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1975 gear ratio

  • Thread starter Thread starter mike weyman
  • Start date Start date
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mike weyman

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does anyone know what the stock l48 rear end gear ratio is on a 75 coupe w/auto transmission?with that wacky rear end, can you install regular g.m. ring gears, or are they like everything else in a vette (except bulbs.lol)special.mike
 
The Corvette Black Book for '75 lists an 'optional rear axle ratio', costing $12.00, but oddly, the RPO# shown is '---', and no specific ratios are listed, either...
:confused
Another source-book I have sheds no extra light on the subject, but shows gear ratio's offered in '76 as:
L-48/4-speed: 3.36:1 (wide ratio)
L-48/THM350: 3.08:1

L-82/4-speed: 3.55:1 (wide ratio)
L-82/4-speed: 3.55 or 3.70:1 (close ratio)
L-82/THM400: 3.36:1

IF the above is true, and since GM/Chevrolet offered fewer ratio choices as the '70s progressed, can we assume the gears available in '76 were also optional a year earlier, in '75?
 
The '75 L-48 only had three axles available - 3.36 was standard with the wide-ratio 4-speed with the 3.08 optional as the "highway" axle, and the 3.08 was standard with the THM-400 with the 2.73 optional as the "highway" axle.

3.36,3.55 and 3.70 were available only with the L-82, and A/C wasn't available on an L-82 with the 3.70.
:beer
 
JohnZ said:
The '75 L-48 only had three axles available - 3.36 was standard with the wide-ratio 4-speed with the 3.08 optional as the "highway" axle, and the 3.08 was standard with the THM-400 with the 2.73 optional as the "highway" axle.

3.36,3.55 and 3.70 were available only with the L-82, and A/C wasn't available on an L-82 with the 3.70.
JohnZ:
Just for my own knowledge, wasn't a close-ratio 4-speed offered in '75?:confused
My Black Book lists 'M21, 4-speed manual trans, close ratio' as a no-cost "option" in '75, of which 1,057 were built.

Thanks, GLEN!!!:w
 
I only drove the car once before the rebuild and was more concerned about the lack of ponies,maybe I should do the spin the axel trick and count since i have the car on stands now.higher gears would explain the slower lawnch.I know the motor will no longer be the cause. mikey
 
Glensgages said:
JohnZ:
Just for my own knowledge, wasn't a close-ratio 4-speed offered in '75?:confused
My Black Book lists 'M21, 4-speed manual trans, close ratio' as a no-cost "option" in '75, of which 1,057 were built.

Thanks, GLEN!!!:w
The M21 was only offered with the L82, not with the L48 engine. Rears ends were either 3.55 standard or 3.70 optional
 

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