OK fellow Middies - ?? on motor/transmission mounts

[74-911]

How are the concave disks aligned on your rear motor and transmission mounts ?
An earlier thread indicated they were changed in 1978.

Originally Posted by dap930

Porsche put out a technical bulletin (1043, 78-01, dated 09/01/1978) that said the washers would be installed concave face down on starting with the 911SC and Turbo. However it did say that the concave down position could be changed to the up position if "rumbling" noise is present.

On my '74, the concave surfaces on the motor and transmission mounts face each other. However, a couple of months ago I changed the orientation on the rear mounts from concave side facing up to facing down as it just never look right facing up and the Bentley manual clearly shows it facing down (yes, I know the Bentley is for SC's.)

Since changing the orientation I have noticed a weird rumble occasionally at low speeds but it never occurred to me that might be what is causing it?

So how are the disks oriented on your car ??

[Lapkritis]

Concave not facing each other; I went with turbo rubber mounts as well. No rumbles.

With concave facing each other, the edge will be more prone to contacting metal on metal.