I have a gear ratio question
04-26-2017, 11:09 PM
#1
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I have a gear ratio question If i have 5.3 2002 ext cab full bolt on hci stall with tire size 305 40 18 nitto drag what would be the gear ratio i need to go up too 120 130 right now i have 456 but the truth is i dont understand that much of what gear ratio is best for my setup i mostly rollrace and sometimes track thanks in advance
04-26-2017, 11:22 PM
#2
A rear axle gear ratio is simply
(differential input rotations) : (1 output rotation i.e one rotation of the tires)
(4.56 driveshaft/pinion gear rotations) : (1 wheel rotation)
The higher the gear ratio number (i.e 4.56), the more torque will be multiplied from the transmission output shaft to the rear wheels. Basically either you'll accelerate faster or you'll blow the tires off. You also won't have as much top speed due to it taking more driveshaft rotations to turn the tires once.
The lower the gear number (i.e 3.23), the faster you will be able to go, but the slower you'll get there. It would take 1.33 less rotations of the driveshaft vs 4.56s to rotate the tires once.
How fast does the truck go now at the end of a pull?
What MPH are you starting at?
Is it 2 or 4wd? If 4, you'll have to change the gears in both front and rear diffs.
Stall rpm?
What is the rpm powerband? How high does the motor rev and still make close to peak power?
(differential input rotations) : (1 output rotation i.e one rotation of the tires)
(4.56 driveshaft/pinion gear rotations) : (1 wheel rotation)
The higher the gear ratio number (i.e 4.56), the more torque will be multiplied from the transmission output shaft to the rear wheels. Basically either you'll accelerate faster or you'll blow the tires off. You also won't have as much top speed due to it taking more driveshaft rotations to turn the tires once.
The lower the gear number (i.e 3.23), the faster you will be able to go, but the slower you'll get there. It would take 1.33 less rotations of the driveshaft vs 4.56s to rotate the tires once.
How fast does the truck go now at the end of a pull?
What MPH are you starting at?
Is it 2 or 4wd? If 4, you'll have to change the gears in both front and rear diffs.
Stall rpm?
What is the rpm powerband? How high does the motor rev and still make close to peak power?
04-27-2017, 12:06 AM
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Its tuned at 6900 and then 7000 rpm and im rolracing from 30 or 60 but like at 80 it like looses power thats why a made another thread on that problem im a newbi on posting on this sight and the the info u all can give me or ur o2 are very apreciated thanks in advance
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04-27-2017, 12:10 AM
#8
TECH Junkie
Using that calculator a 28 in. tire, 4l60e, 7% converter slip, shifting at 6800 rpms with 3.73's will run you out to 140 mph at the end of 3rd gear which if you have a 4l60e that is your 1:1 gear.
04-27-2017, 12:16 AM
#10
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Can u check out my other post there i put all the mods my truck has well imean more specific so u can give me ur o2 bro just by reading u really know alot about this thanks
04-27-2017, 12:18 AM
#11
TECH Junkie
How much the torque converter slips. Kinda like slipping a clutch in a manual to get moving.
A converter will slip which is why it's able to slip to your stall speed.
That's I guess the best way I can explain it.
A converter will slip which is why it's able to slip to your stall speed.
That's I guess the best way I can explain it.
