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StressedDave
689 posts
131 months
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PEJAYMotors said: So again you would rather loose all grip on the front of your car whilst trying to turn a corner?! Track driving or road driving I would the balance of grip to remain on those front wheels to get the car through the corner... The point is this: if you have grip on your front tyres and no grip on your rear tyres you spin uncontrollably - that's why at a very basic level why handbrake turns work. This isn't dab of oppo oversteer this is something that as a driver turns you into a passenger while the car goes wherever the hell it likes dependent on the trajectory it was on when the disaster happens and the topography of the road surface.
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jimmy the hat
191 posts
16 months
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james_gt3rs
2,531 posts
60 months
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PEJAYMotors said: So again you would rather loose all grip on the front of your car whilst trying to turn a corner?! Track driving or road driving I would the balance of grip to remain on those front wheels to get the car through the corner... But if you lost ALL grip on the back instead, no amount of opposite lock is going to save you surely?
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GravelBen
10,029 posts
99 months
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S. Gonzales Esq. said: It's not a slight difference in grip we're talking about here, it's about the tendency to aquaplane on bends at low speeds. That kind of sudden and total loss of control isn't the same thing as a slightly oversteer-y balance. Unless there is a major difference in tread depth it would be a very narrow window of water depth+speed combinations that would cause one end to aquaplane while the other grips fine though, far more likely to either both grip or both aquaplane. And FWIW in 12 years of driving (much less than some on here I'm aware) I have aquaplaned a grand total of zero times.
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GravelBen
10,029 posts
99 months
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james_gt3rs said: But if you lost ALL grip on the back instead, no amount of opposite lock is going to save you surely? To balance that - if you lost ALL grip on the front no amount of lifting off/braking/accelerating is going to save you either, so its a moot point. Do you want to hit the scenery forwards or backwards?
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pmjg66
2,125 posts
83 months
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GravelBen said: james_gt3rs said: But if you lost ALL grip on the back instead, no amount of opposite lock is going to save you surely? To balance that - if you lost ALL grip on the front no amount of lifting off/braking/accelerating is going to save you either, so its a moot point. Do you want to hit the scenery forwards or backwards? There is also a possibility you could hit the scenery sideways on the drivers door,I know which end I would want to hit the scenery/lamp post.
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BorkFactor
4,875 posts
27 months
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I haven't been in this situation often, but when I was I made sure the new tyres were on the front, and the part worn ones that were already on the car went on the back.
This was on both a 1.6 Astra and a 1.8 Mondeo, so not exactly powerful cars. I used Vredstiens on the Astra and Braum (I think?) on the Mondeo and never had any problems. No tail happy nonsense with normal driving, but you could get the back out if you were really trying.
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james_gt3rs
2,531 posts
60 months
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GravelBen said: To balance that - if you lost ALL grip on the front no amount of lifting off/braking/accelerating is going to save you either, so its a moot point. Do you want to hit the scenery forwards or backwards? I agree 100%
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BertBert
7,071 posts
80 months
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Well I'm a "put the good tyres at the back" man. I don't think it's to do with sudden cataclysmic loss of grip. Generally when understeer starts it's easy to remove the input that started it and you don't need much corrective skill. When oversteer starts, corrective skill is all important. I beleive that's why the "industry" says put the good tyres on the back.
Of course, it matters not to such a driving idol as I.
BB
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PEJAYMotors
24 posts
13 months
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It is beginning to concern me somewhat that some of the "advanced" drivers on this forum have such little understating of car control...
Too all those who have commented talking about complete loss of control then please do us all a favour and hang up your car keys now!! No car should ever be completely out of control unless the driver has tried to defy the laws of physics when cornering to the point that no anti crash computer on board can save you. If this is the reason that you've ended up rearranging the shape of your vehicle than that is driver error not tyre placement on the car.
Road, track or loose surface driving should always have the bias of grip favouring the front axle for the following reasons.
Scenario 1 (scrubbed fronts)
With the balance of grip towards the rear of the car one has entered example corner and been treated by understeer as the worn fronts have had too much asked of them. Too recover one has a few options, 1. Lift off the throttle completely and wait for the weight to transfer back over the front wheels and recover some levels a few seconds later and hope that one hasn't gone off the road in the meantime or hit something head on. 2. (not recommended for road use) Give the handbrake a short sharp pull to get the rear axle too break away thus letting car turn into the corner further. 3. Straighten the steering wheel and hope there is some run off area and make the gradient of turn much larger.
Other downside to having the grip levels towards the rear are if the back wheels were too loose traction then you have less grip on the tyres required to save the car from sliding. This is even more apparent with a front wheel drive car as you are going to need too add more power through those front tyres to recover the slide.
Scenario 2 (scrubbed rears)
With the balance of grip now towards the back one enters the same example corner at the same speed with the same grip conditions. As one turns into the corner the back of the car looses traction so too bring the back of the car into shape a slight lift of the throttle add some opposite look if in a rear wheel drive vehicle or point the fronts where you want to go and get on the power if driving a front wheel drive car.
