Thread: Saab issue
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Old 10-11-2009, 07:12 PM   #2
sweetbmxrider
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doesn't look like it but i know vw's have mounts that need to be in a certain position.

Background
The balancer shafts are most effective within the normal working range of the engine, from 1800 rpm and above. From idling speed up to 1800 rpm , the balancer shafts are unable to counteract engine vibration.
To effectively dampen engine vibrations at lower engine speeds, the rear and right-hand front engine mountings are hydraulic. They are most effective between idling speed and approx. 1800 rpm.
The advantages of hydraulic engine mountings:

* improved damping of horizontal engine movements during acceleration
* improved damping of vertical engine movements on bumpy roads
* improved damping of engine vibration at idling speed
* reduction of structure-borne noise between engine and body.

Description
The hydraulic mounting consists of two chambers filled with a special damping fluid. There is a diaphragm and a passage between the two chambers where the length and cross-sectional area of the passage determines the damping characteristics of the mounting. The diaphragm absorbs the forces generated by the normal small movements of the engine.
The affect of the diaphragm is not sufficient to dampen more pronounced engine movement. Fluid is forced from the upper chamber to the lower chamber, equalizing the pressure. This gives the hydraulic mounting a progressive damping action, resulting in increased resistance with increased load.

hope that helps
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