How fast are you going at a given rpm?
Speed comes from four numbers: engine rpm, the ratio of the gear you are in,
the ratio of the axle and the rolling diameter of the tire. Multiply the gear
ratio by the axle ratio to get your total drive ratio, then divide the tire
diameter in inches by it, multiply by rpm and divide by 336. A 28 inch tire
behind a 0.63 overdrive and 3.73 gears turns 2,000 rpm into 71 mph on paper
and about 69 in practice, because a loaded tire rolls slightly shorter than its
size says. Change any one of those four numbers and the answer moves.
What this calculator does
Most gearing calculators answer one quarter of the question. One converts a
tire size to a diameter. Another turns rpm into speed if you already know your
total ratio. A third works out a ratio from ring and pinion tooth counts. The
question people actually have needs all of them at once, because changing the
tire changes the effective gearing, and changing the gearing changes the rpm at
which the tire matters.
So this one takes the whole setup. Tire size in any of the three notations
tires are sold in, every ratio in the gearbox, the axle ratio and a transfer
case if you run one. Out of it comes speed at any rpm in every gear, the rpm
you will hold at 60 and 70, the speed each gear runs out at, the drop in revs
on every upshift and a chart of all of it together.
The URL carries your setup, so the address bar is a link to your exact
configuration. Paste it into a thread and whoever opens it sees your numbers,
not the defaults.
How to work out a gear ratio
A gear ratio is a count of turns. A 3.73 axle means the driveshaft turns 3.73
times for one turn of the wheels. The number comes straight off the gears
inside: divide the teeth on the ring gear by the teeth on the pinion. Forty one
teeth on a ten tooth pinion is 4.10. Forty one on eleven is 3.727, which
everybody calls 3.73.
That is why the available ratios look like an odd set of numbers. They are
not chosen, they are whatever whole tooth counts produce. You can buy 4.10 and
4.56 because 41/10 and 41/9 exist. You cannot buy 4.32 because no sensible
tooth pair lands there.
Transmission ratios work the same way, counted from the input shaft to the
output shaft. First gear in a Muncie M21 is 2.20, so the engine turns 2.20
times for one turn of the driveshaft. Fourth is 1.00, a straight through
connection with no reduction at all, which is what direct drive means. An
overdrive gear is below 1.00: the driveshaft turns faster than the engine.
Multiply the two together and you have the total drive ratio, which is the
only gearing number that matters to the road. A 2.20 first gear behind a 4.10
axle is 9.02:1. The same first gear behind 3.08s is 6.78:1. Same gearbox, very
different car.
Speed at rpm, worked through once
A tire is a ruler that measures the road. One revolution covers its
circumference, which is pi times its diameter. A mile is 63,360 inches, so a 28
inch tire covers a mile in 720 turns. At 60 mph it is turning 720 times a
minute.
Work backwards from there. If the wheels are turning 720 rpm and the total
drive ratio is 2.35, the engine is turning 1,692. Fold the unit conversions
into one constant and the whole thing collapses to:
MPH = (Tire diameter x Engine RPM) / (336 x Total drive ratio)
RPM = (MPH x 336 x Total drive ratio) / Tire diameter
That 336 is 63,360 inches per mile divided by 60 minutes and by pi. The exact
figure is 336.135, and every calculator that prints 336 is rounding it. The
difference is four hundredths of a percent, which is nothing next to the
question of what diameter you put in the top.
What tire size does to your rpm
A metric tire size is three measurements. In 275/60R15 the 275 is the section
width in millimetres, the 60 is the sidewall height as a percentage of that
width and the 15 is the wheel diameter in inches. Sidewall height is 275 x 0.60
= 165mm, or 6.5 inches. There are two sidewalls, so the tire stands 15 + 13 =
28 inches tall.
Flotation sizes are easier. In 33×12.50R15 the 33 is the diameter in inches
outright. The trap is reading the second number as the height, which turns a 33
inch tire into a 12.5 inch one and every answer after it into nonsense.
Taller tires raise the total gearing. Going from 31s to 33s on the same 4.10
axle gives you the same acceleration as 3.85 gears did on the old tires, a 6
percent reduction you did not ask for. The engine drops about 6 percent of its
revs at any given speed, the car feels lazier off the line and a truck that
towed comfortably starts hunting between gears on hills.
