All The Bells And Whistles

This is the Cross RC EMO AT4 4×4 Crawler Kit review. It’s a 1/10 scale RC rock crawler and it is excellent! Is it good enough to take the top spot from the TRX4? Read on to find out!

A 1/10 Kit To Make Traxxas Nervous!

When the Traxxas TRX-4 hit the scene, it was ground-breaking in a number of ways. Before that, no other 1/10 scale RC rock crawler had engageable, locking diffs and a two-speed transmission. Icing on the cake, it was fully waterproof and super durable!

Today, Cross RC challenges the TRX-4’s dominance in this category with the EMO AT4. This interesting-looking platform also has remotely-lockable differentials and a two-speed transmission. Sealed bearings and heavy beadlock wheels round out a very capable platform. That’s on paper.  But how good is it, really?

Cross RC has a history with very pretty, hard-body rigs. However, the EMO AT4 is an unlicensed blend between an old Chevy Blazer and a Ford Bronco. There’s no badging on the vehicle, but it’s a very attractive looking, American-style off-roader.

Also in the Family

Interestingly, Cross RC has also recently released the JT4, which has the same undercarriage and running gear as the AT4. The difference is the body: a late-50s inspired bus-cum-utility style body with a utility rack behind a twin-cab. It includes rock bars and a roof-rack. There’s nothing else quite like it in the RC crawling space. With this platform’s performance, the JT4 is a compelling and interesting option if you’re in the market for an RC crawler with a difference.

If you’re looking at more traditional car bodies, though, you’re in the right place. The EMO AT4 delivers the scale crawling experience that will be consistent, capable and enjoyable, time and again.

Cross RC 4X4 Crawlers

This is my third Cross RC vehicle. Well, sixth, if you count the trailers I have as well. Trailer or truck, all were kits requiring significant time to complete. However, the AT4 was my first ‘soft-body’ or polycarbonate-bodied vehicle build from Cross RC. I’d avoided earlier such models from Cross, as there were common criticisms about various design issues with some models. For example, the SR-4A Demon had some steering and linkage problems. It seems Cross RC has gone back to the drawing board for the AT4, as this is an all-new vehicle that seems to have been very carefully designed.

Vehicle Dimensions

The machine is not light, being 4.7kg/10.4lb. It has a typical wheelbase of 314mm (313mm seems to be an industry standard), so it should fit many common bodies from other manufacturers. It’s 531mm nose-to-tail, 246mm high and 252mm wide.

What’s Not Included

The Cross RC EMO AT4 does come with a motor. It’s a 540, 35-turn unit that seems about right for the vehicle’s gearing and intended use. However, you’ll need to supply everything else:

• ESC (Electronic Speed Control) – go with the HobbyWing WP-1060 (what we’re using) or its bigger brother, the WP-1080;
• Steering servo – get a waterproof, 6v unit to pair with the WP-1060 (that’s what we’re using) or go a little up-market to a 7.4v coreless or brushless unit to match the WP-1080.
• Shifting and Diff Lock servos (that’s two in total) – you’ll want the ‘mini’ rather than ‘micro’ size here. However, I used a micro (the Power Hobby TR-4) and just added a little plastic to extend the factory bracket, snugging it in nicely. For the diff-lock servo, you’d just need to drill two holes a little closer to the other side and it’ll bolt in just fine.
• Radio system – I recommend the FlySky GT-5 and its 6-ch receiver if you haven’t got anything already, or you could just buy another receiver to match an existing handset if you have one for another model. Just be sure you have 4 channels for this model, as you want to be able to change gears and lock/unlock the diffs.
• Cross RC lists ‘Sound and Light System’ as not included, but the AT4 does include nice little lights for front and rear. These are powered directly by a spare channel on your receiver. You will need your own sound system if you desire that, but the lights it comes with are definitely adequate!

Lockers!

