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Old 12-06-2011, 12:12 AM   #9
azmodela
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Join Date: May 2010
Posts: 352
Default Re: Ruckstell model a ford transmission overdrive 3 speed

Quote:
Originally Posted by Bruce Lancaster View Post
So in modern terminology, it could be termed close-ratio rather than OD.
I have a little manual for this but no trans...
Anything less than 1:1.0 is an 'overdrive' gear/ratio. So a 1:.89 is an overdrive gear. Stock A's are 1:1 for third, or 'direct drive'.

"Close ratio" is simply two gears that are closely spaced together regardless of them being an overdrive or under drive ratio. 1:1 for 3rd gear and 1:.89 for 4th gear are considered a close ratio gearing. 1:3.45 for 3rd and 1:2.90 for 4th are also close ratio. Close ratio trans are more common in 4, 5, and 6 speeds where you have enough gears to keep the engine in it's performance range while still achieving a decent high end speed.
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