Suspension 

Chassis and handling upgrades will improve acceleration, braking and cornering abilities by maximising traction. There is no point in having the most powerful car, without the platform to control and use the power through the wheels. It is always a balancing act between power and handling. With the right upgrades, we can increase torsional stiffness or lower the car's height to achieve a more driver focused compromise. Careful selection of the right products and settings need to be taken into account as minor changes can causes major handling extremes.

Springs and dampers can make a huge difference in the handling department, also upgrading larger Anti-roll bars/Anti sway bars. A car's suspension job is to maximize the friction between the tyres/tires and the road surface. 

Also to provide steering stability with good handling and to ensure the comfort of the passengers. While the aim of a car manufacturer will be to have a comfy ride for passengers, this will not reap the ultimate reward for the driver's car.

If a road were perfectly flat and had no irregularities, then suspensions would not be required. But roads are far from flat, even freshly paved motorways/highways have subtle imperfections that can interact with the wheels­. It's these imperfections that apply forces to the wheels. 

So a cars needs a system to help achieve contact with the road at all time and take any lumps or bumps in the road. Sometimes the difference between winning and losing can come down to the changes a car behaves under various loads.

Over the Years with ongoing technological developments, manufactures have produced a multitude of difference designs and I want to run through some of the common ones:

 

 MacPherson Strut or McPherson strut.

 

The MacPherson strut is a type of car Suspension system commonly used in many modern motor vehicles. This includes both front and rear suspensions, but usually located at the front. It provides a steering pivot (known as a kingpin) as well as a suspension mountings for the wheel. 

Rear positioned struts are also use but these are less common. In 1957 Colin Chapman of Lotus applied the design to the rear suspension of the Lotus Elite. As a result, strut suspension at the rear of an automobile are now commonly called Chapman struts.

To be really successful, the MacPherson strut required the introduction of unibody (or monocoque) construction. This is because it needs a substantial vertical space and a strong top mount, which unibodies can provide and also by distributing stresses greatly increases the set up's results.

The strut normaly also has a steering arm built into the lower inner portion. This assembly is extremely simple and can be pre manufactured into a unit. Also by removing the upper control arm, it allows for more width in the engine bay. 

This is useful for smaller cars, particularly with transverse-mounted engines such as FF drive vehicles.  Further simplification is possible by substituting an anti-roll bar (torsion bar) for the radius arm. Also it offers an easy method to set suspension geometry. Ultimately making the production overheads more cost effective and making this a very common design set up in today's marketplace.

Although it is a simple design and has low manufacturing cost, there is always a compromise and a few disadvantages. The quality of ride it produces and the handling of the car may suffer or be less effective then other set ups. 

Geometric analysis shows it can't allow vertical movement of the wheel without some degree of either camber angle change, sideways movement (or both). So double wishbone suspension is favoured for Motorsport applications. 

Also with the  MacPherson set up, the wheel tends to lean with the body, leading to understeer under extreme cornering. In a FF car, adding to the already natural tendancy to understeer is far from ideal. The ideal situation would be neutral handling, so this might benifit other drivechain set ups.

Also it tends to transmit noise and vibration from the road directly into the body shell. This results in higher road noise levels and sometimes a harsh feeling to the handling compared to a double wishbones set up. This results in manufacture's adding extra noise insulation in a bid to reduce the the negative effects, which can lead to some weight gains as expected.

Double wishbone suspension systems

 

In Motorsports the application of the double wishbone Suspension set up is the preferred system and this is used in F1 for example.This is partially because it allows the engineers more freedom to choose camber levels and roll center, which ultimately will affect the car's handling in certain situations and ultimately could affect lap times and the handling effectiveness of the vehicle. 

Each wishbone (or A arm) has two mounting points to the car's chassisand one joint at the knuckle. The shock absorbers and coil springs mount to the wishbones to control vertical movement.  It is also possible for a single A arm to be used in the MacPherson/ Chapman strutt set up in different car set ups.
 
The main advantages of the double wishbone suspension set up is that it is reasonably easy to work out the effects of the moving joints. This allows engineers to easily tune the kinematic of the set up to optimize wheel motion. In Motorsports where a tenth of a second a lap can mean the difference between winning and losing, having a suspension set up with easy adjustments will yield greater performance for competitiveness. 

 It is more effective to work out the loads that different parts of the suspension are subjected to, which means continued development and progression of lightweight parts. 

They also provide increasing negative camber gain all the way to full jounce travel unlike the MacPherson strut which provides negative camber gain only at the beginning of jounce travel and then reverses into positive camber gain at high jounce amounts. But as is always the case, the disadvantage is that it is slightly more complex than other systems like a MacPherson strut.

Which in terms of Cars and Motorsport, equates to more cost and complex set up to yeild the right results.

