1994-2002 [Subscribe to Daily Digest] |
Many folks are confused by suchgterminology as niether arm is really lower than the other.
Do I have the following correct?
The control arm pivots on the sub frame and also carries the ball joint. On later production is also carries the sway bar end. The radius arm goes from the rear, at the firewall area, to the control arm. The two are joined with a rubber bushing to form a split lower control arm. The bushing that joins them acts like carlidge (sp) which should couple the two quite closely. Many feel that the use of a hydraulic bushing in this location was really stupid. The end the control arm projects past the rubber bushing and terminates with a non renewable ball joint. The ball joint does not absorb any vertical static loads or the weight of the vehicle.
When the early production had the sway bar coupled to the radius arm instead of the control arm, there were two problems created. The sway bar's reaction forces and control were lost by controlling the radius arm instead of the control arm, as some of the reaction forces were not developing control of the suspension movement but produced deformation of the hydraulic bushing. And I believe the long levers on the sway bar needed to pick up on the radius arm location created a mechanical disadvantage for the sway bar that effectively reduced its stiffness and effectiveness.
The early production had some nasty wheel shake dynamics which had the dealers retro fitting this stuff if the problem could not be cleared up via wheel balancing. The freedom of motion created by all of these rubber bits that were indended to absorb road vibration led to elastodynamic instabilities... and the suspension got the shakes.
As the radius arm is bent to clear the wheel when turned to steer, the center of gravity of the radius arm is not centered between its end point rubber bushings. So any vertical movement will induce a tortional load on the radius arm that will cause it to vibrate. The vibration freqency and applitude will increase with the softness of the bushings. For units with the sway bar attached to the radius arm, that motion would probably be dampened significantly. This may have been part of the problem with the vibrations that lead to the retro fit for those who had problems and conplained to the dealers early on. It is all very complicated.
The early VRK components, before there was a collection of them or any Viggens, were different at the steering rack. Replacing both rack clamps and mounting rubbers with two machined solid aluminum clamps was very difficult as one side is buried under the fuse box etc. So now there is only one aluminum clamp, but there is also a lateral brace bar which goes from one clamp bolt to the inner fender. So for the VRK, the full current product does fit the 94-95.5 pruduction rack. But, you still need to get the 'larger' kit to go with the early production's cast aluminum rack housing. Actually, this clamping on the early production is a better solution that the kit applied to the new style fabricated steel rack!
For some reason, the steel spherical bearing cannot be fitted to the 94-95.5 radius arm. The large urethane bushing can be fitted, as well as the subframe brace. So the sherical bearings are the only thing that cannot be used. They will provide a kit to suit, repriced to account for the unneeded sperical bearings.
The transition from aluminum to steel steering racks and the newer arms and sway bar were not timed together, and some units were field retrofitted (at Saab's expense). So it is a mixed bag. You need to determine these two details before ordering.
The strut top mounts, bearings, washers etc were not changed to 1997 I believe. The original design failed in the field for some and not for others. The strut tops are bubbber suspended bushings as the shock shaft squirms and twists with suspension and steering motion. These bushings will get tired and need replacing eventually, and perhaps the new designs have a longer service life other than avoiding early failures. So they are not something that you should expect to last forever. So perhaps the KYB aftermarket units make sense. They might even be better units... who knows?
posted by 208.24.17...
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