The myth of the DSC OFF switch
07-12-2006, 03:47 PM
#51
Originally Posted by two rotors
the ABS system will still act as a Limited Slip Differential.
As I said, completely disregard the nomenclature. It is written for the lower 40th percentile.
They took up the first 30 pages just to explain the seatbelts and airbags.
Remember, manuals and car ads are written for folks who are more concerned with crasing their car than driving it.
Last edited by MazdaManiac; 07-12-2006 at 03:53 PM.
07-12-2006, 04:29 PM
#55
RX8 and a Truk....
Originally Posted by bascho
Do you tend to only push the DSC switch once then at the track to retain some control? Or do you feel it becomes a nanny too conservatively for track use?
I used the DSC-OFF because I enjoyed, and could control, the rear of the car sliding on occasion. I could power-on thru corners and instead of the brakes grabbing, I felt it was 'faster' to get some tire spin.
Imp - Right-on. Your explanation w/ the Autocross nails it.
07-12-2006, 04:57 PM
#56
Registered User
Originally Posted by MazdaManiac
Forget the manual for a sec. It was written by lawyers from second-hand info passed through Japanese to Engrish on its way to the USA and elsewhere.
A few quick notes about the various systems:
The LSD (limited slip differential) has no electronic component. It does what it does in a vacuum. Its job is to simply distribute torque to the rear wheels. It does nothing else and it does so with impunity.
The ABS (anti-lock braking system) is a 4-wheel anti-lock scheme. It detects a sudden non-rotating state of any wheel under braking and automatically modulates that wheel to get it rolling again.
The TCS (traction control system) is a throttle modulating scheme that pulls power from the rear wheels whenever it detects a differential between the rotating speed of the fronts and the backs.
The DSC (dynamic stability control) is an over-arching control scheme that utilizes the TCS and ABS sensors to modulate the throttle and the brakes to dampen yaw.
The ABS cannot be defeated without a fault. Unplugging its harness will kill it and the DSC and throw a CEL.
Pressing the DSC button for a second will lower the threshold of the TCS system and remove the DSC.
Pressing the TCS/DSC button for 3 or 4 seconds faults the DSC system and turns both completely off and throws a fault light.
Neither of those actions affect the ABS or the LSD.
Regardless of what the manual states, this is what happens. I'm sure you are quite earnest in your beliefs Puch96, but they are based on the literature and this forum is chock full of refutations of the literature - some from driving experience and others from people living with their scopemeters and diagonal cutters.
A few quick notes about the various systems:
The LSD (limited slip differential) has no electronic component. It does what it does in a vacuum. Its job is to simply distribute torque to the rear wheels. It does nothing else and it does so with impunity.
The ABS (anti-lock braking system) is a 4-wheel anti-lock scheme. It detects a sudden non-rotating state of any wheel under braking and automatically modulates that wheel to get it rolling again.
The TCS (traction control system) is a throttle modulating scheme that pulls power from the rear wheels whenever it detects a differential between the rotating speed of the fronts and the backs.
The DSC (dynamic stability control) is an over-arching control scheme that utilizes the TCS and ABS sensors to modulate the throttle and the brakes to dampen yaw.
The ABS cannot be defeated without a fault. Unplugging its harness will kill it and the DSC and throw a CEL.
Pressing the DSC button for a second will lower the threshold of the TCS system and remove the DSC.
Pressing the TCS/DSC button for 3 or 4 seconds faults the DSC system and turns both completely off and throws a fault light.
Neither of those actions affect the ABS or the LSD.
Regardless of what the manual states, this is what happens. I'm sure you are quite earnest in your beliefs Puch96, but they are based on the literature and this forum is chock full of refutations of the literature - some from driving experience and others from people living with their scopemeters and diagonal cutters.
07-12-2006, 05:44 PM
#57
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Originally Posted by EyeBall Fixer...(o)(x)
"...in the snow" sum's it up.
Now thats a good way to test the DSC... (sigh..)
Now thats a good way to test the DSC... (sigh..)
... and this has to be the first time i've heard the term "brake assisted LSD" which absolutely make 0 sense
Last edited by r0tor; 07-12-2006 at 05:49 PM.
07-12-2006, 05:50 PM
#58
Originally Posted by two rotors
Well actually the TCS does more than just modulate the throttle,which it does when the road surface friction coefficients vary front to rear,but when there is side to side variation torque reduction is performed by independent left and right wheel brake control.(In that sense it simulates LSD action)
07-12-2006, 07:08 PM
#63
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Originally Posted by MazdaManiac
Oop! Thank! The "S" key on this old Dell laptop in't what it ued to be.
