gear ratio?
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Senior User
Joined: Aug 2007
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From: kingsland,ga
gear ratio?
how can i tell what gear ratio i have?i got my truck with a 8 inch lift and 37 tires so im not sure if the guy before me upgraded the gears or not.is there a way to telll the ratio without takeing the thing all apart? i know this might sound stupid but is it possible to cout the tire rotations with the drive shaft rotation turning it by hand?
Post Fiend
Joined: Mar 2007
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From: Texas
how can i tell what gear ratio i have?i got my truck with a 8 inch lift and 37 tires so im not sure if the guy before me upgraded the gears or not.is there a way to telll the ratio without takeing the thing all apart? i know this might sound stupid but is it possible to cout the tire rotations with the drive shaft rotation turning it by hand?
Gone, but not forgotten
Joined: Oct 2005
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From: Charlotte-Fairbanks-Bflo
Beyond me how you could forget this simple trick. I learned how to do it 40 years ago, and no matter how many billions of brain cells I may have killed with beer over the years I still remember one revolution of the tire compared to how many times the driveshaft turns determines your gear ratio no matter what size tire you may be running.
Cross-Country
Joined: Jan 2009
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Digging up an old thread...
Ok, so I'm a noob and trying to understand this gear ratio thing. I have an '02 Excursion PSD, and supposedly my gear ratio is 3.73.
Simple trick means if I turn the tire once, the driveshaft should rotate 3.73 times right?
I've read other posts where dudes are changing to 4.3 gears or something like that, so having a higher number means more low end for towing? Conversely, if I have a higher gear ratio, less top end for highway cruising?
Thanks in advance for sharing some knowledge...
Ok, so I'm a noob and trying to understand this gear ratio thing. I have an '02 Excursion PSD, and supposedly my gear ratio is 3.73.
Simple trick means if I turn the tire once, the driveshaft should rotate 3.73 times right?
I've read other posts where dudes are changing to 4.3 gears or something like that, so having a higher number means more low end for towing? Conversely, if I have a higher gear ratio, less top end for highway cruising?
Thanks in advance for sharing some knowledge...
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From: kingsland,ga
yup thats what i did jus as i was recomended. i toof some flouresent orange paint i had laying around and sprayed a small dot on the tire at the 12 oclock posistion and then sprayed a small dot on my driveshaft and told the wifey to slowly spin the tire till it made one full rotation and jus counted how many times the driveshaft spun. real simple trick.
as for the gears. going to a..... say 4.10 ratio would give u a a$$ load of umph for the low end (assumeing u have stock tire size) but would increase the RPMS a lot when cruiseing highway...IIRC. most guys put lower gears like that on their trucks when they get a lift because of the larger diameter tires, the lower gear ratio ( low ratio = higher number) makes up for the loss of power and low end that the larger tires cause as well as gets the fuel milage closer back to stock because the larger tires eat more fuel.....if i remeber the larger tires on stock gears raises? rpm.... im not too clear on the reasons for the lower gears getting better milage with say 40 in tires but im sure someone on here will chime in who knows better than i do. good luck to ya
as for the gears. going to a..... say 4.10 ratio would give u a a$$ load of umph for the low end (assumeing u have stock tire size) but would increase the RPMS a lot when cruiseing highway...IIRC. most guys put lower gears like that on their trucks when they get a lift because of the larger diameter tires, the lower gear ratio ( low ratio = higher number) makes up for the loss of power and low end that the larger tires cause as well as gets the fuel milage closer back to stock because the larger tires eat more fuel.....if i remeber the larger tires on stock gears raises? rpm.... im not too clear on the reasons for the lower gears getting better milage with say 40 in tires but im sure someone on here will chime in who knows better than i do. good luck to ya
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