[DiRT 4] Constructive feedback on the subject of car-feel and physics: The Ultimate Thread

[Madhun1967 51]

imho,until tires are modeled properly with new engine,we are stuck with mimic physics.Tire choice,as in real life rallying should be one of the first things and most important things that we should pay attention to,but we cant.Weight and inertia are sure factors,but a lot can be accomplished by modelling the tires correctly.
Watch any WRC or older footage,tire choice is the main factor in getting times,and getting car feel right.
I hope in future installment we will get that choice,as in most other sims.I love any rally games,and have been driving them since the CMR/ RBR days:)
BTW i would love to hear Codies thoughts about how they implemented new tire model,and why choices cant be offered to alter car handling/traction

[gheeD 15]

but more weight and inertia does not simply always translate into understeer. with more weight you can exceed the grip limit of the rear tyres by swinging the car and initiate a slide. Whats displayed right now is rear tyres never really break away from the front, the grip levels tend to stick to same amounts causing the understeer. The rear gains grip too fast and front end has no grip? mostly the issue i have is with the rear tyres grip.

[Headlong 0]

gheeD said:

but more weight and inertia does not simply always translate into understeer. with more weight you can exceed the grip limit of the rear tyres by swinging the car and initiate a slide. Whats displayed right now is rear tyres never really break away from the front, the grip levels tend to stick to same amounts causing the understeer. The rear gains grip too fast and front end has no grip? mostly the issue i have is with the rear tyres grip.

The grip of the tyres is the limiting factor here. To do what you suggest would mean making the tyres more grippy, and that's not what people want. Furthermore I don't have any problems getting the rear to break away. That's not the issue. 

[gheeD 15]

to make rear end slide you need to overcome the grip of rear tyres. if you force the rear to lose grip you cant manage it with throttle to keep the rear stepped out, instead it simply regains grip and goes to understeer.

[versedi 39]

gheeD said:

to make rear end slide you need to overcome the grip of rear tyres. if you force the rear to lose grip you cant manage it with throttle to keep the rear steppes out, instead it simply regains grip and goes to understeer.

Exactly, and this was illustrated on beatiful drawing by @SirPhilMcKraken

[Headlong 0]

gheeD said:

to make rear end slide you need to overcome the grip of rear tyres. if you force the rear to lose grip you cant manage it with throttle to keep the rear steppes out, instead it simply regains grip and goes  to understeer. 

But you can't force the rear tyres to lose grip if the front tyres don't give you enough grip to transfer a sufficient amount of weight to the front of the car. 

[dgeesi0 305]

Headlong said:

gheeD said:

but more weight and inertia does not simply always translate into understeer. with more weight you can exceed the grip limit of the rear tyres by swinging the car and initiate a slide. Whats displayed right now is rear tyres never really break away from the front, the grip levels tend to stick to same amounts causing the understeer. The rear gains grip too fast and front end has no grip? mostly the issue i have is with the rear tyres grip.

The grip of the tyres is the limiting factor here. To do what you suggest would mean making the tyres more grippy, and that's not what people want. Furthermore I don't have any problems getting the rear to break away. That's not the issue. 

cant believe i read the last bit.

" Furthermore I don't have any problems getting the rear to break away. That's not the issue. " what ? :#

we have shown in videos already.the subaru is just one of cars that exibits this.it will start to go then its pulls back in.the tail end should come round more easily and stay there if you can control it.the difference is doesnt matter what control you have it doesnt do it now.

thats one car.i think overall the system is a improvement over dirt rally but some people must be driving with blinkers on.

some cars surfaces are brilliant.some are okay some are not right.

[Headlong 0]

dgeesi0 said:

Headlong said:

gheeD said:

but more weight and inertia does not simply always translate into understeer. with more weight you can exceed the grip limit of the rear tyres by swinging the car and initiate a slide. Whats displayed right now is rear tyres never really break away from the front, the grip levels tend to stick to same amounts causing the understeer. The rear gains grip too fast and front end has no grip? mostly the issue i have is with the rear tyres grip.

The grip of the tyres is the limiting factor here. To do what you suggest would mean making the tyres more grippy, and that's not what people want. Furthermore I don't have any problems getting the rear to break away. That's not the issue. 

cant believe i read the last bit.

" Furthermore I don't have any problems getting the rear to break away. That's not the issue. " what ? :#

we have shown in videos already.the subaru is just one of cars that exibits this.it will start to go then its pulls back in.the tail end should come round more easily and stay there if you can control it.the difference is doesnt matter what control you have it doesnt do it now.

thats one car.i think overall the system is a improvement over dirt rally but some people must be driving with blinkers on.

some cars surfaces are brilliant.some are okay some are not right.