Why this calculator disagrees with your speedometer
Every other gearing calculator on the internet uses the geometric diameter,
the number you get from the sidewall arithmetic above. A loaded tire is not
that tall.
Under the weight of the car the contact patch flattens. The axle sits closer
to the ground than the free radius says, the tread slips a little as it
transitions from round to flat and back, and the distance covered per
revolution drops. Manufacturers publish revolutions per mile as a measured
figure rather than a calculated one, and it always comes out higher than the
geometry predicts.
You can check this on any tire you like. BFGoodrich publishes the All-Terrain
T/A KO2 in LT285/70R17 at an overall diameter of 32.7 inches and 635
revolutions per mile. The sidewall arithmetic agrees on the diameter: 285 x
0.70 x 2, converted to inches, plus a 17 inch wheel is 32.71. But 32.7 inches
of circumference divides into a mile 617 times, not 635. Work backwards from
the published revolutions and the tire is covering ground as though it were
31.76 inches tall. That is 2.9 percent shorter than it measures.
Three percent sounds academic until it is 200 rpm at highway speed, or the
reason a calculator told you 70 and the speedometer says 68. This tool applies
a 3 percent correction by default and lets you switch it off. Switched off, it
reproduces exactly what every other calculator gives you. Switched on, it
matches what tire manufacturers actually measure.
The correction is deliberately conservative. Real deflection depends on load,
pressure, tread depth and construction, and a stiff sidewall on a light car
will squat less than a soft one under a loaded truck. Three percent is the
bottom of the published range.
Choosing a ratio
Gearing is a trade between acceleration and cruising rpm and there is no
setting that wins both. Numerically higher gears multiply torque and shorten
every gear, so the car accelerates harder and runs more revs on the highway.
Numerically lower gears do the reverse.
What decides it is what the car does most of the time.
A highway car wants the engine near the bottom of its
comfortable range in top gear. Somewhere between 1,800 and 2,200 rpm at 70 suits
most V8s. With a double overdrive gearbox you can run a steep axle and still
cruise quietly, which is why a 4.10 behind a 0.63 sixth is a reasonable street
combination and a 4.10 behind a 1:1 four speed is not.
A towing truck wants enough ratio to pull the load without
downshifting on every grade. Fit taller tires and you have to put the ratio
back, which is the calculation the compare panel above is for.
An off-road build cares about crawl ratio, which is first
gear times the transfer case low range times the axle. Anything above about 50:1
is usable, and 70:1 or more is what people mean by a crawler.
A drag car wants to cross the line at the rpm the engine
makes peak power, in top gear, and nothing else about the gearing matters much.
Work backwards from trap speed.
The number worth watching in all four cases is the step between gears, the
percentage drop in revs on each upshift. A close ratio gearbox is not one with
smaller steps than a wide ratio box, which surprises people. A Muncie M21 close
ratio drops 34.1 percent on the one to two shift and the wide ratio M20 drops
34.0. What makes the M21 close is its spread: it covers 2.20 to 1.00 where the
M20 covers 2.52 to 1.00, so every ratio sits nearer to direct drive and the
engine stays in a narrower band through the whole box.
Common ring and pinion ratios
These are the ratios ring and pinion sets are actually sold in. Anything
between them has to be rounded to one of them, which is why the calculator
snaps its recommendation.
