Yeti Jr (RR and TT) Stock Servo Issues and Replacement Options

[monkeyracer]

The other thread was getting cluttered with various topics, so I figured there should be a few threads for the specific topics in that thread so that the information is easier to find.

This first post will hopefully help document the issues users are having with the stock servo, the second post below will be some of the information quoted from the other thread for those that have replaced the servo to show what aftermarket options are known to work.

Please feel free to post in this thread if you have had problems with the stock servo, and what you have done to fix it or what you replaced it with.

There is a different thread for ESC/RX issues, so please keep this thread as OEM servo issues and upgrade/replacements that are known to work.


Stock Servo:
The stock servo seems to be the main weak point and is known to be likely to fail very quickly in these little rigs. Axial provides a warranty, and you can contact them for a replacement if you want to receive the same Tactic servo that came with it.

If you are looking to swap to something better, see post 2 for some examples of what other users have swapped to.

Issues users have reported: (Edited posts to remove irrelevant info and pictures)

Axial didn't splurge on the servo but that is to be expected. TSX106 Micro servo.

Its actually the Metal Gear version based on Axials Web Site
TowerHobbies.com | Tactic Micro Servo Metal Gear 1BB with 25T Adapter

I tightened up the servo saver but it didn't help. That servo just doesn't center well, so it's out.
…
The steering bellcrank is actually one of the least sloppy systems I've seen in a 1/18 and the ball cups are strong too. They did a pretty good job up there.

Ran it for 10 minutes and the servo is toast… That 25oz/in servo is hilariously underpowered and would not self center, even holding the truck off the ground. I'll call Axial tomorrow just to let them know but I won't even ask for a replacement. That stock servo is bad.

my esc burnt up and my servo was basically non functional out of box. It wouldn't center from a left turn at all, even lifted off the ground. I love the machine but the electronics are utter garbage.
I felt like my suspension was binding a little in the front so I took the shocks apart and what not to investigate. Shocks were about half full so I dumped and refilled. Then I noticed that the arms still didn't move freely. After taking off the hinge screw, It was apparent that there was still material on the arm from the parts tree that was creating a very tight fit. After a couple passes with my hobby knife my suspension moves way better, miles better even. The arms have a very tight fit to the bulkhead so some of you guys might wanna look into your suspension and clean up some "casting" material.

well, upgraded to 2s lipo and within 30 seconds esc went up in smoke. stock servo and everything else. ... oh yeah and steering servo is by far the most pathetic i have ever seen.

My son received one from his grandparents today. Steering will not work. It makes a buzzing/crackling sound bit will not move. :x

Yeah my servo sounded like a Skrillex song right before it stopped doing anything at all.

I called and spoke to someone a few minutes ago regarding my lack of steering. They said they would drop a new servo in the mail tomorrow, however, after reading this thread I suspect I should just get a better one.

Drove it twice today. The first time was absolute crap. Steering basically didn't work. I brought it inside, pulled the front wheels, loosened the screws in the c hubs to free up the steering a little, and tried again. It was better but still barely controllable. Steering while stopped doesn't move the wheels at all. Steering while driving on smooth pavement takes a loooong time for the wheels to eventually come around. Steering while driving on rough terrain is slightly better because running over stuff takes weight off the front wheels BUT the ground still has more influence on steering than I do.

Chalk me up for another with burned up servo. It lasted a (stock) battery and a half before it completely seized.

I had binding in my steering too. It was the very tight fitting ball cups. I used a sharp hobby knife to trim some of the inner lip that causes these things to be almost impossibly hard to snap on. I had to do the same thing to my shock links and trim off excess mold material on my A-arms.

Well, like the rest, my electronics crapped out the second after i put a lipo in it. I never even hit the throttle. The second i touched the steering it went down unresponsive.

Hey everyone, I've the same issues as everyone else. Crap electronics.

Just arrived got a run out of it so far with stock electronic and it's quite zippy , servo sucks.

Update ...Two min with lipo and steering servo don't work just makes noise…

I have mine for about a week, and besides the servo which is almost crap, and I understand why, everything else works fine.

I have two packs through the rr without problem. The servo is week and makes the truck hard to steer, but everything still works.

I started off running a pack last night in my garage and the steering was fine, then I ran out into the driveway where it was 40 degrees and raining - after a few minutes the steering started to get stiff again. I then went down into my basement where everything returned to normal.

So, basically, the stock servo is very weak, the servo saver is weak, and you will likely kill the stock servo with 2S LiPo (according to the reports above).
Axial seems to be good about replacing it if it fails, but only with the same servo. See post #2 for some servos other users have reported to work.

