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RPM - Rear End Ratio
Chart
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The chart below may
be of some help in deciding what rear end ratio is right for you.
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Listed are the expected
RPM's at 60 MPH with a given rear end ratio and tire height.
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This
chart applies to all Ford non-overdirve transmissions, manual and automatic.
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Power
is transmitted from the transmission to rear end 1:1 in high gear.
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Ford non-overdrive transmissions
include:
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C-4, three-speed, automatic
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C-6, three-speed, automatic
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FMX, three-speed, automatic
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Top-loader, three-speed, manual
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Top-loader, four-speed, manual
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For
overdrive transmission, RPM's will be approximately 32% less than shown.
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Chart is Calculated for a Speed of
60 MPH
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Tire Height in Inches
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| Ratio |
24
|
24.5
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25
|
25.5
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26
|
26.5
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27
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27.5
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28
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| 3.00:1 |
2520
|
2469
|
2419
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2372
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2326
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2282
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2240
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2199
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2160
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| 3.25:1 |
2730
|
2674
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2621
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2569
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2520
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2472
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2427
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2383
|
2340
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| 3.50:1 |
2940
|
2880
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2822
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2776
|
2714
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2663
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2613
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2566
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2520
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| 3.55:1 |
2982
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2921
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2863
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2807
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2753
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2701
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2651
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2602
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2556
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| 3.70:1 |
3108
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3045
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2984
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2925
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2869
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2815
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2763
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2712
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2664
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| 3.80:1 |
3192
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3125
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3064
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3004
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2946
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2891
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2837
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2786
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2736
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| 3.89:1 |
3268
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3201
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3137
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3075
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3016
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2959
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2905
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2852
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2801
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| 4.11:1 |
3452
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3382
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3314
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3249
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3187
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3127
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3069
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3013
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2959
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| 4.30:1 |
3612
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3538
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3468
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3400
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3334
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3271
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3211
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3152
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3096
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| 4.62:1 |
3881
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3802
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3726
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3653
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3582
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3515
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3450
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3387
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3326
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| 4.86:1 |
4082
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3999
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3919
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3842
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3768
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3697
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3629
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3563
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3499
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Below
is the formula used to calculate RPMs.
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RPM
=
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MPH X Trans Ratio (in
high gear) X Rear End Ratio X 336
Tire Height |
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Return
to Rear End Catalog
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