It pulls back because you give it too much throttle which cause the car to trust forward and therefore straighten out. This is what happens in real life. It's car dynamics 101. Remember, the Subaru is 4WD.

[versedi 39]

Headlong said:

dgeesi0 said:

Headlong said:

gheeD said:

but more weight and inertia does not simply always translate into understeer. with more weight you can exceed the grip limit of the rear tyres by swinging the car and initiate a slide. Whats displayed right now is rear tyres never really break away from the front, the grip levels tend to stick to same amounts causing the understeer. The rear gains grip too fast and front end has no grip? mostly the issue i have is with the rear tyres grip.

The grip of the tyres is the limiting factor here. To do what you suggest would mean making the tyres more grippy, and that's not what people want. Furthermore I don't have any problems getting the rear to break away. That's not the issue. 

cant believe i read the last bit.

" Furthermore I don't have any problems getting the rear to break away. That's not the issue. " what ? :#

we have shown in videos already.the subaru is just one of cars that exibits this.it will start to go then its pulls back in.the tail end should come round more easily and stay there if you can control it.the difference is doesnt matter what control you have it doesnt do it now.

thats one car.i think overall the system is a improvement over dirt rally but some people must be driving with blinkers on.

some cars surfaces are brilliant.some are okay some are not right.

It pulls back because you give it too much throttle which cause the car to trust forward and therefore straighten out. This is what happens in real life. It's car dynamics 101. Remember, the Subaru is 4WD.

With 70 R/30 F balance?

Lancer is 4WD too, why it doesn't happen there? Space star too....

When you don't apply throttle, the car will go straight even faster!

[gheeD 15]

Headlong said:

gheeD said:

to make rear end slide you need to overcome the grip of rear tyres. if you force the rear to lose grip you cant manage it with throttle to keep the rear steppes out, instead it simply regains grip and goes  to understeer. 

But you can't force the rear tyres to lose grip if the front tyres don't give you enough grip to transfer a sufficient amount of weight to the front of the car. 

you can slide the car rear by slamming on the throttle, which transfers all the weight to the back. why? because all that weight will cause the tyre to overcome its grip whilst spinning the tyre up and with only a little steering angle that will cause the rear to step out. 


you are saying that you can only slide the rear end by making it lighter that there isnt any grip. Im saying you can overcome the grip of the tyre by weight transfer to the rear and swinging the car around and with throttle you can keep the tyre spin high enough that the rear will continue to rotate until you get off throttle or spin arouns after the slide has become fast enough and high enough angle that it will swing the rear around

[Headlong 0]

versedi said:

Headlong said:

dgeesi0 said:

Headlong said:

gheeD said:

but more weight and inertia does not simply always translate into understeer. with more weight you can exceed the grip limit of the rear tyres by swinging the car and initiate a slide. Whats displayed right now is rear tyres never really break away from the front, the grip levels tend to stick to same amounts causing the understeer. The rear gains grip too fast and front end has no grip? mostly the issue i have is with the rear tyres grip.

The grip of the tyres is the limiting factor here. To do what you suggest would mean making the tyres more grippy, and that's not what people want. Furthermore I don't have any problems getting the rear to break away. That's not the issue. 

cant believe i read the last bit.

" Furthermore I don't have any problems getting the rear to break away. That's not the issue. " what ? :#

we have shown in videos already.the subaru is just one of cars that exibits this.it will start to go then its pulls back in.the tail end should come round more easily and stay there if you can control it.the difference is doesnt matter what control you have it doesnt do it now.

thats one car.i think overall the system is a improvement over dirt rally but some people must be driving with blinkers on.

some cars surfaces are brilliant.some are okay some are not right.

It pulls back because you give it too much throttle which cause the car to trust forward and therefore straighten out. This is what happens in real life. It's car dynamics 101. Remember, the Subaru is 4WD.

With 70 R/30 F balance?

Lancer is 4WD too, why it doesn't happen there? Space star too....

When you don't apply throttle, the car will go straight even faster!

I honsestly don't know as this hasn't been my experience. I've been finding the Subaru very malleable and intuitive to drive. I'll tell you what. I will give it go again tomorrow and see if I can replicate your problems. Otherwise there is little point discussing the finer points of this particular cars behaviour. 

[SamRWD 2]

We can't expect gameplay onboard proving your point, right? 

[Headlong 0]

gheeD said:

Headlong said:

gheeD said:

to make rear end slide you need to overcome the grip of rear tyres. if you force the rear to lose grip you cant manage it with throttle to keep the rear steppes out, instead it simply regains grip and goes  to understeer. 

