I had heard a great deal about the problems with the 1/4" pins in the torque tube and the now retrofitted 3/8" pins. I liked the solution that Bob Harrison came up with and with his permission i decided that i would retrofit a similar style clamp to the existing setup.

Tony takes all the credit for the clamps and i have to say they have worked well. The assembled torque tube was sized up on the critical diameters, and then a drawing was prepared prior to machining the clamps.

From the outset the idea of the clamp would be to cover new straight dowel pins and clamp the tube to stop any physical movement. The 5mm clamp bolts would be fitted using a thread lock or be wire locked in position. The clamp has been designed and machined in such a way that it grips with an interference fit on all 3 critical diameters and is a neat fit between the ends of the elevator drive plates and the elevator push rod crank. The clamp has been machined from duralumin.

Once the clamps were in position the gap between the inside face of the bronze torque tube bearings and the face of the clamp was measured, and the nylon bushes were machined to this size minus 0.5mm.

Setting up the torque tube in this way has overcome drilling through the torque tube and in to the plastic bush which as the manual says can be a tricky operation. The clamp has helped pull everything together on the torque tube and there is no movement at all.

The following images show the torque tube as supplied plus a drawing by Ferg Kyle and images showing the clamps in place.