With the front tyres having plenty of grip both front wheel drive and rear wheel drive oversteer is exceptionally easy to recover!!
All this only comes into account if the driver has made human error in the first to instigate the slide...
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Speedy11
291 posts
77 months
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PEJAYMotors said: Road, track or loose surface driving should always have the bias of grip favouring the front axle for the following reasons. I don't really like using racing examples for road use, however why do you think when it is damp/wet FWD cars like to use slicks on the front and wets on the rear?
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HustleRussell
4,132 posts
29 months
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PEJAYMotors said: ...(inaccurate and irrelevant twaddle).. ...I don't even know where to start with that, but something tells me that it probably wouldn't be worth my time anyway.
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PEJAYMotors
24 posts
13 months
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Speedy11 said: PEJAYMotors said: Road, track or loose surface driving should always have the bias of grip favouring the front axle for the following reasons. I don't really like using racing examples for road use, however why do you think when it is damp/wet FWD cars like to use slicks on the front and wets on the rear? Because a slick tyre on the front of a FWD car generates so much heat from the accelerating forces, bracking forces and cornering forces, combined with the temperatures induced by left foot braking put through the wheel rim that a hot slick in damp conditions provides more grip than the cold wets on the rear of the car. Again that is another example of putting a higher level of grip on the front of a vehicle!!
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pmjg66
2,125 posts
83 months
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PEJAYMotors said: Speedy11 said: PEJAYMotors said: Road, track or loose surface driving should always have the bias of grip favouring the front axle for the following reasons. I don't really like using racing examples for road use, however why do you think when it is damp/wet FWD cars like to use slicks on the front and wets on the rear? Because a slick tyre on the front of a FWD car generates so much heat from the accelerating forces, bracking forces and cornering forces, combined with the temperatures induced by left foot braking put through the wheel rim that a hot slick in damp conditions provides more grip than the cold wets on the rear of the car. Again that is another example of putting a higher level of grip on the front of a vehicle!! Track use and normal road driving conditions are totally different things. Unfortunately not everybody can be blessed with your driving skills PEJAY that's why all tyre manufacturers say they should be fitted to the rear,It really is inept to recommend this. http://www.hometyre.co.uk/fitment-your-new-tyres
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Speedy11
291 posts
77 months
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PEJAYMotors said: Because a slick tyre on the front of a FWD car generates so much heat from the accelerating forces, bracking forces and cornering forces, combined with the temperatures induced by left foot braking put through the wheel rim that a hot slick in damp conditions provides more grip than the cold wets on the rear of the car.
Again that is another example of putting a higher level of grip on the front of a vehicle!! The question is not why they fit slicks to the front (they put up with it when wet hopping for an advantage at the end when it is dry), more why don't they fit slicks to the rear and instead fit wets. If they don't need the grip at the rear as you wrongly say why fit wets at the rear and not slicks?
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WhoseGeneration
4,090 posts
76 months
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StressedDave said: PEJAYMotors said: So again you would rather loose all grip on the front of your car whilst trying to turn a corner?! Track driving or road driving I would the balance of grip to remain on those front wheels to get the car through the corner... The point is this: if you have grip on your front tyres and no grip on your rear tyres you spin uncontrollably - that's why at a very basic level why handbrake turns work. This isn't dab of oppo oversteer this is something that as a driver turns you into a passenger while the car goes wherever the hell it likes dependent on the trajectory it was on when the disaster happens and the topography of the road surface. You see PEJAY, most of us here respect posts from Stressed Dave. He having a very large knowledge base about vehicle dynamics, he'll do the maths too, when he can be bothered. That aside, the point is that tyre manufacturers are aiming this recommendation at the majority of their customers, not we "driving gods" and BTCC contestants.
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Zero 1
63 posts
13 months
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PEJAYMotors said: It is beginning to concern me somewhat that some of the "advanced" drivers on this forum have such little understating of car control...
Too all those who have commented talking about complete loss of control then please do us all a favour and hang up your car keys now!! No car should ever be completely out of control unless the driver has tried to defy the laws of physics when cornering to the point that no anti crash computer on board can save you. If this is the reason that you've ended up rearranging the shape of your vehicle than that is driver error not tyre placement on the car.
Road, track or loose surface driving should always have the bias of grip favouring the front axle for the following reasons.
Scenario 1 (scrubbed fronts)
With the balance of grip towards the rear of the car one has entered example corner and been treated by understeer as the worn fronts have had too much asked of them. Too recover one has a few options, 1. Lift off the throttle completely and wait for the weight to transfer back over the front wheels and recover some levels a few seconds later and hope that one hasn't gone off the road in the meantime or hit something head on. 2. (not recommended for road use) Give the handbrake a short sharp pull to get the rear axle too break away thus letting car turn into the corner further. 3. Straighten the steering wheel and hope there is some run off area and make the gradient of turn much larger.
