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#1 |
Registered User
Join Date: Mar 2022
Location: ky
Posts: 17
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Gear questions
I have a 69 with a 400 sbc and 3 speed with 3.73s. During the build I swapped in a new posi but kept the factory gears thinking everything would be fine. I know from the factory the different series diffs align with certain gear ratios but do they make aftermarket longer gears i something like a 3.08-3.27 for the series 4? I hate to buy another posi but my first gear is useless and I’m running 3500 rpm’s on the Highway.
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#2 |
Senior Member
![]() Join Date: Nov 2013
Location: East Tennessee
Posts: 2,124
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Re: Gear questions
You can go the opposite way (higher ratio to lower ratio) with a special "thick" ring gear, but you can't go lower to higher without a carrier change.
The pinion gear diameter is much larger on a 3.07 than it is on a 3.73+, therefore the ring gear has to be further away initially. You could swap in an OD transmission and keep the "fun" gear.....but it would be more involved/expensive.
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