How do the Traction Control System (TCS) and Limited Slip Differential (LSD) work?

As described in Honda's technical literature on the NSX:

"The torque control differential is designed to help maintain traction when driving over split friction surface conditions and maintain vehicle stability at speed and in crosswinds. It employs a multi-plate clutch and planetary gearset design. Like many conventional LSD (Limited Slip Differential) systems, this unit resists the rotational speed difference between the rear wheels and attempts to maintain the same rate of rotation at both wheels. But unlike most units, the amount of additional torque resisting the rotational difference is limited to 16 kg-m. This reduces understeer by not trying to keep the car from going towards the direction in which it is being steered. In a cornering situation, too much torque transfer to the inside rear wheel tends to oppose the turning moment from the front wheels, thereby increasing understeer.

If the NSX should be disturbed from its intended direction in a crosswind, the differential will detect the rotational difference between the two rear wheels and transfer torque to the slower rotating wheel. This has the effect of helping to keep the car on the desired path.

Compared to both conventional open differentials and limited slip differentials, straight line tracking is improved, especially in crosswinds. On a split friction road surface, the acceleration time is reduced compared to a conventional open differential."

TCS is not affected when you upgrade wheel/tire sizes as long as you keep the same size ratio. This is because it looks at the ratio of the speeds of the front and rear (and left/right) wheels.

The TCS systems tolerance for the ratio is reported to be 5%. As long as you keep the ratio within 5% of stock TCS should work with any size wheels you can mount on the car. See section 4.4 for a list of wheel sizes that NSX owners have tried and the appropriate tire sizes to use with them.

TCS Comments

[NM] I experimented with Dan O. at a soapy skidpad with the TCS on - as well as separately in a wet and empty parking lot. I have a 91 so I can't speak for later models which may or may not have updated systems.

My experience on the skidpad was that TCS worked very well. Even if I floored it and increased wheel angle, the car just started to predictably understeer at an predictable rate. The TCS was not obtrusive at all.

On a damp, empty parking lot I would accelerate with TCS on in a straight line then take a very sharp 70 to 90 deg turn with lots of throttle. The TCS did little to control the wheel spin in a straight line (seems to kick in a little unpredictably) - but when I would turn the TCS came on rather abruptly in the turn and it was very disorienting. So disorienting it is almost irresistible to hit the breaks and then the fun really begins!!! Once I got the hang of it and was comfortable with the "kick in" it became much more predicable and manageable.

IMO - if you have invested in driving schools and are an alert and confident driver, you will be better off without the TCS in the dry. In the wet, I would definitely use it, but only after going to a parking lot and getting used to it so you know how your car will react to TCS. At the track I only run TCS when it is raining and I have my R1's on (R1's stick in the LIGHT rain better then most people think!). Most good instructors with knowledge of the NSX will ask you to turn it off (in the dry) and will evaluate your driving style, experience, and conditions when recommending TCS in the rain.

[CA] I was driving the NSX after work yesterday, taking in moment and enjoying the idea of keeping it, I was at a stop light, the light turned green and I (believe it or not) slowly accelerated the TCS light started to blink and the power was effectively cut, I was barely rolling and could not accelerate, nor could I turn the TCS off (????) after about 7-8 seconds it cleared and have not been able to duplicate the problem.

I want to reiterate that I was not hot rodding (I have found new inner peace with merely driving normally!) and that this was the softest accerealtion I possibly could have done.

[SS] The only two times I have spun my car ['95 -T]is with TCS on, in dry conditions. My experience: With TCS off, the car slides like any other car, and you just simply steer into the slide and GENTLY let off the gas to line everything back up. Just like you were taught in drivers ed. Just like every other car without TCS.

With TCS on, when the rear looses traction, starts to slide, then TCS kicks in and effectively brakes the rear, trying to put it back in place. Meanwhile, I was steering into the slide as usual, and the car tail whipped in the opposite direction of the slide, and spun. This snap-oversteer condition is very fast, and virtually unrecoverable. I have never fought so hard to recover from a slide. The TCS computer sucks in the dry.

Yeah, OK the initial slides were my fault, but the TCS computer SHOULD NOT INTERFERE with my ability to recover. The owners manual states something to the extent that driving with the TCS on does not require any special technique than driving with TCS off. Total CRAP. With TCS on, and in dry conditions, you continue to steer INTO the curve, not the slide, nail the gas, and let the computer sort out the rear end. Is this Hondas definition of 'no special technique'?

I very much dislike the TCS computer in the dry. And I wish Honda would pay for $10K of suspension and steering damage due to my last spin, with TCS on.

ICBW, but I think they modified the TCS computer in 97+ years to help correct this.

[RKB] Althought the TCS was updated in the 97+ cars to keep the car under power in corners where it's already too deep and a lift would cause oversteer - too many people including myself have noticed some strange throttle behaviour.