Start with a rollbar
02-17-2010, 08:13 AM
#43
You guys that are concentrating on this thing happening on the track, or worried about whether you "need" it for autocross??? This **** could happen to you backing out your driveway. Some ******* in his 6000lb Dodge Ram coming down the street doesn't see you, t-bones you, pushes you up on a curb and flips you over in your own ****** front yard!!!
YOU WILL NEVER, EVER, EVER, EVER GET ME IN A MIATA WITHOUT A ROLLBAR. I WOULDN'T DRIVE ON ON A DYNO... and I let them shoot me off aircraft carriers for a living.
YOU WILL NEVER, EVER, EVER, EVER GET ME IN A MIATA WITHOUT A ROLLBAR. I WOULDN'T DRIVE ON ON A DYNO... and I let them shoot me off aircraft carriers for a living.
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02-17-2010, 08:45 AM
#45
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I've had a turbo FWD chevy up to about 75 MPH during auto-x so I'm a bit curious what this car will be like. I've never been worried about rolling over though.
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02-17-2010, 09:27 AM
#46
Boost Czar
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on that video, he spins right after he lifts off camber, then he slides into the ditch and rolls...it's a classic roll over example. You'd be hard pressed to make that happen at an autox, at least any I've ever attended.
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02-17-2010, 10:51 AM
#48
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In Helena, I'll have be on the lookout for you! The only time you'll see my '91 will be on a trailer being puilled by a Yukon. She's a track-only ride... WITH a roll cage. That's is unless you venture out to Barbers on some track days. Car should be ready for the PBOC weekend Mar28th...
Get that cage and hard top and come play! (and $435 cash for the weekend)
Get that cage and hard top and come play! (and $435 cash for the weekend)
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02-17-2010, 04:32 PM
#50
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A cheap bolt-in cage (but still made from DOM tube and all) seems to run just shy of a grand. Honestly that route looks pretty good considering the fact that a good new bar tends to run 400 or so and then sme folks go and spend hundreds more on chassis reinforcement and harness bars etc.
I guess you might have a comfort penalty, but meh. Half of us will be running harder bushings, no PS, no CC, no AC, etc anyway.
I guess you might have a comfort penalty, but meh. Half of us will be running harder bushings, no PS, no CC, no AC, etc anyway.
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02-17-2010, 05:15 PM
#52
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Wish I could join you. I had intent to last year but found out that my safety was quite lacking. Only have a roll bar and a helmet. That leaves me lacking another $1000 in parts, and the fees to drive. Maybe when I do the LS1 I will bring it. Hell, I only live about a mile up the hill from the track, not like I have to go far.
Back on track... yeah, roll-overs are only part of the worries... this is why I don't like rails! Poor R8...
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02-17-2010, 06:08 PM
#53
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Wow. Now thats scary.
BTW, they have specs such that that wont happen unless something goes very wrong...as in way beyond normal levels of wrong when you hit the rail.
I'll bet that R8 was part of a multiple car incident. Some other vehicle nailed a rail or something and bam.
I wonder if the driver made it.
BTW, they have specs such that that wont happen unless something goes very wrong...as in way beyond normal levels of wrong when you hit the rail.
I'll bet that R8 was part of a multiple car incident. Some other vehicle nailed a rail or something and bam.
I wonder if the driver made it.
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02-17-2010, 06:11 PM
#54
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I don't think that was an on-track wreck... just a scary example of what not to expect! I can see flipping over ontop the rail or tires and w/out a cage you might get pancaked...
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02-17-2010, 09:45 PM
#56
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Perhaps we should talk about what to do in that situation when the rear end walks. The natural reaction is to lift, but I've heard that Miatas are prone to snap oversteer in that situation. Looks like this is what happened?
On a FWD car I always floored it even with 250 FWHP. Always stuck the rear tires back down unless I was WAY over the limit.
