Metal Gear Replacement Servos, Turnigy TGY-50090M

I’ve found a drop in metal gear replacement for Hexy’s servos, the Turnigy TGY-50090M.

I’ve successfully replaced all the servos in the back two legs and they’re working great. Unfortunately I didn’t order enough to replace everything because I wasn’t 100% sure they would fit, so I have to wait for the next shipment to replace the rest.

It was a little tedious replacing the servos. The gear is a little longer in these servos so you need to install the servo horns that come with them instead of using the horns from the original SG92R servos. Otherwise, the servos seem to be an exact match.

These servos give more torque and faster movement, especially at 6v. Based on my experience so far, I would highly recommend them. I am getting much less jitter and the increased torque is a noticeable improvement.

You can get them on Hobby King for $4.99/ea: … duct=27569

Awesome! I ordered some myself, and I’m talking to some of my suppliers about finding these. I’m going to see if I can swap out the metal gears in these with those in the old servos. If so, I’ll order a bunch of replacement gears as well.

Ordered 20 of them.
Thanks for sharing the find!

That’s quite exciting.

Would it be feasible to replace the gears, considering I have no experience in this area, or better to simply buy the complete servo? And with cost in mind, which joints would benefit most from an upgrade?

Based on my own experience and things Joe has posted in the past, I’d guess the 6 hip joints would be the most necessary replacements. Those servos have the longest moment arms/most weight attached to them, and I don’t think I’ve even broken 1 foot or thigh servo yet.

I can say for sure that the neck servo is pretty lightly loaded. I’m using a gimpy replacement gear set from a different brand of servo there, and it works perfectly, but in any other joint it can’t manage to hold it’s position well enough to work.

The thigh servo is usually the one that’s broken on us. If the legs are touching the ground, the hips usually don’t see much force on them (i.e. they’re not the ones trying to pick the robot up.

I ordered these before this was even posted to try if they fit and i can definatly confirm that they fit 100%, i just got 6 today.

Exciting enough to get make me create an account. 5 bucks each is cheap, but I wonder how low we could go as a big bulk purchase? I just finished my little blue monster, and he and I are going to have lots of fun with the cat. As a lifelong rc flyer, I knew the second I saw the splines on the servos that I was going to be needing new ones. These have got to be the cheapest micro servos I’ve ever seen. Not complaining at this price point, but I already know that I’m gonna break them, two were hosed out of the box… Kids, Cats, and an oddly curious 92 year old grandmother put the life span of the others in serious jeopardy.

I’m in for at least 20 if a bulk buy gets organized. Probably more for my other projects.

Excellent find. I haven’t yet taken delivery of a Hexy, but I was excited enough to order 20 in anticipation of it’s arrival.

HobbyKing has quoted me up to 45 days delivery to the UK, though. Just so you know…

Do the horns that come with the new servos fit directly, or did you have to create new holes in them?

This is wonderful news. Thank you for sharing. I think I’ll grab 6 to replace the hips before they have a chance to break. Later, if there’s news of a bulk buy, I’m in for a full set. :slight_smile:

We’re trying to get in contact with the factory for bulk purchasing, but they’re pretty non-responsive. We’ll be sure to post when we do get an order in, though.

I’ve got 12 on the way - planning on swapping out the hips and thighs. Have people that made the switch found the new servo horns align ok with the holes on the hexy?

I have a hexy with 18 Turnigy TGY-50090M servos now and I noticed that they all don’t center on a 1.5ms pulse. Both with my custom electronics and servotor32 they center to approx. 45 degrees off center. I haven’t tested what the -90, 0 and +90 pulse lengths are, but am I the only one seeing this?

Hello koenkooi,

different servos have different puls-times. The normal plastic servos of the hexy have a puls-time from 450-2450 µs. See here:
That means, if you give that servo a puls of 450µs it will go to the very left, with a puls of 2450µs it will go to the very right and with a puls of about 1450µs it will go to the center position.

If you use an other servo, the puls time can be different and a puls of 1450µs will not center the servo. I did not find any technical specification for the TGY-50090M servo but i ordered them already. I will check the puls times when they arrive.

Greetings, Arcanix

My rebuild with the metal gear servos went fairly smoothly: … ology.aspx


I currently don’t own a Hexy, but am seriously looking into tinkering around with robotics. With the discovery of these metal gear servos, would it be smart to buy these outright and just order the hardware for Hexy separate instead of the full kit? Seeing all the problems people are having with their standard servos, I wonder if this would be a better option. It would be a little more upfront, but definitely less than buying a full kit plus the new servos. What is the consensus on these servos so far from those of you who have them installed already?

This forum may be giving the impression that the servo problem is worse than it really is. With some care during construction, I’ve not had a single servo fail. Of course, your mileage may vary. Usually forums don’t proportionately represent the people that don’t have problems.

I’ve lost three in just normal usage - legs getting caught during moves, etc. My metal servos arrived today, so hopefully that will be a problem of the past!

Are there any settings I need to make in the software for these servos? I saw someone earlier saying that they didn’t center correctly.