All The Bells And Whistles

When You Want the Full-Fat 1/10 RC Rock Crawler 4X4 Experience

Two Heavyweights

There are many RC rock crawlers to choose from today, but not many with all the options. Two such vehicles bring everything to the table and present a dilemma on which is best: Cross RC EMO AT4 or Traxxas TRX4. They both include:

• high and low gear,
• front and rear lockers,
• portal axles,
• integrated light kit that goes beyond simple LEDs in the bumpers,
• pretty scale trim atop a durable polycarbonate body,
• quality tires that don’t need immediate replacement,
• decent off-road capability,
• astonishingly capable rock crawling ability, and
• rugged durability (no cast gears to be seen, here), including water resistance.

Pinch me, I must be dreaming – there are at least two different manufacturers with such a vehicle already on the market? Don’t tell 12-year-old me from the 90s. This was the stuff I dreamed of back then, but the technology just wasn’t there. Well, in 2021, now it is! And boy, is it good!

If you have a cool grand burning a hole in your pocket and you want that one, special, do-it-all machine for the rocks and the trails, you may have come to the same dilemma: Cross RC EMO AT4 or Traxxas TRX4? Do you buy the Cross RC EMO AT4 (or JT4) or the Traxxas TRX-4 (Bronco, Chevy Blazer, Defender, etc.)? Both are compelling, given they satisfy all of the above on paper. Let’s take a closer look!

Traxxas Heritage

Traxxas hit it out of the park with their release of the TRX-4 platform. Over the course of 2008 to 2016 or so, I was watching Traxxas and thinking their designs were stagnating. The Slash hadn’t received an update in years. The Stampede and EMAX were still suffering the same design issues and breakages and accordingly, the hop-up market was doing a roaring trade. I had a few of their models but there really wasn’t a lot special going on. This began to change around 2017 when Traxxas began hinting at new models.

We have since seen an overhaul of their off-road vehicles, new road cars, even drones and boats. Part of this reawakening, of course, was the TRX-4. This all-new 4X4 crawler made its debut after much rumour and excitement online. From 2018, the TRX-4 has dominated with the popular vote and has become famous for its unbreakable drivetrain and excellent off-road capability.

Traxxas TRX4

The model line does have its weaknesses. From the RTR Sport to the TRX-6, the same, weak steering servo is the first thing I remove when I unbox a TRX model. The shifting servos will last as long as their end points are set correctly and the servo-saver spring assemblies are adjusted ‘just so’. The ESC is fine on 2S and 3S but what many of us do is replace the servo and ESC on day one. We’ll often change the radio as well. There are numerous good options – I’ll have a video and an article up on this in coming months. Once the electronics are sorted, the TRX-4 is good to go.

A little weight down-low is required to bring its rock crawling performance in particular up to scratch. The links, drivetrain and chassis are fine and the tires are excellent. However, the centre of gravity is too high for more extreme crawling. Adding a little brass on the axles can be helpful, or even just weighted, beadlock wheels. Do note that rotational mass isn’t desirable. With such broad, after-market support for the TRX-4, you’d be better served swapping some of the axle housing outer pieces, like the portal covers. Brass instead of plastic on just a few bits on each corner can be transformative on the rocks.

With the centre of gravity issue addressed, you’ll have a capable and durable vehicle that will go wherever you like and do it well.

Manufacturer site: https://traxxas.com/products/landing/bronco/

Cross RC EMO AT4

Until recently, Cross RC has been best-known for its military trucks. 4X4, 6X6 and 8X8 models have featured detailed styrene bodies, heavy leaf suspension (or even torsion bars on some, like the BC8) and scale military tires. The company’s trucks and trailers are generally excellent for what they are. I have numerous Cross RC models and they’re well engineered with quality materials and clever electronics and design flourishes. Their manuals have needed improvement, but this is slowly but surely happening.

Where Cross RC fell down was with their earlier 4X4 RC rock crawlers. The SP4 Demon was ‘okay’ – not great, not awful, for example, but left much to be desired. There have been some other, light-duty, off-road civilian models in recent times that have avoided such criticisms only because crawling was not part of their design purpose. Engineering a 4X4 vehicle that can actually crawl on rocks is much more difficult than simply building a trail-ready truck. If you’re not copying other existing platforms (*cough* RGT HSP *cough*) then designing such a rig from the ground up is no small thing.

Enter the AT4 and JT4: underneath the bodies, which are a Chevy/Bronco mash-up in the AT4 and a minibus/pickup mash-up in the JT4, you have the same chassis. I recently built, tested and reviewed the EMO AT4. I’m delighted to report that Cross RC has managed to build an exceedingly capable, ‘heavy’ 4X4 crawler with all the features of the TRX-4. Indeed, they’ve done it in a unique way that is very much their own design. And this thing is tough! It out-performed the modified TRX-4 Bronco in my video test and looked amazing doing it.

