Setting up Futaba 3PM for 4ws

[bbeaty]

In the process of deciding how to modify my old Savage radio to have independent rear steer I decided to try and setup some the “advanced” functions of the 3PM I had up until this point never used. Below is one of the ways to setup the radio.

For 4ws the front wheels turn opposite the rear (the same as if you had a reversing y-harness). When the SW2 button on the radio is moved the truck will steer only with the front (mixing turned off), and when the SW1 button is pressed the front wheels will turn the same as the rear enabling crab steering.




Setup Procedure:

To set this up you will need to have a servo plugged into the CH1 and CH3 positions on the radio. For now I’ll assume you have the front servo plugged into CH1 and the rear servo into CH3.

In the system menu setup a new model name in the radio, also while in the system menu, setup SW2 to be MX (programmable mixing) see pg 54 in manual if you do not know how to do this, and SW1 to Conditions 2 selection (pg 56).

Turn the radio on normally; I assume you know how to setup the front steering using the sub trims and EPA. If you need to reverse the front steering do this as well. In order to have the rear steer opposite from the front, the value for CH3 in the reversing menu needs to be opposite that of the steering. For example, if you need to reverse the front steering CH3 should not be reversed, and by the same measure if the front steering does not need to be reversed then you will need to reverse CH3.

To adjust the mixing settings see (pg 41). For a base value set both the right and left side values to +75. You will need to fine-tune them later using the same idea as setting the steering EPA. The master and slave settings are correct by default and then set PMX-MD to ON.

To test the settings try steering the truck, only the front tires should turn. Now if you move the SW2 switch the truck should steer normally with 4ws.

The rear steering will most likely need to be trimmed. The preferred method to trim the rear wheels is to use the sub trim menu and select CH3, then use the + / - buttons to align the rear wheels. Another method is to select CH3 in the main menu and again use the + / - buttons to align the rear wheels.

Here is where the Conditions 2 button you setup earlier comes into play. The conditions 2 button is setup as SW1 (button on the handgrip). When you press the button you will notice the LED will flash, verifying you are in the Condition 2. Now scroll though the menu and setup the mixing function again, however this time instead of setting the right and left values to +75 set them to –75. Now when you have the SW2 moved to activate mixing and have the SW1 button pressed, the front and rear wheels will turn the same direction and the truck will crab steer.

When mixing is turned off via SW2, you can set if you want only the front or rear wheels to steer by switching how the servos are plugged into the receiver (front on CH3, rear on CH1). Keep in mind when you physically switch the front and rear servos on the receiver you will need to readjust the trims, channel reversing, etc.

[RHughes103]

This is great. I've been rackin my head on how to do this with my 3PM for the last week, and this never occured to me. Thanks for the write up.

[utbeamer]

Thanks man! I'll see how it works in a couple of weeks when my TLT is finally done.

[EeePee]

I had one of these radios a while back, and never did get it to do what I want. And over the time I've been here on RCC, I've seen posts come and go about the 3PM. And this post here is the FIRST one I've seen to go into any detail whatsoever. Good job. Now I wish that radio didn't fry and go up in smoke.

[shrek]

would these settings also be the same for a 3pk

[bbeaty]

No problem. For a fairly inexpensive computer radio the 3PM has many "high end" radio features.

As far as the settings being the same on the 3PK I'm sure the terminology will be the same since they are both Futaba radios, but I'd imagine the setup procedure through the menus will differ. You can compare the manuals for the two radios from the following link: http://www.futaba-rc.com/manuals/index.html

[goingvertical]

:-P:-P:-P:-P:-P:-P:-P:-P:-P:-P:-P:-P!!!!!!! thanks for the instructions, finally able to use my radio for 4ws, will use for my tlt's, cause i gave up trying figure it out so went and got a stick radio for my clod. coooooool! now i have two of them set up for 4ws.

[goingvertical]

finished setting my radio, was'nt that hard after all in getting it right, some minor adjusting, other then that it works fine. thanks for the post:-P

[bbeaty]

No problem

[utbeamer]

Works awesome, thanks again.

[RCnJunoir]

i just registered to the site! and i am a noobie to rc rock crawling however not to the rc world by any means i have 10 vehicles. i bought my txt-1 used for $100 with the esc below and no radio/servos . anyway this is an awesome site and topic.been trying to program this radio for 3 days. did everything it said and it worked great just one little problem, the rear wheels will not turn when i turn the wheel to the right. they turn when i turn to the left. when i plug the servo into the #1 slot the servo will move full left and full right but not when in the #3 slot. any suggestions on what to do??? my setup-stock(but not for long ) txt-1, futaba 3pm, two hitec 645, novak rooster reversible

[bbeaty]

RCnJunoir:

When you mention the servo does not travel to the left, can you hear that the servo try to move and maybe it is at the end of its travel, or does it not move at all? I was thinking maybe an sub trim or EPA setting on your third channel might be incorrect.

Scroll through the menu on your radio until it reads PMX-RT. You should see an arrow above which reads L.F.U. and the numerical value above should be positive. Press CH, you will now see the text that reads R.B.D and again the numeral value above should be positive.

[JohnRobHolmes]

Great writup Brian! I just sold my 3pm to MikeB since I prefer stick radios.

The third channel can be set for two position or three position travel i.e. like a throttle only servo or like a steering servo. I bet your radio, RCnJunoir, is set with the third channel on 2 position mode, which would prevent it from turning left. Just a guess though.

Most probably the left EPA is set to zero and that is causing the problem.

[goingvertical]

is there a way to make front or rear steer independent with the this radio

[RCnJunoir]

i didnt mess with the third channel epa. the servo doesnt want to move to the right when plugged into the channel 3 slot on the rx. if i put it into the channel one slot it will move both ways. i havent tried switching the servos yet but i will try that. i thank you guys for trying to help me. any other suggestions are greatly appreciated.

[SammyXp]

I'm so glad I just found this writeup. I've got my 3PM set up for 4WS on my TLT, but I didn't think about using Condition 2 for crab walking! Right now, I've just got it set to minimal rear steer (+25%) for bashing.
This is sweet!

[andrewmp6]

nice write up how hard is it to use once set up and is there anyway to control the rear fully independent or is it mix only

[JamisonWorkshop]

I know I am holding out on buying this radio until I see someone doing it independently as well.

[andrewmp6]

me too jamison i might just buy a 4 channel

[jbrandt]

Originally Posted by goingvertical

is there a way to make front or rear steer independent with the this radio

I think the only way to have independant rear steer is to get a 4+ channel stick radio. That way you can have the right (or left) stick controll the front steer and the other stick control the rear steer. I have a 6 channel JR computer radio (aircraft) that I messed around with in my backyard to see if I could work the 2 sticks, and it's hard as hell to get used to. I found that even with the added advantage of independant rear steer I couldn't hit lines I could easily make with my pistol radio and just 2WS. Apparently, I become retarded when I try to coordinate my two left thumbs.