Critique my spin please

[CanAutM3]

Originally Posted by w00tw00t

Today going up Turn 6 at Pacific Raceways. This area is always slick in the wet (run off from the mud bank on the left) and today it was raining very hard. I was going pretty smooth but I think I turned in too early, and was a tiny bit too throttle happy. Once the car spun, I lifted (mistake!) and tried to steer into the spin but the whole car felt like it was on ice... is there anything I could have done differently?

I felt that the lesson here was to turn later (to square off the turn), and obviously not feed too much throttle in while my wheel was turned.

Luckily car was okay - but it was a close call.

My 2 cents for what it is worth:

The line you take can never be blamed for losing control of the car. Sometime you need to make an unexpected move at the track (avoiding an object or another car). This should never be a reason for not being in full control of the car.

Too much throttle for the amount of steering lock caused the rear end to brake loose. In those low grip conditions, you simply went beyond the rear tires friction circle limits.

Too slow and insufficent correction (counter steering and easing off the throttle) followed by completely lifting off the throttle is what caused you to spin. You need to be quicker and more confident with your corrections and just slightly easing off the throttle is the way to go.

BTW kudos to you for posting this. Great learning opportunity for everyone .

[CanAutM3]

Originally Posted by SenorFunkyPants

I think there is a significant difference between lift off oversteer and a throttle induced slide. In this case the moment the rear tyres lost grip and the rear started to slide what rearward "weight transfer" that existed was almost all lost...no traction no torque to pull the rear of the car down.
The problem was that the amount of counter steer and the speed that it applied was too little and too slow....closing the throttle made little difference.
All IMO of course.

Not really. It also has to do with the friction circle. Lifting off completely is akin to applying some brake due to the engine compression. You therefore have less lateral grip available because some of the grip is used longitudinally.

You are correct, you need to remove some throttle input to regain control, but lifting off completly will only make things worse.

[CanAutM3]

Originally Posted by w00tw00t

** Do not lift!! Use Throttle Steer - use maint. throttle - If you lift the throttle when the car oversteers, you are taking load off the rear. Thereby weight transfers to the front, the rear gets lighter and traction in the rear is decreased even more. So the oversteer will result in a spin

I am not sure I agree with the above point. Completely lifting off will make thing worse, I fully agree. But IMO, you need to give some relief to the rear tires if you want them to regain traction, this is done by slightly easing off the throttle to reduce demand for longitudinal traction and increase lateral grip in exchange.

[w00tw00t]

Originally Posted by CanAutM3

I am not sure I agree with the above point. Completely lifting off will make thing worse, I fully agree. But IMO, you need to give some relief to the rear tires if you want them to regain traction, this is done by slightly easing off the throttle to reduce demand for longitudinal traction and increase lateral grip in exchange.

good point! I completely lifted - which was bad. Need some maintenance.


What's interesting is, for all the theory - in that moment, I still lifted even though I'd always told myself never to lift.

Practice and experience is priceless!

[USCTrojanMan29]

Originally Posted by bigjae1976

So let's say all 4 wheels are pointed forward. So lock the steering wheel and start to rotate the back end around. What happens? The front wheels rotate as the back end rotates. So the back end is chasing the front end in a circle. Hence...spin.

Go back to all 4 wheels pointed forward. Release the steering wheel and rotate the back end around...what happens? The steering wheel turns but the front wheels stay pointed forward.

Basically, the throttle is steering the car. So you apply throttle, the back end steps out more and adds lock into the steering wheel. So let up on the throttle in a controlled manner, the rear end comes back in line with the rear end and the steering wheel goes back towards center.

The rotational inertia (I made that up but you know what I mean) of the rear axle is what is turning the steering wheel.

Do you think that would work on a GT3 where ~70% of the weight is in the rear?

[SenorFunkyPants]

Originally Posted by SenorFunkyPants

I think there is a significant difference between lift off oversteer and a throttle induced slide. In this case the moment the rear tyres lost grip and the rear started to slide what rearward "weight transfer" that existed was almost all lost...no traction no torque to pull the rear of the car down.
The problem was that the amount of counter steer and the speed that it applied was too little and too slow....closing the throttle made little difference.
All IMO of course.

Originally Posted by CanAutM3

Not really. It all has to do with the friction circle. Lifting off completely is akin to applying some brake due to the engine compression. You therefore have less lateral grip available because some of the grip is used longitudinally.
You are correct, you need to remove some throttle input to regain control, but lifting off completly will only make things worse.

I do agree with you in principle however in this case I think closing the throttle was a very minor influence, he was already at low rpms (2.5k) travelling quite slowly on a low grip surface, as the slide progressed the amount that the rear tyres needed to rotate became ever slower until at 90 degrees they needed to be stationary.

