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Observation about the speedo!

Phil Z
Phil Z
in Open Discussions

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comment_548024

I was looking at pictures of my speedometer on my 72 z and realized there are 6 numbers on the dial but only 5 are visible. Since there is a trip meter with tenths I guess they either decided to have you refer to it or they just couldn’t center the speedometer numbers and hid the tenths that are the same color white. Anyone else familiar with this?IMG_0676.JPGIMG_0675.JPG

 

 

Phil Smith

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comment_548025

I was looking at pictures of my speedometer on my 72 z and realized there are 6 numbers on the dial but only 5 are visible. Since there is a trip meter with tenths I guess they either decided to have you refer to it or they just couldn’t center the speedometer numbers and hid the tenths that are the same color white. Anyone else familiar with this?IMG_0676.thumb.JPG.160b67a1738a7ebfd16a077ff3440c7e.JPGIMG_0675.thumb.JPG.322c551472a23415642faad8f9726876.JPG
 
 
Phil Smith


Looks like they had room for 100,000.0 but I think they left it off thinking the car would return to the earth before it rolled over.


Phil Smith

comment_548029

Yup. They're all like that. Even through the ZX. I suspect they ported major portions of the design from an earlier application that didn't have a trip odometer and they didn't want to mess with the design, so they just left the tenths digit in there.

And then they were worried about synchronization between the tenths digit of the trip odo and the tenths digit of the main odometer. They didn't want all the service calls asking "Why don't the two of them agree?"

    • Like 1
    comment_548030

    Oh, and in the later speedos, the space available for a 100K digit is taken up by the wire that detects the ten mph threshold for things like the BCDD. Prior to 73 or so, there wasn't anything there, but after that, I don't think that space is as available as it was on the earlier units.

    • Like 1
    comment_548146

    What i learned was many cars had this and when people manipulated the milage they used a drill and thy could just turn in 1 direction. This could then be detected because of the 100k number. This has been told in the mechanic scool in the early 80s.

    comment_548168
    15 hours ago, munters said:

    What i learned was many cars had this and when people manipulated the milage they used a drill and thy could just turn in 1 direction. This could then be detected because of the 100k number. This has been told in the mechanic scool in the early 80s.

    Danny De-Vito taught me the same thing almost 15 years ago hahaha.

     

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