Both axles lock and unlock simultaneously. The TRX-4 allows independent front and rear locking of your differentials. This sounds like a good thing, and on my TRX4 vehicles, I do make use of it. I’ll often unlock just the rear while I’m trying to crawl up an obstacle, if I need to pull the nose around with the front wheels. The idea is that one of the two rear wheels would be unloaded enough that it could just sit and spin. This allows the front wheels to draw the vehicle onto the line you want. However, this can still be achieved with front and rear unlocked at the same time. It just needs slightly more careful tire placement on the front to get there.

With a little hand-craft or 3D design and printing, one could set this vehicle up to have independent control of each end. However, I’d argue that is unnecessary for this vehicle. It’s quite capable in the default configuration.

Cross RC EMO AT4 Transmission

Mated to the transmission from factory is a non-rebuildable, 35-turn 540 motor. Whilst I typically would stick a 40 or 45-turn 540 in a crawler of this size, I left the stock Cross RC unit in. My thinking was that the manufacturer has tested and knows best. When I burn this motor out eventually, I will still use a 40t rather than another 35t, but we’re splitting hairs. The 35t is a good choice and suits the truck just fine.

The transmission shifts smoothly. There’s a good gap in the ratios between first and second gears. This means you get nice and slow crawling in first and a moderate jogging pace for second. You won’t be getting any epic air in second gear with this crawler, but that’s okay because, y’know, it’s a crawler. I like this transmission, I like the transfer case and I like the motor.

Cross RC EMO AT4 Suspension

The shock bodies are aluminium and well made. There are numerous o-rings throughout the construction of the shafts and I filled them with 40wt. silicone oil, which was perfect. You could really run anything from 25wt. to 50wt. and I expect it’d be fine.

There are a few mounting points on the upper shock mounts, but only the one on the axles (which is normal for most crawlers). The default position is optimal, I think, unless you’re using a different body and therefore may have different needs. Keep it to factory spec for good results if you build one yourself.

The coils are a single-piece, dual-stage spring. The instructions suggested stiffer springs go on the front, which is what I did during my build, though it is the opposite to what I’d usually do in a crawler. You want the heavier spring in the rear to help stop the body squatting down over the rear axle on steep ascents. This allows the suspension to travel fully and to help get the front up as high as possible to help pull the car over an obstacle.

However, the design in this case works. Very well, in fact – more on crawling performance in a moment, but it suffices to say here that in its default configuration, the suspension works brilliantly.

Cross RC EMO AT4 Body & Trim

The unlicensed body looks to be a mix between a late 70s Chevy Blazer and a short wheelbase Ford Bronco from the 80s. The grille is all Blazer, but the nose is Bronco. Though it’s a bit of a mash-up, it just works. The included sticker sheets (not just one, but numerous) are plentiful and varied, so you can go for an upmarket finish or a basic and rugged look, or somewhere in-between.

The included window mask sheet was just fine and had extra pieces to suit your creative taste. This was a thoughtful inclusion over just the basic window lines. I took advantage of some of these by masking out the tailgate and finishing that with copper highlights. Looks good and that’s thanks in part to this well-appointed masking sheet. Thanks, Cross RC!

There are some plastic bits and pieces that attach to the body. Typical of Cross RC models, you need a soldering iron with a flat end to melt flat the stumps that go through the pre-drilled body holes. In other brands, Traxxas in particular, you instead would get injection-moulded pieces that clamp onto both sides of the polycarbonate body with screws. That’s a better, more durable design, so Cross RC loses points for that. However, the Cross method still gets the job done and is simple enough to do. From the outside, you’d not know one from the other.

Wheel Wells, Sliders and Body Mount

The injection-moulded plastic parts that attach to the chassis rails underneath the body are good. The plastic quality is high – strong, but flexible, so I think they’ll all be quite durable. The wheel wells give good coverage to the wheels, so the interior of the body should stay reasonably muck-free even with muddy running.

The sliders can take a decent amount of scraping and impacts, helping to protect the smooth lines and shiny finish on your body sills. There are also narrow gutters that run along each side into which the body sills sit. This helps keep everything straight and protected. It’s a nice, basic system and it works well.

