Monday, July 9, 2012

TBs TechReview 15 – 9398, 4x4 Crawler

Set reference: 9398                                                                                                                                                               
Set name: 4x4 Crawler
Theme: LEGO Technic
Release date: 2012.Aug

Number of parts: 1327 (plus few additional spare parts)

LEGO Designer: Pepe (Jeppe Juul Jensen)

Model under review: Main model
Weight: 1.420g (w/o batteries)
Approximate set dimensions:
Length - 38,6cm (15,2")
Width - 21,4cm (8,4")
Height - 22,0cm (8,7")
Approximate box dimensions:
Length - 47,8cm (18,8")
Width - 57,8cm (22,8")
Height - 9,0cm (3,5")

Stickers: Yes
Building instructions: 3 booklets (84 pages each) plus one addendum: 1/3, 2/3, 3/3, Addendum
B-model: Off-Road Truck - Instructions available online only: 1/2, 2/2

Recommended for ages: 11 - 16
Building difficulty level: Medium+
Estimated building time: 5 - 7 hours

Price range: 170-180€ (Estimated average retail price)
Price per part: 12,8-13,6 euro cents (Estimated)

Inventory (Bricklink): Link
Inventory (Peeron): Link
Other user reviews (Brickset): Link

After the portal axle parts introduced in 2011 Technic flagship, one should have anticipated they could return in 2012 for a TrTr class vehicle or similar. Indeed the 2012 Technic flagship turned to be a 4x4 Crawler (9398) for the delight of many fans.

From the time we had the chance to see the first images until several exemplars get into the hands of some Technic fans, this model got an apparent moderate interest, much because of many expectations raised around the 9396 Helicopter which is also planned to release in this 2H.
Main focus of interest have been the new motors (PF L-motor and PF Servo) which soon we realized to be released with this year's flagship. However that initial perception is changing really fast, now that we got the chance to experiment the first units.

1. The package and contents

The box comes without surprise - Identical in style to all other Technic flagship boxes we got since 2007, when the first PF elements were introduced. Although it has a nice render of a rocky surface, where the Crawler stands, which helps the consumer to easily perceive what is it all about.
The backside view from the box, reveals also the alternative B-model, an Off-Road Truck.

Box has the usual lift-up cover style characteristic of the larger sets (with card perforated side ears and two front-bottom seals, tape sticker type). It also does have the 2nd level folding cover, showing all the functional details, an exclusive from the large flagship models.

As usual the box includes some booklets with the building instructions for the mail model, while the instructions for the B-model must be downloaded online at
There are 3 books and one small addendum to highlight important steps where you should pay extra attention, to avoid common mistakes which would prevent the model from working properly and would also avoid you having to dismantle huge part of the model to fix them.
Without big surprise for a model this size, there are only a few mistakes within the instructions or steps requiring some improvement, but none that turns to be a real obstacle preventing the progress with the construction (most likely you won't even notice them, which is something the brain processes are very effective at...).
Included you get also one sheet with several stickers to decorate the panels in your model.

Still about the building instructions, I really dislike the current approach where black parts are shown some in black (like axles, pins, towball pins, etc...) and others in dark gray. Then Dark Bluish Gray parts are shown in medium gray and Light Bluish Gray in light gray. In the end it turns a big mess, specially if we don't have all the gray variants present in the same step turning it easier to distinguish them and for us to realize what is what...Why not simply show all black parts in black with a white borderline!?...
It would eliminate one grade of gray in the instructions, which would also allow for a better separation of shades and consequent easier color distinction to the user.

The parts inventory comes in the end of the last book as usual. This time with another small mistake - The steering portal axle hubs appear duplicated as you can see from the image on the left below.

The parts are organized in numbered bags ("1" and "2") in order to help you building in steps, instead of mixing-up all them together.
  • Bags numbered with "1" - Parts for the chassis
  • Bags numbered with "2" - Parts for the upper body
Some parts like wheels, tires and the PF elements come outside the numbered bags and are all used within the chassis (except the remote).

With the 1327 parts included, this is not the biggest Technic set ever, by far. However it includes some great goodies as we will see ahead.

