Category Car Chat

Now let’s take a look at the third type of automobile suspension: the MacPherson type system. For simplicity, you can consider the MacPherson suspension to be the double wishbone suspension with the upper A-arm replaced by a vertical strut, whose upper end is rigidly fixed to the car body’s strut tower.

In the following chart, the one highlighted as “Original” is the most original MacPherson suspension. Of course there are multiple variations...

Suspension Design: Double Wishbone

In part II we briefly analyze the first type of suspension: trailing arm. Now let’s take a look at the second major type: double wishbone suspension.

This type of suspension uses two “A” shape arms, one place on the top and the other in the bottom. Because each A arm can limit 2 degrees of freedom, so the two A arms together limits 4 out of the total 6 degrees of freedom. Therefore we still need one more restriction to make the whole system to be 1 degree of freedom.

For front wheels, the extra restriction is the steering arm; for rear wheels, car designers usually use a toe angle control arm.

In the below chart, the one labeled...

Automobile Suspension Design 101 (Part II)

In Part I of this article, I provide a general review and some background knowledge of the automobile suspension system. There are four types of suspension geometry. In this article we will briefly analyze the first type: trailing arm.

A trailing arm system is using a solid arm, which connect one end to two locations of the car chassis (so it can only “swing” in a 2-dimensional plane); and the other end is connected to the wheel hub, with the wheel hub fully fixed to the arm.

Because the arm connected to 2...

To most people, the meaning of suspension systems are: something that can absorb unevenness of the road surface, which makes it comfortable to ride in the car. Although this description is correct to an extent, it is a quite shallow understanding though. There are much more interesting facts that we can explore.

First let’s go to the root of the topic, we look at the car’s wheel hub: assume there is no restriction/connection to the wheel hub, which means it is a totally independent object to the car body, what property will it have?

Six Degrees Of Freedom

The answer is: the wheel hub will have 6 types of movement, we call it 6 degrees of freedom...

Eight years earlier, cars sold under the $35k mark seldom get a 300hp+ engine (with exceptions like the 2005
Mustang GT), not to mention whether it was possible to get a 300hp+ luxury car at that time. Even though the
Mustang GT gets a 300hp V8 engine which is considered “high output” at that time, it sacrifices refinement
and interior material qualities and lots of other features.

But in the end of 2005, after Lexus released the 2GR-FSE engine, which was used in the 2006 IS350, the
situation is permanently changed. Equipped with the dual-injection-system 2GR-FSE engine, The IS350 has
306hp and carries a MSRP of $35,440 and its invoice price is $31,186 (for many peopl...