Help with gear ratio please...

dbpbandit

New Member
Oct 30, 2018
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Oregon
Hi everyone!
I've got a 2010 Mustang V6 base (5 speed manual) and I'm trying to figure out my rear gear ratio so I can get a new tune. The one I have now is throwing off my speedometer by +10 MPH. I thought that it had a 2.73 but that's not the case. On my door sticker all I have under "AXLE" is a "BG" code and I can't seem to find that anywhere. Should be a BB or something else? I can't really crawl under the car and spin my wheels to rotate the drive shaft and count so I'd appreciate it if someone could tell me what the BG code means. Appreciate the help, thanks. -David
 
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GTVin

Member
Jan 15, 2019
52
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San Diego
I'm wondering the same thing... have stock 94 GT with AOD stock wheels and tires . At 60mph I'm at 2000 rpms on highway in overdrive. Trying to figure out what gears I have??? Any help. Some say 308 or 321
 

nickyb

WAIT,you now have a pair?
10 Year Member
Apr 3, 2009
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nevada
Gtvin, Jack rear up , turn wheel one rev.while counting how many times the driveshaft moves.Or you could look for tag on rear end housing bolt.
 

David Young

Active Member
Sep 16, 2012
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Clinton, Tennessee
My 2011 v6 6 speed automatic with 3.73 gears does 2,000 rpm at 60 mph. My 1991 F150 with a 5 speed manual and 3.08 gears does 2,000 rpm at 60 mph. If you don't have a gear ratio code on the door jam I guess you'll have to do what nickyb said to do :)