| Ratio | Ring / pinion teeth | Exact | Typically used for |
|---|---|---|---|
| 2.56 | 41 / 16 | 2.563 | Highway cruising |
| 2.73 | 41 / 15 | 2.733 | Highway cruising |
| 2.94 | 44 / 15 | 2.933 | Highway cruising |
| 3.08 | 40 / 13 | 3.077 | Highway cruising |
| 3.21 | 45 / 14 | 3.214 | General street use |
| 3.31 | 43 / 13 | 3.308 | General street use |
| 3.42 | 41 / 12 | 3.417 | General street use |
| 3.54 | 39 / 11 | 3.545 | General street use |
| 3.73 | 41 / 11 | 3.727 | General street use |
| 3.90 | 39 / 10 | 3.900 | General street use |
| 4.10 | 41 / 10 | 4.100 | Acceleration, towing, large tires |
| 4.27 | 34 / 8 | 4.250 | Acceleration, towing, large tires |
| 4.56 | 41 / 9 | 4.556 | Acceleration, towing, large tires |
| 4.88 | 39 / 8 | 4.875 | Acceleration, towing, large tires |
| 5.29 | 37 / 7 | 5.286 | Acceleration, towing, large tires |
| 5.38 | 43 / 8 | 5.375 | Acceleration, towing, large tires |
| 5.71 | 40 / 7 | 5.714 | Acceleration, towing, large tires |
| 6.17 | 37 / 6 | 6.167 | Acceleration, towing, large tires |
| 7.17 | 43 / 6 | 7.167 | Acceleration, towing, large tires |
Questions
How do you calculate speed at a given RPM?
Multiply your transmission gear ratio by your axle ratio to get the total drive ratio. Then MPH equals tire diameter in inches times engine rpm, divided by 336 times that total ratio. A 28 inch tire behind a 0.63 sixth gear and a 3.73 axle gives a total ratio of 2.35, so at 2,000 rpm the car is doing about 71 mph on paper and 69 in practice once the tire is loaded. The constant 336 is 63,360 inches per mile divided by 60 minutes and by pi.
How do you calculate a gear ratio?
Divide the number of teeth on the driven gear by the number on the drive gear. In an axle that means ring gear teeth divided by pinion teeth: 41 teeth on a 10 tooth pinion is 4.10, and 41 on 11 is 3.727, which everyone calls 3.73. This is also why the available ratios are an odd looking set of numbers. They are not chosen, they are whatever whole tooth counts produce, which is why you can buy 4.10 and 4.56 but not 4.32.
What is a final drive ratio?
Strictly, the final drive is the ratio in the differential, the ring and pinion. In everyday use the term often means the total drive ratio in top gear, which is the axle ratio multiplied by the top gear ratio. A car with 3.73 gears and a 0.63 overdrive has a 3.73 final drive and a 2.35 total drive ratio in sixth. The second number is the one that decides your cruising rpm.
How much does tire size change your RPM?
Engine speed scales with the inverse of tire diameter, so a taller tire always means fewer revs at the same road speed. Going from a 31 inch tire to a 33 inch one makes the tire 6.5 percent taller and drops the engine 6.1 percent at any given speed. On a 4.10 axle that leaves you with the same gearing 3.85 gears would have given on the old tires, so the car cruises quieter and accelerates noticeably worse.
Will bigger tires make my speedometer read wrong?
Yes, and it will read low. The speedometer is calibrated for the diameter the car left the factory with, so a taller tire covers more ground per revolution than the instrument assumes. Going from 31 inch to 33 inch tires puts it out by 6.5 percent: at an indicated 70 mph you are actually doing 74.5, and the odometer logs 939 miles for every 1,000 you drive. Smaller tires do the reverse and make the speedometer read high.
What gear ratio do I need for my tire size?
To keep the gearing you had, multiply your current axle ratio by the new tire diameter and divide by the old one. Going from 31 inch to 33 inch tires on a 4.10 axle gives 4.36, and since nobody sells 4.36 you would fit the nearest available set. The calculator above does this and snaps the answer to a ratio a ring and pinion is actually made in.
What does close ratio mean?
It means the gearbox covers a narrower spread between first and top, so every ratio sits closer to direct drive and the engine stays in a tighter rev band through the whole box. It does not mean each individual shift is shorter. A Muncie M21 close ratio drops 34.1 percent on the one to two shift while the wide ratio M20 drops 34.0, but the M21 spans 2.20 to 1.00 where the M20 spans 2.52 to 1.00.
Why does this calculator give a different answer than the others?
Because it corrects for the loaded rolling diameter by default. Every other gearing calculator uses the geometric diameter from the sidewall arithmetic, but a tire under load flattens at the contact patch and covers less ground per turn. BFGoodrich publishes its All-Terrain T/A KO2 in LT285/70R17 at 32.7 inches and 635 revolutions per mile, and those two figures only reconcile if the tire is working as though it were 31.76 inches tall, 2.9 percent short. You can switch the correction off, and then the answers match everyone else.
