High speed handling response.
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From: Dry Branch
High speed handling response.
I've tried the search function but the threads I have found have only added to my confusion.
I am currently using the UK alignment specs and OEM S02's on my MY00 S2k, and am happy with the handling on both autocross courses and the street. However, now that I've gone FI, I'm seeing track speeds in excess of 130 MPH, and I'm not totally satisfied with the way the car feels at these speeds. The car sticks well and goes where it is pointed, but it is a little *too* responsive for my tastes, almost as if the car was tending more toward oversteer. If what I am feeling is lift at the back then it probably is oversteer, and I suppose the fix is a wing, but I'm wondering if it's not a function of the alignment. The UK specs call for zero toe in the front, so the suspension compliance is going to allow some toe out (I think ???) and what I'm feeling is an excessively quick (for me) turn-in, just like a car with toe out at the front. A search only yields a variety of opinions, and I'm looking for something more useful. In a pinch I can just change the alignment and see how that affects the situation, and follow up with a wing if that doesn't do it for me, but if any of you have already been down this path you can save me the effort. (Yea, I'm lazy.
)
Is it lift or aggressive alignment that makes the car respond so quickly to driver inputs at speed?
(Sorry if this has been discussed before, but I did try and could not find any threads that addressed this directly.)
I am currently using the UK alignment specs and OEM S02's on my MY00 S2k, and am happy with the handling on both autocross courses and the street. However, now that I've gone FI, I'm seeing track speeds in excess of 130 MPH, and I'm not totally satisfied with the way the car feels at these speeds. The car sticks well and goes where it is pointed, but it is a little *too* responsive for my tastes, almost as if the car was tending more toward oversteer. If what I am feeling is lift at the back then it probably is oversteer, and I suppose the fix is a wing, but I'm wondering if it's not a function of the alignment. The UK specs call for zero toe in the front, so the suspension compliance is going to allow some toe out (I think ???) and what I'm feeling is an excessively quick (for me) turn-in, just like a car with toe out at the front. A search only yields a variety of opinions, and I'm looking for something more useful. In a pinch I can just change the alignment and see how that affects the situation, and follow up with a wing if that doesn't do it for me, but if any of you have already been down this path you can save me the effort. (Yea, I'm lazy.
)Is it lift or aggressive alignment that makes the car respond so quickly to driver inputs at speed?
(Sorry if this has been discussed before, but I did try and could not find any threads that addressed this directly.)
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Without a doubt aerodyanmics will have the biggest effect of high speed stability. An aftermarket front bumper with aerodynamics in mind would help (j's racing full bumper, c-west).
And from my experience a gigantic rear spoiler would help the most. Im sure many who race on this board would agree .
And from my experience a gigantic rear spoiler would help the most. Im sure many who race on this board would agree .
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twitcheyness is usually cause by toe, try adding a little more toe in to see if that helps the stability. Its easy and free and if it is the setup you dont want to buy a 1k bumper and realize its not doin you any good.
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From: Dry Branch
Originally Posted by smracer31,Mar 7 2006, 07:04 PM
twitcheyness is usually cause by toe, try adding a little more toe in to see if that helps the stability. Its easy and free and if it is the setup you dont want to buy a 1k bumper and realize its not doin you any good.
Lift at the front is certainly NOT the issue here, so I don't see how a bumper/front-spoiler could help. (Might help other things, but not the issue I'm trying to address.) I hate to add toe-in, because it will reduce the responsiveness at lower speeds, something I really enjoy, so I'm hoping this is a rear lift issue. Hopefully we'll hear from some of the guys who are racing with a rear wing.
Doesn't the car have several hundred pounds of lift in the rear at speed? How big and high does a wing have to be to cancel that out? Does anyone know for sure?
Thanks for the input, but I'm still hoping we'll get some kind of definitive answer.
Anyone??
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There is only one track where I see those kind of speeds and I can't say I've had the same experience. You may not have enough front castor. You should be maxing it to about 6-6.5* Too little castor will make the car a bit fussy, exagerated at speed. Toe out on the front is going to give you more neg camber on the outside tire and more pos camber on the inside in corners. It's a cheap cheat but comes at a price.