 Trailing-arm suspension

 Trailing-arm suspension is a Suspension design in which one or more arms are connected between the axle and the chassis at the front and basically allows the rear to move up and down. Commonly found in Pre 1990's application, when then it was mostly replaced by Multi-linkage suspension. 

Viewed as an older suspension set up and this design does take up a lot of space in the rear chassis area compared to other modern systems. A good place to look is the original Beetle front suspension set up, which uses a double trailing arm set up.


Also semi-trailing arm suspension is a supple independent rear suspension system for cars where each wheel hub is located only by a large, roughly triangular arm that pivots at two points. Viewed from the top, the line formed by the two pivots is somewhere between parallel and perpendicular to the car's longitudinal axis; it is generally parallel to the ground. 


Trailing-arm and Multi-link suspension designs are much more commonly used for the rear wheels of a vehicle where they can allow for a flatter floor and more cargo room. Many small, front-wheel 

drive vehicles feature a MacPherson strut front suspension and trailing-arm rear axle.

 

Solid-axle, Leaf-spring

 Leaf springs suspension was common right up to the 1970s in Europe, Japan and up until the late 1970's in America. When the implementation to front wheel drive and more sophisticated suspension designs were implemented, this convinced car manufacturers to use the later designed systems like the coil springs design instead. Leaf springs are still used in heavy commercial vehicles such as vans and trucks, SUVs, and railway carriages. As they are cheap to manufacture and have excellent load carrying capacities.

The main advantages are for heavy vehicles, they spread the load more widely over the vehicle's chassis, whereas coil springs transfer it to a single point. This reduces the pressure and structural loads which can result in a more robust design. 


Unlike coil springs, leaf springs also locate the rear axle, eliminating the need for trailing arms and a Panhard rod, thereby saving cost and weight in a simple live axle rear suspension.


Also with the more recent technological developments of the parabolic leaf spring, the design is characterised by fewer leaves whose thickness which varies from centre to ends following a parabolic curve. With this design, inter-leaf friction is unwanted and there is only contact between the springs at the ends and at the centre where the axle is connected. 


Spacers prevent contact at other points through out the design. Apart from a weight saving advantages of this design, the other benefits of parabolic springs is their greater flexibility, which means vehicle ride quality that is comparable that of coil springs.


But there is a trade-off in the form of reduced load carrying capabilities, so this will only be used in appropriate applications. Characteristic of the parabolic springs include better ride quality and not a "harsh" as conventional "multi-leaf springs". 


It is widely used on buses for better comfort of the passenger on board, where comfort takes a higher priority over load capacity. A further development by the British GKN company and by Chevrolet with the Corvette amongst others, is the move to composite plastic leaf springs.

 

Solid-axle, Coil-spring

 Another variation and some what update on the leaf spring design. The concept in idea is very similar, but the main difference is that the leaf springs have been removed in favour of either coil-overs spring and shock combomination, or separate coil springs and shock absorbers.

Due to that fact that the leaf springs have been disposed of, the axle will now need lateral support from control arms. On end attached to the chassis and the other to the axle. There can be variations in the different layouts, but fundamentally this design is deemed as older technology. From a perfromance point of view, Handling characteristics can be quite limited in it's application.

 Beam Axle

 

This suspension set up is normally deployed in FF drive cars and it is a relatively simple system designed system. The so called beam runs across under the car width, with the rear wheels attached to either end.

 

Spring/shock combination units or indeed struts are bolted to either ends and normally located in the car body or chassis. The beam has two intergrated trailing arms built in inplace of the separate control arms found on solid-axle coil spring suspension system. Again there are other variations on the system can have either separate springs and shocks, or the combined 'coil-overs. 

One main difference with other designs is the track bar (panhard rod). Basically a diagonal bar which runs from one end of the beam to another point either in front of the opposite control arm or diagonally up to the top of the opposite spring mount. This bar's job is to try and stop side to side in the beam and help make the system more efficeint.

Another variation is the twist axle which is identical with the exception of the panhard rod. In this design the axle is designed to twist slightly, which in effect creates a semi-independent system and a bump on one wheel is partially absorbed by the twisting action of this beam design. 

From a Performance point of view, beam Suspension is not the optimum choice. Due to the construction, this design has a large Unsprung weight compared to other suspension set ups. Also when the suspension is under load, each individual wheel can not operate independently. Similar to a car with a too stiff Anti Roll Bar / Sway bar at the front. Anything which affects one wheel, will transfer to the other.

This is far from ideal for a turn in on a Racetrack, also another disadvantage is the lack of Negative Camber under load. This results in poor Handling compared to other Suspension set ups. Normally when the Suspension is compressed, Negative Camber will result, aiding turn in response.

This design does have some advantages in off Road applications, also due to the lay out. lends itself well for Pick UP and Van applications, due the way it can deal with varied load weights. Another good point is the impact it has on Internal space, due to it's compact design and dimensions.

 
rapid racer
Make a Free Website with Yola.