How-To: Modifying the Futaba 6EX for MOA Crawlers

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Dpdsurf shows us how to modify a Futaba 6EX for MOA Crawlers with add-on dig switches.

Modifying the Futaba 6EX for MOA Crawlers
By dpdsurf

There’s no question that Motor on Axle vehicles (MOA’s) have taken over the 2.2 class in competition RC Rock Crawling in the last year or two. Setting up your electronics on an MOA can be tricky and the first thing you need to decide is if you want to stay with the pistol radio you’re probably comfortable with or give twin sticks a try to truly take FULL advantage of a dual motor and dual ESC setup. After years of racing and crawling with pistols I was surprised that I picked up the twin stick so quickly. It took about 4 hours to feel completely comfortable with it. Your knowledge of how to crawl and which lines to take stays with you. All you’re doing is retraining your muscle memory to operate a different controller. In my first comp after less than a week with it I got a perfect score on my second course. In this tech article we will take a stock Futaba 6EX radio and modify it to eliminate some of the flight related settings that won’t work very well for crawling and add some additional features that will enhance your driving experience.

Before you start contact Futaba and request the necessary parts to modify the left stick to center off. They will send these parts for FREE!

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STEP 1: Modify the left stick to self center.
The left stick will be your primary throttle that you will use for forward and reverse in 4WD and also while in front dig mode.

1.1 – Open up your TX by removing 4 screws from the back. (Don’t be scared yet) You will want to remove the battery cover and battery before opening up the radio.

1.2 – Notice that there is already a spring and gimbal which centers off the left to right motion. Install the new gimbal from Futaba and move the spring to the up and down side.

1.3 – Below you can see the new gimbal and relocated spring on the up/down side. Now install safety wire on the existing gimbal or anything that will lock out the left to right motion as it is not needed for the operation of your crawler.

STEP 2: Modifying the right stick
The right stick is used to steer (left to right motion) and independent rear motor control a.k.a. rear dig (Up and Down motion)

2.1 – The additional spring that Futaba sent you can be added to the up and down position of the right stick. Having two springs doubled up here will make moving the stick more firm in the up and down direction which will help to reduce false throttling while steering, therefore avoiding accidental reverse penalties. I have found that the easiest method is to remove the existing spring and mesh the two springs together before reinstalling both springs at the same time.

STEP 3 (OPTIONAL): Momentary Switch mod for front dig (a.k.a. “Burp Button”)
I have found this to be a huge benefit and use this button almost exclusively for front dig. In this step you will need a quality soldering iron and you will need to purchase a momentary switch (normally open). Radio Shack is a good source for this. Normally open means that the circuit is off until the button is pressed which then makes the connection (closes).…ductId=2062539

3.1 – Solder the button in line with the switch that you plan on using for you front dig. In my case I use the Ch.6 Flaps switch but you do have the option to use other switches.

3.2 – You will need to drill a hole for the switch.

You have now completed the internal modifications and it is time to close the transmitter back up. That wasn’t so bad was it?

STEP 4: Programming the radio for proper operation

4.1 – Turn the TX on and press the Mode and Select buttons at the same time to get into the settings mode.

4.2 – Select the model number using the +- switch on the right of the display screen.

4.3 – Press the Mode button 5 times until you are at PMX1

4.4 – Use the +- switch to turn PMX1 to on

4.5 – Press the Select button and make sure that PMX1 is at 100%, use the +- switch to adjust if necessary.

4.6 – Press select and set the MAS to CH3. Channel 3 will be your master which is the ESC for the front motor.

4.7 – Press select and set SLV to CH2. Channel 2 will be your slave which is the ESC for the rear motor.

4.8 – Press select and set SW to the switch that you want to use for front dig. In my case I like the FLP with the arrow in the up position so you flick the switch to the up position to engage the front dig. This switch seems to be in the closest proximity to where I hold the radio. You could also use CH5 or the D/R switches for front dig.

4.9 – Press Mode and make sure PMX2 is set to INH. There are features that you could use in this second mixing channel like giving more wheel speed to one motor over the other. Play around with it. Personally I found that the switch operating this would get left on by mistake and mess me up in comps. I compensate wheel speed exclusively with the right stick. I’ll expand on this later.

4.10 – The remaining modes should be set to INH (inhibit). FLPR, FLTR, V-TL, ELVN. F/S should be on Nor ^ (up arrow) and ch3.

4.11 – Now turn on your crawler and continue to set the fine tuning. Have the rig resting with the wheels off the ground to avoid any work bench accidents.

4.12 – Set REVR as necessary for steering and throttle. You can also change your motor wiring if the wheels are not spinning in the proper direction.

4.13 – Set EPA mode. I like channel 3 and 2 set at 140% Also set your servo endpoints on channel 1. Moving the right stick left or right will change the arrow on the screen and allow you to adjust both the left and right steering endpoints.

4.14 – Set TRIM mode. Channel 1 should be the only one to adjust. All other channels can be on 100%.

4.15 – D/R & EXPO mode. Continue to press select if you want to program in any exponential. You can play around with channel 2 to decrease the sensitivity of the right stick for example. But keep in mind doing this will effect the sync when in 4WD. You can actually simulate what using different size pinions does. Personally I keep the EXPO at 0.

Your radio should be tuned and ready! Now it’s time to learn how to take full advantage of a twin stick.

I use the “burp button” almost exclusively for front dig. Continuous taps while side hilling will allow the rig to squat down yet maintain a smooth line without dragging the rear.
Moving the right stick up and down gives you independent control of the rear motor. This is huge to learn. You can eliminate clod stall. On technical steep climbs where giving it too much throttle wants to flips you backwards yet too little does not allow the rear wheels to spin you can simply ease the right stick forward and watch your rig push right up that climb.

I also recommend switching over to a 3S Lipo pack for transmitters. Something in the 2200mah range will triple your time between charges in comparison to the stock Nicd.

Be certain to calibrate both ESC’s with the radio to insure smooth operation in 4WD. This can be a tricky process with dual ESC’s.
That’s it for now. Good luck

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