Manufacturer site: https://www.crossrc.us/shop/at4-emo-4wd-kit/

Parts Availability

In considering the EMO AT4 vs TRX4 Bronco, you may be asking: can I get parts for it?

You are going to need replacement parts for the faster RC vehicles, for those times when mass and velocity meet gravity and immobile objects. However, with crawling, the pain points are most often in the spinning bits: diff and transmission gears, broken drive shafts and axles, burned out motors and cooked servos. Gears are usually available from manufacturers. Also, there’s a healthy after-market range of higher-grade (and sometimes lower-grade) gears for most common crawlers.

Cut-steel (or ‘hardened steel’) parts are the gold standard for gears and axles. Steel universal joints are the go-to for front axles and drive shafts. On both models, the gears and shafts are strong enough that you’ll be hard-pressed to break them under normal driving, even vigorous driving. As with all things, if you abuse them hard enough you’ll eventually get breakages. Manufacturer parts are locally available at time of writing, keeping in mind this is in Australia and November 2021. The COVID-induced slow-down is going to affect manufacturing for several years yet, so this situation may change. Rest assured that as long as you keep these vehicles out of the local skate park and on the trails and rocks they’re designed to traverse, it is not likely you’ll need much in the way of specific spares.

For the parts you may be more likely to damage – the electronics – things are absolutely fine for both models. Thankfully, you’re not tied to the manufacturer as long as standard sized components are used. For both the Cross RC and Traxxas models, any brand of motor, ESC and servo that fits can be used if you burn out your first ones. Spend a little more money to get better stuff and it’ll last longer in many cases.

After-Market Support

Brushless motors and controllers are a good longer-term investment over the stock brushed motor, brushed ESC and brushed servos, but for servos especially this does come at a cost. Most folks buy the trucks, run them until they break something, then upgrade from there. This is a wise idea unless you have the budget and experience to unbox the truck and immediately rip out and replace the stock Traxxas electronics like I did, for example. Whatever works; you’ll be fine with both of these models for parts.

I will add that the after-market for hop-ups and modifications is vastly bigger for the Traxxas model. I can’t overstate this point. If you plan on upgrading and playing with various hop-up options, Traxxas is the only answer here. Cross RC is not well supported at all in this regard. But again, for the main running gear, such components are readily available for both models.

Kit vs RTR

The Traxxas TRX4 Bronco and similar are only available as Ready-To-Run (RTR). The Cross RC AT4 and JT4 are available both as RTR and also in kit form. A kit build is where you build the vehicle from loose parts with tools and a manual. For kits you also must provide the electronics yourself. This is less convenient than a RTR vehicle, but it does mean you aren’t paying for wasted things you don’t need or plan to use.

If you’re new to the hobby, you should still consider a kit for the educational element you will definitely get from the build. However, you will also probably need some advice on which electronics to buy to complete the build. Well, that’s great! But there’s no shame in buying a RTR model instead. You do get to play with an RTR vehicle the day you bring it home. You also have the assurance that an RTR vehicle generally will be (or at least, should be, but sometimes isn’t) set up and ready to go with just a battery.

If you want the extra dimension of getting to know the vehicle through the build process, a kit can’t be beaten as a great way to get going with your new truck.

If you really don’t want to assemble it and just want to get out there and enjoy it, both Cross RC and Traxxas sell the AT4/JT4 and TRX4 models in RTR form. Go for it.

EMO AT4 vs TRX4 Bronco – Which To Get?

Given how similar these are, how do you decide? So, replacement parts supply is sufficiently established for both. Each truck seems durable and unlikely to need a constant supply of parts. How, then, do you decide which to buy? This is a tough decision: EMO AT4 vs TRX4 Bronco. They’re both excellent.

We do have an article already here on which RC crawler to buy. Though it isn’t about either of these rigs in particular, it may be helpful in bringing up various elements you may not have considered. Find that article here.

That’s where personal taste, price and reviews come in. There is some value in looking to online forum discussions for a cross-section of opinions from many in the hobby (and rccrawler.com and rcgroups.com forums are great for this). You also may find some of my videos helpful. That includes this playlist, Truck vs Truck, where I’ll put vehicles against each other to assess capability and durability, for example.

We’re living in a golden age for rock crawling, I think, at the moment, things are available, they’re getting cheaper all the time. These are both really, really good rigs. They’re both solid choices and both will deliver many hours of adventure and fun. And isnt’ that awesome to be able to say?