S2000 Suspension
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From: Woodbridge, VA
Originally Posted by RED MX5,May 11 2007, 02:07 PM
I agree, but we're still at the mercy of Honda for an explination, and their explination seems to be reasonable.
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From: Dry Branch
[QUOTE=Guld,May 11 2007, 07:07 PM] When you design a cylindrical torque member, you design with a target or permissible strain in mind (within the mechanical properties of the material).
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From: Dry Branch
Originally Posted by Guld,May 11 2007, 09:38 PM
You might be absulutely right. The truth is that I don't have the data to support my claim, nor have I ever seen one of those shafts in cross-section. In other words I'm simply giving my educated guess. However, I can assure you with a fair degree of certainty that any self respecting engineer would take advantage of the increased diameter to reduce wall thickness. Also, like when it comes to the polar moment of inertia, I should emphasize that any torque capacity gains come from the increased diameter (vs. wall thickness) -- if memory serves me correctly it is a non-linear relationship (e.g., parabolic). Thats why, as a matter of design, one would choose the thin walled shaft with a larger diameter for the same application. With that said, by increasing diameter my money would be on higher torque capacity (stress), less deformation (strain) and/or weight reduction.
If I need greater strength I can get it one of two ways. I can make the diameter larger, or I can increase the wall thickness (or of course some combination of the two). It would not make me a non-self respecting engineer if I use diamater only to get the stringth, and I might decide to do it with diameter, retaining the same wall thickness, for any number of reasons.I'm pretty sure that with an anti-sway bar, a fatter bar with thinner walls will be lighter than a smaller diameter solid bar that gives the same bar rate, and I think that's what your're saying about the half shafts. LOL, I pretty sure you're right, but I'm not absolutely positive.
(Just as a matter of course I am rarely positive about anything.
)Regardless of the diameter and wall thickness, Honda says the axles are stronger than they'd have normally made them (and they look stronger, but I haven't cut on into yet to see how thick they are either), and they state why. I think it's just what you have said here, and what _redruM said long ago. The reduced deformation probably makes a difference in the way the car feels. Honda is the only company I know that claims to have taken feel into consideration in designing their axles, and of course we can't really evaluate their success at it without running tests we have no easy way to run. However, I'll keep saying this until somebody points out a reason that it's wrong. Honda says the axle was strengthened to improve feel, and I see no reason to doubt them. It does make perfectly good sense. Stronger half shaft will deform less, and that might make a difference we can feel. Why whould Honda make the half shafts stronger and then lie about their reasons? It's certainly not a big marketing feature.
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Hey folks,
The quote about the half shafts being stronger was given in Dan Carney's book about the S2000. I'm away from home right now, but will be returning later this evening or early next morning at the latest. I'll see if I can type up the quote about the half shafts online...
If I remember correctly, it was something along the lines of Honda did some research that suggested that the subjective feeling of acceleration was enhanced when there was no flex in the half shafts so they were beefed up.
The quote about the half shafts being stronger was given in Dan Carney's book about the S2000. I'm away from home right now, but will be returning later this evening or early next morning at the latest. I'll see if I can type up the quote about the half shafts online...
If I remember correctly, it was something along the lines of Honda did some research that suggested that the subjective feeling of acceleration was enhanced when there was no flex in the half shafts so they were beefed up.
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From: Farmingdale, NJ
Originally Posted by vishnus11,May 12 2007, 08:36 AM
If I remember correctly, it was something along the lines of Honda did some research that suggested that the subjective feeling of acceleration was enhanced when there was no flex in the half shafts so they were beefed up.
Usually subjective and engineering do not go hand in hand. I'd love to flip through this aforementioned book on the S2000, sounds like a good read.
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Another interesting piece of information with regards to the suspension design was that the AP1 suspension geometry was set up in the rear such that the car wouldn't squat or nose dive during hard braking but bestowed the car with more bumpsteer characteristics. In AP2 version this geometry was revised.
^ This was mentioned in a BMI video I watched about the AP1 vs. AP2.
