Hi all,
In discussing this this rear end stuff, I may have been using the wrong
terminology for our 3/4 and 1-Ton Rear Ends.
The specific quote involved is "12 1/4 Inch Drop Out Unit".
I was told by a gear vendor a long while ago that the HO-72 Corporate Rear
End is called a 12 1/4 Inch Drop Out Unit, based on the size of the Ring
Gear, and adopted the term. I was just studying the spec sheets (for the
1000th time) and realized a discrepancy. (O.K., I'm NOT a "Rocket
Scientist"...)
My truck is a 1959 Chevy Apache 38/NAPCO 4x4. Currently with a Corporate
Model HO-72 rear end carrying a 5.14 to 1 gear set. The front axle is a
NAPCO modified Corporate HO-72 as well. Same gear set.
The Chevy Spec Sheets show the following information for my truck.
Apache 38 / 1-Ton
5.14 to 1 Ratio
Rated axle capacity 7200 Pounds.
Gears - Hypoid
Number of Teeth - Drive Gear = 7
Number of Teeth - Driven Gear = 36
Ring Gear Pitch Diameter = 10.125
Ring Gear Face = 1.500
Drive Pinion is Straddle Mounted
Drive Pinion is adjusted using shims.
Thrust is against Pinion Front Bearing.
Differential type is Four Pinion.
Would the 10.125 Ring Gear Pitch Diameter not make the proper term for the
unit a 10" -or- 10 1/4 inch drop out unit??? Which is correct??? Use of
incorrect terminology could mess up someone's entire day!! What's the
answer?
Kevin P.
'59 Apache 38/NAPCO
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