[CanAutM3]

Originally Posted by SenorFunkyPants

I do agree with you in principle however in this case I think closing the throttle was a very minor influence, he was already at low rpms (2.5k) travelling quite slowly on a low grip surface, as the slide progressed the amount that the rear tyres needed to rotate became ever slower until at 90 degrees they needed to be stationary.

If you watch the video closely with the telemetry, you will notice that he lifted entirely as soon as he felt the oversteer. As discused previously, this has a two fold negative impact: weight transfer and braking force. Those principles apply at any speed. Running in low grip conditions makes them even more obvious despite the lower speed. This is why driving in the wet (or in snow) is such a great learning experience, because you don't need to travel as fast to experience at the limit behaviour.

In my experience, abruptly and entirely lifting of the throttle in an oversteer situation almost always results in a spin .

[SenorFunkyPants]

Originally Posted by CanAutM3

If you watch the video closely with the telemetry, you will notice that he lifted entirely as soon as he felt the oversteer. As discused previously, this has a two fold negative impact: weight transfer and braking force.

The moment the rear tyres lost grip was the moment that most of the "weight" transferred away from the rear of the car. With no grip the rear tyres are no longer pulling the rear of the car down. True the ideal would have been to have matched the throttle input to the every decreasing rotational speed of the rear tyres but *in this case* I don't think stepping off the throttle was a significant component. You can catch those sorts of throttle induced slow slides every day of the week as long as you are quick enough with the steering (I practice it a lot in our often damp UK climate).
Not trying to be nit picking or argumentative, I just find it an interesting topic to discuss.

[CanAutM3]

Originally Posted by SenorFunkyPants

Not trying to be nit picking or argumentative, I just find it an interesting topic to discuss.

That is what forums are for. I enjoy constructive debates, I always end-up learning something from them

Originally Posted by SenorFunkyPants

The moment the rear tyres lost grip was the moment that most of the "weight" transferred away from the rear of the car. With no grip the rear tyres are no longer pulling the rear of the car down. True the ideal would have been to have matched the throttle input to the every decreasing rotational speed of the rear tyres but *in this case* I don't think stepping off the throttle was a significant component. You can catch those sorts of throttle induced slow slides every day of the week as long as you are quick enough with the steering (I practice it a lot in our often damp UK climate).

My understanding:

Thing is, tire grip is not an on or off type of thing. Even if the tires are sliding, they are still generating grip. Further, the transition from static friction to dynamic friction between the tire and the road surface is actually quite complex. Tires generate their maximum grip (or force) with some level of slip.

An oversteer situation simply means that the rear tires are slipping more than the fronts, but the rear tires are still generating some lateral force in the process. By properly managing the car's attitude it is possible to maximize whatever grip there is in the desired direction.

You are correct with the fact that having quick hands is the most important ingredient in the receipe

[w00tw00t]

Great inputs!, I'm going to sign up for some skid pad lessons this year so I can safely practice these concepts.

[1MOREMOD]

Originally Posted by w00tw00t

Great inputs!, I'm going to sign up for some skid pad lessons this year so I can safely practice these concepts.

Good call.

[SenorFunkyPants]

Originally Posted by w00tw00t

I'm going to sign up for some skid pad lessons this year so I can safely practice these concepts.

I was looking for something similar last night as well...I was thinking it can't hurt to get some extra skid and drifting practice without the risk of putting my car into the scenery if it all went tits up.

[1MOREMOD]

Originally Posted by w00tw00t

Great inputs!, I'm going to sign up for some skid pad lessons this year so I can safely practice these concepts.

How do they do that for us, say it isn't raining?

[w00tw00t]

Originally Posted by 1MOREMOD

How do they do that for us, say it isn't raining?

I was thinking of the PCA Bremerton skills day - I believe they use a water tanker to wet the skid pad. I will check with Carl.

[bigjae1976]

Originally Posted by USCTrojanMan29

Do you think that would work on a GT3 where ~70% of the weight is in the rear?

Yes. Even moreso with a Porsche...you steer it with the throttle. With a rear engine/RWD car, your biggest grip advantage is on the rear axle. Weight does not equal grip but its weight that pushes down on the tire which increases the contact patch which results in more grip.

So turning the steering wheel under throttle with at most 30% of the weight over the front axle is not where the grip is.

Originally Posted by SenorFunkyPants

The moment the rear tyres lost grip was the moment that most of the "weight" transferred away from the rear of the car. With no grip the rear tyres are no longer pulling the rear of the car down. True the ideal would have been to have matched the throttle input to the every decreasing rotational speed of the rear tyres but *in this case* I don't think stepping off the throttle was a significant component. You can catch those sorts of throttle induced slow slides every day of the week as long as you are quick enough with the steering (I practice it a lot in our often damp UK climate).
Not trying to be nit picking or argumentative, I just find it an interesting topic to discuss.

