powerbraking - any harm?
08-19-2011, 07:11 PM
#1
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E55 then E63, now back to an E55
powerbraking - any harm?
rarely do I do this, but the other night was doing fairly extensively.
immediately AFTER (while idling at stop sign, not DURING) - serpentine belt shredded and plastic piece of the plastic/steel idler pulley combo assembly broke. I never saw pieces of the plastic in the engine bay at all or underneath (3 of the 7 or so ridges were almost completely missing) it leads me to believe they had cracked off at another time due to heat or age (75k mi.)
Or, did the powerbraking/engine trying to lurch forward but brakes holding back, contribute to the damage? only wondering, thx
immediately AFTER (while idling at stop sign, not DURING) - serpentine belt shredded and plastic piece of the plastic/steel idler pulley combo assembly broke. I never saw pieces of the plastic in the engine bay at all or underneath (3 of the 7 or so ridges were almost completely missing) it leads me to believe they had cracked off at another time due to heat or age (75k mi.)
Or, did the powerbraking/engine trying to lurch forward but brakes holding back, contribute to the damage? only wondering, thx
08-19-2011, 10:25 PM
#3
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Powerbraking? Really?
The enormous energy you're producing at 5000 RPMs is being absorbed by something, and whatever that something is (mostly tranny I would think) is not designed to absorb those 4-500 ferocious angry horses and contain them, it's designed to transfer that into moving your car forward.
This is why I would never buy a used AMG or E55/63.
The enormous energy you're producing at 5000 RPMs is being absorbed by something, and whatever that something is (mostly tranny I would think) is not designed to absorb those 4-500 ferocious angry horses and contain them, it's designed to transfer that into moving your car forward.
This is why I would never buy a used AMG or E55/63.
08-19-2011, 10:37 PM
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2001 E320 Wagon, 2006 LBZ Silverado, 2007 E63 (sold), 2001 E55 (sold)
Power braking is very hard on the car. I also don't see why you'd want to do it considering how much brakes and tires cost.
08-19-2011, 10:55 PM
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E55 then E63, now back to an E55
all valid points,
however it really wasn't THAT high - only about 3000-3500 rpms at most.
I have only done this probably 10 times in almost 4 years of ownership.
however it really wasn't THAT high - only about 3000-3500 rpms at most.
I have only done this probably 10 times in almost 4 years of ownership.
08-20-2011, 01:00 AM
#7
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At 3500rpm the torque the car produces is enough to create a salad in the gearbox. The gearbox is designed to move, it can handle the torque but not in an unconventional way. Why do it anyway? The car has enough low end torque so why would you need it?
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08-20-2011, 01:19 AM
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E55 w/ goods, Z32 Project underway
Long long time ago, had a SC400 that I power braked everywhere. Blew through the ring and pinion, then afterwards threw a rod bearing. Just not worth it. This car produces so much torque, it has to be transferred somewhere if not through the wheels, the drive train is absorbing it.
08-20-2011, 02:31 AM
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2001 E320 Wagon, 2006 LBZ Silverado, 2007 E63 (sold), 2001 E55 (sold)
Same thing happened when I had my '98 Z28 years ago. I loved doing brake stands in that car and the rear finally let go during normal driving one day. It was a horrible sound that I hope to never hear again.
08-20-2011, 12:35 PM
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1995 C36 AMG, 1998 C43 AMG
On the 36/43 cars, the two flex-discs are what usually go out due to power braking. Had to replace one of mine after running a lot of autocrosses last season. I get the best starts by power braking to around 2500, so not too mean. It's the only launch control we have on the autos. At least it's not as bad as my buddy who swears by the "rev-in-neutral, slam-in-drive" method on his prelude x_x
08-20-2011, 01:26 PM
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2005 E55 AMG - - 2005 SL55 AMG - - - - - - 2006 SLK55 AMG - - - - - - 2013 Ducati Diavel AMG -
Power-braking puts a lot of stress on the motor mounts, transmission mounts, transmission, and brakes. 
I like to smoke and had to replace the motor mounts, transmission mounts, and my transmission which I blew!
Weird, but my brakes are fine!
I like to smoke and had to replace the motor mounts, transmission mounts, and my transmission which I blew!
Weird, but my brakes are fine!
08-20-2011, 02:07 PM
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2003 E55 & 2014 GL550
Bout the worst thing I have heard is axle twisting at the track on guys with stockers without LSD. Car is already struggling to brake hard to stop the spinning. Must be off the charts....the stress on those axles.
08-21-2011, 12:59 AM
#13
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Oh, ok, sure--no problem--why didn't you say so? Just 350 frustrated horses tugging for dear life at your gears and transmission while you jam on the brakes and transfer the explosions happening in your engine block to the transmission. That's a whole different story then. Carry on.
08-21-2011, 10:53 AM
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350 hp? Even a not so healthy E55 makes more at the wheels. Or maybe you mean the power at that rpm? It's not the power you need to worry about, it's the torque and the torque curve puts you in the worst place on these car at that RPM.
