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Suspension Tuning & Optimization: Different Suspension Types

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Different Suspension Types

04.39

00:00 - There are a huge number of suspension configurations that different road car manufacturers use.
00:05 And as we spoke about in the previous module, their decisions are generally guided by things not related to pure performance.
00:12 This won't be an exhaustive list of all the possible suspension configurations but more of a summary of what you're most likely to come into contact with when modifying a road based car for competition.
00:24 These configurations have their own strengths and weaknesses that are important to understand and we'll be discussing each as we go.
00:31 As we learned in the last module, priorities for road cars typically include low cost, being easy to mass produce, packaging to maximise interior space and passenger comfort.
00:42 For the most part, none of these factors are particularly important to us in motorsport.
00:46 One of the most common suspension types you'll find in road cars, particularly in the front is the MacPherson strut.
00:53 The upright or hub is rigidly attached to the strut and will have a single lower control arm attached by a ball joint or spherical bearing.
01:02 In this arrangement, the damper body makes up one of the main locating components of the suspension.
01:08 Pros include low cost and ease of manufacture as well as being relatively compact.
01:13 Cons include low stiffness to weight ratio, stiction as the result of the applied side load to the damper, and poor camber recovery in roll.
01:22 Camber recovery refers to the amount of camber gain the wheels have as the chassis rolls.
01:28 No camber gain would mean the camber of the tyres doesn't increase as the suspension is compressed, which isn't ideal for most types of competition.
01:36 In general terms, while a MacPherson strut can be made to work somewhat adequately, it's not well suited for motorsport use.
01:44 Next, let's take a look at multi link suspension.
01:46 In its simplest form, this is made up of two force members meaning each link is purely in tension or compression with no bending forces.
01:56 There are a number of different potential layouts which can include as many as 5 individual suspension members.
02:02 Pros include high flexibility of the kinematic design, giving the designer control over things like camber curves, toe change and roll centre location as well as some packaging flexibility.
02:13 Some cons are the high manufacturing costs and complexity as well as a challenging design and modelling process.
02:21 A multi link can be suitable for motorsport with some modifications from the factory layout.
02:27 Double wishbone suspension is another common system in modern vehicles.
02:30 And is primarily made up of an upper and lower control arm to locate and control the motion of the upright.
02:37 Strictly speaking, the double wishbone is a sub type of a multi link suspension but it's such a popular layout, it's worthy of its own discussion.
02:46 The name comes from the general shape and top down view, resembling the shape of a wishbone.
02:51 A coilover unit will generally be attached to either the upper or lower control arm which is referred to as direct acting.
02:58 Another option would be indirect acting which is uncommon in road cars.
03:03 This is where the coilover is mounted inboard and is actuated by a system of push or pull rods and a rocker.
03:10 Double wishbone pros include being highly configurable to the required kinematics, good camber recovery and roll and a high stiffness to weight ratio.
03:19 On the downside, the system does tend to take up a lot of room which can be a challenge for packaging.
03:25 It's also expensive and time consuming to produce.
03:29 Overall though, a double wishbone suspension is generally an excellent choice for motorsport use.
03:34 Lastly, live axles aren't something that you see too much these days.
03:38 But it's still worth looking at because they were still in widespread use in some sports cars up until the 1980s.
03:44 This suspension consists of a rigid connection between both wheels and is typically found in the rear of rear wheel drive cars.
03:51 WIth the differential being integrated as part of the suspension.
03:55 Pros include relatively low cost and no camber change and heave but the cons for a live axle are big.
04:02 There's extremely high unsprung weight, the lack of independence of the suspension from one side to the other and zero camber recovery in roll.
04:11 In summary, while there are many types of suspension available on road cars, the ones that we've covered here are the most common.
04:17 Each has their own pros and cons.
04:20 Unless you're interested in making significant changes to the way your suspension works, you're going to be largely stuck with a suspension type that the original designers chose for your car.