Buying guides
First upgrades: SCX10 & TRX-4.
The right order, the right parts, no wasted money.
You've driven your SCX10 III or TRX-4 stock for a month and you can feel what's holding it back. Good — that means you're ready to upgrade with purpose instead of guessing. Here's the order that delivers the most performance per dollar, with the exact parts and verified prices.
Stage 1: Tires — the transformation
Stock RTR tires are built for cost, not grip. The right tires are worth more than every other upgrade combined — softer compound, better tread, properly sized for your terrain. This is the one upgrade that's never wrong.
JConcepts Ruptures 1.9 — $28.50
The comp-proven benchmark. Tall, soft, and relentless on rock — the tire everything else gets measured against. If you buy one upgrade this year, make it this one.
Pro-Line BFG KX 1.9 — $24.99
Pro-Line's all-rounder at $24.99 — slightly more trail-mannered than the Ruptures, excellent on mixed surfaces. The smart pick if your driving is half trail, half rock.
JConcepts-style 1.9" crawler tires 123x49.5mm (4) — $21.99
The budget disruptor: a full set of four soft-rubber 1.9s in the classic JConcepts tread pattern for $21.99 (AliExpress). Not Ruptures, but triple the stock tire for a third of the premium price. Perfect for a second set or a beater truck.
Pro tip: vent your tires and tune foams before buying anything else. A $28.50 tire with tuned foams outperforms a $60 tire setup that's sealed and over-stuffed.
Stage 2: Brass weight — down low
Crawlers want weight as low as possible. Brass portal covers, diff covers, and knuckles add mass exactly where it helps — at the axles — dropping your center of gravity without stressing the drivetrain. Both the SCX10 III and TRX-4 are light up high stock; brass fixes that.
INJORA brass diff covers — from $19.99
The cheapest meaningful brass: front and rear diff covers from $19.99. Bolt-on, no setup required, immediately noticeable on side-hills.
INJORA brass skid plates — from $18.99
Transmission skid plates in brass from $18.99 — low, central weight plus genuine skid protection. Two jobs, one part.
INJORA steel driveshafts — $8.99
Not brass, but the $8.99 steel driveshafts eliminate the flex and slop of stock plastic shafts. Cheap durability that pays for itself the first time a plastic shaft twists.
Aim for 60/40 front weight bias — front brass first, then rear. All the weight in the world won't help if it's in the wrong place.
Stage 3: Steering servo — authority
Stock RTR servos are the weakest link once you add grip and weight. A stronger servo doesn't just turn bigger tires — it holds lines under load, where stock servos fade and blow through.
Budget king: GXservo DS3235MG 35KG — $15.49
35kg of torque for $15.49 (Banggood). The best dollars-per-kilogram in crawling — a massive upgrade over any stock RTR servo for the price of a pizza.
Smart mid-range: INJORA INJS235 35KG brushless — $33.99
Brushless efficiency and 35kg at $33.99 direct from INJORA. Cooler running, longer lasting, and quieter than brushed equivalents. The servo we'd buy for our own trucks.
Servo winch bonus: INJORA 25T spool kit — $3.99
While you're in there: the $3.99 25T winch spool kit turns any spare servo into a working winch. Scale points and genuine recovery capability for four bucks.
Don't forget a 25T aluminum servo horn ($3.99–$4.99) — the stock plastic horn will strip the first time your new servo actually works hard.
Stage 4: When you're ready for more
Aluminum links ($13.29+ on clearance) replace flexy plastic with precision — better geometry consistency on technical lines. Shocks come next: threaded aluminum bodies let you actually tune damping instead of guessing. Bearings ($12.99–$13.99 kits) smooth out the whole drivetrain.
Motor/ESC last. The stock brushed systems are fine until everything else is dialed. When you're ready, the Hobbywing Fusion 2-in-1 brushless systems are the definitive crawler power upgrade — our brushless motor guide covers the lineup.
The $75 stage-one build
Here's the whole thing: Ruptures ($28.50) + brass diff covers ($19.99) + GXservo ($15.49) + aluminum servo horn ($4.99) = $68.97. That's a truck that will hang with rigs costing three times as much on 90% of terrain. Everything after this is refinement — this is the transformation.
All prices verified — browse SCX10 parts and TRX-4 parts for today's deals.
Lowest Cost Build Sheet
The $75 build above has exactly one slot with genuine fat in it: the tire. Swap the Ruptures for stage 1's own budget pick and keep everything else:
JConcepts-style 1.9" tires (4) ($21.99) + brass diff covers ($19.99) + GXservo DS3235MG ($15.49) + aluminum servo horn ($4.99) = $62.46.
Framed honestly: the budget 1.9s are genuinely capable cheap tires, and on mud and loose trail they give up little. On clean rock the Ruptures is still the better tire — this sheet is the floor, not a claim that $62.46 equals $68.97. The other three slots were already the cheapest parts that do their job; there is nothing left to cut without cutting function.
Upgrade FAQ
What is the first upgrade I should do to my SCX10 or TRX-4?
Tires. The stock tires on both the SCX10 III and TRX-4 are the single biggest performance limiter — a $28.50 set of JConcepts Ruptures 1.9 transforms either truck more than any other single mod. Everything else is fine-tuning; tires are transformation.
What upgrades do I need for a TRX-4?
In order: tires ($28.50 Ruptures), brass portal covers and diff covers for low weight ($17–$33), a stronger steering servo ($15.49–$33.99), then aluminum links and shocks as you find the limits. The TRX-4's stock electronics are decent — don't touch them until the chassis is dialed.
What upgrades do I need for an SCX10 III?
Same order as the TRX-4: tires first, brass weight second, servo third. The SCX10 III benefits enormously from brass knuckles and diff covers — the stock truck is light up high. A $15.49 GXservo DS3235MG is the budget servo king; the $33.99 INJORA INJS235 brushless is the smart mid-range buy.
How much should I spend upgrading my first crawler?
$60–$100 covers the meaningful stage-one build: tires (around $28.50), brass knuckles or diff covers ($17–$33), and optionally a servo ($15.49). That's 80% of the performance gain. Beyond that you're chasing the last 20% — fun, but not necessary.
Should I upgrade the motor and ESC first?
No — drive the stock power system until you've done tires, weight, and servo. The stock brushed systems in the SCX10 III and TRX-4 are perfectly capable; most beginners can't out-drive them. When you're ready, a Hobbywing Fusion 2-in-1 brushless system is the definitive upgrade.
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