However I know that is not the answer for a RWD car, so I assume it is somewhere between clutching and moderate acceleration. Trying to transfer some weight to the rear without overwhelming the rear tires with power.
In the video it didn't look like he was way over his head, so should he have been able to drive it out?
Edit: I'm not sure it could have been driven out.... I've never tracked at those kind of speeds. Convince me otherwise.
On a FWD car I always floored it even with 250 FWHP. Always stuck the rear tires back down unless I was WAY over the limit.
However I know that is not the answer for a RWD car, so I assume it is somewhere between clutching and moderate acceleration. Trying to transfer some weight to the rear without overwhelming the rear tires with power.
In the video it didn't look like he was way over his head, so should he have been able to drive it out?
Edit: I'm not sure it could have been driven out.... I've never tracked at those kind of speeds. Convince me otherwise.
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02-18-2010, 07:42 AM
#57
I'd say the best he could've possibly done is clutch it and NOT try to steer the car. If you let the car do what it's trying to do, most likely I see a spin out/grass/pissed driver.
When he rolled he had the steering wheel at full lock from the looks of it. If you let the steering wheel do what it wants, it's going to follow where the wheels are being directed, and IMHO (though none of this may make any sense) will be where the momentum is dragging the car. This may be the case w/ PS only, IDK.
It's hard to explain.
I have a friend who did Police Pursuit Driver Training in San Diego and he told me they took you out on an old air strip and amongst other training activities, one was to purposely make you lose control at 60+mph. Granted, this is in a Caprice/Crown Vic which is a lot heavier and not as balanced. The instructions once you lose control was to LET GO OF THE STEERING WHEEL and get into the brakes. My friend said the car hardly got out of shape, and almost straightened up completely once you stop forcing the steering wheel where you want it. Then, they took him out and said, this time try to steer the car back under your control... he said this ended up 5x worse than just letting go.
When he rolled he had the steering wheel at full lock from the looks of it. If you let the steering wheel do what it wants, it's going to follow where the wheels are being directed, and IMHO (though none of this may make any sense) will be where the momentum is dragging the car. This may be the case w/ PS only, IDK.
It's hard to explain.
I have a friend who did Police Pursuit Driver Training in San Diego and he told me they took you out on an old air strip and amongst other training activities, one was to purposely make you lose control at 60+mph. Granted, this is in a Caprice/Crown Vic which is a lot heavier and not as balanced. The instructions once you lose control was to LET GO OF THE STEERING WHEEL and get into the brakes. My friend said the car hardly got out of shape, and almost straightened up completely once you stop forcing the steering wheel where you want it. Then, they took him out and said, this time try to steer the car back under your control... he said this ended up 5x worse than just letting go.
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02-18-2010, 12:43 PM
#59
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Beware, internet racing theory below:
When you lift mid-corner, you have two things happening as far as the rear tires are concerned.
1) The car is now decelerating because the engine is lugging down. Similar effect to downshifting, but not as severe, unless of course you are in the habit of downshifting mid-corner at 10/10ths, in which case I call dibs on your Torsen, but not your hardtop or wheels/tires. This deceleration means the weight is biased to the front tires. So they et more grip while the rears get less.
2) The momentum naturally wants the car to go in a straight line, not turning, and this includes the rear wheels.
So you now have a car being slowed down by the rear tires. This means weight transfer forward and more front grip while the rears are getting less. Not good when you have the rears at the limit of adhesion in the first place going around a corner at 10/10ths.
You also have the rears (with the weight being transfered off of them a bit remember) trying to slow the car due to their connection with the engine which is acting as a brake when you lift but leave it in gear. Again, thats a bit much to ask when they were probably about at the limit of adhesion when the weight was being pushed onto them, let alone off of them.
So you get an effect thats sort of similar to what happens when you brake too late and too hard going into a corner. The tires simply can't do the deceleration and the turning at the same time. They dont have enough grip under the circumstances you have created. Going into a corner and braking, this usualy means understeer because the fronts just sort of skid. In the case of a mid-corner spin, the rears loose it while the car is alread turning, so you get oversteer.
