Is multilink suspension advantageous over double wishbone?

[gorain]

is it correct to replace the double wishbone suspension with multilink suspension in a racing for environment like UK

[Jersey Tom]

Really probably not inherently better or worse. Just different.

[PlatinumZealot]

is it correct to replace the double wishbone suspension with multilink suspension in a racing for environment like UK

The multilink you can take advantage of the movement of the body of the car. You can also make the wheel move in all sorts of ways as it rise/falls. Multilink is the best suspension in my opinion.

BMW's have a hybrid multilink suspenison on the front axle now. Check out the front suspension parts of the 7 series below.

Three ball joints at the bottom of the upright... (two linkages + tie rod)
and a more conventional A-arm at the top.

http://realoem.com/bmw/partgrp.do?model ... g=31&fg=05

[flynfrog]

is it correct to replace the double wishbone suspension with multilink suspension in a racing for environment like UK

The multilink you can take advantage of the movement of the body of the car. You can also make the wheel move in all sorts of ways as it rise/falls. Multilink is the best suspension in my opinion.

BMW's have a hybrid multilink suspenison on the front axle now. Check out the front suspension parts of the 7 series below.

Three ball joints at the bottom of the upright... (two linkages + tie rod)
and a more conventional A-arm at the top.

http://realoem.com/bmw/partgrp.do?model ... g=31&fg=05

you can do all of that with a Double A arm as well. As Tom said they are just different. You certainly wont gain anything by cutting one suspension off a car and trying to adapt another suspension to it.

[Jersey Tom]

One could go so far as to say a double wishbone suspension is a specific assembly of a multi-link design, in which two pair of links share a common wheel-side pivot.

Whatever is gained by removing those constraints in a full multi-link design is likely lost in design and tuning complexity. There is a sophistication in simplicity.

[PlatinumZealot]

Just a point of observation.
The double wishbone there is one constant distance from the outer ball joint to the axis of rotation of the lower A arm.

In the multilink this distance varies as the wheel moves because each linkage in the multi-link can move in more than one plane.

This is because, from the plan view the two separate lower linkages form a non planar quadrilateral (or 3 dimensional 4 link) with their mounting points and the upright.

It is like having a double wishbone with the legs of the A-arm variable length.

This is a significant difference to me. I think the car can ride better over bumps. It could really be useful in F1.

Yes, I expect it to be hell to tune.

[flynfrog]

Just a point of observation.
The double wishbone there is one constant distance from the outer ball joint to the axis of rotation of the lower A arm.

In the multilink this distance varies as the wheel moves because each linkage in the multi-link can move in more than one plane.

This is because, from the plan view the two separate lower linkages form a non planar quadrilateral (or 3 dimensional 4 link) with their mounting points and the upright.

It is like having a double wishbone with the legs of the A-arm variable length.

This is a significant difference to me. I think the car can ride better over bumps. It could really be useful in F1.

Yes, I expect it to be hell to tune.

ride over bumps has little to do with the type of suspension. You could do the same thing you are stating by having your a arm pivots on different axis.

[Caito]

You need to 5 have DOF constrained.

With multi link you have 1 per each. Bear in mind I'm counting wheel steering as one.


Trace your ideal suspension curves and we can tell if it would be adavantageous or not.

[Jersey Tom]

Again.. a double a-arm is just a specific implementation of a multi-link suspension.

[riff_raff]

I would agree with JT. The typical double a-arm race suspension is a form of multi-link, if you consider the steering tie rods in front and toe links in back.

Production automotive suspensions tend to use multiple link geometries to compensate for packaging limitations, and to produce a more "forgiving" suspension movement that keeps the average driver out of trouble.

The trend in F1 suspension design has been towards fewer "moving" parts. Such as replacing spherical joints with flexures. This makes the set-up and performance of the suspension more consistent and predictable. In fact, I'd predict that in the near future, we'll see metallic springs and hydraulic dampeners replaced with electrically active, variable stiffness suspension structures, and piezo-electric actuator control of ride height. A 21st century "solid-state" suspension, instead of the 20th century mechanical approach.

[thisisatest]

f1 had multilink in the rear a long time ago. moved to double wishbone.

[Tim.Wright]

Im with riff_raff and JT here too. Multilink is quite common in production cars now but it always seems to be to overcome packaging or other problems specific to a car. e.g. virtual lower control arms (multilink lower arm) on a mcpherson front axle can help reduce the otherwise large scrub radius. Additionally, the sophisticated multilinks now seen in high end cars (BMW7 Ferrari 458) are there mainly for reasons of comfort because you have more scope to place bushings in the right place to get the desired wheel centre compliance.

I have seen it on a formula one car - I think it was the 1997 Ferrari. It had a virtual lower control arm (made of two links) and a normal upper arm.

In my opinion, for competition use, a multilink suspension is a complication to try and avoid. There is generally no advantage in kinematics to warrant the increase in joints and links. Like I said, its normally only used to solve a particular problem.

Tim

[Caito]

Again.. a double a-arm is just a specific implementation of a multi-link suspension.

In that case, all suspension are, in some way.

[thisisatest]

5-link rear suspension. 1970 f1 car.

http://atspeedimages.com/image.php/4c9a ... ension.jpg

[munks]

Again.. a double a-arm is just a specific implementation of a multi-link suspension.

In that case, all suspension are, in some way.

Not quite true. I believe multi-link only refers to independent suspensions, and there are quite a few types of suspensions that do not qualify as such, for example beam axles.