Your First 5 Crawler Upgrades (And What Order to Do Them)

Every new crawler owner goes through the same progression. You run the stock truck for a while, it’s genuinely fun, and then you start noticing things. The wheels slip when you expect grip. The truck tilts on off-camber terrain and recovery feels awkward. You wonder if better tires would fix it, or if it’s the servo, or maybe the whole thing is just doing what it’s supposed to do.

Usually it’s not doing what it could do. And the good news is that five pretty affordable mods will take your stock SCX24 or TRX4M from “fun right out of the box” to “legitimately capable rig” — without rebuilding the whole truck.

Here’s what to do first, in order, and why.

1. Brass Weight (Start Here)

This is the single most impactful improvement per dollar on almost any micro crawler. More so than tires, more so than a servo — brass weight changes how the truck feels on terrain in a way that’s immediately obvious.

In crawling, center of gravity is everything. A lower CG means the truck sits flatter on off-camber terrain, recovers from tilts more gracefully, and generally keeps its wheels in contact with the ground when the angles get difficult. The stock SCX24 and TRX4M both use plastic in places where brass fits directly — and brass weighs significantly more.

For the SCX24: The high-value brass swaps are front axle knuckles and differential covers. These pieces sit low and outward on the chassis, which is exactly where you want the extra weight. Injora makes a complete brass kit for the SCX24 that’s affordable and a genuine transformation.

For the TRX4M: Brass differential covers and front portal brass are the starting point. Traxxas makes official brass upgrades, and the third-party market from Injora and GPM has solid options at lower price points.

The result: Your truck will hug terrain that used to send it rolling. If you only do one thing, do this.

2. Tire Upgrade

Tires are the biggest variable in whether your crawler can actually handle the terrain in front of it. Stock tires are fine for smooth indoor surfaces, but get your truck out on real rocks, roots, and trail obstacles and the limitations show up fast.

For the TRX4M: Pro-Line 1.0” tires are the standard reference point. The Hyrax is a popular choice for trail use, and the BFGoodrich Mud Terrain is a good option if you’re primarily on dirt and loose terrain. Both fit the stock TRX4M wheels.

For the SCX24: The tire situation is a little more constrained because the wheels are proprietary. RC4WD and Injora both make replacement tires in the right size. The RC4WD Flashpoint is a genuine community favorite — more tread, more grip, meaningful improvement over stock.

Also pay attention to foam inserts. Soft foam inside the tire acts as a suspension assist on rough terrain. Stock inserts are usually pretty firm. Swapping to softer foam — or slicing some material out — makes a real difference on technical rock surfaces.

3. Servo Upgrade

The stock servo in both the SCX24 and TRX4M is where the budget got cut. It works, but it’s the weakest link in the drivetrain, and you’ll feel it most on technical terrain where steering precision and hold power actually matter.

For the SCX24: The Injora 4.5g servo is the community-standard replacement. More torque than stock, better hold on climbs, direct fit, and very affordable. If you want to go further, the Annimos servo offers even more torque at a modest price bump.

For the TRX4M: Traxxas sells the 2215 micro servo as an upgrade, or you can run a quality third-party option with the right servo horn adapter. More torque means better steering hold on steep terrain and less servo buzz trying to maintain a locked wheel.

The result: Your truck holds its steering angle better, responds more precisely, and stops fighting you on the climbs.

4. Extra Battery Pack

This isn’t a performance upgrade — it’s a quality-of-life upgrade that you’ll appreciate the first time you hit a really good afternoon on the trail.

Micro crawlers, especially the SCX24, have small battery packs with limited capacity. Trail sessions go longer than you expect when the terrain is good. Having a second pack means you swap instead of stop.

For the TRX4M: The Traxxas ID system makes this dead simple — pick up an extra Traxxas 1200mAh 2S pack and you’ve doubled your run time. Step up to a 1500mAh if you want even more.

For the SCX24: Some crawlers find a slightly larger pack that still fits the chassis bay, which both extends runtime and marginally lowers CG. Worth researching for your specific body style. But even a spare stock-spec pack eliminates the main frustration.

5. Link Upgrade (SCX24) / Portal Brass (TRX4M)

The fifth upgrade depends on which rig you’re running, and both are genuinely worth doing once the first four are sorted.

For the SCX24: The stock plastic links connecting the axles to the chassis flex under load and contribute to a “mushy” feel on technical terrain. Injora and RC4WD aluminum or steel links are stiffer and more precise. It’s a subtle upgrade, but it tightens up the truck’s response and is one of those changes where once you feel it, the stock setup feels noticeably sloppy.

For the TRX4M: If you held off on portal brass during upgrade number one, now is the time. Traxxas brass portal covers drop the CG while adding durability to higher-wear areas of the drivetrain. Third-party versions from Injora come in at a lower price point and fit well. Either way, it’s a meaningful upgrade to a platform that already handles outdoor terrain well.

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Those five mods — brass weight, tires, servo, extra battery, links or portal brass — build on each other in a logical sequence. Do them in order and you’ll feel each step clearly. The truck that comes out the other side is noticeably more capable, and you’ll understand how it works significantly better than when you started.

That’s the part nobody tells you: the upgrades aren’t just about performance. They’re how you actually learn the platform.

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See also: Best SCX24 Upgrades Under $50 · Best TRX4M Upgrades · Crawler Tires by Terrain · Best LiPo Batteries for Micro Crawlers · The Upgrade Rabbit Hole · Recommended Gear

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