View Full Version : How traction control works...
After all the talk of traction control recently, I was chatting to a mate who knows more than me about cars, and he told me that (apart from in F1 systems) the power is retarded in low-traction situations by applying the brakes!
Apart from seeming to be a cr@p way to do it, doesn't this destroy pads at a rate of knots, especially in wet weather???
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Driving a Citroen AX 1.4D... mmm mmm!
I thought some systems cut engine power too ?
Especially aftermarket types. Not sure all ABS systems will support individual wheel braking ? not sure.
At the end of the day, whatever it does, it has to react very quickly.
You can soon end up with the only option being to apply steering correction, when you get to this point, applying the brakes or cutting engine power will have the back end round faster than a fast thing.
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1996 Blue/Green S14 (manual)
K&N cone filter
2.5" Tube-torque Cat Back Exhaust.
TechTom MDM-100
Race-Technology AP-22
http://tom.marshall.tripod.com
The way that traction control works can vary from system to system. Essentially what you are trying to do when you sense wheelspin is limit the power that is going to the wheels, and there are several ways of doing this. Some of the early systems (and I believe that some manufacturers still do this) grabbed the brakes to prevent wheelspin.
Another method used (this is how the Racelogic system works) is to limit the amount of fuel going to the engine by switching to another fuel map. On non-injection cars a relay is placed in line with the coil to cut the spark.
Hope this helps
Nik
Yeah, cutting engine power makes a lot more sense!
But if you had an engine-based system, does it not ever stall in low-traction situation (say snow or ice)??
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Driving a Citroen AX 1.4D... mmm mmm!
It shouldn't do as there is a maximum amount of cutting out that it will do. Apparantly you still want a little bit of wheelspin to get the optimum speed.
Killing the engine totally would stop any wheelspin though!!!
Nik
Guess my m8 doesn't know as much as he thought!!! http://300zx.co.uk/200sx/ubb/biggrin.gif http://300zx.co.uk/200sx/ubb/biggrin.gif http://300zx.co.uk/200sx/ubb/biggrin.gif http://300zx.co.uk/200sx/ubb/biggrin.gif
geoff_s14
22-10-2001, 11:10
Also, the standard Racelogic system can be switched off for extreme conditions (like snow), as well as varied to allow different percentages of slip.
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Geoff
Emerald S14a
http://www.animfactory.com/animations/transportation/cars/mirror_md_clr.gif
My favourite bit is the launch control......
Originally posted by geoff_s14:
Also, the standard Racelogic system can be switched off for extreme conditions (like snow), as well as varied to allow different percentages of slip.
Geoff,
RL TC also has a WET setting which is for extremely hazardous situations, like torrential race, ice and snow. And NOT rain, which would explain why I thought mine was FUBAR'ed when I had it set to WET when it had rained. http://300zx.co.uk/200sx/ubb/rolleyes.gif Bastid thing kept misfiring whenever I tried to go round a corner http://300zx.co.uk/200sx/ubb/mad.gif
But after reading a small portion of the manual, I now can see the error of my ways.
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John S14a
http://mysmilies.com/s.php?action=random&cat=evil
Originally posted by JohnD76:
Bastid thing kept misfiring whenever I tried to go round a corner http://300zx.co.uk/200sx/ubb/mad.gif
LOL!
So is a misfire the worst that will happen?
The Racelogic TC works by sensing wheelspin through the ABS sensor, it does this in something silly like 1/1000 of a second.
If it senses wheelspin at a higher threshold than it is set, for example, you have got it on 10% slip and it is measuring 11%, it cuts the injectors, which causes the misfire. Hence no power, hence no more wheelspin. There is loads of stuff on the RL site about how this has been tested and RR'ed and does no damage to the engine. Incidentally it is the same TC that the F1 cars use, with launch controll too http://300zx.co.uk/200sx/ubb/biggrin.gif
The one I have got, standard group buy one with launch control has got 20%, 15%, 10%, Dry, Wet and Off. With Dry and Wet for Launch control starts and not dry/wet as you would expect; if you don't read the manual that is http://300zx.co.uk/200sx/ubb/rolleyes.gif . This allows you to set different rev limits for Rain and for Dry weather.
I really like the TC, and would really recommend it to everyone. I still manage to spin the wheels, if I compeletly boot it that is (on 20% slip) http://300zx.co.uk/200sx/ubb/biggrin.gif. But the rear end doesn't come out, which is handy if you really need to get the hell out of somewhere fast.
It doesn't take the fun out of driving a 200, it just gives you more confidence and also IMHO makes the car more stable.
Still haven't tried a standing LC start, has been pi55ing it down whenever I have thought about it. Will be interested to see how my 0-100KPh time has changed with the TC fitted.
Hope that helps,
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John S14a
http://mysmilies.com/s.php?action=random&cat=evil
Yeah, it does, thanks! I've just been to the RaceLogic site too - there's some really interesting cool there.
Have you read about the read-time ECU re-mappers they do? You can fix a lap-top up to re-program it as you drive, and get a cool 3D display of various values!!
I wonder if that was what that guy Brian in The Fast & The Furious http://300zx.co.uk/200sx/ubb/smile.gif http://300zx.co.uk/200sx/ubb/smile.gif http://300zx.co.uk/200sx/ubb/smile.gif was doing with graphs in the first race he has against Vin Diesel...? I did wonder at the time, but thought it was just the usual Hollywood cr@p...
Basically, as I understand it - RL TC cuts the fuel pulses in rotation of cylinders. This stops unburnt fuel from wrecking your cat, which is what would happen if you cut the spark (another option).
Saying that, they do say that you shouldnt keep the car missfiring for more than 30 secs as you could still cause damage - probably through too much heat I suppose.
Launch Control sets another rev limit (say 4k rpm). You press the LC button and then floor the throttle. It wont go any higher than 4k. Then, when you start to move off, the TC wont let you spin it all away (unless its switched off! http://300zx.co.uk/200sx/ubb/smile.gif)
Full throttle shift engages another rev limit about 500rpm short of the redline. This way, if you miss the gear or something it wont bounce off the OE red line (I think that this is just engaged when you put the clutch down), thus saving your engine (if not your gearbox!)
Matt
[This message has been edited by Matt_S (edited 22-10-2001).]
Daniel san
22-10-2001, 19:30
I've got a rev limiter at 6500rpm which engages as soon as you touch the clutch. It stops you killing the engine (and sounds bloody kewl).
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Dan
www.puresx.co.uk
'98 Saphire Blue S14
With a few Blitz and HKS bitz bolted on.
Paul_S13
22-10-2001, 20:26
TC http://300zx.co.uk/200sx/ubb/frown.gif not for me thanks, i'm happy with ABS.
But each to his own
The computer on F1 cars (which incorperates traction control) can also adjust the active diff. to balance out the car's tendancy to oversteer/understeer through a corner although unlike traction control, how well it works depends on how how well the driver can set it up. I think getting an active diff. for an S14 might be a bit of a b*tch so its probably not an option! (although a certain nissan big bruiser uses the same principals so maybe....)
Oh yeah, sounds like your friend has got traction control confused with active yaw control. That works by when turning into a corner, the inside rear brake comes on very slightly to pull the car in to the apex. It was developed by Mclaren in 1997 and now it's just about everywhere (even a focus!) so if you fancy being different, find a written off focus and let us know how you get on!
I have a question....
So Adjustable traction control can be set for driving condition.
Launch control allows you to melt your clutch (If you have one).
and Full throttle shift does exactly what it says on the tin.
So is launch control and full throttle shift(doubt it) sutible for an auto?
According to the auto boys (see past threads ad infinitum http://300zx.co.uk/200sx/ubb/smile.gif http://300zx.co.uk/200sx/ubb/smile.gif ) you don't ever need traction control with auto! And... er... I wasn't aware you had to lift off with an auto... or am I missing the/your point?!?
But let's not go down that road too far..... http://300zx.co.uk/200sx/ubb/wink.gif
[This message has been edited by Tombs (edited 22-10-2001).]
I guess my point was I would like varible traction control but i don't think the other functions are any use on an auto.
And for ref my S14a auto does lose the back end when floored as did my manual S14.
Thanks for your reply.
C.
Cookie,
I don't know, but I also don't see why this shouldn't work on an auto. Since the RL traction control uses the ABS sensor(s) to determine wheelspin.
John.
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