Futaba S-CD500KS Knuckle Servos - The Next Step In RC Drift Tech
July 24, 2026
I had first heard about this project almost 4 years back now. Yasu and Dobashi from Futaba had paid us a visit and this was something in the works at Futaba at the time. I have been eagerly waiting for these to come to market, and they are finally here!
The Futaba S-CD500KS Knuckle Servo Set is basically a steering system that completely eliminates the onboard servo, servo horn, steering rack, linkages, and knuckles, and places all that where the conventional knuckles used to be.
The Knuckle Servos as it stands right now come as a set of 2. They come with 4 rod ends (Incase you break one I’m assuming), a steel insert (for use with the rod ends), fastening hardware, and an axle. You need to supply the 4 - 5x10x4mm bearings and the wheel hex of your choice. I went with an 8mm wheel hex to keep it consistent with what I already had installed. The rod ends are pretty ridged, I’m not sure what material they are made of, but it reminds me of the plastic graphite parts that used to be more popular back in the day. I’ve hit the wall pretty good with these and they are holding up well.
My Test Setup
I kept contemplating which chassis I should dismantle to install these knuckles on. I finally decided to throw them on my main chassis. That was a tough decision since I have it driving just how I like it. I figured if I wanted to give the Knuckle Servos a fair shot, I needed to run them on a chassis I am very familiar with, and one that has a very high baseline. I’m not looking to test something that is just ok (I won’t even waste your or my time on reviewing junk).
The test chassis is my Azada Avalon with an Acuvance Xarvis XX ESC, Fledge 10T with Fan, S-Bus, Futaba CD701 Servo, and a Futaba 10PXR remote.
I removed the Servo, all the linkages, the entire steering wiper assembly, and the Yokomo knuckles I was running. I replaced the Yokomo knuckles with the Futaba S-CD500KS Knuckle Servos.
Weight Difference
This will all depends on which chassis you have, but on the Azada Avalon the Knuckle Servos reduced the overall weight by 50.2g. 14.2g off the front end.
The install was pretty straight forward. There are 3 threaded holes on the bottom so you can run trail if you wish. On the top instead of a splined shaft like a normal servo has, there is a tab where you run the steel insert through to connect to the rod end. Make sure to coat ears and the insert with a light grease to keep things moving freely. It’s all held together with a small M2 screw and nut. Thread lock should be used to prevent losing the nut.
Setup
The installation was pretty straight forward with the only real concern was how to run the wires. Maybe some sort of recommendation from Futaba would have been helpful, initially I settled on giving enough slack to get full articulation while still staying out of the way of the wheels and suspension. I used a small zip tie to secure it to the upper control arm. When I finally went out to the pits, I saw Jonathan Belda was here. Since he’s been running the Knuckle Servos for a good while now, I figured I would pick his brain on how to run the wires. Our’s were almost identical with his zip tie being maybe 5mm more outboard than mine. After giving some thought to it, I finally settled on using a small amount of glue to bring the wire closer to the pivot point. This would allow the least amount of loose wire to get caught up. This has been working really well for me.
Choosing to run the Futaba S-CD500KS system eliminates a few things I always need to take into consideration on every build:
Length of steering linkage
Which servo horn I will us
Which ball studs and ball cups
Which pickup holes to use on the rack and knuckles
Where to place the servo
Angle of rack (If optional)
Spacers to address bump-steer
Bump-steer?
Since bump-steer is induced by the change in angle of the steering linkage, bump-steer is non-existent when running the S-CD500KS system.
The Other Electronics
Futaba states we need to be running the latest firmware to ensure full access to the various features. The latest is on the Futaba USA website. Once my 10PXR was updated, I was ready to go. I first gave it a try in Normal Mode, and I was surprised how slow the Knuckle Servos were. I am accustomed to having really fast servo settings, so this was a concern for me. I then went to UR mode, and found the same to be true.
The default set up is:
Channel 1 - Steering
Channel 2 - Throttle
Channel 3 - Gyro Gain
Channel 4 - Steering 2
I found I could not access Servo 2 wirelessly set up this way. I tried a few things, but the simplest solution for me was to move things around a bit:
Channel 1 - Steering
Channel 2 - Steering 2
Channel 3 - Throttle
This way I could access both steering servos and my esc wirelessly. Yes, I know there is something missing here. More on that coming up.
Futaba GYD560 Required
Futaba specifies the the Servo Knuckles require the use of the GYD560 Gyro. When the Servo Knuckles are used in conjunction with the GYD560, you get all the benefits of a normal, mechanical steering setup, with the added ability to fine tune the Ackerman with a 12 point curve in addition to the normal GYD560 Gyro functions. This can be a huge advantage over the mechanical steering systems if used correctly since there is always some give and take with every mechanical system.
In addition, you can also use Knuckle Servo Mixing with the Throttle and Brake. This allows you to have preset changes in Toe or adjust the Knuckle Servos to change their movement depending on what your Throttle or Brake are doing at that moment.
