Operation Tips


For Muscle Cars and Street Rod Trucks and Street/Strip use.
3speed Automatics and Gear Vendors Standard AutoDrive Electronics

The single most useful tip in ratio splitting through 6 forward gears is to use the AutoLaunch feature.

Camaro 69

When you are standing still with 1st gear selected and the Gear Vendors dash-switch in the manual mode hit our button so that the red light is showing – that is AutoLaunch. As you speed up the electronics will initiate our solenoid on the overdrive at about 20mph and then relative to your rear ratio and tire size the Gear Vendors hydraulic pump will produce the 1st-over shift automatically at the same driveshaft speed every time. This is very consistent on the track and automatically compensates for different ring and pinion or tire size. Using the AutoLaunch feature means you are 28.6% farther down the road or track before you need to shift to 2nd and so it really lets you concentrate on the car control and launch. Feedback we get says it effectively stretches time in the cockpit and you won’t seem so busy.

You will find that 1st-over is the only gear with a significant hydraulic delay from the overdrive (it takes 2.5 times longer to shift than when in high gear because your trannys output shaft is going 2.5 times slower and that is what drives the pump that shifts the overdrive). Having said that, this delay is very useful as long as you know it is there in that gear. Without that delay we would have to measure driveshaft speed or create the electronics for specific speed on ever car relative to ratio and tire size – but with the delay – we can use a combination of mph initiation and then the driveshaft speed automatically buffers the shift point so a 4.88 diff will shift much earlier than a 3.55 diff, like it should -self correcting.

If you are boulevard cruising or already rolling in 1st and you want to nail the throttle and grab 1st-over , just hit the button as soon as you stomp the gas and the overdrive will shift at a very appropriate time based on driveshaft speed. Again, the delay here is handy because a shift under full throttle to 1st-over produces tire spinning torque and the low speed delay gives us time to get our shifting hand back on the wheel to control the car. (If you have a floor-mount shift button – obviously you are going to use your foot instead of your hand to shift).

Note: If you set up for AutoLaunch and roll and then stop again it will disengage (it sees the speedo rotation and then the stop) so either hit it just before you hit the gas or at the same time if you may roll before launching.

Note: When you out-shift (turn off) the overdrive it is purely mechanical and happens about as fast as you can hit the button regardless of gear. The only exception to this is in the AutoDrive side of the switch where both inshifts and outshifts are buffered 1sec for the torque converter interrupt circuit which is not doing anything on your three speed auto as you do not have a torque converter clutch.

El Camino 454 SS

So now lets get to 2nd -direct, that would be 2nd with the overdrive off. You are revving up in 1st -over and want to go just half a gear up so move the main trans shift lever to 2nd and the moment you start to hear the motor pull down (meaning 2nd gear applying) hit the Gear Vendors shift button. Most transmissions take about 350 milliseconds or so once the shift initiates so you will find with just a little practice you can do this real well. You will also become aware that if you have a fully automatic valve body your main trans may not shift up under heavy throttle right when you move the shifter but you will hear it when it does. Full manual valve bodies change immediately but have no automatic functions – with full manuals then it is more the same timing all the time and listening is not needed, just timing.

So now you are in 2nd-direct and to get to 2nd-over you just hit the button. After you have revved out in 2nd-over go to 3rd-direct by moving the shift lever and hitting the button the moment you hear the engine start to pull down as 3rd gear applies. For 3rd-over simply hit the button.

If you drive the car most times at least once a week you should be a pro with this ratio-splitting feature in most 12 sec or slower cars. For those of you with 10 sec and faster cars (1/4mile ET) or those of you who rarely drive your ride – Gear Vendors makes an AutoShift Sequencer that automates the split. You still command the overdrive in-shifts but when you move the lever up to the next ratio the sequencer looks at the command and the tach to pick the appropriate moment to out-shift the overdrive.

As mentioned in the beginning of this tip sheet – The key to enjoying great gear-splitting is grabbing 1st-over early. 1st-over is such a big torque multiplier compared to 2nd that you really cannot get it too early. (ie: a 3.55 diff car with th350 trans – in 1st-over has more torque than a 4.56 car has in 2nd) . You have never felt this much bark from the car. Many bracket racers feel the car is also more consistent lane to lane when using 1st-over as it helps hook on the bad lanes. Depending on your chassis setup, weight transfer, and horsepower this will be true on some cars and not on others, some cars make smoke the tires in 1st-over (most street tire cars do).

The only time you will use the AutoDrive side of the dash-switch is when you are cruising and just want the trans and overdrive in Auto. Your trans will go through its normal 1-2-3 progression and then at 47mph shift in to the overdrive gear just like it came factory with an OD. When you slow down it will shift out and when you start up the car it will display the red light meaning it will shift as you reach the 47mph threshold (so the red light always means the overdrive is going to in-shift automated – either AutoLaunch or AutoDrive depending on what position the dash-switch is in – Manual or Auto).

Passing Gear & Shift points.

Nova 64

Your automatic valve bodied transmission will automatically move all its shift points up by exactly the correct 28.6% speed whenever the overdrive is on. This is because the governor on the trans is in front of the ovedrive so when you shift in the overdrive it slows it down. (On the electronic transmissions we send buffered ratio info to the pcm as part of our kit but its all mechanically done on your three speed – no wonder we all like-em). What is cool about this is that you will automatically get a useable passing gear (2nd -over) at a 28% faster road speed than you currently get 2nd without overdrive. As 2nd-direct is normally too low to do anything but wind out the motor (no headroom) you should find 2nd -over very nice. When it shifts down to 2nd – over automatically and you are accelerating and then the trans shifts back to 3rd without you moving the shift lever (if you want to keep accelerating) hit the Gear Vendors button when you hear 3rd apply and you will be in 3rd- direct. When you are back to just cruising, hit the Gear Vendors button for overdrive.

This is also true if you slow down so low as to get 1st-overdrive. The Gear Vendors AutoDrive circuit will keep the overdrive on until you are down below 25mph – this way the transmission can use the overdriven gears at the appropriate speeds bring the ratios closer to you and we have no hunting caused by being in the wrong gear or between gears. Below 25 we know 1st would be the correct gear so then we turn off the overdrive in both manual and auto positions. In manual it will latch out and not turn the overdrive back on until you hit the button – In Auto it will come back on once you get above 47mph again.

Have a blast driving your Gear Vendors equipped ride and give us a call with any questions or concerns at 800-999-9555. If you are already driving the product ask for Installed product support, if you have questions prior to ordering your overdrive kit ask for New Product Sales for muscle cars and racing.

You can send pictures of your ride and comments by email to info@gearvendors.com and we will put them up on our website in our soon to be live customer gallery.