Will you risk crashing your Dell?
07-12-2006, 07:29 PM
#66
Registered User
Originally Posted by MazdaManiac
The DSC controls letf to right. That is NOT what an LSD does. An LSD ADDS power to a sticking wheel, not subtract it from a spinning one.
07-12-2006, 07:38 PM
#68
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one of the best things about this forum is when relatively new members post threads stating something that everyone else knows. Its obviously not a major offense but it does kinda **** people off, especially when the new member doesn't listen to the opinions of say the autox's who know the answer. Its like me running into an ER surgery and saying,"Hey ********, you're doing it wrong."
07-12-2006, 07:50 PM
#70
RX8 and a Truk....
Originally Posted by abbid
I know this has probably been posted, so ill say it too!
When holding the DSC button off, the car thinks that the switch went bad, and it faults the TCS and the DSC.
and as far as changing the threshold, i dont think its true either, i can and have done whatever the hell i want with just the single DSC off.
To be honest with you, i dont know what the hell the difference between DSC and TCS is?
When holding the DSC button off, the car thinks that the switch went bad, and it faults the TCS and the DSC.
and as far as changing the threshold, i dont think its true either, i can and have done whatever the hell i want with just the single DSC off.
To be honest with you, i dont know what the hell the difference between DSC and TCS is?
TSC/DSC and the difference between them are discussed in this thread.
07-12-2006, 07:56 PM
#71
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Originally Posted by MazdaManiac
The DSC controls letf to right. That is NOT what an LSD does. An LSD ADDS power to a sticking wheel, not subtract it from a spinning one.
Actually, you can use the TCS to provide something like an LSD. If you have an open differential and clamp one of the wheels the power coming from the engine will go only to the wheel that can turn. If you have one wheel on ice and one on pavement the difference in the traction will let all of the power go the one on ice. If the TCS selectively applies braking to the wheel on ice then some of the power will go to the other wheel. However, some of the power will be lost to friction in the brakes on the wheel that didn't have enough traction.
IIRC, Porsche did this at some point in the early Boxsters. It doesn't provide the performance benefits from a real LSD but it does provide a lot of what most people in regular driving would get from an LSD and at a big cost savings because everything to do it already comes as part of the ABS/TCS system.
07-12-2006, 08:04 PM
#72
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Originally Posted by abbid
Io be honest with you, i dont know what the hell the difference between DSC and TCS is?
DSC - Use the sensors of the ABS along with other needed sensors (i.e. accelerometers) to keep the car from rotating or moving in a lateral direction faster than allowed for the current driver inputs (steering, throttle, etc.). It does this by selectively applying brakes to individual wheels and possibly by cutting the throttle. Not too much more expensive to add beyond ABS. Studies indicate that cars that have it have fewer accidents (something on the order of 20-30% fewer).
07-12-2006, 08:21 PM
#73
Funny thing I swear that when TCS is on I can get the wheels to spin but the brakes kick in on the side that is spinning. Hence, controlling traction in a forward movent.
Opposite of ABS.
However, When TCS is off the car cares less is either tire spins or both. It does not apply the brakes to stop wheel spin.
That's why you want it off in tracking. It impeads your acceleration.
Most of you may not be able to tell this is happening because you don't have enough HP.
With a few MODS, and especially lighter wheels/tires you can tell the differance easily.
You can still spin the car in a circle with TCS on.
Just repeating the truth as said by other members.
Opposite of ABS.
However, When TCS is off the car cares less is either tire spins or both. It does not apply the brakes to stop wheel spin.
That's why you want it off in tracking. It impeads your acceleration.
Most of you may not be able to tell this is happening because you don't have enough HP.
With a few MODS, and especially lighter wheels/tires you can tell the differance easily.
You can still spin the car in a circle with TCS on.
Just repeating the truth as said by other members.
07-12-2006, 08:43 PM
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Originally Posted by Razz1
Funny thing I swear that when TCS is on I can get the wheels to spin but the brakes kick in on the side that is spinning. Hence, controlling traction in a forward movent.
Opposite of ABS.
Opposite of ABS.
If you are braking then the system will release the brakes on a wheel that isn't spinning fast enough.
If the throttle is applied then the system will apply the brakes to a wheel that is spinning too fast.
Really no extra hardware required just some more code in the computer for this part of it. Once you add throttle by wire it's easy to add with software only the functionality to reduce the throttle beyond a certain level of wheel slippage instead of braking one wheel.
Last edited by Hyperborea; 07-12-2006 at 08:49 PM.