Ok, I have a 74 dodge dart swinger, I have a dash out of a 4 door, it only goes up to 100, im not sure if the gears in this is different than the ones from the 2 door that went up to 120 so the mph would be off...But i am riding on 15" wheels...Im wondering which is the problem and if it is the tires, im thinking it is 5mph off until i hit about 60 then its about 10 or more off...If someone knows the amount of change there is I would love to know, I never found a speedtrap to really check.
Tire/Spedometer?
- Thread starter 74dart
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3406pk
Well-Known Member
I don't think there is any difference in the speedo in dash. The gear for speedo in the trans makes up difference in rearend ratios and tire sizes. I did a search on this site for speedometer gear info. Go to this site for help on selecting the tranny gear; http://www.moparts.org/Tech/tech/pages/speedo.html. If it's only off by 5 mph, it's not worth correcting. Good luck.
Claudius
Well-Known Member
There are a number of different ratios found in the 7-1/4" differential; I know that this was not what you were hoping to hear. Check out this link and you will see the range from 2.26:1 up to 4.11:1. I do not know how many were used in your car.
http://www.differentials.com/pdfs/4.pdf
You may simply have to jack up the vehicle and manually spin the drive shaft to see how many times around it goes in order to get one wheel revolution.
http://www.differentials.com/pdfs/4.pdf
You may simply have to jack up the vehicle and manually spin the drive shaft to see how many times around it goes in order to get one wheel revolution.
Claudius
Well-Known Member
Thank you for posting this link. I will be making good use of it when the time comes for the transmission rebuild.
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