O_o me like the traction circle smily
Thanks for the edumucation Mr.Fox
Wrecked my car
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Kaioshin1982
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MaineExport
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Originally posted by MrFox "]She had suddenly exceeded her traction limits due to the slick road surface. Reducing power will shorten the red arrow, but her tires now do not have enough lateral traction (blue arrows) to correct any deviation from straight and true driving.
The problem with that is.... she has already gone beyond straight and true driving, so maintaining the present course and speed of tire rotation will keep the lateral traction loss constant... or make it worse. Slowing down the tire rotation will make the red arrow shorter AND increase the yellow circle. The circle isn't just increased by weight, but by friction. A slower spinning tire will create more friction that a faster spinning one when we are referring to lateral traction.
Also, if you're already out of straight alignment, the weight shift of letting off the gas will not shift ONLY forward... it will shift proportionally to the outside. Meaning, the weight is mostly on the front, outside tire.... but still a substantial amount of force being applied to the outside rear, compounded by the centrifugal force of the slide. Leavig the speed constant applies too much force to the rear which is the very source of the problem.
The problem with that is.... she has already gone beyond straight and true driving, so maintaining the present course and speed of tire rotation will keep the lateral traction loss constant... or make it worse. Slowing down the tire rotation will make the red arrow shorter AND increase the yellow circle. The circle isn't just increased by weight, but by friction. A slower spinning tire will create more friction that a faster spinning one when we are referring to lateral traction.
Also, if you're already out of straight alignment, the weight shift of letting off the gas will not shift ONLY forward... it will shift proportionally to the outside. Meaning, the weight is mostly on the front, outside tire.... but still a substantial amount of force being applied to the outside rear, compounded by the centrifugal force of the slide. Leavig the speed constant applies too much force to the rear which is the very source of the problem.
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MaineExport
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[QUOTE]Originally posted by MrFox "]The size of the rear tire traction circle has to increase (at the very least not get any smaller) in order for the rear tires to provide enough lateral force for her to recover.
Sweet.... again we agree!
Either u or N needs to increase for this to happen.
I'm with ya...
Getting better tires or finding a grippier road surface will increase u.
yep...
Transfering more weight on the back by accelerating will increase N.
Ummm.... see this is where the theory diverts from reality. Transferring more weight onto the rear tires MIGHT work in a straight line.... but only if the manner of transferring that weight ISN'T spinning the drivewheels faster!! This is a critical thing to understand. If the drive wheels are NOT gripping the road, than spinning them faster will NOT create enough weight transfer to overcome a traction loss that you are making worse by spinning them. The ONLY weight that will transfer is that created by the drive lines and weight of the tires and wheels (rear axle and driveshaft).
You can not accelerate because:accelerating will cause other problems...
and you can not maintain the present speed of rotation because that is quite literally causing the problem (back to the story of the rear wheels spinning faster than the fronts.. yes even if it's in a hydroplane). So the only way to counter the slide is to shift the weight onto the wheels that have control of the vehicle and slow the rears to the speed of the fronts.... again... pulling them into alignment.
Even if your theory made total sense (I'll give it about 85%
), it is counter indicative to what ACTUALLY happened. This would tend to show that UNDERSTANDING is no substitute for experience.
Sweet.... again we agree!
Either u or N needs to increase for this to happen.
I'm with ya...
Getting better tires or finding a grippier road surface will increase u.
yep...
Transfering more weight on the back by accelerating will increase N.
Ummm.... see this is where the theory diverts from reality. Transferring more weight onto the rear tires MIGHT work in a straight line.... but only if the manner of transferring that weight ISN'T spinning the drivewheels faster!! This is a critical thing to understand. If the drive wheels are NOT gripping the road, than spinning them faster will NOT create enough weight transfer to overcome a traction loss that you are making worse by spinning them. The ONLY weight that will transfer is that created by the drive lines and weight of the tires and wheels (rear axle and driveshaft).
You can not accelerate because:accelerating will cause other problems...
and you can not maintain the present speed of rotation because that is quite literally causing the problem (back to the story of the rear wheels spinning faster than the fronts.. yes even if it's in a hydroplane). So the only way to counter the slide is to shift the weight onto the wheels that have control of the vehicle and slow the rears to the speed of the fronts.... again... pulling them into alignment.
