6 Epoch 6: Heavy Metal
Epoch 6 Total: ~$60-90
Adding brass to the lowest points for tip resistance and traction. The truck already crawls well after Epochs 1-5—this is for when you want to push it harder on technical terrain or compete with larger rigs at the rock park.
After this epoch: Much harder to tip over, better traction (weight on tires), competes with bigger rigs.
The kids’ job: Feeling the weight difference, stability testing.
6.1 Bill of Materials
| Item | Part Number | Source | Est. Cost | Notes |
|---|---|---|---|---|
| Brass Steering Knuckles | 4M-100-101 | Injora | $27 | 11g/pc at wheel hubs |
| Brass Diff Covers | 4M-01 | Injora | $17 | 11g/pc on axles |
| Brass Skid Plate / Trans Mount | 4M-67 | Injora | $19 | 53g center weight |
Alternative: The Injora Brass Upgrade Bundle ($57) includes multiple brass parts at a discount.
6.2 Q&A
Why brass instead of steel or lead?
Brass is dense (heavier than aluminum or steel), corrosion-resistant, and machinable. Lead is denser but toxic and harder to work with. Brass is the standard for RC crawler weights.
Where should weight go first?
Lowest and outermost. Steering knuckles and diff covers are at the lowest points on the truck. The transmission mount adds center weight. Avoid adding weight high up (roof rack weights actually hurt stability).
How much weight is too much?
The TRX-4M can handle 150-200g of added brass without stressing the drivetrain. Beyond that you may need to upgrade motor torque.
Video Guides:
- TRX-4M Brass Weight Comparison — Before/after stability tests
- Portal Cover Install — Axle disassembly
Community Discussions: