Monday, June 21, 2021


I'm a little suspicious of the mileage showing on the odometer.

I'm pretty sure that a few miles were put on this car after it was essentially rebuilt back in 2001.  Receipts for things like tires tell me that it was at least driven to get those tires installed, but the mileage hasn't changed.  So I decided to test the speedometer.  I pulled the cable from the trans and spun it with a drill, and sure enough - the needle moved, but the odometer didn't tick.

Okay.  This means I don't have exactly 43569 miles on the clock, but I don't think it is that far off given the condition of items like the brakes (which look almost new aside from years of sitting).  That means I need to repair the speedo.

The first job was to get the thing out.  This isn't exactly easy in a 1975 given the construction of the dash and the extra bracing behind it.  To get to it, you have to remove the bottom dash cowl, then the defrost control knob and control.  I found that a very specific size of 5/8" deep well socket was needed to get the control's nut free. I also found that I had to (gently?) pull the dash out while sliding the control out of the hole, because it won't just drop out.  But it did eventually work free.  Then you need to make your hand really small to get to the nuts that hold the speedo in place, manage to not lose them behind the dash, and then remove the brackets.  Finally, you can pull the speedo forward and unhook the cable and lights, and remove it from the dash.

I do not want to put this thing back in.

But here you go.

Once it's out, the fun begins. I removed the mechanism and spun it with a square bit in a drill.  As it moved, I could see a couple of things:

  1. There was a periodic dip in the needle.
  2. The odometer was not advancing when the little arm came around to push it.
  3. The gear that moved the arm was cracked, likely because the odometer itself got stuck.

The crack is slightly visible at the 6 o-clock position.

Of course, none of this matters if the odometer itself doesn't work.  So I futzed with it, and while I am not exactly sure why it stuck, I got it free and it appears to spin okay.  I hope it stays that way.

The gear needed to be replaced as it's not repairable.  Fortunately, gears are available from Odometer Gears Ltd. for Jaeger/Smiths speedos.  The gear has to be fitted to the shaft, and it's a bit of a delicate operation.  Fortunately, I have a few spare (broken) gears from Gidget's various adventures into speedometers.  I just pulled one of those and removed the gear.

I very carefully increased the diameter of the hole where the gear fits the shaft to allow a press fit with only a little effort.  I didn't want to add stress to the material.

Then, I used a little superglue (Gorilla Glue, to be exact) on the tip of the shaft, and pressed it into place making sure the gear was properly and fully seated.  I compared to the original and the heights matched, so I think I got it right.  Be very careful here, as that little knob is easily broken off.  Ask me how I know.

I installed the new gear and spun everything up.  The needle stayed stable at 70 and the odometer ticked over nicely.  The mileage has changed!

I cleaned the dial and reassembled the mechanism into the case, and now it waits for cooler weather to be reinstalled into the dash.

No comments:

Post a Comment