Excellent Article on Brakes
05-02-2003, 02:58 AM
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Excellent Article on Brakes
Popular Science wrote <a href="http://www.popsci.com/popsci/auto/article/0,12543,446945,00.html" target="_blank">This Article CLICK HERE</a> 
05-02-2003, 03:19 AM
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I can appreciate what that article said about brake temperature...
This is why we have disc brakes on our cars, as an alternative the drum brakes that HappyTruck, the '66 Ford F100 that I use for airport car duty has.
I've spent plenty of time around high performance and heavy jets; I never had a rejected takeoff in the 727, but I did do one in a 747 once. This was from about 80 knots/90 miles per hour/150 km/h...due to brake temperatures [we have a gauge in the cockpit that tells us this...], we had to stop the plane on the taxiway and wait 39 minutes in position...engines off since we could not set the parking brake-
[If you set the parking brake with overtemped brakes, it is possible for the pads to "weld" to the rotors....]
This 39 minute period was pretty tough- nobody was allowed to approach the aircraft, unless the plane was on fire, a distinct possibility since our discs were glowing pretty much red hot at this point-
N!
'85 S2 5 Speed
This is why we have disc brakes on our cars, as an alternative the drum brakes that HappyTruck, the '66 Ford F100 that I use for airport car duty has.
I've spent plenty of time around high performance and heavy jets; I never had a rejected takeoff in the 727, but I did do one in a 747 once. This was from about 80 knots/90 miles per hour/150 km/h...due to brake temperatures [we have a gauge in the cockpit that tells us this...], we had to stop the plane on the taxiway and wait 39 minutes in position...engines off since we could not set the parking brake-
[If you set the parking brake with overtemped brakes, it is possible for the pads to "weld" to the rotors....]
This 39 minute period was pretty tough- nobody was allowed to approach the aircraft, unless the plane was on fire, a distinct possibility since our discs were glowing pretty much red hot at this point-
N!
'85 S2 5 Speed
05-02-2003, 03:50 AM
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Yanno, when you think about it...the Aviation community has led with advanced technology break throughs for many years. Why is it that Porsche would introduce a PCCB to stop a car and the aviation community is still stopping 747's on magnesium/steel brakes that can burn to a violent fire and take forever to cool down? 
What is wrong with this picture? <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />
What is wrong with this picture? <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />
05-02-2003, 09:19 AM
#5
Burning Brakes
Funny how after just a short time at the track you realize how big a difference good brakes can make.
On my 951 I added about 100hp, then I stiffend up the suspension. I was still running stock sized brakes, though I did use slotted cryo rotors, track pads and some brake ducting. Still, the brakes were by far the weakest link. The brakes were the limiting factor in my lap times.
This time around, the very first modification I did on my car was to upgrade my brakes to the GTS (Big Red) sized calipers and rotors. I must say that not having to worry about fade, boiling fluid and warpage after a session or two is a very welcome change.
I am pretty confident that I will beable to beat my old lap times this summer. I will beat those times in a heavier, slower car, but one with better brakes.
Interesting that a Porsche was the subject car. Our cars come with the best braking systems in the world. You just have to love that
On my 951 I added about 100hp, then I stiffend up the suspension. I was still running stock sized brakes, though I did use slotted cryo rotors, track pads and some brake ducting. Still, the brakes were by far the weakest link. The brakes were the limiting factor in my lap times.
This time around, the very first modification I did on my car was to upgrade my brakes to the GTS (Big Red) sized calipers and rotors. I must say that not having to worry about fade, boiling fluid and warpage after a session or two is a very welcome change.
I am pretty confident that I will beable to beat my old lap times this summer. I will beat those times in a heavier, slower car, but one with better brakes.
Interesting that a Porsche was the subject car. Our cars come with the best braking systems in the world. You just have to love that
05-02-2003, 09:52 AM
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There is one advantage to drum brakes vs disk brakes. Drum brakes do not rub and cause friction in normal operation, disk brakes do. As a result drum brakes have been the choice of drag racers, minimizing rotational friction.
Disk brakes are superior in all other aspects...
Disk brakes are superior in all other aspects...
05-02-2003, 10:13 AM
#7
Burning Brakes
I can think of one more advantage of drums. They have a larger contact surface in general. They make great parking brakes.
For example, my M-B G-wagen uses drums in back. The original military specs called for holding the truck and a 3.5 ton trailer on a 45% grade. Disc brakes would not meet the spec without damage in the long run. Where they fall down is in heat dissipation, they can not touch the discs there.
For example, my M-B G-wagen uses drums in back. The original military specs called for holding the truck and a 3.5 ton trailer on a 45% grade. Disc brakes would not meet the spec without damage in the long run. Where they fall down is in heat dissipation, they can not touch the discs there.
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05-02-2003, 12:36 PM
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The newer tech in large aircraft are carbon brakes. Strangely they not only work better at high temps (300 deg Cel.) they wear less. Some aircraft also have brake fans built into the hub, you press the switch and watch the temps drop. Normy, who do you fly for? I spent 3 years as an oiler on 747s for Flying Tigers, you may be flying some of our old machines. Kevin
05-02-2003, 01:02 PM
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Brent 89 GT
To your point, I find is very interesting that the 928 uses a drum brake for the parking brake. Apparently it holds better and perhaps more to the point, there is less likely to be pad material transfer caused by applying the park break to hot pads and rotors.
Over the winter I rebuilt my brakes and upgraded to zimmermans w/cast holes. This made a significant improvement to Gretch's stopping ability. Yes most of the improvement is likely due to the rebuild, but I really like the "holes"
To your point, I find is very interesting that the 928 uses a drum brake for the parking brake. Apparently it holds better and perhaps more to the point, there is less likely to be pad material transfer caused by applying the park break to hot pads and rotors.
Over the winter I rebuilt my brakes and upgraded to zimmermans w/cast holes. This made a significant improvement to Gretch's stopping ability. Yes most of the improvement is likely due to the rebuild, but I really like the "holes"
05-02-2003, 07:47 PM
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</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Gretch:
<strong>Brent 89 GT
To your point, I find is very interesting that the 928 uses a drum brake for the parking brake. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">HUH?
<strong>Brent 89 GT
To your point, I find is very interesting that the 928 uses a drum brake for the parking brake. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">HUH?
05-02-2003, 09:26 PM
#11
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The 928s rear brake are disk.
Here's the thing though.
Porsche decided that it isn't enough just to have a cool rear disk brakes. They wanted among other things, a completely independent parking brake.
Result, on the inside of the disk brake is the parking brake, and it's a drum brake. The only part that the two systems share is the drum/hat assymbly, and the axle.
Intersting uh?
Here's the thing though.
Porsche decided that it isn't enough just to have a cool rear disk brakes. They wanted among other things, a completely independent parking brake.
Result, on the inside of the disk brake is the parking brake, and it's a drum brake. The only part that the two systems share is the drum/hat assymbly, and the axle.
Intersting uh?
05-02-2003, 10:02 PM
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I don't think Porsche is the only car that has this parking brake setup. My '86 325 had rear rotors with the inside of the rotor forming a drum facing inward. The parking brake shoes fit into this drum.
I don't think Porsche is the only car that has this parking brake setup. My '86 325 had rear rotors with the inside of the rotor forming a drum facing inward. The parking brake shoes fit into this drum.