Options to replace Micro Servo's?

[HumboldtEF]

Thanks for the corrections, I meant to put it in there that I'd love to hear from someone who actually understands the inner workings, I ended up cutting that out though.

I guess the position of the pot when reassembling the gears is important (I realized soon after the first rebuild failed). I have a few more sets of gears to try another rebuild or two, I'm not even looking for a working servo just some understanding.

Would a servo tester be of any use? And if I attempt another rebuild is there anything I should do for the sake of getting a better understanding of what is going on?

[clm]

The output gear (the gear with the shaft the horn sticks on) should key into the potentiometer in only one orientation, the other gears are just transfer gears to transfer the torque from the motor. So as long as you got the output gear assembled on it in the right spot and the pins and transfer gears in the right spot it should work.

Now the fact the potentiometer is working does not mean there is not also another flaw in the gear train causing it to not function, you may also want to prethread the servo retaining screw in the output gear before reassembling it or put a dab of shock oil or gear grease on the screw to make it thread easier. This will protect the gears a bit from the torque which could break the teeth on the small gears. This is not required on larger servos as everything is scaled up and substantially stronger

[meatmonkey]

These almost proprietary micro servos are a joke. My front locker servo quivers, and the rear has already stripped the gears. They are not even worth the time to replace the gears. Kinda hesitant to even bother with the blue bird alternatives. Seems like I might have to suck it up and fab up mounts for real servos. I don't mind ditching the "waterproof" receiver box. Only real disadvantage would seem to be added weight.

Also irritating that traxxas doesn't offer different splined inner sections of the micro servo savers. The cables are not robust enough for me to just run a solid horn and I don't like being limited to 25 splines. I've got a couple Hitec 225's that I think would work well, if they fit the savers that is. Maybe if we pleaded enough we could get RPM to make replacement savers with all the spline counts? Probably wishful thinking...

It's basically a shame that such a mechanically capable rig is almost neutered by cheap electronics.

[HumboldtEF]

I cant argue with that meatmonkey

After taking advise from a few kind folks (clm & Chris Mckay) I was able to successfully rebuild the servo I had been experimenting on. I think I failed to center the pot on my first rebuild. I attempted a rebuild again and centered the servo first along with using the steering channel to test as the diff channels act different. I haven't stripped the gears yet testing it outside of the truck. I greased up the weakest gear real good.

I believe I had the pot offset to one side (when I did the first rebuild) which likely made the servo wind itself into the stop making it strip the new gears.

Oh and the output gear and shaft are not keyed so you need to be careful when assembling, which makes me wonder if its not keyed is it wondering off center somehow?

[clm]

Originally Posted by HumboldtEF

...After taking advise from a few kind folks (clm & Chris Mckay)...

*whisper* Same person

[rm25x]

These damn micro servos are a joke. Stripped rear locker servo twice now. Wish they would have used 2080 servos instead. Or heck, even just a softer servo saver spring would have probably done the trick.

[mobgma]

Thank god I have had no issues with mine (YET). I hope you guys can work out an aftermarket servo option.

The people I have seen in person have issues are the ones shifting or adjust lockers when they shouldn't be. Typically the guys using this poor thing like a basher from hell. I use mine for crawling and when I say crawling i mean low speed scale like driving crawling. Not full petal to the metal crawling like alot I have seen.

[HumboldtEF]

I just noticed an oddity with the switch on the transmitter itself. In the fully unlocked position (all the way left) If i wiggle the switch just a tiny bit, not flipping the switch, it will activate the servo or try to. I'm wondering if the moments of buzzing might be the switch itself being stuck in between.

I wonder how much this switch could be to blame, In the past when it buzzed I'd throttle it thinking it wasn't lined up in the diff, but now I plan on checking the switch.

This toggle switch should be super easy to replace too, but it'd be nice to test first though. Huh maybe the summit guys already know this stuff? I assume they have the same switch.

[AggressorBLUE]

Originally Posted by meatmonkey

These almost proprietary micro servos are a joke. My front locker servo quivers, and the rear has already stripped the gears. They are not even worth the time to replace the gears. Kinda hesitant to even bother with the blue bird alternatives. Seems like I might have to suck it up and fab up mounts for real servos. I don't mind ditching the "waterproof" receiver box. Only real disadvantage would seem to be added weight.

Also irritating that traxxas doesn't offer different splined inner sections of the micro servo savers. The cables are not robust enough for me to just run a solid horn and I don't like being limited to 25 splines. I've got a couple Hitec 225's that I think would work well, if they fit the savers that is. Maybe if we pleaded enough we could get RPM to make replacement savers with all the spline counts? Probably wishful thinking...

It's basically a shame that such a mechanically capable rig is almost neutered by cheap electronics.

You hit the nail on the head with this post! Cheap, hard to replace/upgrade electronics that don't fit the bill are dragging the truck down. I'm sure the aftermarket will catch up (just need about 378 more variations of portal weights, and we should be good to move on to the rest of the damn truck!).

As far as the servo save, I hadn't thought about the linkage being the weak point with using a high torque servo without a saver. Wondering if control cables from large scale aircraft would be a worthwhile mod to accompany more potent servos. Something like sullivan goldenrods maybe?