But you can't force the rear tyres to lose grip if the front tyres don't give you enough grip to transfer a sufficient amount of weight to the front of the car. 

you can slide the car rear by slamming on the throttle, which transfers all the weight to the back. why? because all that weight will cause the tyre to overcome its grip whilst spinning the tyre up and with only a little steering angle that will cause the rear to step out. 


you are saying that you can only slide the rear end by making it lighter that there isnt any grip. Im saying you can overcome the grip of the tyre by weight transfer to the rear and swinging the car around and with throttle you can keep the tyre spin high enough that the rear will continue to rotate until you get off throttle or spin arouns after the slide has become fast enough and high enough angle that it will swing the rear around

I know what your your're saying, it's just that what you are saying is wrong. 

First of all, you cannot get the rear of car to slide by slamming the throttle while it is travelling at speed in a straigh line. In fact slamming the throttle while at speed actually transfers weight to the rear and kills oversteer. 

Secondly to get the rear to kick out you need to have enough grip from the tyres to overcome the inertia of the car, as per original post. 

[battfinkz 34]

Actually GheeD, more weight on the rear would increase grip on the rear tyres, not reduce it due to the added traction meaning more friction. But in saying that, it would also increase momentum and once the tyres go past their grip level the rear end would swing around quicker, lol.

This is why rally drivers use the Scandinavian  flick technique, shift the weight one way, then another as they are reducing speed, which loads the weight onto the front of the car, when braking the rear end becomes light and twitchy as the rear tyres have less weight, meaning less grip, friction, traction etc

[Headlong 0]

Headlong said:

gheeD said:

Headlong said:

gheeD said:

to make rear end slide you need to overcome the grip of rear tyres. if you force the rear to lose grip you cant manage it with throttle to keep the rear steppes out, instead it simply regains grip and goes  to understeer. 

But you can't force the rear tyres to lose grip if the front tyres don't give you enough grip to transfer a sufficient amount of weight to the front of the car. 

you can slide the car rear by slamming on the throttle, which transfers all the weight to the back. why? because all that weight will cause the tyre to overcome its grip whilst spinning the tyre up and with only a little steering angle that will cause the rear to step out. 


you are saying that you can only slide the rear end by making it lighter that there isnt any grip. Im saying you can overcome the grip of the tyre by weight transfer to the rear and swinging the car around and with throttle you can keep the tyre spin high enough that the rear will continue to rotate until you get off throttle or spin arouns after the slide has become fast enough and high enough angle that it will swing the rear around

I know what your your're saying, it's just that what you are saying is wrong. 

First of all, you cannot get the rear of car to slide by slamming the throttle while it is travelling at speed in a straigh line. 

Secondly to get the rear to kick out you need to have enough grip from the tyres to overcome the inertia of the car, as per original post. 

SamRWD said:

We can't expect gameplay onboard proving your point, right? 

Will I need to set up a YouTube channe? How long will it take?

[gheeD 15]

You didnt read my post. read it again. you know i wasnt trying to argue what you are taking away from my post.

[versedi 39]

Headlong said:

SamRWD said:

We can't expect gameplay onboard proving your point, right? 

Will I need to set up a YouTube channe? How long will it take?

If you have Google/Gmail it will take 2 clicks.
If not you'll have to use your existing email and register Youtube account with it.

But there's a lot places where you don't have to register to upload video, eg.
 
https://streamable.com

[Headlong 0]

gheeD said:

You didnt read my post. read it again. you know i wasnt trying to argue what you are taking away from my post.

I've read it again. It doesn't look as though you understand vehicle dynamics. May I recommend a book? It's called "Speed Secrets" by Ross Bentley, the ex indycar driver. It's the go-to book for racing drivers and he explains all this weight transfer stuff and car behaviour stuff really well. 

[Headlong 0]

battfinkz said:

Actually GheeD, more weight on the rear would increase grip on the rear tyres, not reduce it due to the added traction meaning more friction. But in saying that, it would also increase momentum and once the tyres go past their grip level the rear end would swing around quicker, lol.

This is why rally drivers use the Scandinavian  flick technique, shift the weight one way, then another as they are reducing speed, which loads the weight onto the front of the car, when braking the rear end becomes light and twitchy as the rear tyres have less weight, meaning less grip, friction, traction etc

You're almost there. Just keep in mind that you need sufficient grip from the tyres to change the vehicles direction and to overcome its inertia, and to induce sufficient slip angle on the rear. That's the key. 

