Dodge 3-Speed Auto

DODGE 3-Speed Automatic Muscle Car/Street Rod/Restoration

Joe Rogan's, Sick Fish

If you own a car with a TorqueFlite 727 or 904 3 speed auto – you own one of the best transmissions ever built. By adding the Gear Vendors you get to keep this great trans and add overdrive and performance gear-splitting ratios to it. You will then have a 6 speed Semi-Automatic that is just the best performing, most durable transmission package out there. Big increases in fuel mileage (typically 22-28%) and performance while also increasing the fun factor, 6 gears are cool.


Gear Vendors reputation is all about performance and handling horsepower reliably. This is why you have seen GEAR VENDORS in 8 second ¼ mile cars in publications like Hot Rod and National Dragster. This is also why all GM Callaway Corvettes with automatics came with a TH400 and GEAR VENDORS instead of the base Corvette 4-speed auto (700R4 or 4L60), as did all the newer Jensen Interceptors with a TF727. If you’re running more than 1200 horsepower (and we have customers that are) then talk to us at the factory as there are some hydraulic changes we do for vehicles up to 2000hp.

KWS, 69 Charger

Horsepower aside, there are several other reasons you will prefer a GEAR VENDORS to any factory overdrive automatic or manual. You will have a dashswitch that allows both manual and automatic operation. With the switch in “auto” the vehicle will act just like it came from the factory with overdrive. The overdrive will kick in at 47mph or whatever the eprom is set for in our electronics and turn back off at slower speeds without attention of the driver. The ratio is .78 to 1 (see Final Drive Ratios). This equates to 28.6% faster vehicle speed at the same rpm or take your existing rear gear multiplied by .78 (ie 4.10 X .78 = 3.20). In this example a vehicle with a 4.10 behaves just like it had 3.20s when the overdrive is engaged.
Other examples would be that 3.55 becomes 2.77, 3.23 becomes 2.52. With the .78 to 1 ratio you’re good with any torque converter you choose for high performance street/strip use. See our “common questions” section for more converter discussion.

B&M Magnum Grip Street Shifter

Another great feature of the GEAR VENDORS is that you will have a full 6 forward ratios when you switch to manual on the dashswitch. Pull into low, then hit our button (on the shifter or the floor), a red light appears indicating our Auto-Launch circuit – as you are accelerating through 1st gear the overdrive will automatically shift to 1st-over This is directly related to the rear end ratio in the car – so that a 4.56 rear car shifts earlier than a 3.55 etc. If you have a 3.25 or 3.55 rear this brings a whole new level of performance and has a whole bunch more torque multiplication than you have ever felt in your car before. With a 3.55 rear for example the torque multiplication in 1st-over is more than 4.56 diff car would have in 2nd – awesome performance gains. After you have revved up in 1st-over then shift to 2nd and turn us off. Then rev back up and hit the button for 2nd-over for the same benefit (that 3.55 example now get a 4.01 gear). Then 3rd and 3rd-over (the 3.55 in 3rd over is turning like it had a 2.77 diff now hence the trademark Under/Overdrive.

67 Charger

Because of all the performance improvements, if you were thinking of going to a stouter rear gear (higher numerically), wait until after you have driven with these new ratios and you may find you are in love with the performance without a ratio change at all. The performance and sound of the motor is tremendous as it goes through 6 full throttle close ratio shifts. You are in each gear ½ the time you are now so the car is not only faster but it also feels and sounds much faster.

With a 2 year unlimited horsepower, abuse, or mileage warranty and a 30 day money-back guarantee – you are guaranteed you will be happy with everything about how this kit installs and drives in your muscle car, street rod, or restoration project.We are big Mopar fans and all our 727 kits were revamped in 2007 to make the hugely popular B and E bodies a very simple install. Takes us 4 man hours to install start-finish. If you have never done one before plan on 6hrs. No cutting or grinding, two spots the size of quarters get smoothed in the tunnel and one spot the size of a quarter makes clearence for the right angle speedo drive. See Magazine Articles for some of the baddest mopars of all time that run a Gear Vendors 6 speed. Absolutely the best mod you will ever do to your Mopar or your money back.


Gears Under/Overdrive

Find your transmission and rear gear multiplier below. The Final Drive Ratio shows you how many times the engine turns for one complete turn of the tires. This Final Drive number is also your torque multiplier when in that gear. GEAR VENDORS reputation for being the best is because of its sophisticated planetary construction. You are able to shift half gears that keep the engine in the power.

There is not room here to cover all the details and other features (like the automated 2nd-over passing gear) so call the factory to discuss the full benefits demonstrated on these charts.

  Axle Ratio
 Trans RatioFinal Drive Ratio
TORQUEFLITE A904 3-SPEED AUTOMATIC (4 and 6 Cylinder Applications)
  Axle Ratio
 Trans RatioFinal Drive Ratio

Call or e-mail the factory to find out all the options available in your perfomance application.



DODGE 3-Speed Automatic Application Guide