04 ‐ Servo Motor & Linear Rail - chrisjameschamp/DIY-Active-Pedal-Design GitHub Wiki
Servo Motor Modifications
The servo motor comes with pre-attached headers to accommodate included cables, which is great — if you didn’t care about space efficiency. Since we do, we’ll be modifying the servo by removing the unused headers and adding only the cables we need, routed in a more compact path.
Disassembly
Start by removing the six Phillips head screws from the rear of the servo motor.
Once the screws are removed, the rear housing should slide off. You might feel some resistance — this is usually due to the thermal pads sticking to internal components. Apply gentle, even pressure to remove the housing.
There’s also a sticker on the internal header cover that may stick to the rear housing. If it does, gently lift the edge of the sticker to help release it.
With the rear housing removed, you’ll find two more Phillips head screws securing the rear PCB (circled in pink above). Go ahead and remove those.
Next, carefully separate the rear PCB from the side PCB. The two are connected via header pins, and the side PCB slots into the rear PCB.
Gently wiggle or slide them apart — no excessive force should be needed. Once separated, remove the side PCB from its housing and set the rest of the servo motor aside.
Wiring
Grab your soldering iron and a solder sucker or similar tool.
It may also help to use solder flux. Apply a small amount to the joints circled in pink in the image below — there are 13 in total.
To remove the solder:
- Heat the solder joint with your iron until it flows.
- Use the solder sucker to remove it.
- Repeat as needed from different angles.
Once all solder is removed, the headers should lift off. Use pliers if needed, but avoid pulling too hard — lifting a pad will ruin the board.
Now attach your new wires to the pads where the headers were.
Use JST-XH connectors and some included 24 AWG wire, plus two 16 AWG wires for power. Strip a small amount off the end of each wire — for 16 AWG, you may need to remove a few strands to fit the holes.
Hold each wire in place, ensure no stray strands are sticking out, and solder from the underside.
Wiring Pinout
Power Wires
- 16 AWG Red – Positive (V+)
- 16 AWG Black – Negative (V-)
Ribbon Cable 1 (3-pin)
- Brown – TX
- Green – GND
- Blue – RX
Ribbon Cable 2 (4-pin)
- White – Pul+
- Orange – Pul-
- Gray – Dir+
- Purple – Dir-
Now drill a hole in the center of the side housing (with the PCB removed). The hole should fit all cables — ½ inch (12.7 mm) works well. A step drill bit makes this easy.
Tip: Add hot glue over the solder joints to relieve stress on the wires. This helps prevent mechanical strain from damaging the board.
Reassembly
Feed the wires through the hole you drilled and carefully slide the side PCB back into the side housing. It should go in without force.
Now connect the rear PCB to the side PCB. The header pins and notches should align easily.
Reattach the two PCB screws and align the housing cover. It should snap back into place using the LED cutouts as guides.
Finally, reinstall the rear cover and fasten the six screws you removed earlier.
Congrats! You've successfully modified your servo motor. Now let’s attach it to the linear rail.
Attaching the Servo Motor to the Rail
Grab your rail from JLC MC — either JKK60-5-P-150-A1-F4-M (recommended for brake pedals) or JKK60-10 for throttle/clutch.
Start by loosening the screw on the coupling so it can slide off the shaft.
If it gets stuck on the motor adapter bracket, you’ll need to remove that too — there are four screws holding it to the rail.
Now slide the coupling onto the servo shaft. It won’t seat fully, just make sure an equal amount of both shafts are inserted into it.
Reattach the adapter bracket to the rail, then slide the servo motor into place. If needed, loosen the coupling slightly to help it pass through the bracket.
Check the orientation: the top of the servo (with the side PCB housing) should align with the bottom of the linear rail.
Secure the servo motor using four M4x18 Socket Head Screws.
✅ Boom! You’ve successfully modified, wired, and assembled the Servo Motor and Linear Rail Assembly.