NGWClub®, Inc.

Ready for more questions.

With careful progress the gauge will open as shown in the picture.
Notice that the ring is nice and flat and there is no damage to the bezel or the bottom half.

Now you can hold the bezel and movement while you remove the two loosened bottom screws.

With the sharp end of the start tool you can carefully pry the trip boot from the inside of the bezel.
It is glued to the bezel so work carefully.
Done with care, the boot may be pushed inside the bezel.

In picture 16, use a points file and gently file the sharp corner off from the trip knob.
Picture 17 shows how much to file. The small amount filed away will allow you to remove the movement with trip attached, out of the trip hole in the bezel.

Now you can safely remove the crimp ring.

The removed un-crimped ring should look similar to the picture below.

With the movement out of the cases, you should mark the speed bell as shown so the needle can be replaced close to the correct position.

Hold firmly the speed bell and remove the needle with a firm clockwise twisting movement as shown in picture 20 and 21
Avoid touching the face unless it is to be replaced.

Now the faceplate can be removed

To remove the trip knob, please note that the movement shaft has a small keyway in it.
This should be positioned so the keyway can be gripped by the knurl of a strong set of pointed pliers.
On the 75 and 76 the trip knob shaft is aluminum and red Loc-Tited to the threaded end of the movement shaft.
Using a butane lighter, heat the trip shaft at the end for approx. 30 seconds on low flame.
Firmly twist the trip knob clockwise to remove.
This may take 2 tries, but it will come off.

On a 77 thru 79 the shaft is plastic and with a firm grip it should be able to be removed without heat.

OK fellows, let me know what you think.
Pete

wog wrote:Ok, I'll go...
Do you use a wet grinder or just let the screwdriver air cool after just a little grinding, then grind some more?
Won't take much to get the tips hot and lose their harness.

When I rough-sharpen wood chisels, I fold up a piece of paper towel so's it's just wider than the chisel and a couple of inches long, soak it in water and hold it on top of the blade down to within 1/8" or so of the cutting edge. I grind slowly and dunk the chisel often in cold water, never letting it get too hot. The wet towels keep things cool by evaporation.
Should work with a screwdriver too.

Great idea Terry.
Thanks
Pete

Wel, you've clearly demonstrated that you're worth every penny you charge. I'm sure I could botch that two or three times over. Thanks for sharing your insight here at NGW.

Thanks Eric...,
Our shop method is a little more refined but I do hate to see guys have problems doing their own gauges hit or miss.
Pete

Pete, do you have any information how calibration is done while the guts are accessable?

I'm following the post.
I still think I need to find a sacrificial unit to experiment with before trying the good units.

Sandy,
Great approach and of course I did the same thing.

Bob and others,
Cut off the gauge end of a bad cable insert about 1" long.
Put the piece in a drill motor before beginning the removal procedures above.
It must turn in reverse before before you place it into the end of the tacho or speedo.
Turn it on full speed and see where the needle of the gauge stops.
Mark down the reading and then when the movement is finished with faceplate and needle, repeat the drill motor operation and carefully move the needle til the readings match what you wrote down.
Pete

Pete, do you have a similarly intelligent method of recrimping the ring once the speedo had been serviced?
(I can't help but think you've been laying in wait for this question.)

Bob,

Yes

Pete

Ummm, that you'd be willing to share with us?