Technical Question on T/C

[roger.daltrey]

I've always thought (although I have no engineering training) that it would be possible to fit a simple traction control to any fly-by-wire throttle based vehicle at little or no cost.

The software within the ECU would measure the revs against the measured road speed and if it differs by a percentage figure (the 'delta') then stop the flow of petrol (or whatever the technical phrase is).

This should operate at any speed and in any gear - as its just comparing the input speed requirements (throttle pedal) to the output engine revs and actual road speed.

There would be an 'envelope' of normal throttle/revs/speed and anything that fell outside this could resonably be assumed to be a loss of traction - and therefore cut the engine.

To make things even simpler you could limit the speed at which it operated to improve the accuracy of the envelope.

I remember some years ago thinking that just such a system would be a workaround to the ban on traction control in F1, as you are not actually measuring whether the tyres have lost traction merely the disproportionate rise in engine revs against road speed.

Comments anyone ???

[bogie]

I think thats basically all the Lotus system is - its just some software they wrote and put in the ECU - like everyone else - develop it once, make profit on every car sold with it etc

[roger.daltrey]

Okay, so if it is just an ECU thing - could it be offered as a retro-fit to existing Lotus fly-by-wire car owners ?

Does anyone know which model/year vehicles use an electronic throttle ??

[bogie]

im sure it could, dunno when it came in exactly, it may just be the throttle and of course wheel speed sensors in the the bearing packs, as Lotus have only been supplying bearing packs with them in now for quite some years, I would think all later cars would have them

but yeah, it should just be an ECU re-flash I guess...of course they are not going to give it away

dunno how much it is an an option, but you can fit a Race Logic system for about £600-700 ish, and its fully adjustable, rather than just on/off

[F.C.]

The traction control in my Exige S2 is adjustable for slip from 0-10% via a knob on the steering wheel cowl.
It is a fairly crude affair but works ok and could save an off in some circumstances.
F.C.

[calvert86]

I was at a Lotus dealership in Leeds about 3 years ago now and was looking at a 111R at the time.
They said it would be possible to retro-fit traction control to the car for about £500 if i remember!

Sure someone else has more info on this though! :-)

[piooly]

have a look at Race Logic website. They sell these types of traction control units. Work pretty well and bascialy just wire in. Doesnt need to interact with the ECU or anything....

[Wildfire]

Yep, heard good things from the TVR world about the Race Logic TC system. Steve Heath (shpub) has fitted one, to one of his cars at some point, I believe.

[roger.daltrey]

I took a look a the Racelogic website - and it does look good stuff.

But I liked the idea of a unit supplied by Lotus - keeping the warranty and all that.

Racelogic say that Lotus use their product - is that so and are Lotus just OEM'ing the Racelogic thing ??

[TonyHetherington]

F.C. said:

The traction control in my Exige S2 is adjustable for slip from 0-10% via a knob on the steering wheel cowl.
It is a fairly crude affair but works ok and could save an off in some circumstances.
F.C.

Do you have an extremely new car? My TC in my 06 Exige S is only on or off.

[Gad-Westy]

Out of curiosity, how does the ECU measure road speeds on an S2 Elise/Exige and how would it know what gear you're in? If it measures road speed at a front wheel and compares it to that at the back wheel, I could see the system working although it would need to measure the speed at both rear wheels seeing as the car would have an open diff.

[calvert86]

TonyHetherington said:

F.C. said:

The traction control in my Exige S2 is adjustable for slip from 0-10% via a knob on the steering wheel cowl.
It is a fairly crude affair but works ok and could save an off in some circumstances.
F.C.

Do you have an extremely new car? My TC in my 06 Exige S is only on or off.

Think they introduced this on the 08 cars!

[TonyHetherington]

Ahhhhh. I knew they had it on the 2-11 but didn't know on the new Exige cars. Thanks

[LivinLaVidaLotus]

They use the ABS sensors for the TC Don't they?

[Sonicboon]

Fly by wire throttles came in on '06 cars I believe, same as the LED lights and change over to Probax seats.

[bogie]

no Lotus wrote their own software, they dont use Race Logic in their current road cars AFAIK

yes they use the wheel speed sensors from the ABS - 4 corners independantly

I had the full RaceLogic traction and launch control in my old SC Honda Elise - awesome for standing starts on sprints etc - could do 0-60 in sub 4secs and 0-100 in 10 ish in the WET on A048s

The Racelogic system with the digital adjust in dash, is very nice - you can have pre-sets for different conditions, and different slip allowed pre-set across speed bands, per condition - so a lot more programmable than the Lotus system, which is either on/off or a knob for 0-10%

[RobM77]

Yes, I think it would indeed be that simple. I think TC is rather over-rated though. I've got switchable TC on my 328i and not on the Elise or Caterham, all of which I regularly drive quickly in slippery conditions and I'm not entirely sure that I see the point of TC. DSC and ABS work miracles due to their differential wheel control, but TC can just be done with your right foot IMHO.

[F.C.]

TonyHetherington said:

F.C. said:

The traction control in my Exige S2 is adjustable for slip from 0-10% via a knob on the steering wheel cowl.
It is a fairly crude affair but works ok and could save an off in some circumstances.
F.C.

Do you have an extremely new car? My TC in my 06 Exige S is only on or off.

Sorry for the late reply!
Yes my car is Sept 08 S2 Exige, Incidentally the traction control unit also has a launch control facility, I haven't used it yet though cos I am a driving god. (read can't work out how to use it )
F.C.

[cyberface]

The sort of system you describe (cut the fuelling at the first sign of driven wheel slip) is *very* crude and what the first TC systems did. Thinking about it, in a car like the Elise you really don't want a system like this. Imagine what this'd be like if you did this yourself - going hot into a corner, getting on the gas and the back starts to come round - lift off entirely. This is the cause of many of the Lotus stacks that occur. There's no way on earth I'd drive a car with TC like this hard.

Incidentally, this is the type of TC that's fitted to my other car - the MG ZT - and the guys who did the supercharger conversion would not convert the car unless the TC was removed. With the TC on, getting the car sideways would result in the TC 'lifting off' completely and causing irretrievable lift-off oversteer. And that's a front-engined rear-drive car - it's a lot harder to catch lift-off oversteer in a mid-engined car.

So to be sensible, in long corners where oversteer threatens, the fly-by-wire should balance the throttle steady rather than cut fuelling completely. Ideally there'd be a lateral G accelerometer input as well to add to the equation - the type of TC required to provide hard acceleration on a varied grip surface (i.e. maximise forward thrust) is different to the balance required when in a long corner, where cutting the fuel completely could cause irretrievable spins.

In bends, it's not so much traction as weight transfer, which can be more important and cause a positive feedback situation (TC cuts the gas, weight goes forward, rear goes light and spins more, TC cuts more gas or applies brakes to rear wheels, car spins).

I'm not a fan of TC for these reasons, but the sophisticated versions apparently rectify all of these shortcomings. A bit like the early ABS systems could be confused by certain road conditions and be *less* effective than a skilled driver, the 'basic' TC systems can easily be fooled and make a bad situation worse. I'm not sure what system the Exige can have since I don't have it on mine, but a basic 'cut the fuel when there's wheelspin' would be dangerous in a 'live for the corners' car like the Exige...

[bogie]

so the Lotus TC system is dangerous then? ...better tell them