Double Wishbone vs. MacPherson Suspension

Lifting the double wishbone suspension, many people have the impression that it is a suspension structure that only high-end models will be equipped with, and the MacPherson suspension seems to be the economical and practical first choice. However, the domestically-produced sedans that sold for only a little over 100,000 back then already had models with double-wishbone suspension. Nowadays, luxury brands with high prices still have models with MacPherson suspension. So what is the difference between the two suspensions? How much can the cost difference be?

Double wishbone comparison MacPherson suspension-structure and performance difference

Among the common independent suspension structures of automobiles, the double-wishbone suspension is considered by many to be the best type of handling performance. Most performance cars and even F1 cars use the double-wishbone suspension structure. So back to our question today, what is the difference between Double Wishbone and McPherson?

Macpherson suspension consists of spiral springs, shock absorbers, and triangular lower arms. Most models will also Plus the stabilizer bar. In simple terms, the main structure is composed of a coil spring sleeved on a shock absorber. The shock absorber can avoid the forward, backward, left and right deviation of the coil spring when the coil spring is stressed, and limit the spring to only vibrate up and down. And you can use the stroke length and tightness of the shock absorber to set the hardness and performance of the suspension.

The structure of the double-wishbone suspension is much more complicated than the Macpherson type, it is composed of two lengths. It is composed of unequal A-shaped arms, shock absorbers acting as pillars, and coil springs. The upper and lower A-shaped arms are respectively connected to the upper and lower section arms of the steering knuckle on the wheels through ball hinges. The upper and lower A-shaped swing arms are responsible for absorbing the lateral force during steering, while the series-connected shock absorbers and coil springs act as pillars and steering The role of the kingpin is responsible for controlling the up and down movement of the wheels and supporting the weight of the body.

The structural difference is also reflected in the performance. The Macpherson suspension can obtain lighter weight due to its simple structure , The response speed is faster. And under the geometric structure of a lower arm and pillar, the camber angle of the wheel can be automatically adjusted, so that it can adapt to the road surface when cornering, and maximize the tire contact area. However, because the MacPherson suspension has only one L-shaped adjuster arm, the use of such a suspension cannot suppress the body's roll and brake nodding.

Next, let’s talk about the double wishbone suspension. The upper and lower A-shaped arms of the double wishbone suspension have similar The triangular stable structure not only has sufficient torsion strength, but also has a good guiding effect on the lateral force of the upper and lower A-arms. The unequal lengths of the upper and lower A-shaped swing arms can make the wheels stick to the ground well. Therefore, when the double wishbone suspension is used on a performance sports car, it can well restrain the vehicle’s roll when cornering. At the same time, if used on an SUV, it can also cope with extreme off-road conditions. Great impact.

In addition, in the double-wishbone suspension structure, the front and rear camber angle, front wheel toe amount, kingpin inclination angle and The positioning parameters of the caster angle of the kingpin are precisely adjustable, and because the structure of the double wishbone has a high degree of freedom in the design, engineers can reasonably arrange the position of the hinge point of the space guide rod and the length of the control arm to fix the positioning The change range of the parameters is reduced, thereby improving the overall control stability of the vehicle.

Although it looks complicated, the main difference in structure between the double wishbone and McPherson lies in the wishbone and shock absorber. The double-wishbone shock absorber is generally installed on the lower swing arm, while the MacPherson shock absorber is generally installed on the steering knuckle.

After understanding the structure and performance differences of the two suspensions, let’s take a look at why the low-end models will increase The more you like McPherson instead of the better double wishbone?

Double Wishbone vs. MacPherson Suspension-The Cost Issues Behind Platformization

Nowadays, wherever there are car companies that want to test drive , We must be developing our own platform-based modules. This is a platform-based strategy that has emerged to meet market demand and shorten the development time for new models.

For example, Volkswagen’s MQB and Toyota’s TNGA share a high proportion of vehicle parts under the platform module. Platform-based car manufacturing can use a set of chassis platforms to adapt to different models only by changing the wheelbase and track, from A to B, and even SUVs and MPVs.

So if the platform can choose both Macpherson and double wishbone suspension, the development cost of the platform will be Much higher. Therefore, most car companies will choose the MacPherson suspension that is simple in structure, low in cost, and does not take up much space. Compared with the MacPherson suspension, the double-wishbone suspension has a more complicated structure, a larger space, and a higher cost. Therefore, it is not suitable for the front suspension of a small car. In addition, the determination of positioning parameters requires accurate calculation and adjustment. The technical strength requirements for manufacturers are also relatively high. Therefore, the double-wishbone suspension is destined to be unsuitable for platform-based production by large manufacturers with widely distributed models.

Although platform-based car manufacturing is to shorten the development cycle and save costs, the development cost of the platform itself is actually very high. Astonishing. Volkswagen has invested about 50 billion pounds in the development and application of the MQB platform in the past four years. However, if the same platform can produce more models, the less development costs of the platform will be allocated to each model.

But how much more expensive a double wishbone suspension can be compared to a MacPherson suspension?

First, let’s look at the material cost. Compared with the ordinary MacPherson suspension, the double-wishbone suspension has an additional upper swing arm, upper swing arm support and lower shock absorber bracket. In terms of shock absorber installation, a double-wishbone suspension generally has an extra bracket for connecting the lower swing arm and the shock absorber, while MacPherson is directly fixed to the steering knuckle.

In addition, the R&D cost of the double wishbone is also very important, and the extra suspension parts also need to be pre-designed and trial-produced , Mold opening and other processes, the current cost of opening a mold for a vacuum cast aluminum suspension lower arm may be more than 5 million yuan. In addition, in view of the characteristics of the double-wishbone suspension, the manufacturer's tuning ability is particularly important. A poorly-tuned double-wishbone suspension may have poor handling and comfort, and the experience is not as good as the simple structure of MacPherson.

Including R&D costs and material costs, the suspension of the same car adopts the same material and technology, the double wishbone suspension is better than Mcphern The price of the suspension is much more expensive, but the average price of each car is not easy to estimate, because only from the extra parts and materials, the price difference may only be a few thousand yuan, but the research and development behind it, The cost of mold opening and tuning is immeasurable.

Double wishbone vs. MacPherson suspension——The double wishbone suspension is gradually disappearing?

Since the double wishbone is inherently higher performance than the MacPherson, why are more and more mid-to-high-end models on the market now turning to MacPherson suspension What about ? Stronger than the Porsche 911, why is it also MacPherson?

Let’s not talk about extreme cases like 911. In fact, many Macpherson-based cases have been derived in the market. Suspension Improved suspension structure.

For example, BMW’s double ball joint, compared with the standard MacPherson suspension, the double ball joint suspension A The shaped lower swing arm is replaced with two connecting rods, one front and one rear, so that the guiding mechanism controls the wheel positioning parameters more accurately, and at the same time, it can better bear the lateral force after the rod system angle is reasonably arranged.

In addition, there are general-purpose hiper-strut, connecting rod strut-type independent suspension, etc., which are all derived from MacPherson style The design not only strengthens the lateral stability, but also continues the advantages of low cost and small space. Under this trend, the double-wishbone suspension with high cost and technical difficulty is slowly being abandoned, but the classic design from the 1930s will not be outdated, and it is still the favorite of performance cars. .