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#18738 04/12/04 11:18 PM
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Okay,
This may be the part where I show my lack of knowledge...

I am trying to determine the rear end gear ratio on my '55 chevrolet truck driveline. I am told that this can be be expressed as the number of complete turns that the driveshaft must make to ensure one complete rotation of a rear tire. Using this formula, I have measured a driveshaft rotation of about 1.8 to achieve a single tire rotation. This cant be correct, so where do I have it wrong? Regards...

#18739 04/12/04 11:47 PM
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If you counted the driveshaft revolutions against
one tire rotation with only ONE WHEEL RAISED you need to double your final number,1.8= 3.60/1. It's more acurate to raise both wheels assuming you have a stock open rear. My '55 powerglide car
has a 3.55/1. Not sure what the trucks have.You
can always open the rear and count the ring and
pinion teeth.


Drew
Mid-Atlantic Chapter
#18740 04/12/04 11:50 PM
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The double answer made sense to me at the time, but I didnt quite have a handle on the why. Both wheels were raised (the truck is on jackstands all round). Thanks much

#18741 04/13/04 02:35 PM
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I believe 3.90 and 3.36 were the only possible gears for a '55 1/2 ton. 3.36 gears are available new, also. I can double check when I get home.


I.I. #3174
#18742 04/16/04 01:34 AM
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If the rear end is not a posi-tract it is best to leave one wheel on the ground. I always turn the wheel 10 turns if a posi and 20 turns if a single legger while some one counts the pinion turns. posi will =35.5 turns /10=3.55-- single will be 71turns/20=3.55. Another way to peel the same apple \:\) --Paul


BAN LOW PERFORFMANCE DRIVERS.....
NOT HIGH PERFORMANCE CARS!!
#18743 04/16/04 09:45 PM
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In the chevy manule i beleave most 1/2 ton trucks had a 411 rear gear six with a stick. almost all came that way unless ordered different.

#18744 04/17/04 01:02 AM
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My "Standard catalog of Chevrolet Trucks" shows 1/2 tons have a 3.90 ratio and 3/4 ton and larger 4.57 or 5.14 ratio. I know my 57 1/2 ton has a 3.90

Gael


Gael
37 chevy sedan, 261,t5
57 pickup
58 burb

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