Suspension System1. Mc Pherson Strut for all four

1.1 AboutThe MacPherson strut is a type of car suspension system which uses the top of a telescopic damper as the upper steering pivot.

The system was invented in 1955 and used on the first Ford Consul. The MacPherson suspension is a technology for front and rear suspension. It is an independent suspension type, including a single suspension arm (spring and damper), an anti-roll bar and a lower arm

1.2 Design

MacPherson For front

Use of MacPherson in Front MacPherson Section

MacPherson For Rear

Vehicle Using Macpherson strut

1.2.1Terminology

Camber angle angle between the wheel plane and the vertical taken to be positive when the wheel leans outwards from the vehicle

Swivel pin (kingpin) inclination angle between the swivel pin axis and the vertical Swivel pin (kingpin) offset distance between the centre of the tire contact patch and intersection of the swivel pin axis and the ground plane Castor angleinclination of the swivel pin axis projected into the foreaft plane through the wheel centrepositive in the direction shown.provides a self-aligning torque for non-driven wheels. Toe-in and Toe-outdifference between the front and rear distances separating the centre plane of a pair of wheels,quoted at static ride height toe-in is when the wheel centre planes converge towards the front of the vehicle

1.2 Advantages

The struts are designed with more simplicity, and thus takes up less space horizontally. They also display low un-sprung weight, an advantage that reduces the overall weight of the vehicle as well as increases the cars acceleration. Lower un-sprung weight also makes your ride more comfortable Another major advantage of this system is its ease of manufacturing as well as low cost of manufacture compared to other stand-alone suspension systems Compact, compliance close to completely independent suspension and hence good for vehicle stability. reducing the unsprung weight (like with MacPherson Struts) has a big effect on ride Comfort, and it greatly reduces the work the suspension has to do, which ends up in some parts lasting longer and staying in peak condition longer double wishbones may perform better, but the MacPherson struts would prove to be more affordable in the long run.

1.3 Disadvantage

Vibrations from the wheel are transmitted directly into the body of the vehicle. That can result in excessive road noise and vibration, which is mitigated somewhat by bushings and other components and mechanisms. the strut in a MacPherson strut system is an integral part of both the steering and suspension systems, a failure can be catastrophic The MacPherson struts also have problems working with wider wheels that have increased scrub radius, where you would need extra effort to navigate your car in this situation. Small camber change with vertical movement of the suspension, which could mean the tires have less contact with the road during cornering. This could reduce handling abilities of your vehicle.

2 Double wishbone or double A2.1 AboutA double wishbone (or upper and lower A-arm) suspension is an independent suspension design using two (occasionally parallel) wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckle. The shock absorber and coil spring mount to the wishbones to control vertical movement.

2.2 Design

A cad model of double wishbone

Double Wishbone in Rear

For Front

Different Suspensions

Double wishbone in buggyA simpler design

Wishbone design

A cad model using front double wishbone2.3.1 Advantages Independent suspension and hence best for vehicle stability and relatively simpler to manufacture and assemble as compared to McPherson strut DOUBLE WISHBONE suspension is the simplest, most effective way to maintain a constant camber angle in an independent suspension. increase of negative chamber as a result of the vertical suspension movement of the upper and lower arms better stability properties for the car as the tires on the outside maintain more contact with the road surface The double suspension system is much more rigid and stable than other suspension system steering and wheel alignments are constant even when undergoing high amounts of stress.2.3.2 Disadvantages Costly, needs more space and high maintenance. Repair, modification and maintenance costs and complexities for double wishbone suspension systems are normally higher Due to the increased number of components within the suspension set up it takes much longer to service and is heavier than an equivalent MacPherson design More unsprung Weight

3.Cost1. The cost of the suspension in both MacPherson and wishbone would remain same2. The double wishbone require more parts and bushing while the MacPherson require less Components3.