Suspension and Steering Systems
 
Suspension – Spring Types
 
Front Suspensions
 
Rear Suspensions
 
Steering Overview
 
Steering Gears
 
Steering Linkages
 
Quiz

 

    

Front Suspensions

Front Suspensions
 Since the front of the car is where steering takes place, front and rear suspensions differ considerably.
 

There are two fundamental types of front suspensions:
 
1. Solid Axle
 2. Independent Axle
 
 
 
1. The solid axle suspension is used mostly on medium and heavy-duty trucks. In this suspension, a rigid solid axle connects both wheels. What happens to one side affects the other.
 
 
2. Independent suspensions let each wheel move independently, and have more moving parts to absorb road shock, providing a more comfortable ride. The independent systems described here are most often used on passenger cars and light trucks. 
 
 
The five main types of independent suspensions are:

  • Short / Long Arm (SLA)
  • Modified Strut
  • MacPherson Strut
  • Multi-Link
  • Twin I-Beam
Short / long arm (SLA), also referred to as double wishbone, unequal length control arm, or conventional ball joint suspension. This suspension can work with front wheel drive (FWD) or rear wheel drive (RWD) and can use coil springs or torsion bars for support.
 
 
UNEQUAL LENGTH CONTROL ARMS
WITH COIL SPRING (above)
The most common SLA design has the coil spring mounted on the lower control arm and is used on many RWD vehicles. The control arm can also be a single inner pivot and use a strut rod and bushing.
 
TORSION BAR - REAR WHEEL DRIVE 
Above design is used on some early passenger cars and some light trucks. The torsion bar is anchored at the lower control arm and the vehicle underbody. A strut rod is used to add rigidity to the control arm.
 

TORSION BAR - FRONT, FOUR, and ALL WHEEL DRIVE (right)
This design uses unequal length control arms. The torsion bar is anchored at the lower control arm and vehicle under body. Some import 4X4s have the torsion bar anchored to the upper arm.

Modified strut (left)
This design has a lower control arm mounted spring combined with a strut. The strut replaces the upper control arm as a suspension member.
MacPherson strut
Originally used on small rear wheel drive imports, the MacPherson strut now is used primarily as a front wheel drive suspension by both domestic and import vehicle manufacturers. The front wheel drive variation uses a coil spring mounted on the strut which is connected to the upper body structure and the steering knuckle (spindle). The lower control arm can have one or two inner pivots. If only one inner pivot is used, it will be reinforced with a strut rod.

MacPHERSON STRUT - FWD (below)

MacPHERSON STRUT - RWD (above)

Multi-link
Front wheel drive MacPherson strut suspensions have evolved into many variations according to manufacturers’ preferences and requirements. One term frequently used to describe some later MacPherson variations is “multi-link” or "wishbone". This term is general and applies to several designs. It is helpful, though, in that they employ an upper arm, or link, to give the vehicle more stability. 

MULTI-LINK STRUT - FWD (above)  


RWD (above)

Twin I-Beam (right)
Ford introduced this suspension in 1965 and used it for most of its light trucks until recently. The twin I-Beam originally was a two wheel drive suspension and later was adapted to four wheel drive. This suspension is still very important because many trucks on the road use it. 
 
 

                               TWIN I-BEAM

 

 

 
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