Avoiding a sudden transfer of weight forward mid-corner while using the rears to slow down is probably a good idea. Clutching would allow the rears to roll freely and eliminate the deceleration caused by the engine, and that might save you. But if you get too radical you are going to be decelerating just by virtue of the tires not pointed straight ahead and you are probably screwed. If you brake theres a pretty good reason to think that the rears will just skid again as now you have tons of weight transfer forward and yet more grip to the front while asking the tires to do even more work.
FWDs are lucky this way, as they usualy will go where you point the wheel when you floor it. Of course, you also have the wonderful problem of trying to get out of a corner fast when the fronts are still trying to steer and at the same time accelerate the car with the weight transfering to the rears.
Long story short, try to avoid asking any given tire to do a lot of acceleration or deceleration and/or turning while you siultaneously take weight (and thus traction) away from it.
This is why you generally want to brake/decelerate while decelerating in a straight or almost strait line. The fronts do most of the breaking and if they dont have to turn much and have lots of weight on them, they will probably stck just fine.
When you lift mid-corner, you have two things happening as far as the rear tires are concerned.
1) The car is now decelerating because the engine is lugging down. Similar effect to downshifting, but not as severe, unless of course you are in the habit of downshifting mid-corner at 10/10ths, in which case I call dibs on your Torsen, but not your hardtop or wheels/tires. This deceleration means the weight is biased to the front tires. So they et more grip while the rears get less.
2) The momentum naturally wants the car to go in a straight line, not turning, and this includes the rear wheels.
So you now have a car being slowed down by the rear tires. This means weight transfer forward and more front grip while the rears are getting less. Not good when you have the rears at the limit of adhesion in the first place going around a corner at 10/10ths.
You also have the rears (with the weight being transfered off of them a bit remember) trying to slow the car due to their connection with the engine which is acting as a brake when you lift but leave it in gear. Again, thats a bit much to ask when they were probably about at the limit of adhesion when the weight was being pushed onto them, let alone off of them.
So you get an effect thats sort of similar to what happens when you brake too late and too hard going into a corner. The tires simply can't do the deceleration and the turning at the same time. They dont have enough grip under the circumstances you have created. Going into a corner and braking, this usualy means understeer because the fronts just sort of skid. In the case of a mid-corner spin, the rears loose it while the car is alread turning, so you get oversteer.
Avoiding a sudden transfer of weight forward mid-corner while using the rears to slow down is probably a good idea. Clutching would allow the rears to roll freely and eliminate the deceleration caused by the engine, and that might save you. But if you get too radical you are going to be decelerating just by virtue of the tires not pointed straight ahead and you are probably screwed. If you brake theres a pretty good reason to think that the rears will just skid again as now you have tons of weight transfer forward and yet more grip to the front while asking the tires to do even more work.
FWDs are lucky this way, as they usualy will go where you point the wheel when you floor it. Of course, you also have the wonderful problem of trying to get out of a corner fast when the fronts are still trying to steer and at the same time accelerate the car with the weight transfering to the rears.
Long story short, try to avoid asking any given tire to do a lot of acceleration or deceleration and/or turning while you siultaneously take weight (and thus traction) away from it.
This is why you generally want to brake/decelerate while decelerating in a straight or almost strait line. The fronts do most of the breaking and if they dont have to turn much and have lots of weight on them, they will probably stck just fine.
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02-18-2010, 01:52 PM
#60
Lifting in a corner is a huge mistake in just about any car. Much more so with rear engined cars like Porsche. The local PCA is my favorite club to run with here in Portland and you should hear them drill this into everyone at the driver meetings. You are always better off leaving the track going forwards and keeping the ability to steer. It's all about training and fighting your instincts which is very hard to do. That mistake happens at every level of the sport, weekend warriors to pros.
I need more safety gear.
I need more safety gear.
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