08-21-2011, 10:42 PM
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you guys are crazy using these analogys like creating a salad in the gearbox??? No clue whatsoever. First you cannot power brake at 5000 rpm. You can only powerbrake up to the stall speed of the convertor. If your at 5k rpm, then the tires are spinning, or something is broke, which you would know about
08-22-2011, 12:11 AM
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08-22-2011, 12:13 AM
#17
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you guys are crazy using these analogys like creating a salad in the gearbox??? No clue whatsoever. First you cannot power brake at 5000 rpm. You can only powerbrake up to the stall speed of the convertor. If your at 5k rpm, then the tires are spinning, or something is broke, which you would know about
Just a thought.
08-22-2011, 12:33 AM
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you guys are crazy using these analogys like creating a salad in the gearbox??? No clue whatsoever. First you cannot power brake at 5000 rpm. You can only powerbrake up to the stall speed of the convertor. If your at 5k rpm, then the tires are spinning, or something is broke, which you would know about
08-22-2011, 09:26 PM
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2004 E55 AMG
Shock loads are what break parts. With the tires spinning there is less torque going through the drive train than if you were doing a simple wot pull. The only way you're going to hurt anything is if the tires suddenly stop spinning under power, or you shock the drive train by hitting a pothole or something like that. There is no more wear on the rear breaks than if you were quickly slowing down. No need to push the brake or the throttle to the floor. I bet it only takes a about half the engine's power to keep the tires going.
08-22-2011, 11:33 PM
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E55 w/ goods, Z32 Project underway
Powerbreaking is generally regarded as LOADING the drivetrain- NOT SPINNING THE TIRES!
One does this to launch hard, not sit there and spin the tires at the intersection. How many drag races have you seen where the person is spinning the tires before launching? The drivetrain is 'loaded' to prepare it for a hard launch. Look at all of the launch control systems in newer cars. Do you see any that allow for tire spin? NO! Also, notice new GT-Rs no longer even offer launch control-yes, too many blown transmissions. Also keep in mind that power breaking is not the same as rev dropping a car by putting in in neutral to 5k and then putting it in gear. Ruined a car doing that long ago. Also went through two 944 ring and pinions dropping from 5k.
Also, just because the torque converter is at the stall speed does not mean it will break the tires loose. It just means that it is no longer slipping, yet that torque is still getting transferred to the rest of the drivetrain. You can still go past the stall speed and not get any tire spin whatsoever. Not to 5k, but certainly a little over.
One does this to launch hard, not sit there and spin the tires at the intersection. How many drag races have you seen where the person is spinning the tires before launching? The drivetrain is 'loaded' to prepare it for a hard launch. Look at all of the launch control systems in newer cars. Do you see any that allow for tire spin? NO! Also, notice new GT-Rs no longer even offer launch control-yes, too many blown transmissions. Also keep in mind that power breaking is not the same as rev dropping a car by putting in in neutral to 5k and then putting it in gear. Ruined a car doing that long ago. Also went through two 944 ring and pinions dropping from 5k.
Also, just because the torque converter is at the stall speed does not mean it will break the tires loose. It just means that it is no longer slipping, yet that torque is still getting transferred to the rest of the drivetrain. You can still go past the stall speed and not get any tire spin whatsoever. Not to 5k, but certainly a little over.
Last edited by pearlpower; 08-22-2011 at 11:45 PM.
08-22-2011, 11:55 PM
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2004 E55 AMG
Powerbreaking is generally regarded as LOADING the drivetrain- NOT SPINNING THE TIRES!
One does this to launch hard, not sit there and spin the tires at the intersection. How many drag races have you seen where the person is spinning the tires before launching? The drivetrain is 'loaded' to prepare it for a hard launch. Look at all of the launch control systems in newer cars. Do you see any that allow for tire spin? NO! Also, notice new GT-Rs no longer even offer launch control-yes, too many blown transmissions. Also keep in mind that power breaking is not the same as rev dropping a car by putting in in neutral to 5k and then putting it in gear. Ruined a car doing that long ago. Also went through two 944 ring and pinions dropping from 5k.
Also, just because the torque converter is at the stall speed does not mean it will break the tires loose. It just means that it is no longer slipping, yet that torque is still getting transferred to the rest of the drivetrain. You can still go past the stall speed and not get any tire spin whatsoever. Not to 5k, but certainly a little over.
One does this to launch hard, not sit there and spin the tires at the intersection. How many drag races have you seen where the person is spinning the tires before launching? The drivetrain is 'loaded' to prepare it for a hard launch. Look at all of the launch control systems in newer cars. Do you see any that allow for tire spin? NO! Also, notice new GT-Rs no longer even offer launch control-yes, too many blown transmissions. Also keep in mind that power breaking is not the same as rev dropping a car by putting in in neutral to 5k and then putting it in gear. Ruined a car doing that long ago. Also went through two 944 ring and pinions dropping from 5k.
Also, just because the torque converter is at the stall speed does not mean it will break the tires loose. It just means that it is no longer slipping, yet that torque is still getting transferred to the rest of the drivetrain. You can still go past the stall speed and not get any tire spin whatsoever. Not to 5k, but certainly a little over.
You're absolutely right. I was thinking of doing a brakestand I guess. Since were talking about loading the converter I'll offer the fact that powerbraking to load the converter is actually easier on the drive train than smashing the gas from idle and flashing the converter. These converters are so tight that it doesn't matter much, but when you start getting up there in stall speed with sticky tires it can make a big difference.
Last edited by izzyz28; 08-22-2011 at 11:58 PM.
