Monoleaf Spring
● It is a single leaf design
● It is thicker in the center and tapered toward the ends
○ This is commonly seen in corvettes or suspensions with high performance
● It has a neat design and is not seen more often
● Advantages
○ The spring rate is adjustable by its spring-mounted brackets on either left or right
side
○ It has a variable rate
■ The thinness of the ends makes them softer and more flex compared to
the center of the spring which is thick making them less flex
○ It gives a smooth ride
○ It has good load carrying capability
○ It has reduced friction and noise compared to multi-leaf springs
■ No rubbing of metal-metal components of springs
Fiber Composite Spring
● It is FRP (fiber reinforced plastic
● It has a monoleaf design
● It is comprised of fiberglass laminates bonded together
● It has a very light design and it’s the reason why manufacturers use this often
● It has a quicker response to road shock compared to steel spring does
● It has two bolts holding it to the differential with an upside-down shape compared to a
normal spring
● Advantages
○ It has a transverse mount (upside down) reducing body roll
■ This is reserved for more high priced car
○ It dampens noise
○ It has a smooth action
○ It resists sagging
Torsion Bar
● It is a big bar (50mm-150mm) by itself
○ The bigger the bar is, the easier will it flex, the more suspension it can handle
● It is a pre-stressed bar made up of a steel spring that acts as a coil spring
● It absorbs road shock when the torsion bar twists
○ The lower control arm has the little stop sign on the end that lines up with the
octagonal design on one end of the torsion bar
■ The one end of the torsion bar fits inside the lower control arm
○ The other end of the torsion bar matches inside the crossmember of the frame
○ The torsion bar on the crossmember can’t move compared to the bar on the
lower control arm which moves up and down with the suspension
○ The whole bar spend its life twisting left and right
● It is used in four-wheel application
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○ It will allow spring travel and spring suspension
It has a torsion bar adjuster nut that can control the spring tension to how much tension
we needed
○ If the right side is lower than the left, we could adjust the tension on one side and
raises the tension on the other side
Another style of torsion bar design is one end mounted to the frame while the other is
connected to the lower control arm
○ This is not a common used design because of the high cost
○ It has a directional design (left or right)
○ It is mainly used on 4WD trucks
○ It rarely fails or breaks
Air Springs
● It is also known as airbags or air suspension
● Inflating the rubber bag supports the vehicle weight
● They are located in the same positions where coil springs are usually found
● Compared to a coil spring, they offer a smoother ride and are adjustable
● They have a simple design
● If you increase the air in the bag, the lower control arm will be pushed down while if you
let air out, the bag will collapse and the lower control arm will go up changing the height
● It has a height sensor that is attached to the control arm of the vehicles and frame and
will tell us the right height
● Each spring consists of a reinforced rubber bag pressurized with air
● Each airbag is attached to an inverted piston-like mount that reduces the interior volume
of the airbag during jounce
● Advantages
○ They have a smoother ride due to the air being compressed
○ Ride height sensors indicate to the computer when the vehicle is low
● The ground clearance of the front wheel of 100mm should be the same on the back
● Every car have different specifications where ride height can be measured
○ From ground to fender tip
○ From point specified on the bumper to the ground
○ From rocker sill to the ground
● Example
○ A customer goes to home depot and puts 200 lbs on the back of the car
■ The suspension will drop on the back (50mm)
■ The weight sensor sees that the suspension on the back is sagging
■ It will tell the on-board computer that the rear is sagging and tells the air
compressor to turn on, puts more air on the rear compression until it gets
back to the consistent right height
■ Once the customer goes home and removes the load at the back, the
suspension should be modified in the same way
● The suspension of the car is very important.
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If you have a load at the back, the front will point upward and this will have an
effect if the height was not modified
■ During a night drive, the headlights will be pointing upwards to the trees
and not on the road