Massive M4 Track Crash

[Demxsr]

Just stumbled on this tonight. This was also posted in the track section. I'm not sure if he's a member. I'm not posting this to bash or create any negativity towards them. He seems to know what he's doing on the track, and it's sad to see a situation like this. I just wanted to create some awareness of his video. It will help a fellow F8X owner out, and hopefully help him go through the rebuild process.

It's a crazy crash. Glad everyone walked away. Looks like the car flies over 100ft in the air and he thinks it did a quadruple rollover. I've always thought about the strength of the roof in these cars without a cage. I'm amazed how well the roof held up considering that. Actual crash footage starts at 2:54

[khoa@x-ph.com]

Crazy how things could go wrong in a quick second on the track. It's a bless that both driver and passenger got out in one piece.

[arashir]

What could have happened to explain that crash? It looks like as soon as he started to give steering input to the left, zero front grip shortly after and the car is maybe already locked in a spin losing the back end.

Just makes me think if I was in his shoes if there was anything that could have been done to save the car

[Demxsr]

Originally Posted by arashir

What could have happened to explain that crash? It looks like as soon as he started to give steering input to the left, zero front grip shortly after and the car is maybe already locked in a spin losing the back end.

Just makes me think if I was in his shoes if there was anything that could have been done to save the car

I looks like there is a bump in that section, so probably had negative G's that totally reduced his grip and then unsettled the suspension.

[hatepotholez]

Looks like DSC was fully off. This car is a handful when DSC is off and on street tires.

[Wanted_M]

Wow, glad he's ok. I doubt that car is salvageable.

[arashir]

Originally Posted by Demxsr

I looks like there is a bump in that section, so probably had negative G's that totally reduced his grip and then unsettled the suspension.

Looking at this some more and reading a few more resources, I don't see a bump here. But it does look like if he was too much on the throttle while going over the crest, especially upon changing steering from left to right that could unload the suspension and explain it

we need an expert assessment if he would be so kind to weigh in CanAutM3

[Demxsr]

Originally Posted by arashir

Looking at this some more and reading a few more resources, I don't see a bump here. But it does look like if he was too much on the throttle while going over the crest, especially upon changing steering from left to right that could unload the suspension and explain it

we need an expert assessment if he would be so kind to weigh in CanAutM3

Crest is the word I should have used. Not bump

[Tommy L Garage]

Here is my take.
- Throttle lift
- traction off

When I used to ride with instructors we never took traction off. It was not allowed.

Glad they’re both okay. Could have been so terrible.

[CanAutM3]

Originally Posted by arashir

Looking at this some more and reading a few more resources, I don't see a bump here. But it does look like if he was too much on the throttle while going over the crest, especially upon changing steering from left to right that could unload the suspension and explain it

we need an expert assessment if he would be so kind to weigh in CanAutM3

I don't consider myself an "expert", but I can share my take:

It's quite difficult for me to figure exactly what went wrong, he is obviously quite an experienced driver and the car snapped on him. I hear a lot of people on the forum complaining about snap oversteer when it clearly isn't the case; but here, it really snapped on him. Most posted mishap videos are quite straight forward to figure out, this one not so much. Even after watching the video several times, it is not clear cut to me what happened. We don't know the suspension setup nor the tire condition which can also be contributing factors.

From the little we see and hear in the video, I would speculate too much lift off throttle during the left-right transition that caused the rear to get light over the crest and then not enough correction right after the car started to oversteer. And I am not implying I would have faired any better at saving it.

[Redacre]

I saw something very similar at Thunderhill Raceway a while back. The owner also walked away unharmed but his M4 rolled at T1E, which is an uphill banked turn. I was in a slower run group and gridded up when they towed the car past us and it scared the heck out of me.

[jmg]

My humble take:

Immediately after the crest the driver tries to correct to the right, meaning his rear stepped out to the right. That means he must have still had yaw velocity as he crested which created a left rotational momentum. The front got light with a counter-clockwise rotational yaw velocity and it sent the rear right, the front left. Additionally, throttle life shifts even more weight toward the front, causing the rear to get too light. If throttle lift was just after the front lost traction as the rear was already starting to break loose and the car was experiencing yaw velocity, then it will actually make the problem WORSE!

Not that I would have been able to save this either, nor am I an expert driver, but what little I know says that if that corner needed throttle lift, it should have happened just BEFORE the peak of the crest to shift weight to the front of the wheels. IMHO it looks like that corner didn't need throttle lift necessarily, but he turned in slightly too early which means his car was still trying to rotate at the peak of the crest. In navigating a mid turn elevation change at my local track (WSIR), the later apex is necessary as to not be rotating at the peak... a recipe for imbalance.

