Shim on speedometer drive?

texasSlick said:

For the third time, measure the thickness of the speedo drive. It should be no more than 0.825 inches not including the top hat spacer. If it measures more, the center part is bulged out. This bulge causes the inboard side of the drive to encroach on the wheel hub cover.

Apply some heat to the drive housing, and squeeze it to size in a vise using a socket of approx 1.25" outside diameter bridging the hole.



View attachment 7860

Slick

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I just went through this on my '71 Roadster. Speedo drive was rubbing on the hub cover.

texasSlick said:

For the third time, measure the thickness of the speedo drive. It should be no more than 0.825 inches not including the top hat spacer. If it measures more, the center part is bulged out. This bulge causes the inboard side of the drive to encroach on the wheel hub cover.

texasSlick said:

For the third time, measure the thickness of the speedo drive. It should be no more than 0.825 inches not including the top hat spacer. If it measures more, the center part is bulged out. This bulge causes the inboard side of the drive to encroach on the wheel hub cover.

Apply some heat to the drive housing, and squeeze it to size in a vise using a socket of approx 1.25" outside diameter bridging the hole.

No spacers other than the proper top hat spacer are required. The spread of the swing arms is not a factor.

View attachment 7860

Slick

Click to expand...

Apply some heat to the drive housing, and squeeze it to size in a vise using a socket of approx 1.25" outside diameter bridging the hole.

No spacers other than the proper top hat spacer are required. The spread of the swing arms is not a factor.

View attachment 7860

Slick

Click to expand...

Drive housing was definitely bowed. I measured about 0.9" (with top hat).
To fix it I used the inner race from a steering head bearing and a 15/16" socket against a piece of wood on the other side in a vice with heat.
I might have gone too far.... it now measures between .825" and .840" with the top hat in place (which I think is about 0.050"). It looks much flatter now, and the gears turn much more freely now, but I am worried that now there is less engagement between the dogs on the ring gear in the drive and the slots on the lock ring on the wheel hub. I noticed that the point of wear was only half way down the ring gear dog before I straightened the drive housing. I would think it is less now, but I haven't figured a way to measure it.

NickZ said:

I am worried that now there is less engagement between the dogs on the ring gear in the drive and the slots on the lock ring on the wheel hub.

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TS is spot on!
Don't worry about engagement...straightening the warped speedo cover back to original form is the correct remedy. Over tightening the rear axle is the cause for warping (extruding ) the soft pot metal. Putting a new drive works too.