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 Transmission / Driveline and Traction
 Turbo 400 speed gears???
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455rebel
Tribal Scout

USA
10 Posts

Posted - 28 Dec 2014 :  5:00:43 PM  Show Profile  Reply with Quote
I have 26 in tall rear tires, 315 gears,
Which tail gear and which cable drive gear will get me close?
Tranny came from a 73 Bonnie
Speedo is of now about 30-35 mph.
It really freaks passengers out, when doing about 90-100 mph the speedo hand is all way around entering my gas gauge.
All help welcome.

1970 amc rebel faded blue 4-door ,455 with 400heads lunati tq monster cam ci intake and logs q jet,turbo 400, posi 315 gears,

455rebel
Tribal Scout

USA
10 Posts

Posted - 12 Jan 2015 :  11:45:21 AM  Show Profile  Reply with Quote
Come om u all, someone knows math on these gears???

1970 amc rebel faded blue 4-door ,455 with 400heads lunati tq monster cam ci intake and logs q jet,turbo 400, posi 315 gears,
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cortcomp
Coyote

USA
5448 Posts

Posted - 12 Jan 2015 :  12:06:53 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Assuming it's a TH400 trans? there are charts for this, you probably need to know one gear with a quick look at tci's site.

3.15 is a weird gear, is that a factory gear? I'm not saying it's not that, i don't know, i'd just triple check it before getting speedo gears.

http://www.tciauto.com/tc/speedometer-gear-calculator/
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Phil
The Great White Buffalo

USA
7293 Posts

Posted - 12 Jan 2015 :  1:54:34 PM  Show Profile  Reply with Quote
I found all the tranny gear speedo parts I needed online after doing a few quick searches. Some of them (like the one I last bought from) had charts to help answer your questions. It's not so much a matter of "knowing the math" as it is knowing the actual drive and driven gears, their tooth count(s) and colors as well as series and combos for a given transmission type.

Bowties are for Pee-wee Herman. LS swaps in Pontiacs should only apply to Fieros.
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