2. The new parts

The 2012 Technic flagship brings us some new parts as we might expect from a flagship, but also one existing part in a color never released before.

From the top left to the right, we clearly see the new PF SV-motor, the PF L-motor and a new version of the PF RC Receiver. These are included with this set in quantities of 1, 2 and 1 respectively.
On the lower row we have a new type of 90º connecter (first released with the Monster Fighter sets), an 'Axle 4 with Center Stop' (the real surprise kept up to the release date) and the already existing '11x3 Curved Panel', although released in white color for the first time.

The PF RC Receiver got a new element number (6020086) and a closer look to the receiver itself, reveals a new "V2" printed label. This means we have now a new version of the receiver which got an improved CMOS motor driver with lower power loss. Although the firmware version implementing the RC Protocol remains the same (v1.20).

As for the 'Axle 4 with Center Stop' it might be useful in situations where gears or the axle itself may tend to slip out due to the forces involved. The center section of the axle, won't pass through a gear axle-hole or vice-versa.

3. The parts assortment

Like with other recent Technic sets, once again we get an handful of orange parts, which definitely will help us to build stock on this great color.

Because it uses a similar suspension style and scale, this Crawler set makes use of most of the parts introduced with the 8110 Unimog U400. Namely the suspension and portal axle specific parts.

Apart from that, this set includes an huge and diversified amount of parts which might be very useful for all those beginning or returning to the LEGO hobby, and who may want a good starter set to initiate or build-up their stock of Technic parts (most useful if one wants to build large vehicles with great suspensions, namely for TrTr competitions).

4. Building experience

Ready to go! (with my new and lovely IKEA cutlery trays...)

I think it was the first time I've organized all the parts per element type, before starting to build a set. However I must admit it made the parts search a lot easier, which speeds up the building time considerably.

The building steps start with a procedure to power on the PF SV-motor and force it to automatically align at the center position. This is an important step to guaranty that all further building steps are done properly and this 4WS model is aligned and drives straight in the end.

There are also eight new 'Axle 4 with Center Stop' parts included in this set, all used in places where there is the risk of a rotating axle to slip out (on steering ball-joints, differentials and PF L-motors output shaft).

Then this is how it looks by the end of the first instructions book. Big leap here, but at least we have something substantial to look at...

You see the first photo published at TechnicBRICKs facebook page, the day I started to build this set.

We can clearly see the PF SV-motor which is responsible to control the steering and the space to install the battery box on top of it.

Below a front axle close-up, with the PF L-motor already in place. The rear axle will look identical to this, a few steps ahead.

Unlike the gearing used at the portal axle housing in the Unimog (1:1), the Designers have chosen for a 12t/20t double bevel gears combination for an effective gear reduction (0,6:1) - Lower speed and higher torque to overtake obstacles more easily.
The overall axle reduction achieved is in the magnitude of 1:6,5. More precisely 27:175 or 0,154 (12:20 > 16:16 > 20:28 > 12:20 >12:20).
Considering the PF L-motor spins at 390rpm, the wheels should spin at aprox. 60rpm if there was no load neither friction forces involved.

If we look further at the portal axle housing, we see the Designers have used a 92907 connector without apparent reason. Guess it is there to prevent the 'Axle 3' on the upper gear to slip away (where the speed and stress are higher). This reveals a visible concern from the Designers to take preventive measures in place, wherever there is an axle risking to slip out.

Another big leap and here we are at the end of the 2nd book (more precisely, at the first page of the 3rd book).

Here we can see a detail with the dual head PF SV-motor (steering control), from where two shafts leave in the direction of the respective front and rear steering ball joints.

The chassis is ready, the doors are installed and the PF RC Receiver is already in place.
We will now proceed to the third book, which gives instructions to build the body part that goes on top of the chassis.

Once ready all we have to is to attach the upper part through the linkage arms already in place.

This model corresponds to an 'average plus' build difficulty level in the sense there are not much cabling or tubing to route inside the model, there are no complex gearboxes to assemble or very tight parts requiring small fingers to handle them. Some gearing in the axles, a compact building style and that's it!

We are done and I leave you with two images of the complete model. With and without wheels (or vice-verse...) for you to see the difference.

