Highway gears is one thing, but this???

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Vortex

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I have an 8 1/4 rearend under my 68 barracuda. I did the old "jack it up and turn the tire" to get my gear ratio.
This is how I did it:
Jacked up both rear tires. (I have suregrip)
Chalked my tire and the floor.
Made 2 full turns of my tire.
Counted the 1/4 rotations of my drive shaft by watching the caps on my u-joint.
I counted 25.25 1/4 turns.
25.25/4=6.3125 ratio

So, did I do something wrong or do I just have really high gears?
 
That would actually be a VERY VERY low gear, you'd probably red line in a school zone lol
You did something wrong. Just jack it up, mark the tire and mark the driveshaft, now count how many times the driveshaft turns all the way around to one complete turn of the tire.
 
Since you turned the tire twice, shouldnt you divide by two? That would seem to make sense, and you would end up with what is probably a 3.23 gear ratio.
 
Yep, my math was all fouled up. That's what I get for using rubbing compound all day. Must have been the fumes. lol
 
Vortex said:
I have an 8 1/4 rearend under my 68 barracuda. I did the old "jack it up and turn the tire" to get my gear ratio.
This is how I did it:
Jacked up both rear tires. (I have suregrip)
Chalked my tire and the floor.
Made 2 full turns of my tire.
Counted the 1/4 rotations of my drive shaft by watching the caps on my u-joint.
I counted 25.25 1/4 turns.
25.25/4=6.3125 ratio

So, did I do something wrong or do I just have really high gears?
Click to expand...

3.15:1 which is a weird number. 3.23 I believe is a standard ratio.
 
most likely a 3.21:1 ratio in an 8 1/4" rear not a 3.23:1 the 3.23 is for 8 3/4" rears ;)
 
duster340 said:
most likely a 3.21:1 ratio in an 8 1/4" rear not a 3.23:1 the 3.23 is for 8 3/4" rears ;)
Click to expand...
Now THAT, I didn't know. Explains some things I had read elsewhere.
 
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