Mercedes-Benz uses Double Wishbone for all of their cars except the C Class and, now, the E Class. I was told this was to make the car cheaper to build although Double Wishbone is the superior design.

What are your thoughts on this?

 

+1 on no idea what difference it makes

 

I'm not smart enough to answer this, but I'd love to learn about it.

 

The biggest advantage for the double wishbone was that you get negative camber when the suspension is compressed during a turn. It helps plant the wheel, giving you a larger contact patch, while MacPherson Strut usually creates positive camber when compressed. You can also slam the hell out of a car with double wishbone suspension. :P

For a daily driver, I don't think it matters which design your car has.

 

Double Wishbone design is actually more costly than MacPherson strut design. May be it's easier if I just list the advantages and disadvantages of each design.

Double wishbone:
- Ideal camber control
- The wheel always stays perpendicular to the road - > good handling
- Costly due to more components involved
- Takes up more space

Macpherson strut:
- cheap
- doesn't take up much space
- variation in camber when cornering due to body roll -> average handling

Of course, a poorly tuned double wishbone suspension system can lead to pour handling too (ie. a lot of old American cars).

One major difference IMO is torque steer on FWD cars. With a double wishbone design, it's much easier to minimize torque steer just by building more kingpin inclination. This can also be done to a car with Macpherson strut suspension. The problem is, the kingpin also serves as the shock absorber and spring. If the kingpin is inclined too much, then it will cause too much lateral force being transmitted to the body, causing vibration, shaking, and instability. This is why there's much more torque steer in a Nissan Altima/Maxima than an Accord/TL.

 

Great answer there iforyou! Now do you happen to know what is better in terms of rear suspension. Wishbone or multi-link, or what the positives and negatives of each are? I know wishbone is better up front than a Macpherson strut system, but not so sure about the rear... glad to see we have a mechanical engineering student on here haha!

 

Leaf springs are best for the rear

 

I was told that, over time, a Double Wishbone will produce fewer rattles in the car because it is stronger and transmits less vibration into the car to be absorbed by it. True?

 

Great response, also to add MacPherson struts tend to be lighter than double wishbone designs.

Honda claims on the 7G Civic switch from double wishbone to MacPherson that another reason was safety (I presume it gave more room for collapsable structure in the front to absorb energy in a frontal crash) but I think that was just a spin since Honda/Acura use double wishbone on Accord/TL/TSX/RL.

 

Hard to say but I kinda doubt it, my guess is the choice of suspension bushing materials is a larger factor than the design itself. Also the harmonic frequencies of the various parts of the vehicle structure and damping materials (carpet, insulation,...) make a the largest part of rattles and vibration.

 

Rear Suspension

Wishbone
+ rigid control of camber/toe
- does not provide much if any geometry control

Multi-Link
+ provides rear gemetry control (typically toe-in during large compression to avoid oversteer)
- more complicated
- more components

 

Multi-link IMO is a pretty broad term. Any independent suspension with 3 or more control arms are pretty much multi-link. There are so many different designs out there. BMW ones look like the letter "Z" and obviously they offer great handling in the expense of taking up more space. Honda switched to rear multi-link setup too and it's basically a double wishbone design plus a 5th control arm.

A lot of sports cars still use double wishbones, but there are some that use multi-link, like the GTR and 911.

By the way...I should update my account..I just graduated recently..lol!

 

I had a 6G Civic, with the double wishbone. And it still had torque steer, with all of its mighty 96 lb/ft of torque

 

I hate MacPherson suspensions personally.

 

lol....never drive a maxima man. haha

 

One important design factor in torque steer on FWD is having equal length driveshafts. Most Acura's have equal length driveshafts with a intermediate shaft on the engine side of the drivetrain. This attempts to reduce the driveshaft rotational inertia and torsion. It's not as good as a equal length driveshaft w/o the intermediate shaft. The only FWD Acura I know that had that setup is the 2G Legend since the engine/transaxle were mounted longitudinally. I drove one once and it had almost no noticle torque steer. I also had a Audi 100LS in collge and had the same drivetrain setup and had almost no torque steer.

The Maxima and all Civics make do with un-equal length driveshafts and the long shaft is clearly thicker to compensate for the longer length to give it the same rotational torsion as the short shaft. However that creates a torque rotational inertia difference which produces alot of torque steer under heavy throttle while accelerating. Adjusting the kingpin helps but equal length driveshafts are the way to go to minimize torque steer.