 

[monkeyracer]

If you are looking to replace the stock servo with something else, Axial included some parts in the box to be able to do so relatively easily.
There are various servo savers for different servo splines, and a set of servo mounts for servos that are larger than the stock size.

There are reports of users replacing the servo on the stock 2-in-1 ESC/RX combo, but also reports of it not working. Most recommend replacing the entire electronics set-up. (That means new ESC, Receiver, Servo, and possibly motor and battery as well!)

Here are some reports of other servos that may work:

Hitec HS-65MG dropped right in. They included 21T, 23T, 24T and 25T servo saver adapters. Notice anything missing there? Yep, the 22T for Hitecs. Used a standard horn instead for now. I'll look for a Kimbrough at the LHS's on Friday. Returns to center every time now.

The 225 fits, barely. 54oz/in at 4.8v, 67 at 6v. Used losi mrc servo mounts. Filed slot on bottom of the chassis a hair. No room for the saver but on my losi minis usually a steering link will pop off the ball stud in a bad crash before anything breaks.

And here is the Spektrum servo I'm using for $11. I can't tell you the specs because Spektrum doesn't even know them. All I know is, it's bigger, stronger, waterproof and it fits…. Still looking for that perfect servo.

Alright, got the new servo installed. Hitec HS-85MG, 49oz/in at 6v so almost double stock torque, the size specs are 29x13x30mm, it's a 23 spline output, and it was cheap. Picked it up at the LHS for $22. This servo fits like it was made for the Yeti JR., with just a tiny bit of room everywhere so there's no contact on the center shaft or anywhere else. If you're looking at replacement servos, stay as close as you can to these dimensions for a good fit. There's maybe another 2-3 millimeters on the back side before hitting the center shaft but there's only a millimeter or less of available width before needing to modify the chassis pan. The Hitec HS-5085MG is good for another 10oz/in of torque for a total of 60oz/in at 6v and is almost the exact same size but the LHS didn't have one. If this one fails, I'll move up to the 5085. Here it is all tucked in and ready to go. There was no way to fit the servo saver without cutting the side of the chassis off so I need to find a way to attach it to the steering rack now. I'll post up my solution as soon as I figure it out.

Chalk me up for another with burned up servo. It lasted a (stock) battery and a half before it completely seized. The only micro servos that I had on hand are Hitec HS-5087MH. It was simple to install. I used a standard aluminum servo horn and mystery servo mounts. Other than bench testing I have not ran with the new servo. I am thinking of installing a BEC to maybe take a load off the ESC/Receiver. …FYI, the stock ESC feeds the servo 5 Volts.

Also put the hitec hs-85 mg. Beastly steering with beastly power

Got the 1711mg installed:
Fits REALLY well in there.
Good strong servo that doesn't cost alot:
Pololu - $12
Aloft Hobbies - $7.30

Double the torque of the stock servo (49oz-in @ 6v). Also the 23 spline servo saver that comes in the kit works, but I didn't want a servo saver for my build.
You don't have to spend a lot to get better stuff installed...
By the way, I tried this on the stock RX/ESC and it didn't like it. I have a feeling there is something weird about using other servos on the 2-in-1 unit that comes with these.

FWIW I just put the HS-65MG in and ran a pack through it with no issues. Steering is pretty good now.

Hs-5245mg- left over from a dig setup i removed… With 61oz. @ 4.8v the steering is excellent. This thing is an absolute blast to drive now.

Already replaced the steering servo with a HS-85 and got a 2S battery for it. Now the rest of the stuff burned out. I need to get an esc and receiver fir it

Ok, steering is finished. I used a Losi servo arm with my HS-85 servo and was able to reuse the stock ball end on the horn and the stock drag link. There was more than enough steering throw so I had to dial back about 40% on the steering rate. Everything swings lock to lock with no contact or interference anywhere and the servo has enough torque to push steer the front of the truck so I'm really happy with the results.

I got the HS-85MG installed tonight with a Dynamite servo arm. Also has the larger holes so the ball joint dropped right in. Wow, the truck turns great now. I decided to cut off the motor plugs and soldered them direct to the motor. I'm not sure if I missed it in the thread, but to get the HS-85mg installed with the stock ESC case, I had to use a cut off wheel/Dremel off the servo ear from the ESC case to get it to fit as the servo is wider. No problem. The ear I cut off I still used to mount the servo.

So I broke my micro Traxxas servo ..Gear stripped lol
Got pissed off and managed to install full size servo with 126 torque haha and now the truck is fun and runs for a long time on a 2000 ,2s 35c.