Weight transfer is important for grip. As I mentioned above, weight increases the contact patch resulting in more grip. So lifting throws the weight onto the front axle at a time where you don't want to take away grip.

But let's look at the condition of the track. If the back end is coming around, what does that tell you? That you've exceeded the available grip. As I've mentioned earlier, a lot of corners will have a polished surface, especially from the apex to track out on the dry line.

Really, the goal should have been to get the car to a part of the track that has more grip which is probably anywhere but the dry line.

Originally Posted by w00tw00t

Great inputs!, I'm going to sign up for some skid pad lessons this year so I can safely practice these concepts.

Drifting, IMO, provides more practice and really challenges you to think about the balance of the car by purposely upsetting the car to initiate a drift. Not sure a vette would do real well though...not a lot of steering lock.

[bigjae1976]

Originally Posted by CanAutM3

The line you take can never be blamed for losing control of the car.

Agreed. The line and track conditions can affect lap times but really it comes down to being able to keep the car balanced and under control.

[w00tw00t]

Originally Posted by bigjae1976

Drifting, IMO, provides more practice and really challenges you to think about the balance of the car by purposely upsetting the car to initiate a drift. Not sure a vette would do real well though...not a lot of steering lock.

Unfortunately I know of no drifting events here in PacNW, only PCA does a skills day where they have a wet skid pad.

What would you say to a rally driving school though - there is a great rally/offroading school here called dirtfish.

The other hobby I want to start but don't have the time is to do karting - which I think will help in car control skills.

[bigjae1976]

Originally Posted by w00tw00t

Unfortunately I know of no drifting events here in PacNW, only PCA does a skills day where they have a wet skid pad.

What would you say to a rally driving school though - there is a great rally/offroading school here called dirtfish.

The other hobby I want to start but don't have the time is to do karting - which I think will help in car control skills.

I'm sure there is...just got to look. The drifting crowd will probably not be the same guys that rally, HPDE, and kart for the most part. Generally its made up of younger guys who are not interested in lap times but looking good going slow although there are plenty who are serious about it. Ideally you'd find an event with good instruction. From what I've seen, the good ones are feeders into Formula Drift. Most others are just a bunch of people trying to figure it out.

[Sapper_M3]

Originally Posted by bigjae1976

I'm sure there is...just got to look. The drifting crowd will probably not be the same guys that rally, HPDE, and kart for the most part. Generally its made up of younger guys who are not interested in lap times but looking good going slow although there are plenty who are serious about it. Ideally you'd find an event with good instruction. From what I've seen, the good ones are feeders into Formula Drift. Most others are just a bunch of people trying to figure it out.

http://www.evergreendrift.com/#

June 8 is the next open drift event. I just moved to the area fairly recently, and I haven't participated in any of their events yet so I can't actually vouch for the crowd. With that said, I've been to a few drift event with a few different groups over the past 18 months, and I've never seen a crowd that wasn't supportive and extremely willing to instruct beginners (much like the general road-course tracking community).

[w00tw00t]

Originally Posted by Sapper_M3

http://www.evergreendrift.com/#

June 8 is the next open drift event. I just moved to the area fairly recently, and I haven't participated in any of their events yet so I can't actually vouch for the crowd. With that said, I've been to a few drift event with a few different groups over the past 18 months, and I've never seen a crowd that wasn't supportive and extremely willing to instruct beginners (much like the general road-course tracking community).

huh cool!

[LiM3y]

Originally Posted by w00tw00t

Great inputs!, I'm going to sign up for some skid pad lessons this year so I can safely practice these concepts.

It is actually fun too!

The weirdest thing is letting the steering wheel slip in your fingers and let the "momentum' point the front wheels and setting up a drift...I still don't quite trust it...but it feels really good when you get it right and it is comforting to "work with the car" to straighten out rather than fighting it with a steely grip. I have difficulty with unloading springs, but that's the fun of practising. I have progressed to doing this on an auto-X track, but hopefully I won't have to at 80mph on a full track. That means something has gone wrong...and once is enough...

[USCTrojanMan29]

Originally Posted by bigjae1976

Yes. Even moreso with a Porsche...you steer it with the throttle. With a rear engine/RWD car, your biggest grip advantage is on the rear axle. Weight does not equal grip but its weight that pushes down on the tire which increases the contact patch which results in more grip.

Gotcha, makes sense as I've heard the following from several PCA instructors...."when in doubt stay on gas and turn the wheel where you want to go"