[battfinkz 34]

'you can slide the car rear by slamming on the throttle, which transfers all the weight to the back. why? because all that weight will cause the tyre to overcome its grip whilst spinning the tyre up and with only a little steering angle that will cause the rear to step out.'

This is what i took from your post mate, this is incorrect, unless of course your diff is set to the rear and the rest of the car is tuned to allow the power to stay in the rear, sending all the POWER to the rear, not the weight, then yes, you could do doughnuts in 4wd rally tuned wrc car.

I think it should be pointed out that rally drivers in the 2000's, when hydraulics and electric diffs were not banned, could change diff settings on the fly, it wouldnt suprise me if a driver had to change settings in the car before doing a doughnut mid race for the fans, like we used to see in the burns days, as the car would not have been set up to allow this i imagine 

[gheeD 15]

So me initiating a slide in my friends subaru on a gravel road by giving it throttle and bit of steering input is not how you initiate a slide? Has my whole experience driving a car been a lie? it was just so easy and fun and i could powerslide through finnish forest with a breeze holding a slide through a corner.

[MrDeap 12]

Added weight improve traction, but mass put velocity you make you lose traction.
https://en.wikipedia.org/wiki/Mass_versus_weight

@gheeD is correct.

[Headlong 0]

battfinkz said:

'you can slide the car rear by slamming on the throttle, which transfers all the weight to the back. why? because all that weight will cause the tyre to overcome its grip whilst spinning the tyre up and with only a little steering angle that will cause the rear to step out.'

This is what i took from your post mate, this is incorrect, unless of course your diff is set to the rear and the rest of the car is tuned to allow the power to stay in the rear, sending all the POWER to the rear, not the weight, then yes, you could do doughnuts in 4wd rally tuned wrc car.

I think it should be pointed out that rally drivers in the 2000's, when hydraulics and electric diffs were not banned, could change diff settings on the fly, it wouldnt suprise me if a driver had to change settings in the car before doing a doughnut mid race for the fans, like we used to see in the burns days, as the car would not have been set up to allow this i imagine 

A spinning tyre will by itself not cause the rear to step out, you also need to induce enough of a slip angle, as you've correctly pointed out.

But it here is the problem. How do you do this when approaching a corner and you're already at max speed and the car has so much inertia that the front tyres don't provide enough grip to allow you to induce this slip angle. Or you're in a bend but the  revs are at max and you've got no more torque to induce wheelspin. Plus the surface is soft and a spinning tyre sinks into the gravel or clay. 

That's why I said that adding more weigh to the cars would be counterproductive. 

[battfinkz 34]

You can initiate a slide by going over the maximum grip level of the rear tyres yes, of course. What you were doing though is a power slide, pushing past the limit of the tyres, rally drivers do this, they do most of their steering with the pedals lol. You have to remember though, your friends scooby isnt quite as technically advanced as a wrc car costing a few hundred G's lol, the diffs alone would cost more, and they are intelligently making hundreds of decisions per second

You mentioned specifically transferring weight to the rear to reduce grip in your last post, that wasnt correct.

Imagine you are superman, someone is sitting in a rear wheel drive car, in 1st gear, foot to the floor, wheels are spinning but you are holding the back of the car in the air. As you slowly put the car down, the wheels start to reach the floor, the car isnt going anywhere.

Eventually you put the car down but now you have to hold on as the tyres have the weight on them, meaning they're digging in with traction. This is all i was saying mate

[Headlong 0]

battfinkz said:

You can initiate a slide by going over the maximum grip level of the rear tyres yes, of course. What you were doing though is a power slide, pushing past the limit of the tyres, rally drivers do this, they do most of their steering with the pedals lol. You to remember though, your friends scooby isnt quite as technically advanced as a wrc car costing a few hundred K lol, the diffs alone would cost more, and they are intelligent making hundreds of decisions per second

You mentioned specifically transferring weight to the rear to reduce grip in your last post, that wasnt correct.

Imagine you are superman, someone is sitting in a rear wheel drive car, in 1st gear, foot to the floor, wheels are spinning but you are holding the back of the car in the air. As you slowly put the car down, the wheels start to reach the floor, the car isnt going anywhere.

Eventually you put the car down but now you have to hold on as the tyres have the weight on them, meaning they're digging in with traction. This is all i was saying mate

I'm sorry but I don't really understand how what you've just said relates to what we discussed before. 

Plus I never said that transferring weight to the rear reduces grip. I said that transferring weigh to the rear minimises oversteer, which obviously increases grip on the rear axle and reduces grip on th front axle.