[Bill Harris]

Those reinforced perches will probably survive the next world war. However, it might be good to reflect on what happened and try to identify the root cause of the original failure. It is easy to say that the Moser perches are defective/weak/junk/chinese, etc. and that they should know better since they build axles for drag racing and have for many years. But before crucifying them, the posted pictures show that this might well have been a case of mixing incompatible suspension components.

Looking at the end view of the collapsed perch it is apparent that the wedge used to set the pinion angle is too narrow for the perch. The implementation created a pyramidal structure with the spring at the base, a narrower spacer and an even narrower wedge working against an unsupported surface. The compressive force generated by the housing rotation was applied through the unsupported horizontal portion of the perch to the narrow wedge. That force on the horizontal part was more than it could support and it collapsed.

The horizontal portion isn't supposed to take the load, the vertical portions of the perch should be taking the load and transferring it (ultimately) to the spring. The vertical portions of the perch were essentially unsupported in this application as witnessed by their being forced apart and actually torn away from the horizontal part of the perch on one side. The modified perches, as well as the Calvert perches provide additional support to the horizontal portion of the perch, certainly a much more robust design.

As witnessed by many racers, even stock 40 year old perches can withstand the forces generated by drag race launches, although it certainly isn't a good idea. I suspect that if the springs were in direct contact with these perches they would never have failed. That wedge, in that position, was the ultimate culprit. Putting the wedge between the spring and the slightly wider solid spacers might have provided enough support to prevent the failure too, but since the spacers look to be narrower than the perch it would be marginal.

Also, Calvert can supply their springs with different amounts of arc so that the ride height can be set without having to have a bunch of spacers between the perch and spring. He also has wedges which are wider than the usual 2" parts.