Options to replace Micro Servo's?

[magic_yeti]

Originally Posted by high plains drifter

So... How would someone go about ensuring that they don't overload these servos? Look for a tx with capability to limit travel? If so... any recommendations as to a decent tx that someone can run with the stock TRX4 electronics ( compatibility).

Any more detailed info would be greatly appreciated. I've got a couple Bluebird 373mg servos that I'd like to drop in without watching them get ruined. Thank you, if anyone could elaborate in regards to getting these servos to work successfully.

Wireless Winch and Diff Locker Controller

maybe this is a option for you
otherwise a hacked gt3b or c gives you up to 8ch and the receivers are under 15$

[high plains drifter]

Originally Posted by magic_yeti

Wireless Winch and Diff Locker Controller

maybe this is a option for you
otherwise a hacked gt3b or c gives you up to 8ch and the receivers are under 15$

Yep! I haven't contacted Ken yet but I'm thinking that I may want to get in on this. Thank you for the link!

I guess that the reason I've kinda stalled on this is because I'm still a bit confused as to the exact issue and best solution ( assuming that my stock 2065's fail like so many seem to be).

Just thinking out loud here...

I thought that the stock mini's had less throw ( or travel?) than the Bluebirds. Idk if that's correct but if so, why are they failing? I know that the stock servos utilize plastic gears but still... seems like Traxxas would be using ( or in conjunction with Hitec or other manufacturer, designing) another servo that would be upgraded, direct fit, and have the correct end-points already calibrated.

Also regarding the linkage side of things... it thought that a servo-saver is supposed to protect the servo from issues like this. Tbh I've never even used a servo with this type of "spring-buffered" servo horn. The whole thing looks weird to me and I don't quite understand why a more conventional type of horn/ servo saver hasn't been successfully utilized in this particular application.

I guess lastly, I've been wondering... does the cable ( or mechanism that activates/ deactivates the locker) have some sort of inherent design flaw that could be corrected ( limited?/ extended? idk) so that the servo shaft isn't over-extending upon activation of the locker switch.

I hate the idea of having to upgrade the tx, esc, rx at this time. I've spent a good chunk of change on this rig and spending more just isn't an option atm nor is it something that I really want to have to do anyway... at least not based upon this issue. I guess I never researched deep enough into all of this at the time that I made the decision to purchase the TRX4.

All of that was probably pretty ignorant, so apologies for the possibly unwarranted rant lol.

[Björn]

Originally Posted by Björn

Ok, so like I said above, I ordered this one from the first page of this topic:

https://hobbyking.com/nl_nl/bms-373m...sec-11-4g.html

I installed it with the servo saver and it stopped working after one minute. I think the throw might be the issue. As far as I can see the original servo's have a throw of around 90 degrees. This one has 120 degrees. I have a second one that I'll install tonight, but I expect it to fail also.

Second one also stopped working after a minute. It seems the constant load of the spring is killing it very fast.
Ordered replacement gears for the Traxxas servos now since it seems to be the only more or less working option :(

[Björn]

Originally Posted by rockhugger

I'm using the bluebird option from the original first page of this thread with absolutely outstanding results. I did have to trim the ears a touch for a perfect fit, but that's okay with me.

Did you use the standard servo saver? How did you come around the end-point issue? See my posts above. The Bluebird is around 120 degrees. while the standard servo does less than 90 degrees.

[magic_yeti]

but the cruise control is very nice. something i wish it could be possible with a hacked gt3b/c.

[Björn]

Just replaced the gears of the original servo and reinstalled it. I tested the endpoints first before attaching the high-low gear link, but strange enough the servo moves over a 1cm distance, while the link can only move 5mm. In high gear the servo is constantly trying to push further than it can.. I also noticed that the diff-lock servo's keep working in locked position. It seems to me that the endpoints are not configured at all, and that Traxxas is using the spring-horns to more or less compensate for it. This might explain the many complaints about stripped gears imho. I'm really disappointed about this :(

[HumboldtEF]

Originally Posted by Björn

Just replaced the gears of the original servo and reinstalled it. I tested the endpoints first before attaching the high-low gear link, but strange enough the servo moves over a 1cm distance, while the link can only move 5mm. In high gear the servo is constantly trying to push further than it can.. I also noticed that the diff-lock servo's keep working in locked position. It seems to me that the endpoints are not configured at all, and that Traxxas is using the spring-horns to more or less compensate for it. This might explain the many complaints about stripped gears imho. I'm really disappointed about this :(

Back on page 3 I went over how the length of the cables can be adjusted, Its no fix but its a bit of insurance to help give them a fighting chance. One other note, cables strech so adjustment over time to account for this should help. I also posted a short video explaining it



I think the easiest way to ruin one of the micro servos is by wrenching on the servo saver, you absolutely must hold the top of the servo saver with needle nose pliers to avoid stripping the tiny internal gears.
Another potential killer is how you shift, and whether you wait for it to engage and click in place or if you just keep on driving. I've made a habit of never shifting or locking the diffs without rolling back and forth a bit and listening for the click as well as occasionally listening for a buzzing servo. If you just keep on trucking without rolling back you're likely to be putting this weak little servo in the position where its not able to engage but its gonna keep trying until you tell it not to or it simply burns up.
A kinked cable is also a concern, adjusting the cable length should make that as good as it can get.