Lights & Electronic Setup

As noted above, you don’t get much in the way of included electronics, other than the motor and a set of front and rear lights. Cross RC have paid attention to the lights though, as even a simple set can really set the body off from the competition if done right.

And done it right they have! You get a pair of basic PCBs for both front and rear clusters. The body itself comes with light buckets and plastic brackets to fit the PCBs nice and flush with the body. Then, the wiring is done in one continuous series from front-left to front-right to rear-right to rear-left. It results in a working set of double-bright (and old-school yellow coloured! Yes!!) and pleasingly-dim but still functional rear red tail lights.

The single cable that comes out of the setup goes into a spare radio receiver port and expects 6v. Note, I can’t find whether it’ll take 7.4v, so be careful if you end up running a WP-1080 on 7.4v. A small, 6v BEC may be advisable. Alternatively, run everything but the steering servo from the WP-1080’s 6v output and fit a separate 7.4v BEC to run your stronger steering servo – if you go that way.

I stuck with a basic, waterproof ‘LV’ steering servo and it was well suited to the Cross RC EMO AT4. I do have high-powered servos in other crawlers, but this truck doesn’t seem to need it, despite being on the heavy end of the spectrum.

Crawling Performance

Here’s where the magic happens. In testing the EMO AT4 on my 6-problem course, the vehicle is being tested against every other rig to ever have been tried on it. And for what it’s worth, only one other 4×4 1/10 scale crawler (in stock configuration) has been able to finish all 6 problems, and that was the recently-reviewed GMade BOM TC GS02F. The EMO AT4 is seriously impressive. Check out our video to get the full detail on crawling performance, but to put it bluntly, this thing is really, really good. (And spoiler alert, it beats the TRX4 Bronco, 6 problems to 4).

Trail Performance

Having live axles is a pro on the rocks but a con on the trail. Independent suspension is ideal for higher-speed driving, but of course, rock crawlers usually have live axles for maximum articulation and performance, and rightly so. Having a second gear gives the EMO AT4 that extra layer of usable speed that some single-speed rigs really are lacking. It’s stable, has a good centre of gravity for its class and handles well at speed. Being able to unlock the diffs goes a long way to increasing trail stability, so overall I’d rate this as a very capable truck.

Just remember you don’t have a waterproof receiver box in the kit, so you’ll want to be sure your radio receiver is either already waterproof or that you’ve taken measures to protect it from the wet stuff. Otherwise, go for it – this is a rock and trail machine I can heartily recommend.

Cross RC EMO AT4 Durability

How well a model will last comes down to a few factors. Some elements are within your own control, like where you drive and how you drive. Some are obvious, like the quality of build materials in a rig. I think one of the biggest factors is actually how the rig is designed. You could have good materials, careful driving and appropriate terrain but still have breakages if there’s a poorly engineered linkage mount, for example. Stress on parts can be mitigated with good design and research, to some extent at least. When I build or examine a model, one thing I often look for is design oversights, as well as areas where care and attention was obviously given.

The Cross RC EMO AT4 is well designed, overall. I can’t think of any particular area where this vehicle has an obvious weak point, apart from – and I’m nit-picking here – the omission of a waterproof receiver box. It’s overall design is good, the materials are solid and the construction is well thought-out. I expect this vehicle will need minimal attention over its service life. At this early point in my ownership of one, I can heartily recommend it as a solid trail and rock machine.

How It Stacks Up

It out-performed the TRX4 on the rocks. It’s similar in handling and capability on the trail to the Traxxas. It looks great, is a fun build and gives you the option to go all-out or cheap and cheerful with the electronics. The body detail is a little lacking and the plastic attachment methods for trim isn’t ideal, but overall this is already one of my all-time favourite crawlers. It’s very, very good. Recommended.

>> Find more info on the EMO AT4 on the official Cross RC website.

 >> Wondering if this is the best RC rock crawler for you? Well, it’s an excellent machine, but here are a few other ideas for you!