My only qualification for this info is that I made the same mistake. I didn't flip, but I spun at 100 on a very similar turn at SOW because I apexed too early and came out the other side facing the wrong way with a very light rear end.

[AR_Motorwerkz]

Amazing how he walked away even without a cage! Sorry for his loss though.

[Demxsr]

Originally Posted by AR_Motorwerkz

Amazing how he walked away even without a cage! Sorry for his loss though.

I was surprised too. I'm not sure how hard the roof impacted during the roll overs. The carbon skin peeled and crumpled, but I would expect that. Amazing how little deformation on the actual roof structure there is. The most looks like it's on rear passenger side, and it's not that bad considering his speed and the amount of times it went over.

[TrevorM3]

good to hear hes ok.

i think he definitely needs to get some sleep, he's clearly delirious....


he seems to think that car isn't in bad shape...

[CanAutM3]

Originally Posted by AR_Motorwerkz

Amazing how he walked away even without a cage! Sorry for his loss though.

Safety systems in modern cars are quite impressive, but they function as complete systems.

We've had multiple discussions and debates around what is the safest setup with our group of track rats. We've pretty much all ended up agreeing that a modern street car with all of its stock safety system is safer than any partial race setup. Once you start modifying any component of that stock system, you need to go all the way. For instance, the stock seats and seat belts will allow your body to slouch in case of a roof cave in. Once you install a race seat with 4/5/6 point harnesses, you need a roll cage. With a roll cage, you need a helmet (obvious for the track, not so much when driving on the street). With a stiff race seat and belts that will not allow your body to absorb an impact, you need a Hanz device as well as seat side head restraints to avoid your skull from being ripped out. In other words, either you keep it all stock or go all out race setup. Any partial is less safe.

[MaynardZed]

Agree, it’s a very hard crash to decipher because the mistakes are so minimal it’s very difficult to interpret. But, after watching (and listening) to the video many times (in slo-mo), I agree with the others here. The left steering input (at 2:57) combined with the throttle lift over the crest of the hill caused the slow oversteer releasing the rear to the right. We can’t ever feel what the driver’s butt was feeling at the time, but these higher speed slow drifts are very difficult to pick up and correct.

Very glad the driver and passenger and fine and the car’s safety mechanisms should be applauded.

[CanAutM3]

Here's an old video I did to show examples of oversteer early recoveries. The first too examples are power oversteers resulting from me applying too much throttle without enough steering release (pinching the steering wheel). The third one is a ~100mph trailing throttle oversteer (similar to the OP) resulting from me going in too hot for the grip and not enough throttle to keep the rear planted. Quick hand reaction is what is desired in all case (combined with a slight throttle lift in the two power oversteer cases) to avoid going into that scary zone.

[Demxsr]

It's pretty fascinating, and almost counter intuitive to the uninitiated, that keeping your foot on the gas can save you. But makes total sense with the physics of it. I just hope if that ever happens to me I have the presence of mind to make that split second decision to stay on it, if that is what is needed.

[MaynardZed]

Originally Posted by Demxsr

It's pretty fascinating, and almost counter intuitive to the uninitiated, that keeping your foot on the gas can save you. But makes total sense with the physics of it. I just hope if that ever happens to me I have the presence of mind to make that split second decision to stay on it, if that is what is needed.

Well, there is no "presence of mind" or conscious "decision" made in making these corrections when it happens in real time. It happens too fast. Its something that has to be learned over many years with a lot of seat time so that it becomes muscle memory for the most part.

[drroc]

fast forward 1:20. Corrections at that speed need to be really fast, and you will have to go hand over hand as otherwise you will cross lock your arms won't be able to add further corrections.

At 50 second mark

[CanAutM3]

Originally Posted by Demxsr

It's pretty fascinating, and almost counter intuitive to the uninitiated, that keeping your foot on the gas can save you. But makes total sense with the physics of it. I just hope if that ever happens to me I have the presence of mind to make that split second decision to stay on it, if that is what is needed.

There's nuance here. On trailing throttle oversteer, adding a little throttle if possible can definitely help settle the rear. If you're off throttle because you came in too hot in a corner, it is likely will not possible to add more throttle, so you just have to work it out with countersteering. On power oversteer, you need to lift just enough to allow the tires to regain grip without lifting to the point of shifting too much weight off the rear. Tough reflex to build to get it just right but it does come with practice. If you keep the throttle constant on power oversteer, you can ride the slide with only countersteer, but you need to ensure you have enough room to do it.