[Orb]

Originally Posted by fe1rx

For those that are not familiar with the upper shock mounting point, here is a look at the hole where it mounts in the body, looking from below. The pressed in steel insert fully supports the lower half of the upper shock mount.

Attachment 1140746

The same mounting point looking from above shows that the support area for the top half of the mount is reduced by a counterbore and large countersink.

Attachment 1140747

For the bench test of the upper shock mounts to be representative the test fixture needs to have this feature. My fixture block has been adjusted for bore diameter and thickness to compensate for the dust boot that is normally installed on the lower mount. I did not want to test with this boot in place because it obscures what is happening.

Attachment 1140748

Here is the test fixture assembled finger tight with the OE microcellular urethane mounts at their uncompressed thickness. The orientation is as installed in the vehicle.

Attachment 1140749

Here the assembly has been fully torqued showing the urethane mounts compressed to their installed thickness. An internal bushing controls the amount of installed compression. Because the lower half of the mount is fully supported and the upper half is only partially supported, they compress different amounts when installed. The top mount loses 38% of its uncompressed thickness, while the lower mount loses 20%.

Attachment 1140750

Here is the test setup for the OE mount. Applied force is measured by an electronic load cell and deflection with a dial indicator.

Attachment 1140751

Here is the test fixture assembled finger tight with the Powerflex yellow urethane mounts at their uncompressed thickness.

Attachment 1140752

Here the assembly has been fully torqued showing the Powerflex mounts compressed to their installed thickness. The top mount loses 28% of its uncompressed thickness, while the lower mount loses 19%.

Attachment 1140753

Here is the test setup for the Powerflex mount. This is at maximum applied force of approximately 1800 lbs.

Attachment 1140754

Load vs Deflection was plotted for each of the mounts and a linear regression line was fitted to give the stiffness. Below the stiffness of the OE lower shock mount, OE upper shock mount and Powerflex Yellow upper shock mount are shown in Imperial units. As can be seen, the Powerflex mount is comparable in stiffness to the OE lower mount and is approximately 7 times stiffer than the OE upper mount.

Attachment 1140755

Same again in Metric units:

Attachment 1140756

Interesting data. You mentioned that the lower OEM and Powerflex bushing are plotted but I only see the OEM bushing.

What bother me about the Powerflex busing is how much load would be put on the shock shaft when articulating. I do believe this is about 10 degree angle maximum. The added friction to the system might not be worth any benefits?