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I would say your issue is most likely because of suspension/alignment/tires more than aerodynamics. While it can help stabilize high-speed cornering on the track, I wouldn't want a wing to cover up a different problem. I've done close to 130 at the bumpy turn 1 at PR in my S (and same corner on the old faster layout of SIR in my miata) both topdown and I've never felt lift to be a problem. While my miata with full suspension felt extremely stable there, my S with bone-stock suspension has had twitchy backend because of suspension/alignment/tires but not aerodynamics. If I were you, I would 1st narrow down to whether it's the front that's too responsive or the rear that's unstable.
For super responsive front end, some people may not get use to the quick steering response of the S. But seeing you coming from the miata world, I doubt you would be uncomfortable with the S quick steering response.
For a twitchy back end, it should be more noticeable during hard braking even on the straights, varying throttle even very little while mid-corner, and over bumpy pavement mid-corner.
Super responsive front end makes you want to ease up on steering input while twitchy back end makes you constantly correct your heading with steering input.
My MY00 twitchy back end was pretty bad. It was like each rear tire was fighting for its own direction of travel, depending on which of them gets marginally more instant traction. Even with rear swaybar removed and the car understeered a lot naturally, varying the throttle just a tiny bit (I'm not talking about lifting) or hitting some mildly bumpy pavement would bring the tail out mid-corner. It was so bad that even cruising straight on the highway, varying the throttle just a tiny bit would veer the car from side to side. Now that with a new set of tires, the problem seems to be totally gone. I'm waiting to try out on the track to be 100% sure the problem is totally gone. My point is that worn-out rear tires especially unevenly can do some very evil things.
So, are you sure it's the front not the rear of your car that's doing its thing?
For super responsive front end, some people may not get use to the quick steering response of the S. But seeing you coming from the miata world, I doubt you would be uncomfortable with the S quick steering response.
For a twitchy back end, it should be more noticeable during hard braking even on the straights, varying throttle even very little while mid-corner, and over bumpy pavement mid-corner.
Super responsive front end makes you want to ease up on steering input while twitchy back end makes you constantly correct your heading with steering input.
My MY00 twitchy back end was pretty bad. It was like each rear tire was fighting for its own direction of travel, depending on which of them gets marginally more instant traction. Even with rear swaybar removed and the car understeered a lot naturally, varying the throttle just a tiny bit (I'm not talking about lifting) or hitting some mildly bumpy pavement would bring the tail out mid-corner. It was so bad that even cruising straight on the highway, varying the throttle just a tiny bit would veer the car from side to side. Now that with a new set of tires, the problem seems to be totally gone. I'm waiting to try out on the track to be 100% sure the problem is totally gone. My point is that worn-out rear tires especially unevenly can do some very evil things.
So, are you sure it's the front not the rear of your car that's doing its thing?
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From: Dry Branch
Originally Posted by cthree,Mar 7 2006, 08:48 PM
There is only one track where I see those kind of speeds and I can't say I've had the same experience. You may not have enough front castor. You should be maxing it to about 6-6.5* Too little castor will make the car a bit fussy, exagerated at speed. Toe out on the front is going to give you more neg camber on the outside tire and more pos camber on the inside in corners. It's a cheap cheat but comes at a price.
The more I think about this the more I realize how little I know. I've driven cars that had enough lift in the back to yield conspicuously more oversteer at high speeds but this is different, so I don't know how to be sure it's not the result of toe-out at speed. If I go to more toe-in the situation will most certainly improve, but I may not be addressing the real problem. If I put a wing on the back the down force will give me more grip at the back and potentially less at the front, so this too might make the car feel much better without actually addressing the real problem (which might be toe rather than aerodynamics).
I am really struggling with this guys. I'm concerned that I'm now reaching speeds where aerodynamics might be becoming an important factor, and I sure as heck don't want to mask excessive lift at the back with suspension tuning. At the same time, I don't want to cover up suspension tuning problems with down force. I'd like to get it right, but I'll be damned if I know how.