Other downside to having the grip levels towards the rear are if the back wheels were too loose traction then you have less grip on the tyres required to save the car from sliding. This is even more apparent with a front wheel drive car as you are going to need too add more power through those front tyres to recover the slide.
Scenario 2 (scrubbed rears)
With the balance of grip now towards the back one enters the same example corner at the same speed with the same grip conditions. As one turns into the corner the back of the car looses traction so too bring the back of the car into shape a slight lift of the throttle add some opposite look if in a rear wheel drive vehicle or point the fronts where you want to go and get on the power if driving a front wheel drive car.
With the front tyres having plenty of grip both front wheel drive and rear wheel drive oversteer is exceptionally easy to recover!!
All this only comes into account if the driver has made human error in the first to instigate the slide... Exactly right. My experience both on and off track support what you stated above. You worded it a bit more clearly than I did. Given the choice I would rather have an oversteer condition than an understeer condition because in my experience it is easier to prevent oversteer than it is to prevent understeer. To the guys saying the track and the street are two different things...they're really not. The track due to the higher speed brings out the character of the car or setup you have. If you have a well setup car on the track that is planted, easy to control it will be the same on the street. The two aren't really different at all, rather, one is an extension of the other. Really the only difference between driving fast and slow is the timing between inputs. If the car is setup correct at the track, it will be setup correct on the street. I raced a Miata that doubled as my street car for about 4 years and found that the setup that was right at the track gave me the most control on the street. I'd recommend the following to anyone who is interested in this kind of stuff: http://www.amazon.com/Competition-Car-Suspension-P...http://www.amazon.com/Going-Faster-Mastering-Race-...http://www.amazon.com/Ultimate-Speed-Secrets-Compl...http://www.amazon.com/Inner-Speed-Secrets-Strategi...
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davepoth
19,931 posts
68 months
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PEJAYMotors said: Scenario 2 (scrubbed rears)
With the balance of grip now towards the back one enters the same example corner at the same speed with the same grip conditions. As one turns into the corner the back of the car looses traction so too bring the back of the car into shape a slight lift of the throttle add some opposite look if in a rear wheel drive vehicle or point the fronts where you want to go and get on the power if driving a front wheel drive car.
With the front tyres having plenty of grip both front wheel drive and rear wheel drive oversteer is exceptionally easy to recover!!
All this only comes into account if the driver has made human error in the first to instigate the slide... Got that, but would it not be easier to slow down and steer more for all vehicle configurations? That's why you should put the good tyres on the back.
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pmjg66
2,125 posts
83 months
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Zero 1 said: To the guys saying the track and the street are two different things...they're really not. The track due to the higher speed brings out the character of the car or setup you have. If you have a well setup car on the track that is planted, easy to control it will be the same on the street.
The two aren't really different at all, rather, one is an extension of the other. Really the only difference between driving fast and slow is the timing between inputs. If the car is setup correct at the track, it will be setup correct on the street. I raced a Miata that doubled as my street car for about 4 years and found that the setup that was right at the track gave me the most control on the street. I totally disagree,a well sorted race/track car will be set up differently for dry or wet conditions ie different camber angles and spring rates and toe settings etc,etc. A normal road car supplied to the general public will have settings for good tyre wear and safe handling ie no snap oversteer. This is why ALL tyre manufactures also say new tyres should be fitted to the rear under all circumstances for ROAD use !
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Zero 1
63 posts
13 months
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davepoth said: Got that, but would it not be easier to slow down and steer more for all vehicle configurations? That's why you should put the good tyres on the back. Tire compound and tread levels affect braking more than any upgrade of rotors or pads. Think about it like this: The front of a car is responsible for 70-80% of the load under heavy braking. If all that weight transfers to the front of the car and you have worn out tires at the front, and brand new rubber at the back, how well do you think the car is going to stop? Now if you remember the original posters question was about a front wheel drive car, you are asking the front of the car on worn tires to handle the braking load, acceleration load (longitudinal) AND cornering loads (lateral). It is simply too much for the tire. Physics are physics. The terms are coefficient of friction- Measure of the ratio at which a tire converts download to traction and Slip angle- difference between the direction the wheel rim is pointing and the direction the tire is traveling. This difference is reffered to as the slip angle. Tires have a range of slip angle where they deliver their maximum level of cornering traction. Street tires tend to work over a wider range of slip angles and produce lower coefficients of friction. Slick tires (racing tires) tend to operate in a narrow band of slip angle and produce high coefficient of friction but drop off much faster once you exceed the limit. Street tires tend to break away progressively so they are easier to control. The bottom line is without tread you are asking the tire to do too much and you are exceeding it's capabilities of traction. There for you want more traction at the front ESPECIALLY on a FWD car where the tire is responsible not only for steering, but acceleration AND correcting the car once it has gone into an oversteer condition...
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