14" Rims and Larger Tires

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jhdeval

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Ok, so I purchased a set of 14" original rims for my 65 Barracuda. I plan to put on a set of P205/75r14 tires because I want as much exposed side wall as I can. I am trying to fill the wheel well. I am not sure if this is where I need to be for my question but here goes.

My speedometer cable is already shot so I need to replace it any way, but how do I compensate for the tire and wheel differential? I know if you go larger, like I am, the speedometer will read less because it takes longer to complete a revolution. The converse is true if you go smaller. Where can I get the right gear ratios and cable for my situation?
 
Mopar speedo calibration is the easiest in the industry, "back when." This is because of the design of the speedo housing. The gear on the mainshaft is part of the shaft, and therefore "a standard." The plug that holds the driven gear is off center, and compensates for different sized gears. READ your shop manual, download one here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

There's a chart right in the book that shows tire size versus gear ratio for the right gear. You will have to go online or contact a tire store to convert the old sizes to the new.

Read this:

http://www.forabodiesonly.com/mopar/showthread.php?t=137442&highlight=speedometer
 
Ok I went to the page on year thank you for that. According to the 1965 Barracuda Service Manual the axle ratios are as follows
AV-1
225 Cu. In.
Engine

Manual Trans 3.91
Optional 2.93, 3.55
Automatic Trans 2.93
Optional 3.23,3.55

http://www.yearone.com/pco/1_0210/full.asp?page=395
This does not list a 2.93 which I believe is my stock Barracudas gear ratio. Am I missing something or should I assume a 3.23 is the correct ratio?
 
jhdeval said:
.............does not list a 2.93 which I believe is my stock Barracudas gear ratio.
Click to expand...

I agree, find out what you have first, easy to do:

Jack up ONE wheel with FRONT tires blocked. Put car in NEUTRAL, and release emergency brake. See if you can turn one wheel. If you can, you have no limited slip (suregrip). Now mark or just look at an identifiable point on the driveshaft, and mark the wheel. Just pointing the filler valve somewhere is good enough. Rotate the wheel TWO turns while counting the driveshaft. With the chart, it's easy to figure what you have. 2.7, the shaft turns 2 3/4 turns. 2.93, JUST barely shy of 3

If you are having trouble getting accuracy, get a friend to count the shaft, and turn the wheel 20 turns. A 2.93 would then be 29 and 3/10 turns

If you have limited slip (can't turn the one wheel) jack up BOTH rear wheels, turn the wheel only ONE turn and count shaft revs.


The chart from the 67 shop manual:

ilbtlk.jpg


The chart from the 72 shop manual:

15x274.jpg
 
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