What is a good cruising RPM?
For most V8s, somewhere between 1,800 and 2,200 rpm at 70 mph. Much below that and the engine labours and will not hold top gear on a grade. Much above it and the noise and fuel consumption stop being worth it. Small displacement and high revving engines sit comfortably higher, and diesels sit lower.
How do I find my gear ratio without opening the axle?
Jack up both rear wheels, mark the driveshaft and one tire, then turn the tire exactly one full revolution and count the driveshaft turns. Around 3.7 turns means 3.73 gears. With only one wheel off the ground, turn it twice and count, because an open differential sends all the motion to the lifted wheel. Many axles also carry a tag or a casting code that states the ratio outright.
Gear ratios for every gearbox in this calculator
Every preset is a gearbox, not a promise about your car. The same model was
frequently sold in more than one ratio set and the same car was frequently
built with more than one gearbox, so the presets are listed by variant and
every ratio is editable. Check yours against a tag or a turn count if it
matters. Where sources disagreed, the manufacturer’s own catalogue won.
GM / Chevrolet manual
| Gearbox | Years | Ratios | Spread |
|---|---|---|---|
| Muncie M20 (wide ratio, 2.56 first) | 1963-1965 | 2.56 · 1.91 · 1.48 · 1.00 | 2.56:1 |
| Muncie M20 (wide ratio, 2.52 first) | 1966-1974 | 2.52 · 1.88 · 1.46 · 1.00 | 2.52:1 |
| Muncie M21 (close ratio, 2.20 first) | 1966-1974 | 2.20 · 1.64 · 1.28 · 1.00 | 2.20:1 |
| Muncie M22 (close ratio, heavy-duty gearset) | 1966-1971 | 2.20 · 1.64 · 1.28 · 1.00 | 2.20:1 |
| Saginaw 4-speed (wide ratio) | 1966-1985 | 2.84 · 2.01 · 1.35 · 1.00 | 2.84:1 |
| Borg-Warner Super T10 (close ratio, 2.43 first) | 1974-1981 | 2.43 · 1.61 · 1.23 · 1.00 | 2.43:1 |
| Borg-Warner Super T10 (wide ratio, 2.64 first) | 1974-1981 | 2.64 · 1.75 · 1.34 · 1.00 | 2.64:1 |
| Borg-Warner T5 World Class (F-body V8, 2.95 first) | 1983-1992 | 2.95 · 1.94 · 1.34 · 1.00 · 0.63 | 4.68:1 |
| BorgWarner T56 (1993 LT1 F-body, 3.36 first) | 1993 | 3.36 · 2.07 · 1.35 · 1.00 · 0.80 · 0.62 | 5.42:1 |
| BorgWarner / TREMEC T56 (LT1 and LS1 F-body, 2.66 first) | 1994-2002 | 2.66 · 1.78 · 1.30 · 1.00 · 0.74 · 0.50 | 5.32:1 |
| TREMEC T56 (C5 Corvette Z06 (MZ6), 2.97 first) | 2001-2004 | 2.97 · 2.07 · 1.43 · 1.00 · 0.84 · 0.56 | 5.30:1 |
| TREMEC T56 Magnum (close ratio, 2.66 first) | 2009-present | 2.66 · 1.78 · 1.30 · 1.00 · 0.80 · 0.63 | 4.22:1 |
| TREMEC T56 Magnum (wide ratio, 2.97 first) | 2009-present | 2.97 · 2.10 · 1.46 · 1.00 · 0.74 · 0.50 | 5.94:1 |
| TREMEC TR-6060 (Camaro ZL1, 2.29 first) | 2017-2024 | 2.29 · 1.63 · 1.21 · 1.00 · 0.82 · 0.54 | 4.24:1 |
