Suspension question
09-11-2005, 05:08 PM
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driver
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Suspension question
What is the major advantage to the double wishbone front and rear suspension like on all the later model Hondas/Acuras as opposed to a worse set up like strut front and torsion beam rear?
09-11-2005, 09:08 PM
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CHRISTMASTIME IN IRAQ
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As I understand it:
The coil-over-shock double-wishbone suspension is nice because:
Pros:
*The wheels increase camber as the spring is compressed, allowing better tire contact patches while turning
*The rate of camber increase is theoretically manageable and can be tailored for every car
Cons:
Complex design
Expensive to design and build
MacPhearson Strut:
Pros:
Simple design
In a straight line, the contact patches are better
Cons:
Adjustable spring coilovers can become undone due to the twisting at the bottom of the strut.
Doesn't compensate for turning as well as the double-wishbones do.
Torsion bars are weird, and I dunno about them. My brother's 944 S2 has them, but I've never really looked at them myself
The coil-over-shock double-wishbone suspension is nice because:
Pros:
*The wheels increase camber as the spring is compressed, allowing better tire contact patches while turning
*The rate of camber increase is theoretically manageable and can be tailored for every car
Cons:
Complex design
Expensive to design and build
MacPhearson Strut:
Pros:
Simple design
In a straight line, the contact patches are better
Cons:
Adjustable spring coilovers can become undone due to the twisting at the bottom of the strut.
Doesn't compensate for turning as well as the double-wishbones do.
Torsion bars are weird, and I dunno about them. My brother's 944 S2 has them, but I've never really looked at them myself
09-12-2005, 02:27 PM
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Push to shock!
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Epoch pretty much got it...
Inherently there is no real disadvantage of a MacPherson strut setup that is well desiged for the car versus a double wishbone SLA suspension. However, I would submit that the main reason a lot of sports/race cars use SLA is because it is very adjustable, and given the right setup you can change caster, camber, camber rate, kingpin axis, kingpin angle, etc. etc. independent of where the suspension and strut/shock mounts to the car by changing the ball joint locations. Also, things like anti-dive and anti-squat can be designed into these suspensions, which strut suspensions cannot do. In my experience, it is also easier to design an SLA suspension because you have so much room for correction.
I think strut suspensions typically get knocked because they tend to transmit more NVH into the body since the strut is a structural member of the car. Also, another issue is that since the wheel sort of swings from the lower arm on a strut suspension, there is no way to allow vertical movement of the wheel without movement of the tire patch laterally (this can be dialed out of an SLA setup). Both these effects, I think, tend to make the car feel less "planted." However, the strut suspensions tend to be cheaper to make and less intrusive into passenger cabin, which is why they are popular on a lot of cars.
Inherently there is no real disadvantage of a MacPherson strut setup that is well desiged for the car versus a double wishbone SLA suspension. However, I would submit that the main reason a lot of sports/race cars use SLA is because it is very adjustable, and given the right setup you can change caster, camber, camber rate, kingpin axis, kingpin angle, etc. etc. independent of where the suspension and strut/shock mounts to the car by changing the ball joint locations. Also, things like anti-dive and anti-squat can be designed into these suspensions, which strut suspensions cannot do. In my experience, it is also easier to design an SLA suspension because you have so much room for correction.
I think strut suspensions typically get knocked because they tend to transmit more NVH into the body since the strut is a structural member of the car. Also, another issue is that since the wheel sort of swings from the lower arm on a strut suspension, there is no way to allow vertical movement of the wheel without movement of the tire patch laterally (this can be dialed out of an SLA setup). Both these effects, I think, tend to make the car feel less "planted." However, the strut suspensions tend to be cheaper to make and less intrusive into passenger cabin, which is why they are popular on a lot of cars.
09-12-2005, 03:39 PM
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SLA = short long arm (double wishbone is one variant of this)
Kingpin is the axis about which the upright/hub assembly turns when you steer. In Macpherson strut suspensions, this is the strut (that's why it isn't adjustable). The angle of kingpin has effects on the return to center ability of your steering, and on steering feel.
Kingpin is the axis about which the upright/hub assembly turns when you steer. In Macpherson strut suspensions, this is the strut (that's why it isn't adjustable). The angle of kingpin has effects on the return to center ability of your steering, and on steering feel.