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GM/CHEVROLET FINAL DRIVE RATIOS

Gears Under/Overdrive It is the gear under your seat that counts. Gearing is what you are buying when you purchase a Gear Vendors Under/Overdrive. If you take a few moments to study the gear chart for your transmission and rear end ratio combination you will see why this product is so popular. The Final Drive Ratio shows you how many times the engine turns for one complete turn of the tires. Gears are multiplier of torque. The mathematical equation for Horsepower is; Torque X RPM/5252 = HP. Close ratio gearing lets us work both the torque and rpm side of this equation for big gains in HP and performance. Notice for instance that 1st-over has a lot more torque multiplication than 2nd - now look how low you would have to go in rear end ratio to make your second gear have as much torque as 1st-over. Same with 2nd-over compared to 3rd.

Whatever your 2nd-over final drive number is - that is equivalent to having that ratio for a rear end torque multiplier. Of course, with gear-splitting we are keeping the engine rpm up from one shift to the next and further exploiting the ratio benefit.

There is not room here to cover all the details (like the benefit to passing gear and such) so call us at the factory to discuss your exact application - we have customer service guys on hand for you to ask these types of questions.

 

TH350 3-SPEED AUTOMATIC
  Axle Ratio 4.56 4.10 3.73 3.55 3.42 3.08
  Trans Ratio Final Drive Ratio
1st 2.52 11.49 10.33 9.40 8.95 8.62 7.76
Over 1.97 8.96 8.06 7.33 6.98 6.72 6.05
2nd 1.52 6.93 6.23 5.67 5.40 5.20 4.68
Over 1.19 5.41 4.86 4.42 4.20 4.06 3.65
3rd 1.00 4.56 4.10 3.73 3.55 3.42 3.08
Over 0.78 3.56 3.20 2.91 2.77 2.67 2.40

 

TH375/400/475 3-SPEED AUTOMATIC
  Axle Ratio 4.88 4.56 4.10 3.73 3.55 3.42
  Trans Ratio Final Drive Ratio
1st 2.48 12.10 11.31 10.17 9.25 8.80 8.48
Over 1.93 9.44 8.82 7.93 7.22 6.85 6.60
2nd 1.48 7.22 6.75 6.07 5.52 5.25 5.06
Over 1.15 5.63 5.27 4.73 4.31 4.09 3.95
3rd 1.00 4.88 4.56 4.10 3.73 3.55 3.42
Over 0.78 3.81 3.56 3.20 2.91 2.77 2.67

 

700R4/4L60E 4-SPEED AUTOMATIC OVERDRIVE
  Axle Ratio 4.88 4.56 4.10 3.73 3.42 3.23
  Trans Ratio Final Drive Ratio
1st 3.06 14.93 13.95 12.55 11.41 10.47 9.88
Over 2.39 11.64 10.88 9.79 8.90 8.17 7.71
2nd 1.63 7.95 7.43 6.68 6.08 5.57 5.26
Over 1.27 6.20 5.80 5.21 4.74 4.34 4.10
3rd 1.00 4.88 4.56 4.10 3.73 3.42 3.23
Over 0.78 3.81 3.56 3.20 2.91 2.67 2.52
4th GM O/D 0.70 3.42 3.19 2.87 2.61 2.39 2.26
Double OD* 0.55 2.67 2.49 2.24 2.04 1.86 1.76
*Note: Double Overdrive not to be used when towing or loaded.

 

4L80E 4-SPEED AUTOMATIC OVERDRIVE
  Axle Ratio 5.13 4.88 4.63 4.56 4.10 3.73 3.42
  Trans Ratio Final Drive Ratio
1st 2.48 12.72 12.10 11.48 11.31 10.17 9.25 8.48
Over 1.93 9.92 9.44 8.95 8.82 7.93 7.22 6.60
2nd 1.48 7.59 7.22 6.85 6.75 6.07 5.52 5.06
Over 1.15 5.92 5.63 5.34 5.27 4.73 4.31 3.95
3rd 1.00 5.13 4.88 4.63 4.56 4.10 3.73 3.42
Over 0.78 4.00 3.81 3.61 3.56 3.20 2.91 2.67
4th GM O/D 0.75 3.85 3.66 3.47 3.42 3.08 2.80 2.57
Double OD* 0.59 3.00 2.85 2.71 2.67 2.40 2.18 2.00
*Note: Double Overdrive not to be used when towing or loaded.

 

M465 4-SPEED MANUAL
  Axle Ratio 4.56 4.10 3.73 3.42
  Trans Ratio Final Drive Ratio
1st 6.55 28.91 26.86 24.43 22.40
2nd 3.58 16.32 14.68 13.35 12.24
Over 2.79 12.73 11.45 10.41 9.55
3rd 1.70 7.75 6.97 6.34 5.81
Over 1.33 6.05 5.44 4.95 4.53
4th 1.00 4.56 4.10 3.73 3.42
Over 0.78 3.56 3.20 2.77 2.67

 

GM NV4500 5-SPEED MANUAL
    Axle Ratio
    4.56 4.10 3.90 3.73 3.55
  Trans Ratio Final Drive Ratio
1st 5.61 25.58 23.00 21.88 20.92 19.92
2nd 3.04 13.86 12.46 11.86 11.34 10.79
Over 2.37 10.81 9.72 9.25 8.84 8.42
3rd 1.67 7.62 6.85 6.51 6.23 5.93
Over 1.30 5.94 5.34 5.08 4.85 4.63
4th 1.00 4.56 4.10 3.90 3.73 3.55
Over 0.78 3.56 3.20 3.04 2.91 2.77
5th Dodge O/D 0.74 3.37 3.03 2.89 2.76 2.63
Double Over* 0.58 2.63 2.37 2.26 2.16 2.06
*Note: Double Overdrive not to be used when towing or loaded.

 

M21/22 4-SPEED Close Ratio - showing clutchless options
  Axle Ratio 4.88 4.56 4.10 3.73 3.55 3.42
  Trans Ratio Final Drive Ratio
1st 2.20 10.74 10.03 9.02 8.21 7.81 7.52
Over 1.71 8.35 7.81 7.02 6.38 6.08 5.85
2nd 1.64 8.01 7.48 6.72 6.12 5.82 5.61
Over 1.28 6.23 5.82 5.23 4.76 4.53 4.36
3rd 1.28 6.25 5.84 5.25 4.77 4.54 4.38
Over 0.99 4.86 4.54 4.08 3.71 3.54 3.41
4th 1.00 4.88 4.56 4.11 3.73 3.55 3.42
Over 0.78 3.79 3.55 3.19 2.91 2.77 2.66

info@gearvendors.com

GEAR VENDORS, INC. 1717 North Magnolia Avenue, El Cajon, CA 92020
Toll Free 800-999-9555 • Telephone (619) 562-0060 • Fax (619) 562-1186