Even if your theory made total sense (I'll give it about 85%
), it is counter indicative to what ACTUALLY happened. This would tend to show that UNDERSTANDING is no substitute for experience.-
skydragoness
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Maineimport, after a good night's sleep and reading your latest post, I think I'm finally seeing what you are trying to say. The critical factor between our misunderstanding is wheelspin. "Keeping on the gas" and "Letting off the gas" was pretty vague in terms of driver action!
The instant you feel the rear-end give out or lose traction you should let off the gas. This will slow down the drive wheels and drag them back into grabbing traction.
Your "Letting off" to me meant releasing the gas pedal completely, unloading and "dragging" the rear wheels via engine braking into "grabbing traction", which I maintain is very bad in my book.
"Keeping it on" to me meant modulating the throttle to keep the drive wheels from unloading. I didn't intend for it to mean lead footing it enough to cause/maintain excessive wheelspin. "Modulating the throttle to prevent unloading the rear while avoiding excessive wheelspin" would probably be a better way to phrase it.
Transferring more weight onto the rear tires MIGHT work in a straight line.... but only if the manner of transferring that weight ISN'T spinning the drivewheels faster!
I agree!
Looking back, the chief cause for the incident was not hydroplaning... The real curpit for the oversteer can be found by going back to HKCs original post.
then..the unthinkable happened!!! i was on the highway going home, doing only 50mph, went over a little hill, on the way down, my back......my back..... started to lose control....
It is a classic case of oversteer caused by the unloading of the rear wheels, excaggerated by wet conditions.
The instant you feel the rear-end give out or lose traction you should let off the gas. This will slow down the drive wheels and drag them back into grabbing traction.
Your "Letting off" to me meant releasing the gas pedal completely, unloading and "dragging" the rear wheels via engine braking into "grabbing traction", which I maintain is very bad in my book.
"Keeping it on" to me meant modulating the throttle to keep the drive wheels from unloading. I didn't intend for it to mean lead footing it enough to cause/maintain excessive wheelspin. "Modulating the throttle to prevent unloading the rear while avoiding excessive wheelspin" would probably be a better way to phrase it.
Transferring more weight onto the rear tires MIGHT work in a straight line.... but only if the manner of transferring that weight ISN'T spinning the drivewheels faster!
I agree!
Looking back, the chief cause for the incident was not hydroplaning... The real curpit for the oversteer can be found by going back to HKCs original post.
then..the unthinkable happened!!! i was on the highway going home, doing only 50mph, went over a little hill, on the way down, my back......my back..... started to lose control....
It is a classic case of oversteer caused by the unloading of the rear wheels, excaggerated by wet conditions.
I'm sure I contributed to the misunderstanding with the following...
Transfering more weight on the back by accelerating will increase N. However accelerating will cause other problems... Even though powering through oversteer can work, lets not get into why it does work for now (another can of worms). My point was that letting off the gas will not be benificial in recovery.
That was definitely a useless tangent that diverged from the point. Damn NICO addiction, typing at 12am. Sense no make, everything more the confusing!
Transfering more weight on the back by accelerating will increase N. However accelerating will cause other problems... Even though powering through oversteer can work, lets not get into why it does work for now (another can of worms). My point was that letting off the gas will not be benificial in recovery.
That was definitely a useless tangent that diverged from the point. Damn NICO addiction, typing at 12am. Sense no make, everything more the confusing!
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MaineExport
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Originally posted by MrFox "]"Keeping it on" to me meant modulating the throttle to keep the drive wheels from unloading. I didn't intend for it to mean lead footing it enough to cause/maintain excessive wheelspin.
Haha... nice.I think that might be the catalyst of the disagreement. I DID in fact take your meaning wrongly.
"Modulating the throttle to prevent unloading the rear while avoiding excessive wheelspin" would probably be a better way to phrase it.
Yes, that is a much better way to phrase it. I think we are coming to a similar conclusion from two diametrically opposed angles.