| TREMEC TR-6060 (Cadillac ATS-V / CTS-V, 2.66 first) | 2004-2019 | 2.66 · 1.78 · 1.30 · 1.00 · 0.80 · 0.63 | 4.22:1 |
Ford manual
| Gearbox | Years | Ratios | Spread |
|---|---|---|---|
| Ford Toploader 4-speed (wide ratio, 2.78 first) | 1964-1973 | 2.78 · 1.93 · 1.36 · 1.00 | 2.78:1 |
| Ford Toploader 4-speed (close ratio, 2.32 first) | 1964-1973 | 2.32 · 1.69 · 1.29 · 1.00 | 2.32:1 |
| Borg-Warner T5 World Class (1985-1988 Mustang 5.0) | 1985-1988 | 3.35 · 1.93 · 1.29 · 1.00 · 0.68 | 4.93:1 |
| Borg-Warner T5 World Class (1989-1995 Mustang 5.0) | 1989-1995 | 3.35 · 1.99 · 1.33 · 1.00 · 0.68 | 4.93:1 |
| TREMEC T-45 (3.37 first) | 1996-2001 | 3.37 · 1.99 · 1.33 · 1.00 · 0.67 | 5.03:1 |
| TREMEC TR-3650 (0.68 fifth) | 2001-2010 | 3.38 · 2.00 · 1.32 · 1.00 · 0.68 | 4.97:1 |
| TREMEC TKO-500 (3.27 first) | 1997-present | 3.27 · 1.98 · 1.34 · 1.00 · 0.68 | 4.81:1 |
| TREMEC TKO-600 (2.87 first, 0.82 fifth) | 1997-present | 2.87 · 1.89 · 1.28 · 1.00 · 0.82 | 3.50:1 |
| TREMEC TKO-600 (2.87 first, 0.64 fifth) | 1997-present | 2.87 · 1.89 · 1.28 · 1.00 · 0.64 | 4.48:1 |
| Getrag MT82 (3.66 first) | 2011-2017 | 3.66 · 2.43 · 1.69 · 1.32 · 1.00 · 0.65 | 5.63:1 |
| Getrag MT82-D4 (3.24 first, direct fourth) | 2018-2021 | 3.24 · 2.10 · 1.42 · 1.00 · 0.81 · 0.62 | 5.20:1 |
| TREMEC TR-6060 (2007-2010 Shelby GT500) | 2007-2010 | 2.97 · 1.78 · 1.30 · 1.00 · 0.80 · 0.63 | 4.71:1 |
Mopar manual
| Gearbox | Years | Ratios | Spread |
|---|---|---|---|
| Chrysler A833 4-speed (2.66 first) | 1964-1974 | 2.66 · 1.91 · 1.39 · 1.00 | 2.66:1 |
| Chrysler A833 4-speed (2.44 first, high performance) | 1970-1974 | 2.44 · 1.91 · 1.34 · 1.00 | 2.44:1 |
| Chrysler A833 4-speed (3.09 first, economy) | 1964-1966 | 3.09 · 1.92 · 1.40 · 1.00 | 3.09:1 |
| Chrysler A833-OD (overdrive 4-speed, 0.73 fourth) | 1975-1987 | 3.09 · 1.67 · 1.00 · 0.73 | 4.23:1 |
| TREMEC TR-6060 (Challenger R/T, SRT8 and 392) | 2009-2023 | 2.97 · 2.10 · 1.46 · 1.00 · 0.74 · 0.50 | 5.94:1 |
| TREMEC TR-6060 (Challenger Hellcat / Viper, 2.26 first) | 2013-2023 | 2.26 · 1.58 · 1.19 · 1.00 · 0.77 · 0.63 | 3.59:1 |
Import & sports manual
| Gearbox | Years | Ratios | Spread |
|---|---|---|---|
| Mazda MX-5 Miata 5-speed (NA, 1.6L and 1.8L) | 1990-1997 | 3.14 · 1.89 · 1.33 · 1.00 · 0.81 | 3.85:1 |
| Mazda MX-5 Miata 6-speed (NB) | 1999-2005 | 3.76 · 2.27 · 1.65 · 1.26 · 1.00 · 0.84 | 4.48:1 |
| Mazda MX-5 6-speed (NC, 2.0L MZR) | 2006-2015 | 3.82 · 2.26 · 1.64 · 1.18 · 1.00 · 0.83 | 4.60:1 |
| Mazda MX-5 6-speed (ND, 2.0L SKYACTIV-G) | 2016-present | 5.09 · 2.99 · 2.04 · 1.59 · 1.29 · 1.00 | 5.09:1 |
| Honda K20 6-speed (RSX Type-S) | 2002-2006 | 3.27 · 2.13 · 1.52 · 1.15 · 0.92 · 0.74 | 4.43:1 |
| Honda K20Z3 6-speed (Civic Si FG2/FA5) | 2006-2011 | 3.27 · 2.13 · 1.52 · 1.15 · 0.92 · 0.66 | 4.96:1 |