Gold-N-Rods

[clm]

If you were going to replace the servo saver with a solid horn on some servos you might want to swap to some sort of linkage from a nitro truck.



They would allow some play in the system to accommodate when the dogs are not lined up with diff housings, there should not require much torque to hold it in the locked position seeing as they are square teeth dogs used to lock and unlock the diffs (and shift the 2 speed). If you require excess torque to lock or unlock I would be worried the cable is seizing.

[HumboldtEF]

So I just tried to capture the switch acting up on video, and wouldn't you know it acted perfectly normal. I'd be curious to know if anyone else can make this happen.

Originally Posted by HumboldtEF

I just noticed an oddity with the switch on the transmitter itself. In the fully unlocked position (all the way left) If i wiggle the switch just a tiny bit, not flipping the switch, it will activate the servo or try to. I'm wondering if the moments of buzzing might be the switch itself being stuck in between.

I wonder how much this switch could be to blame, In the past when it buzzed I'd throttle it thinking it wasn't lined up in the diff, but now I plan on checking the switch.

This toggle switch should be super easy to replace too, but it'd be nice to test first though. Huh maybe the summit guys already know this stuff? I assume they have the same switch.

[penguin1]

All my micro servo's are dead. Both diff lock and trans shift servos are inop. No buzzing just don't work. Kinda PO'd the truck is only a month old. My guess is that they are not as water proof as advertised.

[HumboldtEF]

So I noticed one of my diff servos was in need of adjustment, a different one this time. After taking stock of how it was acting I decided it needed to be shortened.
I took off the plastic end link from the servo saver and threaded it into the cable end 2 threads. It was on the "push" end of the throw.

It only took a few moments for me to put it together, just like in 1/1's cables stretch so they will need periodic adjustments

So when you've got a case of buzzing servos, take a moment to observe which side of the throw is causing it and adjust it accordingly. ensure its fully engaged before you come to a conclusion. Always give some throttle when toggling the servos, go back and forth if you can see its not fully engaged. Buzzing while the diff hasn't engaged is not to be confused with buzzing when it has engaged properly.


Buzzing when on the Pull side indicates the cable needs more length.

Buzzing on the push side indicates the cable needs shortening.

Buzzing on both ends..... I think we're out of luck there.

I've still yet to kill a sub micro servo while driving, but I know its very common.

I did however strip the gears in one when trying to unscrew the servo saver (beware the gears inside are not strong enough to allow you to unscrew the servo saver, you absolutely need to hold onto the little bit that sticks up with pliers while you undo the screw)

[cartronicshn]

, Reading through this thread, makes me nervous to drive my trx4 again, i have only 3 packs through it, i haven't had any servo issues so far, but i did manage to stuff the motor in mud and it stopped working until i rinsed it with clean water

[HumboldtEF]

Originally Posted by cartronicshn

, Reading through this thread, makes me nervous to drive my trx4 again, i have only 3 packs through it, i haven't had any servo issues so far, but i did manage to stuff the motor in mud and it stopped working until i rinsed it with clean water

Dont worry, there's plenty of info here on how to prevent potential issues.

Now that you know what to look out for and what to listen for you should fare better than those who dont.

[spaceman5280]

Originally Posted by HumboldtEF

So I noticed one of my diff servos was in need of adjustment, a different one this time. After taking stock of how it was acting I decided it needed to be shortened.

I took off the plastic end link from the servo saver and threaded it into the cable end 2 threads. It was on the "push" end of the throw.



It only took a few moments for me to put it together, just like in 1/1's cables stretch so they will need periodic adjustments



So when you've got a case of buzzing servos, take a moment to observe which side of the throw is causing it and adjust it accordingly. ensure its fully engaged before you come to a conclusion. Always give some throttle when toggling the servos, go back and forth if you can see its not fully engaged. Buzzing while the diff hasn't engaged is not to be confused with buzzing when it has engaged properly.





Buzzing when on the Pull side indicates the cable needs more length.



Buzzing on the push side indicates the cable needs shortening.



Buzzing on both ends..... I think we're out of luck there.



I've still yet to kill a sub micro servo while driving, but I know its very common.



I did however strip the gears in one when trying to unscrew the servo saver (beware the gears inside are not strong enough to allow you to unscrew the servo saver, you absolutely need to hold onto the little bit that sticks up with pliers while you undo the screw)

I stripped one of my gearsets the same way and then I read in the manual how to avoid stripping


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[CODYBOY]

Originally Posted by HumboldtEF

Dont worry, there's plenty of info here on how to prevent potential issues.

Now that you know what to look out for and what to listen for you should fare better than those who dont.

Great job trouble shooting Casey, You the man!!!
Ernie

[HumboldtEF]

Originally Posted by spaceman5280

I stripped one of my gearsets the same way and then I read in the manual how to avoid stripping


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Well thats better than I handled it, I was warned first but ignored it

[joely]

Got my TRX last week, reset all linkages/cables properly and still all 3 gear sets only lasted about 10 cycles each. The radio system really needs some EPA for the shift and locker channels in my opinion. Some half decent servos would have helped too


Will definately be replacing the radio system with a hacked GT3B to solve the no EPA problems.

[BDR]

I just put in some BlueBird BMS-21HV servos, seem to work really well, and being good for 7.4v saves me farting around with different BECs and what not.

These are NOT a bolt in servo though