction is linear (which even considering the simple and common effect that starting friction is usually greater than sliding friction > NON LINEAR) the ability of Newtons law to very accurately describe an enormous range of phenomena is truly amazing. Ff = uFn is very often a rough approximation. Comparing the two is like comparing apples and organges in terms of their power, accuracy, importance, universality, etc. We digress... but indeed entertaining. Cheers. 
Appreciate
0

08252008, 06:09 AM  #194 
Major General
188
Rep 7,507
Posts
Drives: ????????????
Join Date: Oct 2007
Location: BMW M3 will get a V6TT

This debate has been going on for 9 pages now, whether floating or fixed is better, 1 piston or multipiston.
Can we agree on one thing, all racing cars use multipiston fixed calipers. So for racing at least the other route that is not used by BMW on the M3 is best, but not necessary for normal road/trackday use. 
Appreciate
0

08252008, 07:33 AM  #195 
Brigadier General
47
Rep 3,065
Posts
Drives: 2008 E92 Space Gray M3 & E36M3
Join Date: Dec 2006
Location: Greater St Louis Metro area

Ok, I just got done with a 3 day driver's school at the brand new Thunderbolt Circuit at NJ Motorsports Park in southern NJ. The track has 5 braking zones on a 2.1 mile circuit. 2 of these braking zones include braking from 100+ mph to about 60ish including the turn 1 where I was getting to 135+ and had to brake to 6570.
The brakes never faded at all the entire weekend. They were just as strong on the last lap as they were when I arrived at the track. Also, I was braking nearly as deep as some of the guys with aftermarket brakes which says a lot considering the weight of the E92. I was using stock pads and stock tires. Bottom Line: The brakes are very effective on the track, there is truly no need to change them or upgrade to an aftermarket brake system for track use. The only reason to upgrade the brakes, is because they aren't all that nice to look at (calipers not rotors).
__________________
Get a professional motorsports full featured stopwatch app for your Blackberry here: http://appworld.blackberry.com/webstore/content/19464 Invest Wisely...The best mod for your money?? BMWCCA high performance driver's school. The mod that lasts a lifetime and improves the performance of any car you drive 
Appreciate
0

08252008, 09:16 AM  #196  
Major General
299
Rep 7,557
Posts 
Quote:


Appreciate
0

08252008, 01:16 PM  #197 
Brigadier General
179
Rep 4,853
Posts 
NO  we can not agree on that. there are many racing classes that use stock brakes.

Appreciate
0

08252008, 01:31 PM  #198  
Lieutenant
14
Rep 568
Posts 
I ran my car for almost 2 hours in the canyons... up and down, up and down... and I was really running it at those canyons too to the point that I've seen the DSC light come on several times... and during that time, not a single shudder or change in the pedal feel... I was a little concerned with what I've read on the M3 brakes but after this little exercise, I think i'll be okay.... not to say that it can handle a full weekend of high speed tracking but that's to be expected Cheers.
Quote:
__________________
"What a car.... what a masterpiece...." Jeremy Clarkson


Appreciate
0

Post Reply 
Bookmarks 
Thread Tools  Search this Thread 