As usual there are some leftovers, although a bit more than usual even for such large models - This made me wonder if none was left behind during the building process. However I noticed in the review from Blakbird that he was left exactly with the same set of extra parts, which made me relief... Maybe some of these are required for the B-model!?

Nice looking model, isn't it?

5. Functionality and playability

I'd say it is not a set plenty of functions but it compensates in terms of extensive playability, as I hope
to show you ahead.

5.1. The doors

The doors open the standard way - Sideways.

Notice here also the IR remote used to remote control the model

Although the interior space behind the doors is really meager. Because of the high suspension required for this type of vehicle, in order to keep pleasant proportions we remain with a very slim upper body, thus the seats had to be fake (no back reclining, neither legs or proper seat space) once the space available is quite scarce. Still there was space for a decorative gearbox lever though.

As you will see ahead this Crawler has some tendency for rolling, under certain terrain or maneuvering conditions. This was probably the reason for the Designers to include an interesting, although simple and effective door locking mechanism.

5.2. The suspension

The main feature of this model might be the suspension certainly!

The suspension is quite high and long travel, as it is large the space between the tires and the respective mudguards. Although the rubber can still hit the mudguards when the suspension gets completely compressed towards one of the sides.

The model exhibits a Live Axle suspension type, at both front and rear axles. Unlike the 8110 Unimog U400, which used a similar suspension design, this one doesn’t use a Panhard Rod to prevent the suspension to move sideways. Instead it uses four 6L links on the sides to prevent such undesired effect.

The ground clearance is very good in the middle for the model scale and distance between axles, but not optimal under those same axles. It looks like the portal is not really portal thus not fitting the purpose… However it can be slightly improved, if we remove a few parts used to protect the axles underside from shock and scratches.

As you should have already noticed, the 4x4 Crawler lacks a center differential thus falling into the category of the most basic 4WD vehicles. Although this solution is quite effective for off-road type vehicles, while permanent 4WD and AWD systems are most suitable for dry pavement and slippery surfaces.

Pain point here are exactly the differentials used within the front and rear axles. The suspension travel is very generous but still has some limits. Once a wheel leaves the ground surface, it gets transferred all the power from the other wheel in the same axle, which gets completely stuck meanwhile!
Under such conditions the Crawler is much more unlikely to move further or surpass any obstacle. If the same happens at both axles simultaneously then it definitely stops.
Several AFOLs have proposed different solutions to implement limited slip differentials which can lock automatically. If one finds a solution to make a major arrangement and makes it fit, then we might have a solution. Otherwise the differential replacement with knob wheels might be also an option, if one wants to improve the driving and crawling capabilities of this model and accept the consequences.

All in all and as long as you can manage to keep the four wheels on the ground you'll have the best playing experience with this model.

As one can easily see, the steering pivot point is not close the center of the wheels as it was also not on the 8110 Unimog U400 - I’m pretty sure Nicjasno (Alex Zorko) will come over on this topic sooner or later, to say horrors about the LEGO Designers.
Furthermore the caster is again negative instead of positive as it should be, according to Alex's teachings.
However and from my POV we can live with such limitations in a LEGO model for the sake of simplicity, despite not 100% correct.

5.3. Batteries replacement

Special care was taken to choose the PF Battery Box location, in order to fulfill two main purposes.
  • Make it serviceable and easily replace drained batteries.
  • Keep the center of gravity at the lowest possible point, to increase model stability and reduce the penchant to roll. Although it still rolls quite easily, as you will see from the videos ahead.
Thus the battery box goes in the chassis and the body must be lifted up, to replace it.
In order to do it, a couple of locking 'Long Pins with Stop Bush" must be released (one at each side).

The upper body is hold vertically and the batteries compartment becomes easily accessible.
The blue lock releases the inner hatch, which then gives access to the PF Battery Box.

Below you can see the battery box outside its compartment for easy servicing. And also the compartment where it fits immediately above the the PF SV-motor.

Once everything is closed and locked again we can power on, accessing the battery box's switch behind the drivers door and underneath the seat.

5.4. Video footage

But nothing better than see all the functions live, in a short film...

