The 928 dash gives an install angle of 28 degrees from horizontal. This is above the maximum recommended (16 degrees). However, the reason for this is that the shock mounts are designed to work at a certain angle for near-vertical compression. Also, they are compliant to allow the disk mount sled to move around a bit under vibration.

If you mount above the recommended angle, then it means the shock mounts are operating off-centre and the degree of freedom the drives will enjoy is somewhat reduced.

In practice, no one has yet reported drive failure due to incorrect mounting angle, but there's been no reports of anyone actually mounting a unit this way yet, either ...

One of the few remaining Mk1 owners... #00015