The Knuckle Servos are really the next step in infinite adjustability.
Futaba GYD560 Required?
So one thing I kept coming across on everything I had read about the Knuckle Servos was I needed to be on the latest firmware update for the Remote (10PXR) and the GYD560 Gyro. This was an issue for me since I don't run a gyro. In speaking with Skyler from Futaba, he had informed me that they would work with the standard dual servo setup which did not require a gyro.
As it turns out, to access some of the additional assist features the GYD560 is required. For standard (basic) operation the GYD560 is not required.
The functionality of the Knuckle Servos without the use of a Gyro is pretty straight forward. Each Knuckle Servo is treated as a separate servo. So instead of using your linkages to adjust initial Toe, you can trim each one independently. Once the initial Toe is set, (I set it using the Neutral Point of each servo), you can set the endpoint of each Servo Knuckle. Then finally you can select the the Ackerman at lock. The Ackerman is adjusted linearly throughout the steering throw. I really like this as I'm not searching for more assist, but adjustability is nice.
The Real Cost
Listed is what I have replaced with the Knuckle Servos:
$324.00 Servo - Futaba HPS-CD701
$40.00 Knuckles - Yokomo SP Knuckles
$14.00 Servo Horn - Yokomo 17mm
$14.00 x 2 - Titanium Turnbuckle (42mm)
$10.00 Yokomo Ball Cup Set
$7.00 Yokomo Ball Stud Pack
$423.00 - Total for my current steering setup that I replaced.
Price can vary as I run an expensive Servo. Going to a Yokomo SP03D v2 can bring the total down to $294.00
The Futaba S-CD500KS coming in at $330.00ish (I at not sure of the actual price at the time of writing this) seems to be right there where cost is not a huge factor with all things considered.
How Do They Drive
I must admit they were far better than I expected right out of the gate. Just with an eyeball tune, I was definitely in the ballpark. Within 2 laps my chassis was driving as good as it was with my previous setup. Being able to make small adjustments on the fly was amazing. What was even more amazing was being able to try different Ackerman settings back to back. Literally making changes within seconds. Making the smallest of adjustments allowed me to really zero in on what setting I was most happiest with. I adjusted to the slower servo speed pretty quickly and I found the Knuckle Servos to be more than acceptable.
Pros and Cons
The Knuckle Servos are one of those things where I find myself torn. Not on how they work because I feel they are awesome, especially being the first release, so I have no doubt they will only get even better. I do however find myself wondering if we are losing something to technology.
First the Pros
I feel the Knuckle Servos have brought to market the simplest way to achieve really good steering to just about any chassis. They eliminate limitations of some of the less sorted steering systems out there. I believe even non-drift specific chassis can now achieve the steering needed to drift well. Not to mention possibly changing the game where provisions for steering racks and wipers will no longer be needed. This can lead to very different chassis designs and open the doors other possibilities that have not even been explored yet. Being able to optimize Ackerman at different points of the steering throw can prove to be a huge advantage while breaking the limitations of physical linkage.
Now the Cons
This is just my personal opinion, so I hope this doesn't land differently than I am intending. This has nothing to do with how they function, but more so about how they achieve it. I feel in some ways it is removing an important skill everyone who can effectively tune a chassis has had to spend the time to learn.
Learning about the relationship between the steering rack, linkage length, linkage attachment points, knuckle pick up points, the way the rack swings, etc. Learning how all these factors come together to create a well functioning steering setup in my opinion is an invaluable skill. It is kind of a gateway into the reward of tuning.
Being able to achieve this with a few button pushes doesn't force that learning that takes place. Yes, it eliminates a lot of frustration, but it also robs one of the reward of figuring it out as well. I believe there is something to be said for possessing tuning skills, and understanding how to achieve the results you are after.
One thing that I am always interested in on any new chassis is the steering system. So much goes into each design, and each one achieves something a little different. The Knuckle Servos remove the physical limitations, and makes the possibilities endless. Is this a pro or a con? I guess it depends how you view it. Do you really need to learn math if you always have a calculator?
Final Thoughts
The Futaba S-CD500KS Knuckle Servo System is really the next step in tech for RC Drift. It builds upon the advanced features provided by running a high-end Gyro. It can address many limitations of traditional mechanical steering systems, and completes the advanced electronic steering system based on the Futaba GYD560 Gyro. Being UR Mode compatible, you can be assured the response is quick and accurate. Making adjustments to your steering on the fly is really something to be experienced. For someone who likes to tune, that feature alone is amazing. For what Futaba set out to do, I think they more than accomplished it. I hope in the near future we can see a Knuckle Servo set with specs closer to what many of us are used to running, something closer to the performance of the Futaba HPS-CD701. I find myself very curious about how these will integrate into the RC Drift movement. If ultimate performance is the goal, the S-CD500KS Knuckle Servos should settle right in as part of the norm.
