Smith Speedo Gearbox parts.

rick in seattle said:

By "four rivets" I mean the rivets seen in the center of your photo. They do not engage the circular location plate. Again, in both of my units, this plate simply pries off.

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OK, as the only purpose of the four rivets is to hold the retaining plate in position which should have a stepped lip that retains the ring gear?





However, the tiny rivets are not very strong, so the heads break off over time, and then the plate becomes loose and often falls out when the drive box is removed.

The rivet heads of the pattern drive boxes (as the one shown in the photo is) do seem to be spread more than the original Smiths.

LAB,

Thanks for the clear explanation. In fact, both of my units have ring gears that are not secured by the step (it appears to have been ground off), pointing to ham-handed attempts at cleaning by the same DPO. I'll get a new one.

rick in seattle said:

In fact, both of my units have ring gears that are not secured by the step (it appears to have been ground off), pointing to ham-handed attempts at cleaning by the same DPO. I'll get a new one.

Click to expand...

It may work like that, I don't know? As the ring gear can't really move far out of position, once the drive box has been fitted to the wheel.

As far as I know, all the Smiths drive boxes normally had the retaining lip on the plate (please somebody correct me if I'm wrong?) and the lip is shown in the cross-sectional view drawings of the Smiths drive boxes.