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Discussion Starter #1
On my '69, The odometer appears to be turning at the correct rate, but the speedometer needle only reads about 25 MPH at approx. 50 MPH. What gives?? :confused:
 

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On my '69, The odometer appears to be turning at the correct rate, but the speedometer needle only reads about 25 MPH at approx. 50 MPH. What gives?? :confused:
.......no mention of tire size which "could" be a factor.
.......no mention of condition of speedo and cable...if old and worn, that's a possibility.
.......worn speedo gear in trans is also a "possibility".

David F.
 

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It's time for a new speedo gear!.....You'll need to know your tire diameter and gear ratio for the correct speedo gear.....If, by chance, you're running 3.55 gears and 27" diameter tires like me, then you'll need the red, 21 tooth speedo gear....NOTE: This is for the Muncie 4 speed tranny!
 

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Discussion Starter #4
.......no mention of tire size which "could" be a factor.
.......no mention of condition of speedo and cable...if old and worn, that's a possibility.
.......worn speedo gear in trans is also a "possibility".

David F.
Don't know the age of the speedo, it was in the car when i bought it.
Cable and speedo gear are brand new. I and a friend rebuilt the M21. When I ordered the rebuild kit along with a new reverse gear, I gave the vendor the tire size and 3:55 rear end gear ratio. I guess I'll have to re-check the gear tomorrow.
 

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Discussion Starter #6
The odometer appears to be turning at the correct rate,
Find out on a measured distance...use google maps they are real close

On has to know, not assume (***-u&me)
I plan on taking my portable GPS with me next time I drive it. I'm real familiar with the *** part of assume :D
 

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Discussion Starter #7
OK here's the info: With my GPS, here's what I observed.

GPS showing 45 mph, Speedometer= 12 mph
GPS showing 55 mph, Speedometer= 20 mph
GPS showing a trip of 3.9 miles Odometer showing 2.9 miles.

Tire diameter 26 inches, 3:55 rear end, Tranny, M21
1500 rpm, 4th gear 25 mph
2550 rpm, 4th gear 55 mph
3000 rpm, 4th gear 64 mph

If I recall correctly, my speedo gear was green.
 
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