Looking back, the chief cause for the incident was not hydroplaning... The real curpit for the oversteer can be found by going back to HKCs original post.
then..the unthinkable happened!!! i was on the highway going home, doing only 50mph, went over a little hill, on the way down, my back......my back..... started to lose control....
It is a classic case of oversteer caused by the unloading of the rear wheels, excaggerated by wet conditions.
Yeah... perhaps I should have read her post more carefully. Coming over the hill would usually include a weight transfer forward.... this coupled with the wet conditions and crappy tires would be a disaster waiting to happen. Also, with bald tires all the rules kind of go out the window anyway.
So, now that that's behind us... what do you think of pulling the e-brake? I'm still up in the air about how much help that could ever be... as far as I can tell it's bad news.
Haha... nice.I think that might be the catalyst of the disagreement. I DID in fact take your meaning wrongly.
"Modulating the throttle to prevent unloading the rear while avoiding excessive wheelspin" would probably be a better way to phrase it.
Yes, that is a much better way to phrase it. I think we are coming to a similar conclusion from two diametrically opposed angles.
Looking back, the chief cause for the incident was not hydroplaning... The real curpit for the oversteer can be found by going back to HKCs original post.
then..the unthinkable happened!!! i was on the highway going home, doing only 50mph, went over a little hill, on the way down, my back......my back..... started to lose control....
It is a classic case of oversteer caused by the unloading of the rear wheels, excaggerated by wet conditions.
Yeah... perhaps I should have read her post more carefully. Coming over the hill would usually include a weight transfer forward.... this coupled with the wet conditions and crappy tires would be a disaster waiting to happen. Also, with bald tires all the rules kind of go out the window anyway.
So, now that that's behind us... what do you think of pulling the e-brake? I'm still up in the air about how much help that could ever be... as far as I can tell it's bad news.
Re: Wrecked my car
I'm also very pleased that we were able to arrive at reasonable conclusions while maintaining a civil discussion.
Regarding the e-brake.
Originally posted by HongKongChick "]...still my left rear hit the median, and that led my car to spin 180 degrees, then i pulled my e brake
It appears that she had pulled the e-brake while her car was flying backwards. From her description, it sounded like a reasonable course of action, trying to lock the rears in order to swap the pointy end back up in front.
In fact, if this is really the case, then Bravo to HKC for keeping a cool head and thinking logically under pressure.
Usually once a car spins past 90 degrees it is most likely impossible to recover. At that point, it would be better to put both clutch and brake in and lock up all 4 wheels. Doing this will slow the car, and allow the driver to control where the car spins to. With the wheels locked, the car will keep spinning in a straight line until brakes are released or the car is stopped. At the very least you can control where you'd like to crash. With the most amazing luck you might end up doing a complete 360 and drive right out of it! (don't bet on it!)
Regarding the e-brake.
Originally posted by HongKongChick "]...still my left rear hit the median, and that led my car to spin 180 degrees, then i pulled my e brake
It appears that she had pulled the e-brake while her car was flying backwards. From her description, it sounded like a reasonable course of action, trying to lock the rears in order to swap the pointy end back up in front.
In fact, if this is really the case, then Bravo to HKC for keeping a cool head and thinking logically under pressure.
Usually once a car spins past 90 degrees it is most likely impossible to recover. At that point, it would be better to put both clutch and brake in and lock up all 4 wheels. Doing this will slow the car, and allow the driver to control where the car spins to. With the wheels locked, the car will keep spinning in a straight line until brakes are released or the car is stopped. At the very least you can control where you'd like to crash. With the most amazing luck you might end up doing a complete 360 and drive right out of it!
(don't bet on it!)HKC sorry to have blown your upsetting incident into a nerdy tech discussion.... But hopefully, our analysis of what had happened can be of some help to you in understanding, and get you on your way in regaining your confidence behind the wheel.
Read my first reply to your topic. Its on page 2 and only has 3 words.
Read my first reply to your topic. Its on page 2 and only has 3 words.
how bout this to the 2 debators: once the wheels have lost traction and the car begins to spin out, put the clutch in so the wheels will go how fast it is easiest for them (most likely same speed as the ground beneath them) so from there u have gained the traction of the rear wheels and then u put the car into a higher gear so the engine doesnt have to jump up as high RPMs when the clutch is engaged (possibly causing traction loss of the rear wheels again)and from there gently add gas to move the weight to the rear of the car and move the car back into alignment
Theoretically that should work also. Putting the clutch in will cut all engine load to the rear, allowing maximum lateral traction for recovery.
