1 Epoch 1: Big Build Day
Epoch 1 Total: ~$143
Complete chassis swap with new suspension, servo, and bearings. Alasdair wants a “beetle car” so we’re going with the BUG18 body kit which includes the LCG aluminum chassis. You have to disassemble most of the truck anyway for the chassis swap—might as well do all the internal upgrades while it’s apart.
After this epoch: New beetle body, lower center of gravity, better articulation, reliable waterproof steering, smoother drivetrain, brass weight at the lowest points.
The kids’ job: Sorting screws, handing parts, pressing bearings in, unwrapping the new beetle body.
1.1 Bill of Materials
| Item | Part Number | Source | Price | Notes |
|---|---|---|---|---|
| BUG18 Body with LCG Aluminum Universal Chassis (Black) | INJORA BUG18 | Injora | $55.99 | Beetle body + chassis + bumper + roll cage + rock sliders + magnetic body mount |
| 7KG Waterproof Servo with Mount and Servo Horn | INJS2065 | Injora | $28.98 | IP66 waterproof; handles rain/snow/puddles |
| 59mm Brass & Aluminum Oil Shocks (4-pack) | 4M-63 | Injora | $25.97 | Threaded preload + brass ends for low weight |
| Sealed Bearing Kit (22pcs) | 4M-03 | Injora | $13.98 | Replaces stock bushings |
| Silicone Shock Oil 50WT 710CST 2oz | TLR74013 | Team Losi Racing | $5.99 | Heavy oil for slow, controlled rebound |
| Carbon Fiber Double Decker ESC/Battery/Receiver Tray | Injora | Injora | ~$12 | Clean mounting for electronics |
1.2 Why These Parts
BUG18 body: Alasdair specifically requested a “beetle car”—this body satisfies that request while including the LCG aluminum chassis, bumper, roll cage, rock sliders, and magnetic body mount in one kit.
Why 7kg over 11kg? The INJS2065 is IP66 waterproof (can run in rain or underwater). The 11kg INJS11 has more torque but is NOT waterproof. Michigan weather wins.
7kg servo over 11kg: The INJS2065 is IP66 waterproof (can run in rain or underwater). The 11kg INJS11 has more torque but is NOT waterproof. Given Michigan weather, snow driving, and unpredictable toddler situations, waterproofing was prioritized. 7kg torque is plenty for a TRX-4M even with brass weight upgrades.
59mm brass/aluminum shocks: Brass ends add ~20g of unsprung weight at the lowest point possible, improving stability. Threaded preload adjustment allows tuning. These replace stock shocks that were causing body sag.
50wt/710CST shock oil: Heavier oil = slower rebound = more forgiving suspension. When a toddler drives off a step or tips sideways, the shocks compress and recover slowly and predictably instead of bouncing. This weight is on the heavier side (710CST is closer to 60-70wt equivalent) which is ideal for slow, deliberate crawler movement with a young driver.
Sealed bearing kit: Stock TRX-4M uses bushings, not bearings. Sealed bearings roll smoother, reduce friction, and keep out water/dirt—important for snow and wet conditions.
Carbon fiber double decker tray: Provides clean mounting for the brushless ESC, receiver, and battery. Two-tier design keeps wiring organized and components accessible. Lighter than aluminum alternatives.
1.3 Alasdair’s Tasks (Age 3)
- Handing dad the correct parts when asked
- Pressing bearings into place with supervision (satisfying click!)
- Helping remove the old body and saying goodbye to the Defender
- Unwrapping the new BUG18 beetle body
- First test drive on stock electronics before Epoch 2 parts arrive
1.4 Reference
1.4.1 Alternative Shocks
| Option | Length | Price | Features |
|---|---|---|---|
| Injora 4M-63 (brass) | 59mm | $26 | Threaded preload + brass weight; our pick |
| Injora 4M-42 | 59mm | $25 | Threaded preload; lighter |
| Pro-Line Big Bore Scaler | 60mm | $50 | Three spring rates included |
| Little Guy Racing Parts | 60-62mm | $30-31 | Two spring rates, billet aluminum |
Video Guides:
- TRX-4M LCG Chassis Install — Search for current build videos
- Oil Shock Basics — Understanding preload and damping
Community Discussions:
1.5 Poster
