3.15 gears and stall vs 3.73/3.90 gears

Jay Dee

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Hello all. I plan on doing some 1/8th mile bracket racing with a 2011 mustang gt automatic with basic bolt-ons and drag radials and updated suspension. No cam, heads, forced induction etc...I'm trying to figure out which is the better route to go. Keep the factory 3.15 gears and add a stall converter or just swap out the 3.15 gears for 3.73/3.90 gears. Looks like both options would be about the same cost. It's not a daily driver, just some fun on the weekends bracket racing.

Jay Dee
 
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Hello all. I plan on doing some 1/8th mile bracket racing with a 2011 mustang gt automatic with basic bolt-ons and drag radials and updated suspension. No cam, heads, forced induction etc...I'm trying to figure out which is the better route to go. Keep the factory 3.15 gears and add a stall converter or just swap out the 3.15 gears for 3.73/3.90 gears. Looks like both options would be about the same cost. It's not a daily driver, just some fun on the weekends bracket racing.

Jay Dee

You'll get the best results from the high stall torque converter. The gearing is fine for the automatic. Given the fact that first gear is 4.17, combined with the 3.15 gear set will give you a 13.14 first gear final drive (manual with a 3.66 first gear and a 3.73 axle is 13.65). My 2014 GT with the 6R80 automatic has gone 12.17 at 115 MPH with minimal modifications, CAI, 93 octane tune, FPP lower control arms, and 285/40R18 M/T drag radials. The car still has the factory converter and the stock 3.15 axle.

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stkjock

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if you search the site, the 3.15 gear w/ 6r80 transmission has shown to be the best combo, going steeper doesn't seem to help as the 1st gear ratio is very steep
 

Jay Dee

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Thanks for the quick replies. I believe the E.T cutoff for the 1/8 mile is 7.50ET.
 

Jay Dee

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Done. I'm gonna keep the 3.15 gears and get a torque converter, maybe 3500-4000 stall from what I researched. Does anyone run the Yank converter? It's around $400 cheaper than the Circle D converter.
 

Sledder

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As has been mentioned here the stock gears will work best. I am going the Circle D route as we speak. Call them, they are great at suggesting what you need for your set up.
 

lwarrior1016

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Please don’t use a yank converter. I have seen too many of them fail, and take out the transmission with it.
 

JEWC_Motorsports

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3.31's are BEST and since your car is a bracket car a Circle D 6F will work best.
 

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