I had experimented with this particular technique before. With the clutch completely disengaged, I found that the initial slide recovery was good as expected. However, for me, the recovery often degenerated into fishtailing... I found myself overcontrolling, because my steering inputs are slighty out of phase with the yaw motions of the car. When I had the clutch engaged, I was able to get on the throttle smoothly near the end of the recovery, and damp my inprecise steering inputs with power. Without an engaged clutch and avaliable power, I am lost. The clutch, was a crutch for a clutz(me)...
On closer retrospection, I think I actually do lean on the clutch a little bit at the beginning of recovery, in order to smooth out the power delivery. The clutch never completly disengages though, and I have full control over power at all times.
TKA37 I see nothing wrong with what you are suggesting. The only objection I have is the need for ultra smooth re-engagement in the middle of recovery, or the lack of throttle control near the end of recovery (going into 4th/5th gear is pretty useless for throttle control). This may be an acceptable tradeoff for someone who prefers not to deal with throttle/clutch modulation at the beginning of recovery.
I had experimented with this particular technique before. With the clutch completely disengaged, I found that the initial slide recovery was good as expected. However, for me, the recovery often degenerated into fishtailing... I found myself overcontrolling, because my steering inputs are slighty out of phase with the yaw motions of the car. When I had the clutch engaged, I was able to get on the throttle smoothly near the end of the recovery, and damp my inprecise steering inputs with power. Without an engaged clutch and avaliable power, I am lost. The clutch, was a crutch for a clutz(me)...
On closer retrospection, I think I actually do lean on the clutch a little bit at the beginning of recovery, in order to smooth out the power delivery. The clutch never completly disengages though, and I have full control over power at all times.
TKA37 I see nothing wrong with what you are suggesting. The only objection I have is the need for ultra smooth re-engagement in the middle of recovery, or the lack of throttle control near the end of recovery (going into 4th/5th gear is pretty useless for throttle control). This may be an acceptable tradeoff for someone who prefers not to deal with throttle/clutch modulation at the beginning of recovery.
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HongKongChick
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MrFox wrote:HKC sorry to have blown your upsetting incident into a nerdy tech discussion.... But hopefully, our analysis of what had happened can be of some help to you in understanding, and get you on your way in regaining your confidence behind the wheel.
Read my first reply to your topic. Its on page 2 and only has 3 words.
no no no,,,this is perfect for me, to hear different opinions about this, and hey i am a super newbie when it comes to driving, let alone the RWD, so this is not at all bad for me or my thread ! it is rather informational, and we are all very civil about this, so i like it alot!
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HongKongChick
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Re: Re: Wrecked my car
MrFox wrote:It appears that she had pulled the e-brake while her car was flying backwards. From her description, it sounded like a reasonable course of action, trying to lock the rears in order to swap the pointy end back up in front.
In fact, if this is really the case, then Bravo to HKC for keeping a cool head and thinking logically under pressure.
Usually once a car spins past 90 degrees it is most likely impossible to recover. At that point, it would be better to put both clutch and brake in and lock up all 4 wheels. Doing this will slow the car, and allow the driver to control where the car spins to. With the wheels locked, the car will keep spinning in a straight line until brakes are released or the car is stopped. At the very least you can control where you'd like to crash. With the most amazing luck you might end up doing a complete 360 and drive right out of it!
that's what i intended to do when i pulled my e-brake, to at least stop the car where i want it to, coz i could tell i was almost gonna fly off that on-ramp....... so if i hadnt pulled the e-brake, i might have done a 360, but that's not too guranteed.
i figured that my car was slowing down after i hit the median, so it was "ok" for me to brake, so that's what i did.
didnt cry or nothing, or even scream, just cursed like a sailor the whole time hehe
the only problem i see with it is that there are alot fo steps that must be completed quickly in a scary situation.
