I have a C4S and in the rain today I stepped on the accelerator about 80%. In second gear as the engine spun to 5000+rpm, the rear broke traction slid sideways. The stability control quickly caught it of cause.

What I'm surprised is that this happened! I thought the torque will be sent forwards to the front wheels and so this won't happen unless all 4 wheels broke traction together? Or is it just me under-estimating the amazing torque of our S?

 

How many miles / km do you have on the car? In my experience, tires need some time to break in and be sticky enough.

Also, depends on the rain. If the rain was light, it tends to create a sheen between the water and the oils on the road, which is naturally very slippery.

 

2700 miles on the car (so I expect the tyres to be run in by now?)

I'm aware that light rain (especially at the beginning) is ultra slippery. However it's been raining for a week (so all the oil should be gone) and it was raining moderately.

 

I've had Quatro audi's, which may or not be a reasonable comparison just in terms of how a 4WD system behaves.

And both that I have were very stable in the rain, although probably not capable of delivering the same amount of torque.. But given the right conditions I could get the rear wheels loose... but similar to what you described the traction control took over and stabilized.

Sure the system is supposed to shift traction to the front, but it depends on the exact conditions on each wheel.. maybe all were slipping to some extent and the best result the system could generate was what you experienced.. At some point other than overriding the throttle, it can't do better traction wise than physics dictates..

I'm not sure for example if say you put yourself on some low traction surface like glassy ice.. And then full throttled it.. If none of the wheels had any traction what would happen..? I don't think you can assume you can blast the throttle in any condition and assume the outcome will be perfect..

 

I think one of the problems is the car is designed to almost always deliver more power to the rear. There could be many reasons for this but one may be because if they did not all the drifters would blow a fuse because they would not get to act like Chris Harris and destroy their tires.

Seriously people are always posting here about how they prefer a C2 so they can let the back end drift out. Funny thing is you can easily get the back end to drift on a C4 and probably at the expense of wet weather handling.

 

305 section rear tire, rear power biased ===== rear slip, and frankly it should be that way!!!

 

Exactly

It also depends on what in mode the car is. In Sport it allows a little bit oversteer, before the nannies step in. In Sport+ it allows a lot more. In Normal it's very hard to get the car to oversteer.

But I agree, the car should be rear biased. That's IMO the great thing about the C4(S)... Most of the time, you don't notice it's AWD. Maybe the facelift gets a kind of Terrain Response System, incl. Downhill assist LOL

 

I wanna see a dial in the c4 so that I could manually set fore - aft percentages !

 

Most likey oils from the road mixed with the rain. Similar to ice during winter.