speedo acuracy after conversion: 1968 /6 to an 83 318

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4.20

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Hello All,

got a question for the experts. I've just acquired an 83 5th ave (M-body) donor for my 68 dart. now in 68 the speedo was in miles per hour, but up here in Canada some genious changed us over to metric, kilometers per hour back in 1975. How is this going to affect my speedo when I go from the /6 trans to the A904 that's on this 318

Do I need to change some kind of gear ratio somewhere?

Also, will the driveshaft from the 318 fit the 7 1/4 rear from the slant six?

any advice would be helpful, thanks

:read2:
 
4.20 said:
Hello All,

got a question for the experts. I've just acquired an 83 5th ave (M-body) donor for my 68 dart. now in 68 the speedo was in miles per hour, but up here in Canada some genious changed us over to metric, kilometers per hour back in 1975. How is this going to affect my speedo when I go from the /6 trans to the A904 that's on this 318

Do I need to change some kind of gear ratio somewhere?

Also, will the driveshaft from the 318 fit the 7 1/4 rear from the slant six?

any advice would be helpful, thanks

:read2:
Click to expand...

Use this conversion....it should not matter for mph to kph.


http://www.moparts.org/Tech/tech/img/AUTOMATICchart.xls
 
................Use the gear from ur old trans.............or Im sure some1 will post the conversion chart....................kim...........
 
Where can you get speedometer gears in different tooth counts?
I have 4.10's in the car now with 325x50x15's on the rear.
Calc says 38.6 gear so probably a 39
 
Put the speedo gear from the 68 into the transmission you are going to use. The length of the driveshaft for the 904 is the same for the v8 as the /6 depanding on the rear end. If the rear of the 83 was a 7¼ and the 68 is also a 7¼, there shouldn't be a problem.

You can verify by measuring from the mount pad to the end of the transmission tailshaft. If this is the same for both transmissions, you can use the existing driveshaft.
 
If you have a local trans./rearend shop near you give them a call. when I converted to a newer trans. I got the proper gear and a housing for $20.
 
Yep, according to my chart it's right. Try Camd64's idea, it may be cheaper, but when I called no one had the tooth count I needed.
 
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