Chassis and Top Plate Assembly Guide

Parts Preparation

• Empty SRX8 chassis.
  Empty SRX8 chassis

• All components needed for one car.
  Full set of required components

• Power harnesses are unified to XT-60.
  
  LiDAR and BEC inputs/outputs converted to XT-60
  
  XT-60 adapters for servo 3-pin and NUC barrel jack

• The wiring diagram is for understanding only; do not pre-assemble yet.
  Overall wiring diagram

Lower Plate Assembly

Mounting the VESC

We machined additional holes in the aluminum lower plate for VESC mounting and positioned the VESC using those holes.
Machined holes for VESC mounting

To prevent the top cover from bending, washers were added so bolts/nuts are not over-tightened.
VESC fastened with washers

After mounting, we confirmed the driveshaft travel does not interfere with the VESC.

Battery Velcro Strap Mount

Using existing holes, we fixed a Velcro strap so the battery can be secured later.
Velcro strap mounted to the lower plate

Mounting the Servo Motor

A support piece removes the height gap, and the servo cable is routed inward.
Servo support and mounting example

Center the servo first, then attach the horn. See /unicorn-racing/posts/servo-horn-after-alignment/ for details.

Motor Installation

Mount the DC motor after setting the gap between the pinion gear and the drivetrain gear.
Pinion-to-driveshaft gear gap

Gap adjustment steps: /unicorn-racing/posts/motor-pinion-gear-gap-adjustment/.

Standoff Nuts

Once the lower assembly is done, install standoff nuts to support the top plate.
Standoff nuts installed

Top Plate Assembly

Mounting the IMU

Attach the IMU to the underside of the top plate first.
IMU mounted under the top plate

Mounting the NUC

Align the NUC with the two mounting holes and use a nut/washer stack to prevent the bottom from lifting.
NUC mounting with nut/washer stack

Mounting the LiDAR

Finally, secure the LiDAR on the top plate.
LiDAR mounted on the top plate

Wrap-up

Standardizing power connectors, checking mechanical interference, and setting proper clamping force are all critical for this assembly. Washers protected the VESC housing, and precise alignment/gaps were set for the servo and motor before tightening. After standoffs and top plate installation, finish with tidy cable management to prevent vibration or disconnection during driving.