Thats motivation for us to learn and practice before it happens!
didnt cry or nothing, or even scream, just cursed like a sailor the whole time hehe
Cursed like a dirty sailor ah? or did you just keep repeating "Sai-Lar"?
Thats motivation for us to learn and practice before it happens!
didnt cry or nothing, or even scream, just cursed like a sailor the whole time hehe
Cursed like a dirty sailor ah? or did you just keep repeating "Sai-Lar"?
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HongKongChick
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HongKongChick
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thanks! i dont feel tooo ooooo bad nowMr1der wrote:in all the car wrecks I've been in, I remember saying $hit right before it happened...
all things considered, I'd say you did pretty good though, because the car came out only a little banged up
well a little banged up....my poor baby..when i took it to get some tires (yeah) and an alignment done after changing out the control arm at the salvageyard, they said they couldnt do the alignment coz my front cambers are too messed up???
how could i have messed up my front cambers? or was it like that when i got my car??-
HongKongChick
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HongKongChick
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skydragoness
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Quote »Usually once a car spins past 90 degrees it is most likely impossible to recover. At that point, it would be better to put both clutch and brake in and lock up all 4 wheels. Doing this will slow the car, and allow the driver to control where the car spins to. With the wheels locked, the car will keep spinning in a straight line until brakes are released or the car is stopped. At the very least you can control where you'd like to crash.[/quote]
very good! that would be the best choice.
Quote »couldnt do the alignment coz my front cambers are too messed up??? how could i have messed up my front cambers? or was it like that when i got my car??[/quote]
camber can get messed up very easily in a accident like that. either from a blow to the wheel/tire or from the way the car slid its front wheels. (240's camber out while turning)i don't see why it couldn't be fixed, but if you took it to a specialty alignment shop they could fix it. or if you have a friend in that business, which i do. fortunately
very good! that would be the best choice.
Quote »couldnt do the alignment coz my front cambers are too messed up??? how could i have messed up my front cambers? or was it like that when i got my car??[/quote]
camber can get messed up very easily in a accident like that. either from a blow to the wheel/tire or from the way the car slid its front wheels. (240's camber out while turning)i don't see why it couldn't be fixed, but if you took it to a specialty alignment shop they could fix it. or if you have a friend in that business, which i do. fortunately
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HongKongChick
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skydragoness5 wrote:camber can get messed up very easily in a accident like that. either from a blow to the wheel/tire or from the way the car slid its front wheels. (240's camber out while turning)i don't see why it couldn't be fixed, but if you took it to a specialty alignment shop they could fix it. or if you have a friend in that business, which i do. fortunately
um...the guy told me that i should take it to a body shop to get my frame pulled.... he said cambers are messed up BAD!!! so..??!!
Can you ask for the actual measurements? Degrees camber, castor, toe (mm/inches)? We can offer our 2 cents on whether its really "messed up BAD".
Sometimes auto repair peeps like to exaggerate to scare their customers, for profit, or just for fun.
And also how much lowering was done on your car? How was it done? Springs? Coilovers? Bandsaw/torch? Clamps?
Dont worry too much about it... Everything is fixable. Your car is just a big piece of metal. It bends, you bend it back. No big deal.
Sometimes auto repair peeps like to exaggerate to scare their customers, for profit, or just for fun.
And also how much lowering was done on your car? How was it done? Springs? Coilovers? Bandsaw/torch? Clamps?
Dont worry too much about it... Everything is fixable. Your car is just a big piece of metal. It bends, you bend it back. No big deal.
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MaineExport
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szhosain wrote:Best in rain: Firestone Firehawk SZ50EP hands down! Not available in all sizes though ... unfortunately.
Z
I've had very good luck with Goodyear Eagle GA's. BUT I recently switched to Kumho Ecsta 711's. They are a directional tire... so lateral traction is slightly less than the goodyears, but off the line they hold like no other! They are both great in the rain, but I'd give the Kumho's the better rating of the two. They are also UBER cheap for performance tires.
What's the price like on the Firestones? I hear good reviews about them.. but I thought they were kinda pricey. The Goodyear Eagle GA's were about $125 per corner.. and the Kumho Ecsta's are $65 per corner!!!