HYDRAULIC Issue 18/2017
SUSPENSION BUSHES SHOCK ABSORBER, SUSPENSION, BRAKES, TOWBARS AND WHEEL ALIGNMENT SPECIALISTS
Hydraulic Suspension Bushes Over the years of steering and suspension development, one of the areas that has had major advancement is the suspension mounting bush. In the design of compliance type bushes, there is a conflict between high frequency noise isolation and high damping at low frequency. With fluid-filled bushes: it is possible to achieve both at the same time low dynamic stiffness for good Noise Vibration Harshness (NVH) performance. The fluid-filled bushes have replaced the standard rubber variants used in the previous vehicles. The advantages in terms of comfort and road noise isolation are substantial. The system creates a lower spring rate, reducing road noise while also offering high damping characteristics to absorb shock and vibrations on bumps.
What are the Advantages of Hydraulic Suspension Bushes? hile designs differ slightly, all hydraulic bushes rely on W the same principle and comprise an inner and an outer sleeve separated by a void filled with hydraulic damping fluid. The bush is firm due to the incompressibility of the fluid, yet the NVH properties of the fluid dramatically reduces road noise being transmitted. he fluid, being glycol based, is injected inside the T bushes as a buffer material. It creates a large damping force and optimizes the dynamic spring constant. his concept reduces unpleasant vibrations felt when T driving on rough road surfaces or going over road surfaces of different levels.
What are the disadvantages of Hydraulic Suspension Bushes?
How can a Hydraulic Suspension Bush be identified? sually the construction will give you a clue if it is a U Hydraulic Bush, as the outer casing will be rolled over and crimped. This is done to create a seal to stop the fluid from escaping. (see Diagram A over page.)
How do you know they require replacement? hen checking the suspension, if a fluid type of bush W has failed, there is a big chance you may not notice any witness marks, like residue of the fluid. We are all aware that mineral based oils are the enemy of rubber so the fluid used is of a glycol base and as such is water soluble, and will wash off when the vehicle travels through water (wet roads when it rains). When the fluid does exit the bush, it leaves behind a cavity completely devoid of fluid and this will allow for increased movement of the component. The checking procedure is no different for fluid filled bushes to that of non-fluid filled bushes, if there is excessive travel in the components, then its time to change the bush.
Is there a need to replace the Hydraulic Suspension Bushes with O.E.? he quick answer is no, but prior to fitting new bushes T to the suspension, please make careful consideration regarding the type of material the bush is constructed from. Have a look at the function of the suspension arms and assess whether or not, by fitting an aftermarket bush, it will restrict movement and place extra load on other components as well as creating any NVH. Rubber constructed bushes may be the ideal replacement, whether hydraulic or not.
hilst these new generation bushes are highly effective W when in a serviceable condition, they don’t appear to have a long service life, as the fluid tends to escape. When this situation occurs, the bushes compliance tends to increase thus allowing increased movement. This may cause unstable steering and braking, with the car pulling because of an ever changing wheel base.
Straight advice, specialists you understand and...
d to replace the Hydraulic Suspension Bushes with O.E.?
there a need to replace the Hydraulic HYDRAULIC Bushes with O.E.? ckIs answer is no, but prior to fitting new Suspension bushes to the suspension, please make careful ration type isofno,material constructed from. Have a look at make the careful ďƒ˜regarding The quickthe answer but priorthe to bush fittingisnew bushes to the suspension, please n of the suspension and assess whether or not, fitting an aftermarket bush,awill considerationarms regarding the type of material theby bush is constructed from. Have lookitat the Issue 18/2017 function of the extra suspension arms and components assess whetherasorwell not, as bycreating fitting anan aftermarket bush, will it movement and place load on other Noise Vibration restrict movementbushes and place load on other components as wellhydraulic as creatingor annot. Noise Vibration ess. Rubber constructed mayextra be the ideal replacement, whether SHOCK ABSORBER, SUSPENSION, BRAKES, TOWBARS
SUSPENSION BUSHES
Harshness. Rubber constructed bushes the ideal replacement, whether hydraulic or not. ANDmay WHEELbe ALIGNMENT SPECIALISTS
Holden Commodore Radius Arm Bush
Rolled and crimped edges
Whilst the bush is in a serviceable condition, the amount of movement is kept to a minimum, but as soon as the fluid escapes (the yellow in Diagram A) it leaves behind modore Arm Bush. HoldenRadius Radius Arm Bush. a Commodore void.
Rolled and crimped edges
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this chamber condition, no longer has the fluid in it, this willof allow for h Whilst is in a As serviceable amount the bushtravel is inofa the serviceable condition, amount of increased radius arm and the lowerthe control ept to a arm, minimum, but asaffect soon theasbase. fluid which willto in a turn theas wheel movement is kept minimum, but soonescapes as the fluid escapes aves void. behind a void. (the behind green) italeaves
chamber no longer it, thisfor will allow for rAs nothis longer has fluid in it,has thisfluid willinallow travel of the arm and the lower l increased of the radius arm andradius the lower control arm,control arm, which will in wheel turn effect urn effect the base.the wheel base.
Ford Falcon Lower Front Arm Bush As the bush compresses and releases under normal road operations, the fluid is allowed to transfer from one side to the other through a series of galleries (refer to Diagram B). The reason for this is to keep a constant even tension around the full circumference of the bush. If the fluid escapes the empty cavities allow for increased compression and greater movement of the arm.
Fluid filled
Fluid filled Diagram A
Ford Falcon Lower Front Arm Bush
Lower Front Arm Bush
Diagram B As the bush ,compresses and releases under normal road operations, the fluid is allowed to transfer from one side to the other through a series of galleries. The reason for this is to keep a constant even tension around the full circumference of the bush. If the fluid escapes the empty cavities allow for increased mpresses andand releases normal road operations, the fluid is allowed to transfer from compression greaterunder movement of the arm. Straight advice, specialists you understand and...
other through a series of galleries. The reason for this is to keep a constant even tension circumference of the bush. If the fluid escapes the empty cavities allow for increased