| Honda K20C1 6-speed (Civic Type R FK8) | 2017-2021 | 3.63 · 2.12 · 1.53 · 1.13 · 0.91 · 0.73 | 4.94:1 |
| ZF S5-31 (S5D 320Z) (BMW 5-speed) | 1992-1999 | 4.21 · 2.49 · 1.67 · 1.24 · 1.00 | 4.21:1 |
| Getrag 420G (BMW 6-speed) | 1996-2006 | 4.23 · 2.53 · 1.67 · 1.23 · 1.00 · 0.83 | 5.11:1 |
| Subaru WRX 5-speed (TY754) | 2002-2005 | 3.45 · 1.95 · 1.37 · 0.97 · 0.74 | 4.68:1 |
| Subaru WRX 5-speed (TY758) | 2008-2013 | 3.17 · 1.88 · 1.30 · 0.97 · 0.74 | 4.29:1 |
| Subaru WRX STI 6-speed (TY856, 2004-2006) | 2004-2006 | 3.64 · 2.38 · 1.76 · 1.35 · 0.97 · 0.76 | 4.81:1 |
| Subaru WRX STI 6-speed (TY856, 2007-2018) | 2007-2018 | 3.64 · 2.24 · 1.52 · 1.14 · 0.97 · 0.76 | 4.81:1 |
| Toyota R154 (5-speed) | 1986-2004 | 3.25 · 1.96 · 1.31 · 1.00 · 0.75 | 4.32:1 |
| Toyota W58 (5-speed) | 1982-1998 | 3.29 · 1.89 · 1.28 · 1.00 · 0.78 | 4.20:1 |
| Nissan CD009 6-speed (VQ35/VQ37) | 2003-2020 | 3.79 · 2.32 · 1.62 · 1.27 · 1.00 · 0.79 | 4.78:1 |
Truck & 4×4 manual
| Gearbox | Years | Ratios | Spread |
|---|---|---|---|
| New Venture NV4500 (early GM, 6.34 first) | 1993-1994 | 6.34 · 3.44 · 1.71 · 1.00 · 0.73 | 8.68:1 |
| New Venture NV4500 (late GM and Dodge, 5.61 first) | 1995-2007 | 5.61 · 3.04 · 1.67 · 1.00 · 0.74 | 7.58:1 |
| New Venture NV3500 (wide ratio) | 1992-2006 | 4.02 · 2.32 · 1.40 · 1.00 · 0.73 | 5.51:1 |
| Muncie SM465 (4-speed, 6.55 first) | 1968-1991 | 6.55 · 3.58 · 1.70 · 1.00 | 6.55:1 |
| Muncie SM420 (4-speed, 7.05 first) | 1947-1967 | 7.05 · 3.57 · 1.70 · 1.00 | 7.05:1 |
| Aisin AX15 (5-speed) | 1989-1999 | 3.83 · 2.33 · 1.44 · 1.00 · 0.79 | 4.85:1 |
| Mercedes NSG370 (6-speed) | 2005-2011 | 4.46 · 2.61 · 1.72 · 1.25 · 1.00 · 0.84 | 5.31:1 |
| ZF S5-42 (close ratio) | 1987-1994 | 4.14 · 2.37 · 1.42 · 1.00 · 0.77 | 5.38:1 |
| ZF S5-47 (close ratio) | 1995-1998 | 5.08 · 2.60 · 1.53 · 1.00 · 0.77 | 6.60:1 |
| Getrag G360 (5-speed) | 1989-1993 | 5.53 · 3.02 · 1.60 · 1.00 · 0.77 | 7.18:1 |
| Borg-Warner T18 (6.32 first) | 1965-1987 | 6.32 · 3.09 · 1.69 · 1.00 | 6.32:1 |
Automatic
| Gearbox | Years | Ratios | Spread |
|---|---|---|---|
| GM TH350 (3-speed) | 1969-1986 | 2.52 · 1.52 · 1.00 | 2.52:1 |
| GM TH400 (3-speed, heavy duty) | 1964-1990 | 2.48 · 1.48 · 1.00 | 2.48:1 |
| GM 700R4 / TH700-R4 (4-speed overdrive) | 1982-1993 | 3.06 · 1.63 · 1.00 · 0.70 | 4.40:1 |
| GM 4L60E (4-speed overdrive, electronic) | 1993-2011 | 3.06 · 1.63 · 1.00 · 0.70 | 4.40:1 |
| GM 4L80E (4-speed overdrive, heavy duty) | 1991-2009 | 2.48 · 1.48 · 1.00 · 0.75 | 3.31:1 |
| GM 6L80E (6-speed) | 2006-2023 | 4.03 · 2.36 · 1.53 · 1.15 · 0.85 · 0.67 | 6.04:1 |
| GM 10L80 / 10L90 (10-speed) | 2017-present | 4.70 · 2.99 · 2.15 · 1.77 · 1.52 · 1.28 · 1.00 · 0.85 · 0.69 · 0.64 | 7.38:1 |