Interestingly, BMI observed that the AP2 chassis was about 0.5 seconds quicker than the AP1 chassis when both cars were running the same tire/wheel combo. The 17" tire/wheel combo made the AP1 chassis 0.5 seconds quicker as well. So in conclusion, the AP2 chassis and larger tire/wheel combo made the car approx. 1 second quicker.
The drivers of both the vehicles observed that the revised chassis was more planted in the corners allowing them to power out of the corner earlier, whilst carrying more corner speed.
^ This was mentioned in a BMI video I watched about the AP1 vs. AP2.
Interestingly, BMI observed that the AP2 chassis was about 0.5 seconds quicker than the AP1 chassis when both cars were running the same tire/wheel combo. The 17" tire/wheel combo made the AP1 chassis 0.5 seconds quicker as well. So in conclusion, the AP2 chassis and larger tire/wheel combo made the car approx. 1 second quicker.
The drivers of both the vehicles observed that the revised chassis was more planted in the corners allowing them to power out of the corner earlier, whilst carrying more corner speed.
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From: Woodbridge, VA
Originally Posted by vishnus11,May 12 2007, 05:36 AM
If I remember correctly, it was something along the lines of Honda did some research that suggested that the subjective feeling of acceleration was enhanced when there was no flex in the half shafts so they were beefed up.
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From: Woodbridge, VA
Originally Posted by RED MX5,May 11 2007, 07:29 PM
I mostly agree. If I need greater strength I can get it one of two ways. I can make the diameter larger, or I can increase the wall thickness (or of course some combination of the two). It would not make me a non-self respecting engineer if I use diamater only to get the stringth, and I might decide to do it with diameter, retaining the same wall thickness, for any number of reasons.
I'm pretty sure that with an anti-sway bar, a fatter bar with thinner walls will be lighter than a smaller diameter solid bar that gives the same bar rate, and I think that's what your're saying about the half shafts. LOL, I pretty sure you're right, but I'm not absolutely positive.
(Just as a matter of course I am rarely positive about anything.)
Regardless of the diameter and wall thickness, Honda says the axles are stronger than they'd have normally made them (and they look stronger, but I haven't cut on into yet to see how thick they are either), and they state why. I think it's just what you have said here, and what _redruM said long ago. The reduced deformation probably makes a difference in the way the car feels. Honda is the only company I know that claims to have taken feel into consideration in designing their axles, and of course we can't really evaluate their success at it without running tests we have no easy way to run. However, I'll keep saying this until somebody points out a reason that it's wrong. Honda says the axle was strengthened to improve feel, and I see no reason to doubt them. It does make perfectly good sense. Stronger half shaft will deform less, and that might make a difference we can feel. Why whould Honda make the half shafts stronger and then lie about their reasons? It's certainly not a big marketing feature.
If I need greater strength I can get it one of two ways. I can make the diameter larger, or I can increase the wall thickness (or of course some combination of the two). It would not make me a non-self respecting engineer if I use diamater only to get the stringth, and I might decide to do it with diameter, retaining the same wall thickness, for any number of reasons.I'm pretty sure that with an anti-sway bar, a fatter bar with thinner walls will be lighter than a smaller diameter solid bar that gives the same bar rate, and I think that's what your're saying about the half shafts. LOL, I pretty sure you're right, but I'm not absolutely positive.
(Just as a matter of course I am rarely positive about anything.
)Regardless of the diameter and wall thickness, Honda says the axles are stronger than they'd have normally made them (and they look stronger, but I haven't cut on into yet to see how thick they are either), and they state why. I think it's just what you have said here, and what _redruM said long ago. The reduced deformation probably makes a difference in the way the car feels. Honda is the only company I know that claims to have taken feel into consideration in designing their axles, and of course we can't really evaluate their success at it without running tests we have no easy way to run. However, I'll keep saying this until somebody points out a reason that it's wrong. Honda says the axle was strengthened to improve feel, and I see no reason to doubt them. It does make perfectly good sense. Stronger half shaft will deform less, and that might make a difference we can feel. Why whould Honda make the half shafts stronger and then lie about their reasons? It's certainly not a big marketing feature.