I guess my question has changed. How can I determine whether the quickness of the steering at speed is the result of toe or aerodynamics?
Here are my current alignment settings:
LF Camber = -1.0 degree
RF Camber = -1.0 degree
LF Caster = 6.4 degrees
RF Caster = 6.4 degrees
LF Toe = -0.01 degrees
RF Toe = 0.01 degrees
Total F Toe = 0.00 degrees
Steer Ahead = -0.01 degrees
LR Camber = -2.0 degrees
RR Camber = -2.0 degrees
LR Toe = 0.03 degrees
RR Toe = 0.01 degrees
Total R Toe = 0.04 degrees
Thrust Angle = 0.01 degrees
Pretty hard to get any closer to the "ideal" UK specs.
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From: Dry Branch
Originally Posted by Race Miata,Mar 7 2006, 10:07 PM
I would say your issue is most likely because of suspension/alignment/tires more than aerodynamics. While it can help stabilize high-speed cornering on the track, I wouldn't want a wing to cover up a different problem. I've done close to 130 at the bumpy turn 1 at PR in my S (and same corner on the old faster layout of SIR in my miata) both topdown and I've never felt lift to be a problem. While my miata with full suspension felt extremely stable there, my S with bone-stock suspension has had twitchy backend because of suspension/alignment/tires but not aerodynamics. If I were you, I would 1st narrow down to whether it's the front that's too responsive or the rear that's unstable.
For super responsive front end, some people may not get use to the quick steering response of the S. But seeing you coming from the miata world, I doubt you would be uncomfortable with the S quick steering response.
For a twitchy back end, it should be more noticeable during hard braking even on the straights, varying throttle even very little while mid-corner, and over bumpy pavement mid-corner.
Super responsive front end makes you want to ease up on steering input while twitchy back end makes you constantly correct your heading with steering input.
My MY00 twitchy back end was pretty bad. It was like each rear tire was fighting for its own direction of travel, depending on which of them gets marginally more instant traction. Even with rear swaybar removed and the car understeered a lot naturally, varying the throttle just a tiny bit (I'm not talking about lifting) or hitting some mildly bumpy pavement would bring the tail out mid-corner. It was so bad that even cruising straight on the highway, varying the throttle just a tiny bit would veer the car from side to side. Now that with a new set of tires, the problem seems to be totally gone. I'm waiting to try out on the track to be 100% sure the problem is totally gone. My point is that worn-out rear tires especially unevenly can do some very evil things.
So, are you sure it's the front not the rear of your car that's doing its thing?
For super responsive front end, some people may not get use to the quick steering response of the S. But seeing you coming from the miata world, I doubt you would be uncomfortable with the S quick steering response.
For a twitchy back end, it should be more noticeable during hard braking even on the straights, varying throttle even very little while mid-corner, and over bumpy pavement mid-corner.
Super responsive front end makes you want to ease up on steering input while twitchy back end makes you constantly correct your heading with steering input.
My MY00 twitchy back end was pretty bad. It was like each rear tire was fighting for its own direction of travel, depending on which of them gets marginally more instant traction. Even with rear swaybar removed and the car understeered a lot naturally, varying the throttle just a tiny bit (I'm not talking about lifting) or hitting some mildly bumpy pavement would bring the tail out mid-corner. It was so bad that even cruising straight on the highway, varying the throttle just a tiny bit would veer the car from side to side. Now that with a new set of tires, the problem seems to be totally gone. I'm waiting to try out on the track to be 100% sure the problem is totally gone. My point is that worn-out rear tires especially unevenly can do some very evil things.
So, are you sure it's the front not the rear of your car that's doing its thing?
THIS is the kind of input I'm looking for. MANY THANKS! 
I'm going to study your comments for a while before I post a full response, but I wanted to say "thanks" right away.
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from the alignment specs, i would go with 0 toe in the rear, remember the toe in the rear of the s2000 changes as the suspenion compresses. i would however do as i suggested above, add i would say 0.75 toe in in the front on each side and see if that doesnt help your problem. thats is where i would start.