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How to fix color changing speedo?


MarcDeSoto

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I have a 48 DeSoto, which had one of those color changing speedos.  MoPar speedos had these for quite of few years starting in the 30s.  It was green up to 30, then it turned amber up to 50, then red over 50, I think.  Can these be easily restored?  When I took my speedo out of my car, I saw a curled up piece plastic, which I think were the translucent colors.  Is there anyone with some knowledge on how to rebuild this feature, or know where the parts are?  Thanks, Marc.

 

 

 

 

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In the search box type 3 words color change speedometer.  While in the box, look down at the open menu tab about mid way. You have to click/check the "all of the search term words" .

 

I wish someone would make that the default. "Any of the search term words" is the default now, and won't find anything.

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I would send it to an instrument repair specialist.  About 12 yrs ago I had an extra speedometer out of a junker and thought I would take it apart, restore the translucent colors, put it together again and put it in my car.  It never made it.  In the process of taking it apart I broke it in several ways that I was unable to repair.  I chalked it up to a learning experience. 

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5 hours ago, MarcDeSoto said:

Wish I could find it.  Nothing comes up on a search except my post.

 

Use Google for your searches, works much better:

 

site:p15-d24.com color change speedometer

 

This search returned several threads.

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Assuming the speed works and you are just needing to deal with the color...

 

What I did 20 years ago...

 

I went to a local model shop and purchased red, green and yellow transparent paint. it was from a Japanese manufacturer if I remember correctly. This stuff allows light to pass through.

 

I purchased a very fine small brush and I painted the plastic prism just like AutoLite did when they made the speedometer.  One work of caution. I painted the green too dark and the light barely comes through until I hit about 34 MPH and the yellow comes in.  So, go thin on the color green and red.

 

James

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Marc: If yours is like my 39 Desoto there is just a color strip of paper that has the appropriate color and as the needle moves these is a little white round knob that lets the color come through the knob and it is the color on the paper.

 

Not sure if your is the same but might be the same.

 

Rich Hartung

desoto1939@aol.com

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I took some pics of my speedo and have some questions.  What is that toothpaste that is in there?  Where precisely do I paint the colors?  At the base of the pointer?  And how do I put the speedo back in the instrument panel.  It Doesn't seem to fit.  

 

 

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The white stuff is either glue or it's for balancing.  It's in my speedo also.  The color wheel is at the base of the needle.  The deluxe had one color and the special deluxe had multiple colors.  This is a picture of the 47 P15 speedo in pieces.  Had to clean out the old dried grease.  I got this one off the internet.  The one that was in the car had a broken speed cup and needle.  It's repairable but I couldn't find the parts.

Replacement Speedo.jpg

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From Dave Maxwells old P15 site: The mystery of the P15's color changing speedometer is solved by looking carefully at this photo. Light is shined on the prism/lens and directed at the rotating colored dyes on the shaft of the speedometer needle. 

 

Speed_diagram.jpg.3c8e7db84e4edca10b26d30819b49038.jpg

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The part you should paint is the disc that is part of the speedo needle.  Yes your speedo should have the prism.  If you look close at the picture I attached above you can see the colors on the base of the needle.  That's the part that should be painted.  

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