| Ford C4 (3-speed) | 1964-1981 | 2.46 · 1.46 · 1.00 | 2.46:1 |
| Ford C6 (3-speed, heavy duty) | 1966-1996 | 2.46 · 1.46 · 1.00 | 2.46:1 |
| Ford AOD (4-speed overdrive) | 1980-1993 | 2.40 · 1.47 · 1.00 · 0.67 | 3.58:1 |
| Ford 4R70W (wide ratio) | 1993-2008 | 2.84 · 1.55 · 1.00 · 0.70 | 4.06:1 |
| Chrysler A727 TorqueFlite (3-speed) | 1962-1991 | 2.45 · 1.45 · 1.00 | 2.45:1 |
| Chrysler A904 TorqueFlite (3-speed, light duty) | 1960-1989 | 2.45 · 1.45 · 1.00 | 2.45:1 |
| ZF 8HP (8HP45 / 8HP70) | 2010-present | 4.71 · 3.14 · 2.11 · 1.67 · 1.29 · 1.00 · 0.84 · 0.67 | 7.07:1 |
| Aisin AS69RC (6-speed) | 2013-present | 3.75 · 2.00 · 1.34 · 1.00 · 0.77 · 0.63 | 5.95:1 |
Transfer case low ranges
A transfer case multiplies everything behind it. Crawl ratio is first gear
times low range times the axle, which is why a 4.88 geared Wrangler in low
range is turning the wheels more than a hundred times slower than the
engine.
| Transfer case | Years | Low range | Notes |
|---|---|---|---|
| NP231 | 2.72:1 | Chain-driven part-time case used across Jeep and GM light trucks, with a direct high range. | |
| NP241 | 2.72:1 | Chain-driven part-time case for Dodge and GM three-quarter and one-ton trucks. The DHD and DLD variants share this low range and differ only in internal strength. | |
| NP241OR RockTrac | 4.00:1 | Rubicon-specific case with its own housing and internals, not a re-geared NP241. | |
| NP242 | 2.72:1 | Full-time case offering two-wheel drive, full-time four-wheel drive and part-time four-wheel drive. | |
| NP205 | 1.96:1 | Cast-iron gear-driven case with no neutral position and a tall low range. | |
| Dana 300 | 2.62:1 | Iron-case gear-driven transfer case fitted to the late Jeep CJ. | |
| Dana 20 | 2.03:1 | Jeep, Scout and Blazer low range. Ford Bronco versions of the same case use 2.46 for 1966-1972 and 2.34 for 1973-1977. | |
| Atlas 3.8 | 3.82:1 | One of six low-range options for the Advance Adapters two-speed Atlas. | |
| Atlas 4.3 | 4.29:1 | The most common Atlas low range for rock crawling; 1.5, 2.11, 3.03 and 5.048 are also offered. |
Read next
- Manual vs Automatic Transmission
- CVT vs Automatic Transmission
- 60s Muscle Cars
- 70s Muscle Cars
- Pony Car vs Muscle Car
- Inline 6 vs V6 Engine
- All Season Tires vs Summer Tires
- Benefits of Winter Tires
- Car Inflation Calculator
Sources
- 5speeds.com, Ford Toploader 4 Speed Transmission
- Advance Adapters, Atlas Transfer Case Gear Ratio Options
- Advance Adapters, Saginaw 3 & 4 Speed Transmission Tech Vault
- BritishV8, Identification Guide to Borg-Warner T5 Transmissions
- DieselHub, GM TH700R4 Transmission Specs & Ratios
- DieselHub, Aisin AS69RC Transmission Specs & Ratios