After pretty heavy use I've still got working micro servos all around (though I did destroy one trying to remove the servo saver to tinker with it, my fault)

[Björn]

In my case I am talking about the shifter servo, so can't really adjust anything..

But I get mixed messages about the endpoints above. If I interprest Natedog correctly, it is normal that the servo travel is more than the link/cable travel and thus it's normal that in at least one position the servo is under constant tension of the spring. If I interpret HumboldtEF correctly he says the opposite, or at least he says that putting constant tension on the servo causes it to burn up:

If you just keep on trucking without rolling back you're likely to be putting this weak little servo in the position where its not able to engage but its gonna keep trying until you tell it not to or it simply burns up.

When I put the car in high gear, or when I lock the diffs, the servo's are only able to make their full travel by putting tension on the servo saver. In this position the servo's are buzzing because of this.

[Björn]

Ok, I just got a message from the NL importer. He says it is normal the servo travels more than the link can travel.. With this knowledge I am not surprised to read many issues with the servo's.

[HumboldtEF]

Originally Posted by Björn

But I get mixed messages about the endpoints above. If I interprest Natedog correctly, it is normal that the servo travel is more than the link/cable travel and thus it's normal that in at least one position the servo is under constant tension of the spring. If I interpret HumboldtEF correctly he says the opposite, or at least he says that putting constant tension on the servo causes it to burn up:

The context of that comment was if you shift without making sure that it properly engages the servo could be under a lot of stress as its still trying to engage but may be stuck. My other comments about adjusting the cable length reflects what Nate said, the throw will be longer than needed....... but adjusting the length of the cable will at least make things as good as they can be all things considered.

I hope that makes sense.

[high plains drifter]

Originally Posted by HumboldtEF

The context of that comment was if you shift without making sure that it properly engages the servo could be under a lot of stress as its still trying to engage but may be stuck. My other comments about adjusting the cable length reflects what Nate said, the throw will be longer than needed....... but adjusting the length of the cable will at least make things as good as they can be all things considered.

I hope that makes sense.

So essentially adjusting ( shortening) the cable takes some of the strain off of the servo and instead puts that strain onto the cable?

Sorry for the newb comments and thoughts... still learning.

[HumboldtEF]

Originally Posted by high plains drifter

So essentially adjusting ( shortening) the cable takes some of the strain off of the servo and instead puts that strain onto the cable?

Sorry for the newb comments and thoughts... still learning.

No worries

The point is to get the cable centered so that the throw on each side is equal. If one side is longer than the other its likely to be stressing the servo on that side and since the servo throw is already longer than needed thats just asking for trouble. This can also lead to kinking the cable which is no good for transmitting its forces, just remember the cable is being pushed at times.

I just ended up shortening my front cable because it was a bit long, BUT every truck is likely to be assembled different so you will need to use your own judgement as to whether to shorten or lengthen or do nothing, I didn't have to do anything to my rear cable at first but over time it seems to have stretched, then I did adjust it a tiny bit. I could tell it needed adjustment by the buzzing that popped up one day, but don't wait for that to happen just look them over and go from there.

[high plains drifter]

Watched the video several times now. Since everyone's rigs are a bit different, it seems the first step is to evaluate what ( if any) adjustments are necessary. I definitely understand things now and feel confident to at least try to equal-out the throw of each mini if necessary. The tip on delicate servo-saver handling may prove invaluable also. Thanks so much, HumboldtEF.

[Björn]

Thanks for all the info guys. I'll try to get my servo horns / links / cables centered so the 'extra throw' is equal in both directions.

[Turtlejon]

Has anyone made a list of servos that will fit yet?
Is it just as easy to make the micro ones waterproof as a standard size?
Or are there any waterproof micros?

[joely]

Originally Posted by Turtlejon

Has anyone made a list of servos that will fit yet?
Is it just as easy to make the micro ones waterproof as a standard size?
Or are there any waterproof micros?

I can tell you the Savox SH-0263MG fit with minimal modification. Just a slight shave to the tabs on the servo. You will have to use the included horns but the hole closest to the centre seemed close to the needed throw. I use a GT3B so can set endpoints so not sure.


As for water proof, they aren't listed as a waterproof servo but I've had mine in water up to the bonnet (hood as you US people say) and havent had a problem. Some conformal coating (I've even heard nail polish) on the board would save any worry though.

[Björn]

If you can adjust the throw, the bluebirds from the first page will work as well. They fit the servo saver that comes with the TRX. The ears needed some minor modifications as well to fit.

https://hobbyking.com/nl_nl/bms-373m...sec-11-4g.html

If you have the default TX, these servo's will burn within a minute! Only use when you can set the endpoints.

[AggressorBLUE]

Originally Posted by Björn

If you can adjust the throw, the bluebirds from the first page will work as well. They fit the servo saver that comes with the TRX. The ears needed some minor modifications as well to fit.

https://hobbyking.com/nl_nl/bms-373m...sec-11-4g.html

If you have the default TX, these servo's will burn within a minute! Only use when you can set the endpoints.

Any alternatives? These seem to always be out of stock :(

[JatoTheRipper]

Are any of these 100% drop in?

It looks like there's either a size issue, spline count issue, or travel issue (90° vs 120°).

[magic_yeti]

Originally Posted by AggressorBLUE

Any alternatives? These seem to always be out of stock :(

I have the bms-21hv as replacements in my box. 2s planty of Torque and 25t, but they need endpoints adj..
So far the Stock are still alive and working......

Send by my Pixel 2 XL with Tapatalk