Steering servo upgrade
 

Just got the TRX4 and before I run it I'm going to do a servo swap. Few questions first.
1. What exactly is a BEC and is it needed?
2. What is a good or the popular servo being used in the TRX4? I've read about Savox, Power Hd, HiTech. I'd like to stay waterproof.
3. Are the upgraded servos a direct drop in or is there modifications needed for a proper fit?

Re: Steering servo upgrade
 

All Standard servos should fit well, no need modifications. I have Savox waterproof servo and they are quite reliable in my humble opinion. You need BEC if your rig power by S3 power and high torque digital servo. BEC will help you to regulate right voltage to your servo or you can run 12v servo direct power from your 3s battery.


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Re: Steering servo upgrade
 

My first upgrade was changing to a powerhd 20kg waterproof servo, which is a great and cheap improvement. But after upgrading with all the brass to get weight down low, i mentioned that 20kg are getting at their limit, so i changed to an HH HV500v2 which can run direct from 2s and unofficially 3s :mrgreen: so no need for a bec. also if you use the powerhd the internal handled it well.
if you change to a high torque servo you will/have to use a bec, cause the internal bec of stock esc is crap rated only 1A.
many good option for servos today just depending on your budget:
powerhd, savöx with the ip67 rated line, promodeller, hitec, holmes ........

Re: Steering servo upgrade
 

here are a couple links to what you'll need

servo
SW-1210SG "Tall" Waterproof Aluminum Case Digital Steel Gear Servo by Savox

servo extension lead
Heavy Duty 15cm (6") Servo Extension Lead (Male/Female) by ProTek RC

aluminum servo horn
Hot Racing TRXF25SH06 Aluminum Servo Horn 25t TRX-4 (Stock)

bec
10 Amp Adjustable BEC by Castle Creations

as for the servo i linked above, it's just a reccomendation. i would go no lower than 250 oz/in @6volts. The bec will need to be soldered to the battery connection and the thin wires will plug into one of the receivers unused ch.1 ports ***do not plug into any of the telemetry ports. that bec i linked to is not water proof but all everyone does is squirt silicone into each end of the shrink wrap. they do offer a waterproof one but its double the money. the trx4 oem servo horn has a 22mm c2c measurement, the one i linked to is also a 22mm c2c and the spline is a 25t which will work great on savox servos. most servos do not come with long wires so you'll need an extension in order to plug it into a receiver . I would also get the bec programed to 6 volts by your local hobby store. i think they come preset 5.1v ?

some servos are a direct fit some are not i know my savox i took a hobby file to one side of the mounting holes and made then straight due to the weird mounting locating pins on the trx4 mount. also what ever servo you get make sure the servo horn spline count matches the servo spline count.
one more thing after upgrading to a better and stronger servo, reset your end points so you do not damage the servo or start breaking steering components.

Re: Steering servo upgrade
 

The guy at my HS sold me and installed a Hitec to replace the original one without having to add any thing else. It's waterproof model hs-8335sh.

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Some good suggestions, thanks guys!

Just ordered the Power HD 23kg and 6" extension lead and the HR servo horn.

Re: Steering servo upgrade
 

i have had 0 issues no bec and a savox 1283 sg.. yeah i did need a 3in extension

Re: Steering servo upgrade
 

I've been looking into this for a while now, my stock servo won't center worth a damn. Thanks for the info everyone. "thumbsup" Skyjacker56, I've been interested in a Savox too. What did you do for a steering horn?

Re: Steering servo upgrade
 

Servo horn, Hot Racing or SSD.

Re: Steering servo upgrade
 

might try removing the horn and then power up the trx, then set the steering trim knob to "0". make sure the wheels are straight ahead and then press the horn back onto the servo. power off the trx then tighten the horn. if that still does not fix it you might have to adjust the steering sub-trim in the programming menu (pages 34-35) in the manual....while in there might reset the endpoints too.

https://traxxas.com/sites/default/fi...-OM-EN-R03.pdf

when it comes time to upgrade the servo and you do not play in deep water i recommend the savox sc-1230sg 500 oz/in @ 6v ! the first thing i did was set the end points because that beast will break stuff. although not the blue waterproof model all savox servos are splash proof.
https://www.hobbytown.com/sc1230sg-t...1230sg/p234358

let us know if you resolve this.

Re: Steering servo upgrade
 

I got myself a Holmes Hobbies SHV500 servo. It can run directly of a 3S battery and has a JST plug. The TRX4 ESC provides the same plug for the light system, so if you do not use it (the light system) you can plug in the servo there and do not need an additional BEC.

Re: Steering servo upgrade
 

I actually started with that, I did the same thing to sync the dual steering servos on my old Summit. Sadly that didn't fix the problem, and it let me check that the horn isn't stripped. :cry: I didn't do the endpoints but the servo doesn't seem to bind the linkage at full turn.

No, my problem is that I can center the steering, then go play for a few minutes and it wanders off center. If I turn the wheels left more often, the servo is off to the left; same for the right. And yes, I've picked the truck up to make sure it isn't the tires not turning.

I pulled the stock servo apart and sprayed the pot with contact cleaner and that didn't help either. :roll: I bit the bullet and bought a Castle 10 amp BEC, going to try that before I break down and buy a new servo.

I'll try to get the BEC wired in and report back later this week.

Re: Steering servo upgrade
 

Parts are in. Just waiting on the Castle BEC.
http://i1039.photobucket.com/albums/...pslfzxktsx.jpg

Re: Steering servo upgrade
 

The Power HD 23kg servo is much better than stock but as was mentioned earlier, you may find the steering torque lacking if you start adding weight. I ran that same servo for a while and even stock I had times where it stalled out trying to keep the wheels pointed on the line I wanted.

Re: Steering servo upgrade
 

Did you run a BEC with the Power HD servo?

Re: Steering servo upgrade
 

I run a Mamba X, the internal BEC has plenty of power.

Re: Steering servo upgrade
 

So I didn't get to the BEC yet. (Infants make planning free time impossible.) BUT!!

I did set my endpoints and hit the trail to see if that fixed my problem. :D
And... it made no difference at all. :sad: I ran a second, smaller 2 cell pack after my main discharged and found the servo was worse than the first pack! Turns out the second pack was at storage voltage, not fully charged. But based on that, I'm pretty sure that my problem specifically is voltage drop/brownouts. It only stands to reason that if a smaller capacity pack with less charge amplifies the problem, it's based on not getting enough amperage to the receiver.

I am going to install the Castle BEC I mentioned and do a before-and-after on the voltage at the receiver. I'll also try to get my truck out after with a run-down battery and test the results. "thumbsup"

Re: Steering servo upgrade
 

Leave the receiver out of the equation. It's not the problem. The new servo needs the additional power so, you run the BEC power directly to the servo. Holmes has a bypass adapter if you prefer not to solder. Also, the Castle 2.0 waterproof BEC has 2 sets of power out wires so you can power a new servo and lighting without involving the receiver.

https://holmeshobbies.com/electronic...s-adapter.html

By running a BEC this way, you can set the voltage to 7.0v and not burn up the receiver.

Re: Steering servo upgrade
 

If your running a quicrun wp 1080 do you need a bec?

Re: Steering servo upgrade
 

Going off of the rated specs, that Savox 1210sg has a stall current of 6 amps, the WP1080's BEC is 3 amps, so ideally, yes you'd still want to run an external BEC....

...but in actuality, I've never experienced a brown out from the 1080, even running a much more demanding servo (2290) so I'd personally take that risk.