- DieselHub, Getrag G360 Transmission Specs & Ratios
- DieselHub, New Process NP205 Transfer Case Specs
- DieselHub, New Process NP241 Transfer Case Specs
- DieselHub, New Venture NV3500 Manual Transmission Specs & Ratios
- DieselHub, Muncie SM420 Transmission Specs & Ratios
- DieselHub, Muncie SM465 Transmission Specs & Ratios
- DieselHub, ZF S5-42, S5-47 Transmission Specs & Ratios
- F150Hub, Ford C4 and C6 Transmission Specs, Ratios
- F150Hub, Dana 20 Transfer Case Specs
- F150Hub, BorgWarner T-18 Transmission Specs & Ratios
- Hybrid Racing, K-Series Transmission Guide
- Jalopnik, What's The Difference Between The Muncie M20, M21, And M22 Transmissions?
- Mazda North American Operations, 2004 Mazda MX-5 Miata Technical Specifications
- Mazda North American Operations, 2006 Mazda MX-5 Miata Technical Specifications
- Mazda North American Operations, 2016 Mazda MX-5 Miata Specification Deck
- Modern Driveline, Mustangs & Tremec Manual Transmissions
- Moss Miata, 1990 Mazda MX-5 Miata Car Specifications
- MyMopar, A833 Manual Trans Identification and Gear Ratios
- Novak Conversions, The Novak Guide to the Aisin-Warner AX15 Transmission
- Novak Conversions, The Novak Guide to the Dana Spicer Model 300 Transfer Case
- Novak Conversions, The Novak Guide to the New Process / New Venture Gear 231 Transfer Case
- Novak Conversions, The Novak Guide to the New Process / NVG 241OR RockTrac Transfer Case
- Novak Conversions, The Novak Guide to the New Process / New Venture Gear 242 Transfer Case
- Novak Conversions, The Novak Guide to the Jeep NSG370 Transmission
- Novak Conversions, The Novak Guide to the New Venture Gear 4500 Transmission
- Rallispec, Subaru Transmission ID Chart
- Richmond Gear, Ring and Pinion Catalog (cat-32)
- Richmond Gear, Super T-10 4-Speed Transmission Catalog (RG25)
- Steeda, Complete Mustang Manual Transmission Guide
- Subaru Canada, 2005 Impreza (WRX Sedan / WRX Sport Wagon) Specifications
- Subaru Canada, 2005 Impreza WRX STi Specifications
- Subaru Canada, 2011 WRX and WRX STI Vehicle Specifications
- TREMEC, TREMEC Performance Products Catalogue (TRMC-R8-0212)
- TREMEC, TREMEC TR-6060 Transmission Product Sheet (F-TR6060-0519)
- Wikipedia, Ford-GM 10-speed automatic transmission
- Wikipedia, GM 4L60-E transmission
- Wikipedia, GM 4L80-E transmission
- Wikipedia, GM 6L transmission
- Wikipedia, Ford AOD transmission
- Wikipedia, Getrag 420G transmission
- Wikipedia, Borg-Warner T-56 transmission
- Wikipedia, TorqueFlite
- Wikipedia, Toyota R transmission
- Wikipedia, Toyota W transmission
- Wikipedia, Tremec TR-6060 transmission
- Wikipedia, Turbo-Hydramatic
- Wikipedia, ZF S5-31 transmission
- Wikipedia, ZF 8HP transmission
- Z1 Motorsports, Transmission Quick Guide