MOA Dual ESC issues

[shizzz]

Here is the issue. I have a dual fxr set up (using CC bec) and use a hacked
gt3b radio. One fxr is quite new and never glitched before. The second i got from a rccrawler fellow, used, but still claimed as ok one and i trust that guy.
Rig XR10

all wired up and soldered correctly.
1. When i turn on the radio and esc see it, the rear wheels do a one round spin back and then stop. I can drive after that "normally" but!
2. Once you pull the trigger softly front axle goes first and you need to pull a bit more for rear to start rolling.
3. Rear wheels spin slower than the front. Pinions are stock.
4. Today the rig became unexpectedly out of control, once. It started going forward at full throttle. Was hardly caught and cut the power.
5. I can't calibrate the esc with radio. I mean it work, but if i do want to calibrate esc with radio, then, when i pull full throtle nothing happens.

What is wrong?
Thanks
Boggie

[CREEPERBOB]

sounds like your FXR's may have differant firmware. Do you have or have access to a Tekin Hotwire? That is where I would first start.
and as for the front motor running before the rear , that may just be clod stall, what type of motors are you running?

[shizzz]

Originally Posted by CREEPERBOB

sounds like your FXR's may have differant firmware. Do you have or have access to a Tekin Hotwire? That is where I would first start......

Well, this was my first guess. I don't have any and it looks, like i need to get one somehow (sigh....)

Originally Posted by CREEPERBOB

and as for the front motor running before the rear , that may just be clod stall, what type of motors are you running?

motors are JP warriors 45T. Used, but properly rebuilt

[CREEPERBOB]

Originally Posted by shizzz

Well, this was my first guess. I don't have any and it looks, like i need to get one somehow (sigh....)


motors are JP warriors 45T. Used, but properly rebuilt

Yeah, I would say get the Hotwire and download the latest firmware.
Check the fimware version on both esc's and update to latest version.
Then start over, recal TX and go from there.

[cartronicshn]

How much weight difference front to rear on the wheels, if any, this can also make a difference when a motor starts spinning first.

[Randy P]

Firmware won't cause this. This is a transmitter issue. The Esc will only apply power when it's told to do so. both esc's are on different channels right? Did you radio calibrate both esc's?

[shizzz]

I was trying to calibrate them but no successes. As long as it comes to throttle, esc can not get signal from tx. I don't know why, but it just do not see tx:(. One more question - do I need to desolder the esc to set them up and calibrate, or I can do it as is? I am totally desperate. Am I becoming too old for that stuff?
Btw I don't have any weight on rear wheels yet.

[Charlie-III]

Here is the FX-R manual.... http://www.teamtekin.com/manuals/FXManual.pdf

You may be able to recalibrate both ESC's at once, but one at a time is usually preferred.

The normal method to start is:
TX throttle trim (& subtrim) to "0"
TX throttle EPA's (endpoints) to "100%"
No Mixing set in the TX
You "may" need to reverse the throttle in the TX to do the calibration.
You "may" need to open up the throttle deadband for the ESC to see the neutral.
Then do the recalibration, test operation.

[shizzz]

What does "open up a deadband" mean?

[Charlie-III]

Originally Posted by shizzz

What does "open up a deadband" mean?

The range in the TX that is considered neutral, it also changes how far the throttle trigger needs to move before the TX sends/changes the throttle signal to the RX.
If the throttle deadband is too small, the TX "may" be sending a forward or reverse signal to the ESC so the ESC never actually sees neutral.
Other radios use the "deadband" as a timer.
Either one is cause for the ESC to not arm if it needs to be changed.
I never had to adjust this, my son & I run Futaba radios, most of our ESC's are Castle Creations, we also have a few FX-R's.

[SMR 510RR]

1. Buy a hotwire
2. Make sure the firmware is the same, the old firmware had slow speed startup issues
3. Calibrate the ESC's...I like to do them at the same time, dont know why everyone else likes it the other way because if you do it at the same time you know they will match. You may need to go reverse instead of forward if it isnt recognizing it.

After that if it still is not working right then you have to check for binding and do some more troubleshooting to figure out what is causing the problem.

[shizzz]

Thank you, guys
It worked.
I did a reverse on my tx and apparently i could calibrate both of ecs'

Bout the clod stall. I do not have any right now. The only issue is rear now spins a bit faster but that could be easily fixed with mixing.
Thanks a lot for everybody's input

[Charlie-III]

Originally Posted by shizzz

Thank you, guys
It worked.
I did a reverse on my TX and apparently I could calibrate both of ESC's.

Bout the clod stall, I do not have any right now. The only issue is rear now spins a bit faster but that could be easily fixed with mixing.
Thanks a lot for everybody's input

Cool deal, glad it's working.

As to motor speed, make sure the front is not binding (maybe tighter gear mesh is why it's slow) and check throttle curves in each ESC to make sure they're the same. Also check brushes (if you're running brushed) to make sure they are in similar condition as well as the brush springs.

[shizzz]

Thanks, man. Motors have been just rebuilt, as I know. As for the curve, do you mean the throttle profile on fxr or smth else?

[Charlie-III]

Originally Posted by shizzz

Thanks, man. Motors have been just rebuilt, as I know. As for the curve, do you mean the throttle profile on FX-R or something else?

Yes, throttle profile/curve. In the CC ESC's, you can save the ESC settings & throttle/brake curves from one ESC and copy to another.
The FX-R's don't allow this, so I screen shot the settings, save as a ".png" in Microsoft paint and put it in a folder. Then I set up the second ESC using the same settings from the first ESC. Make sure the firmwares are the same, otherwise things "may" work different.
You can't do some of this without a HotWire though. You can only use their curves.

[shizzz]

Now I see. I did set the same profiles. The are actually three standard curves. But, in case I put the mildest start in rear, then it does not spin at all. If i put the mild start, then:
-Before calibration it was stalling
-after calibration it spins a bit faster

Think I have to get Hotwire... And check. Ain't easy, have to wait for a week or two for it. But I don't have an option :(

[SMR 510RR]

If they arent matched after calibrating and when on the same profile then it sounds like a motor timing issue. Check the timing on both motors, they will have to be reversed from one another.

[Charlie-III]

Originally Posted by SMR 510RR

If they aren't matched after calibrating and when on the same profile then it sounds like a motor timing issue. Check the timing on both motors, they will have to be reversed from one another.

+1.......unless you order a "MOA set" of motors, they may have some timing. This means one motor will be advanced while the other motor is retarded.
As a quick check, set both motors to "0*" timing and see what happens.

[shizzz]

Those motors supposed to be already matched. But anyway, how to do that? Do I have to disassemble'm?

[SMR 510RR]

Originally Posted by shizzz

Those motors supposed to be already matched. But anyway, how to do that? Do I have to disassemble'm?

Could you have put the motors in the opposite locations?

What happens in reverse, does the front start before the rear?

To time them you just loosen the endbell screws (2 of them right on the end) and then spin the endbell in the direction of rotation to advance the timing. The motor builders recommend between 6-8 degrees of advance, there should be some markings on the side of the endbell and one on the can to line it up with. You want the two motors set to the same advance but in the opposite direction.

Before you go and do that I would just look at the markings and see if they are advanced the correct direction, you may need to pull one off and spin the first gear by hand to check what direction they need to be advanced. If that is not the case then put the rear motor on the front and the front on the rear and you should be good to go.