I replaced the stock junk servo with the hitec HS-85. I didn't have a screw in the right size that was long enough to be able to put the servo saver back on the hitec servo so I just used an aluminum servo arm that I had laying around.

Apparently the answer is something with the dimensions of 22.8X12.0X25.4, but with more than Torque(@6.0V oz-in): 30.6. When I purchased a Yeti Jr. Trophy last night at my local hobby shop, these are the specifications of the best micro server they had available - a Savox 253. It does a marginally better job than the stock servo at centering the wheels. I'm going to need something more powerful.

Keep in mind that most of the above users replaced the ESC and Receiver along with the Servo, and it may be something for you to consider as well.

 

[TrilloThrillo110]

Great idea! If anyone has much info on fitting a fullsize servo (Poprivet), it would be much appreciated! Looks like people just servo tape them down?

 

[monkeyracer]

Great idea! If anyone has much info on fitting a fullsize servo (Poprivet), it would be much appreciated! Looks like people just servo tape them down?

I think EXIwolfman has a standard servo mounted vertically on some spacers. I believe he drilled new holes in the chassis tub and used M3 screws to hold it all in.
There may be other ways to stuff one in, and I'd love to see it done.

 

[84yoda]

Hitec 225mg with losi mrc steering post. 67oz, .11sec at 6v.

 

[svt923]

I just installed a Gotek DC2124T in my truck; 80 oz and .12 at 6V. It is the same size as the stock servo but the mounting ears are moved up higher.

I'll get a driving report as soon as I can get some soldering done in my garage without freezing.

Goteck vs stock servo: just a hair taller but much different mounting ears.

Installed in the truck. I used the servo mounts and a couple of spacers from the spare parts plus a couple M2.5x10 screws for mounting.

 

[colbynobo]

Great idea! If anyone has much info on fitting a fullsize servo (Poprivet), it would be much appreciated! Looks like people just servo tape them down?

I would also love to see a write up from one of the full-size servo installations. I killed the gears in a 5 day old Savox Sh253 and am getting ready to replace it with a Hitec 5085. I have my doubts as to whether it'll last very long or if the 30 more ounces of torque will really make that much of a difference. Plus, with the announcement of the Spektrum S6240 it looks like we may start seeing more one-piece servo/receivers on the market. That'll make it easier to cram stuff into smaller chassis.

 

[andy551]

My stock servos gears stripped, and I replaced it with a Savox sh0255mg. Huge difference in performance. The profile and size is nearly identical to stock and the stock servo saver fit. It's plenty fast and the power greatly increased over the stock unit. Specs- .13 and 54oz at 6v. I swapped to a Hobbywing 1080 esc (internal BEC set @ 6v) and am using a Spektrum srs4210 reciever with AVC. Using a 2200 2s the thing is a blast.

 

[DenisLM]

anyone tried the Savox SW0250MG ?
Also it uses the 21t servo horn that I cant find anywhere...

 

[Fookison]

anyone tried the Savox SW0250MG ?
Also it uses the 21t servo horn that I cant find anywhere...

Try eBay for the metal 21t servo horn.


Sent from my iPad using Tapatalk

 

[NVCrawler]

anyone tried the Savox SW0250MG ?
Also it uses the 21t servo horn that I cant find anywhere...

its to long to fit like the stock one. That is the new road block I am at with the yeti jr

 

[DenisLM]

its to long to fit like the stock one. That is the new road block I am at with the yeti jr

mine should arrive today and I'll try tonight.
Thinking about use it upright if didn't fit in stock position.

 

[NVCrawler]

mine should arrive today and I'll try tonight.
Thinking about use it upright if didn't fit in stock position.

I was getting frustrated with it at the time I found your post and replied to it. Looking at it if you use the axial servo mounts in your parts bag you will need to make spacers in between the servo and the mounts to get the back end of the servo off the axle shaft. I will have to work on it later but that should do the trick

 

[Brake Weight]

I put one of these in: JX PDI-1171MG 17g Metal Gear Core Motor Micro Analog Servo for RC Models Sale - Banggood.com

So far so good without a servo saver.

 

[DenisLM]

I was getting frustrated with it at the time I found your post and replied to it. Looking at it if you use the axial servo mounts in your parts bag you will need to make spacers in between the servo and the mounts to get the back end of the servo off the axle shaft. I will have to work on it later but that should do the trick

yeah, definitely not a plug and play but with some dremel it fits just right.

 

[Yeti guy]

I striped out my spur gear. Where can I get a steel one and a different pinion?

 

[sneaky_pete]

I just got a HS-85 servo to replace the stock and am having some trouble installing, any suggestions or pictures, thanks in advance