How exactly does TC work?
Thread Starter
Le Mans Master
Joined: Nov 2000
Posts: 7,020
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From: Durham NC
How exactly does TC work?
Come someone please provide a detailed explanationm as to how Traction COntrol works?
While we are at it, can someone also describe how the rev limiter functions?
Thank you!
While we are at it, can someone also describe how the rev limiter functions?
Thank you!
Race Director
Joined: Oct 1999
Posts: 11,527
Likes: 115
From: Arlington TX
Re: How exactly does TC work? (QWK SLVR)
Traction control uses the same sensors that are already in the car for abs and functions similarly in recognizing slip. It reads the front wheel speed versus the rear wheel speed. I do not know if it also takes into account wheel acceleration (some abs systems do) and am curious of that myself.
To control it it uses brakes to slow the spining (using the same module as the abs), spark retard and closing the throttle to limit power and speed of the motor.
The rev limiter cuts spark at a certain rpm. It cuts spark because cutting fuel can lead to a lean out condition that could hurt the motor.
To control it it uses brakes to slow the spining (using the same module as the abs), spark retard and closing the throttle to limit power and speed of the motor.
The rev limiter cuts spark at a certain rpm. It cuts spark because cutting fuel can lead to a lean out condition that could hurt the motor.
Thread Starter
Le Mans Master
Joined: Nov 2000
Posts: 7,020
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From: Durham NC
Re: How exactly does TC work? (rgregory)
So, why exactly do folks turn this off for drag racing? Seems that you could risk getting side ways, etc. Or does the Active Handling sufficiently take care of that? :confused:
Le Mans Master
Joined: Aug 2000
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From: Austin Texas
Re: How exactly does TC work? (QWK SLVR)
People turn this OFF because:
To extract maximum acceleration from the tires, the tires HAVE to turn faster than the road surface under them is running (about 5% to 7% slip for max acceleration). Under this condition, the front tires will read the actual velocity of the vehicle while the rear tires will read 5% to 7% faster. This is outside the limits imposed by TC and it activates, reducting the acceleration to that which can be accomplished with only 2% to 3% slip.
TC attempts to keep you and the car within a safe operating environment. Drag racing requires one to dance on/just-over the edge of the traction envelope. The two are not compatible.
To extract maximum acceleration from the tires, the tires HAVE to turn faster than the road surface under them is running (about 5% to 7% slip for max acceleration). Under this condition, the front tires will read the actual velocity of the vehicle while the rear tires will read 5% to 7% faster. This is outside the limits imposed by TC and it activates, reducting the acceleration to that which can be accomplished with only 2% to 3% slip.
TC attempts to keep you and the car within a safe operating environment. Drag racing requires one to dance on/just-over the edge of the traction envelope. The two are not compatible.
Race Director
Joined: Oct 1999
Posts: 11,527
Likes: 115
From: Arlington TX
Re: How exactly does TC work? (MitchAlsup)
As what Mitch said is the way it needs to be. However auto makes don't run TC on the edge like they do with ABS. They don't want the liability. If Formula 1 uses traction control it can be made to maximize acceleration.
Drifting
Joined: Feb 1999
Posts: 1,481
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From: San Diego CA
Re: How exactly does TC work? (QWK SLVR)
One other thing...
In the C5, Traction Control works by chopping the throttle (easy enough with drive-by-wire). It's not very smooth or sophisticated, especially in the first generation system.
When Traction Control kicks in, it significantly retards the throttle causing the car to bog, it then takes a second or two for the throttle to return to normal. Besides being disruptive, it leaves the driver stuck with no way to accelerate for a second or two.
That's why many people prefer to run with Traction Control off, or in Competition Mode if they have Active Handling.
On certain other cars, Traction Control works with the ABS system to apply the brakes to control rear wheel spin. This works MUCH better and provides more power to the pavement and an instant response from the computer when traction returns.
We make a product called the TracActive Controller which allows you to automatically set Competition Mode or disable Traction Control and/or Active Handling when you start the car.
For more info, please see http://www.laptrax.com
Mike
In the C5, Traction Control works by chopping the throttle (easy enough with drive-by-wire). It's not very smooth or sophisticated, especially in the first generation system.
When Traction Control kicks in, it significantly retards the throttle causing the car to bog, it then takes a second or two for the throttle to return to normal. Besides being disruptive, it leaves the driver stuck with no way to accelerate for a second or two.
That's why many people prefer to run with Traction Control off, or in Competition Mode if they have Active Handling.
On certain other cars, Traction Control works with the ABS system to apply the brakes to control rear wheel spin. This works MUCH better and provides more power to the pavement and an instant response from the computer when traction returns.
We make a product called the TracActive Controller which allows you to automatically set Competition Mode or disable Traction Control and/or Active Handling when you start the car.
For more info, please see http://www.laptrax.com
Mike
