I think you are looking for something to blame for a mistake that you made. Cars aren't prefect and no reactive traction control system is going to save you from that kind of sudden input. I did the same thing once upon a time in a BMW and it put me into a wall at 50 mph, so consider yourself lucky that there was no harm done and learn from the situation.

 

I think the lesson from this post and mine is that there is definitely a driver component to this, but in cooler weather and wet roads with P-Zeros this car has some propensity to go sideways in a straight line, in a way I haven't experienced before, with an application of power and a downshift this one was paddle induced, mine was an auto downshift.

Be careful peeps. Use rain mode and use the power cautiously if the road is wet and the weather cool.

 

Just for clarification....I didn't even have a chance to make it to the throttle....I didn't do anything that I haven't done before in the R coupe and countless times in my XFR which had a 6 speed with much wider spaced ratios.

Also, the car lost its rear but was still traveling predominantly forward and not laterally...

I have gone to BMW M School, R Performance Academy twice, 2 courses at Monticello and 1 at NJMSP. Believe me, I know vehicle dynamics, and that's probably how I kept it off the wall...

It's the fact that it surprised me, and bit me that freaked me out.

 

If no additional throttle input, driver error.
If accompanied by sufficient additional throttle input to prevent engine braking, DSC error.

 

I disagree. I don't care how good a DSC system is, it remains a reactive system. That was the wrong situation to be down-shifting 2 gears in.

However, one thing I have noticed when using the paddles is that they are very sensitive. With just the slightest finger twitch, you can accidentally go down two gears when only one was intended.

 

I don't know guys...I just don't think a car should be that inconsistent...some days you can do something and be fine and then in another instance, it will kill you....

Either the DSC. was way too late or unavailable or the tires just suck. It's not like I downshifted at high speed on a curve in the soaking rain....

 

You keep referring to all your high performance experience, but if you had truly incorporated the lessons that excellent professional instruction should have taught you, you wouldn't be counting on DSC to save you from yourself. You would be driving as if it were turned off or didn't exist.

With regard to tires, you have 15K miles on high-performance, summer tires, and you were driving on cool, wet pavement. Obviously, they are not as good as were when new, but again, I would have thought your considerable experience would have taught you those lessons as well.

A sudden, double-downshift on cool wet pavement at highway speeds can make almost any car spin, even going straight. Fortunately, you did recover without consequences, but rather than engage in denial and looking to shift the blame elsewhere, it would serve you well to look inward and incorporate the lesson.

 

Downshifting harshly enough to cause the rear tires to lose traction is hardly a sign of an experienced 'performance' driver.

 

Uh huh. Uh huh.

Crazy HP cars are better served to be AWD with really active electronics directing power to the wheels for exactly the case you describe. 550hp can get quickly out of control and few of us are professional race car drivers.

 

You lose traction because the wheels are trying to spin faster than the road speed or slower than the road speed. If slower, then the DSC can't help out. If faster, then the DSC should immediately modulate throttle to bring the wheels back to the right speed. If you can't rely on the DSC to throttle back, it shouldn't be there offering false assurance. Downshifting 2 or more gears should present no issue in any conditions as long as you are rev matching. I suspect the OP failed to add more throttle during the down shift.

 

Here's what you did:

You put the car 2 gears down. That shifted the weight to the front. Your tires were already cold and on water. You lost traction in the rear. The front was gripping because of the weight transfer. The rear was loose - once more due to the weight transfer. Then you stepped on the gas - while your rear was loose making it even more loose. You were going to spin and you did spin. Traction control does not change the laws of physics.

AWD would not have changed the weight transfer with resultant increased grip in the front and decreased grip in the rear. You would have still spun the car. However, depending on the suddenness of the move and the jab on the happy pedal - maybe, just maybe, the power to the front might have saved your bacon.

 

I have to say the snarky comments are simply disappointing.

Foosh - instead of concentrating on trying to be the "smartest guy on the thread", why don't you pay attention to what I've been saying: the tires seem to have changed their traction capabilities considerably after 15,000 miles EVEN THOUGH they still have plenty of tread.

So I am commenting on that fact plus inquiring about why this car seems to have this evil bite to it when compared to other cars like my XFR.

Here is what you and others need to understand:

I've driven this car many times in the rain and never previously had stability problems no matter whether I downshifted or not...

The tires were not cold. I had been driving for 30 minutes

The temperature was 52 degrees, well within the functionality of these tires.

So why don't we try to be supportive and collaborative on this forum.





M

 

I think in the beginning everyone was trying to be very helpful and collaborative, but your responses to various helpful observations have been to blame the car and the tires. You don't seem to be listening and much more interested blaming something other than yourself. The overwhelming consensus from folks here about why your incident occurred is very clear.

Just because you managed to get away with questionable driving in the past, doesn't mean it won't eventually bite you.

Good luck!

 

He wasn't using 550 hp. At 60
Mph dropping to 4th with a closed throttle would put him at the bottom of the hp curve. What he experienced was more engine braking than available traction could accomdate.

The rear unweighted due to the increased engine braking at higher RPM in 4th than what he had experienced in 6th. The rears got light, the wheel speed did not match the road speed and the back end got squirrelly. AWD would have just made all 4 wheels get squirrely.

This was at best a heads up to all of us to get winter tires or plan to drive very smoothly on the cold pirellis, especially when it's wet. That goes for those with AWD as well as RWD.

 

I suspect the DSC system did engage and primarily applied wheel appropriate braking to bring the car back into line. Perhaps it was the car that recovered, not the driver.

No current DSC system is going to completely prevent a driver-induced upset, but I hear driverless cars are on the horizon.

 

I disagree about the AWD... Remember the rears have 100 percent of the power UNTIL they slip. At that point, in a few milliseconds 50 percent of the power would have been sent to drive the fronts and possibly saved the spin. When the downshift took place there was no power to the fronts so they had no reason to lose traction. AWD may have prevented the spin...

(This relating only to the FType AWD system, not full time AWD.)

 

So you're saying the AWD car would have acted like a RWD car and broke the back tires loose either way, but then after the car had already lost traction at the rear, shifting more engine braking to the front would have helped control the car? Doubtful. The only thing that would correct the imbalance would have been the proper amount of throttle.

In any event, my post was in response to one I really disagree with which was on the assertion of 550 hp being too much for a RWD sports car. The OP wasn't using enough of his available HP and in fact should have been using the correct amount of power to match wheel speed to road speed.

I'm hoping they bring back RWD V8 F-types in the U.S. market. The last thing we need is more misinformation about the so-called "dangers" of spinning high powered RWD cars when the spin was not even remotely related to high horsepower.

 

Agreed, this had nothing to do with HP and torque.

 

I lost an XJ6 like this:

Paris in the rain, traffic lights, I thought I pulled away gently, but the back end overtook the front and I went over a high curb.

European roads are known for being very slippery after a long dry spell and a little rain, on that day Paris was almost stopped for minor accidents like mine.

If you go to an airfield they have a tool to measure the friction on the runway, because you can't tell "by eye" how slippery it is.

Road surfaces are very different to tracks, it sounds like you got away with the one I didn't, I have always accepted that the road was far slippier than I expected, sounds like simple misjudgement (IMHO).

 

I did get away with it, and I'm thankful. Clearly my actions was the triggering event, but my question has been ... Should it have? I never had this ever come close to happening in any other performance car.

Also, I don't think 550 hp has anything to do with it. At 60 mph, shifting to 4th, doesn't get you anywhere that is outside of the range of lots of cars....

I'm not saying I had nothing to do with it, of course I did...but I think there was a huge aggravating factor, and that's what I'm trying to figure out....