@Mustangman … just curious, comparing two sedans of similar physical dimensions & weight, and configured w/passive suspension systems, it doesn’t seem like there’s much in the way of optimization choices for the manufacturer except the spring constant and maybe strut vs coil over. Or is it more complicated than that?
It is much more complicated than that. Springrate is but one, strut mount rates in 3 directions and design… single path, dual path, damping rates in the struts, control arm bushing rates, stabilizer bar rates and their bushing rates, stiffening braces.
Suspension design… strut, double a-arm, multi-link and a million variations of mounting points. Steering system design and rates. Bump steer, ride steer and deflection steer from the suspension design and bushing deflection.
Then there is body stiffness. Whether using an isolated engine cradle or suspension cradle. How the engine is mounted and those stiffnesses have a big effect.
All modeled on computers but the final rates are stil decided by engineers in the driver’s seat because people still buy cars, not robots!
Tire choice is a biggie. Tire suppliers to premium cars have a wider latitude in characteristics.
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The Every Day Driver tv show that’s only on Motor Trend at about 4:30am Saturday mornings did a comparison of the Mustang Mach 1 and the BMW M4, the Mach1 would have reviewed even better if Ford had given them a manual version but the 10spd Auto was all that was available at the time. Of the many things they noticed is that the Mustang felt lighter on those roads even though it’s actually heavier than the Bmw,
?? Isn’t one end of a strut just bolted to the thing that holds the wheel? How could that arrangement have different characteristics? Or are you referring to the other end of the strut, the bearing end, where it connects to the car’s chassis, typically under the hood near the inner fender?
You make a good point about the tires being an important factor in handling and ride. I wasn’t aware that tires designed for a Mercedes or BMW wouldn’t fit on a Corolla.
Of course the tires will fit, but their performance capabilities will go largely unused on a Corolla.
There are MANY different parameters that go into suspension geometry, bushing characteristics, spring design, and shock/strut design.
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Seriously , if they are the correct size they can go on any vehicle .
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The strut lower attachment is rigid.
The upper attachment, the mount, has the strut rod isolated in rubber. That rubber has different rates in fore-aft, lateral and vertical. The shape of the rate curves can be chosen as well. In a dual path mount, the spring would rest on the steer bearing and the bearing would be isolated from the car body. The rubber stiffness, shape and voids can be specified for the ride you want.
Wander over to TireRack and look at Continentals, Michelins and sometimes Dunlops. You will see listings for OE Porsche, Mercedes, Audi, BMW models of the very same model and size tire as those not marked.
Our Audi has replacement Continentals… but Audi spec Contis, not the regular spec. The previous owner must have bought them.
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Thanks for the explanation , good info.
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