All the video footage below was taken with fresh 1,2V rechargeable batteries (7,2V in total) instead of 1,5V Alkaline batteries (9,0V) – Hence the delivered mechanical power is certainly sacrificed a bit (hopefully not much), for the sake of environmental saving.

As one can see the model drives straight with ease, even with the observed tolerance at the initial PF SV-motor alignment procedure. Such tolerance is however expected to be always below the practical backlash in Technic gearing trains.
Also and as mentioned above, the model still turns over easily, despite the relative low center of gravity.

Now an outdoors performance...

Besides all the details seen in the video that we have already discussed above, another thing that cames up is that probably one may want more torque available on the wheels, for improved crawling performance, even if having to sacrifice the overall end speed.

In that sense, the portal axle housing could be used with a different and more favorable gearing ratio. A pair of 8t/24t gears would produce a 1:3 reduction (higher than the 12t/20t gears in use).
This would lead us into an overall gearing reduction of 3:35 or 0,086 (12:20 > 16:16 > 20:28 > 12:20 >8:24), instead of 27:135 or 0,154 (12:20 > 16:16 > 20:28 > 12:20 >12:20).
The corresponding wheel spin would be at aprox. 33rpm, in ideal non-friction/load conditions.

The most surprising factor for me was the overall model sturdiness while rolling downhill. Really impressive!...
Taking a closer look at the model it turns incredible that no parts at all, had fall apart while rolling. The Designers definitely did an excellent job in this respect!

6. The B-model

The alternative model the Designers propose for this set is an Off-Road Truck, as illustrated in the LEGO promotional images shown below. However this model was not covered in this review.

This alternative is built on top of the same chassis which is used for the main model (the 4x4 Crawler). Thus the delivered features are identical among the two models.

IMHO it is a downgrade when compared to the main model, from the aesthetics POV, hence the weakest point delivered with this reference. But we all know how misleading the first impressions can be...
Hopefully the stickers from the main model could bring some improvement on this matter.

7. Final thoughts

Once this model has motorized drive, one thing you should realize is this is not a traditional push/pull LEGO car. You cannot play it as a push/pull model… I noticed it particularly when I was positioning the Crawler to take photos for this review. Fortunately it has a generous ground clearance in the middle so that you can handle it from the bottom side easily.
Eventually a couple of driving rings could be used somewhere to lock/unlock the main shafts. It could be a nice modification to try (if one finds the required space without major modifications).

Main model aesthetics looks really nice and there was a great job done with the stickers artwork, as usual.
There are also some other nice details included, which give a very positive contribution to improve the overall aspect of the model. Namely the bumpers, front bar guard, the step bars and roof bars, not to speak about the overall highlights in orange...

On the shortfalls I'd highlight the missing functional steering wheel and the absent fake engine - These could have been great additions for a motorized and remotely controlled vehicle like this. Although the available space is indeed not abundant, which may have been one of the reasons for not including these!
Nevertheless not a big issue for the latest, if we realize do bonnet does not open also. An advantage if we think this model is very prone to roll on steepy ground.

The dashboard also exhibits a minor flaw. There are a couple of 3/4 pins preventing it from turning upwards, but nothing preventing it to go down, where the gravity gives always big push... resulting in the fact that the dashboard remains misplaced almost all the time. It should have been easy to fix this!

And finally on the remote control aspect, instead of the 8885 PF Remote Control, I feel the 8879 PF Speed Remote Control could have been a better choice if include of the shelf, with this model. For challenging TrTr tracks, the speed remote allows for more precise steering control making it easier to surpass certain obstacles and tracks.

Personally I found this model quite surprising and it definitely behaved above my best expectations. Overall it was a very good and positive surprise!

It is however important that you set your expectations right! This is not an Hobby RC Crawler, which are optimized for extreme outdoor performance!! This is a LEGO Technic 4x4 Crawler set, with standard differentials and it performs accordingly.

To finalize I leave you with some additional photos.

1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg 1.jpg

8. The Ratings

This is a worthy LEGO Technic flagship in almost all aspects. Besides not an huge part count set it comes with three new PF motors, a revised IR Receiver and a few other new elements. Giving the high price these will likely reach as separate items at the secondary market in the short term, most will find it more cost effective to buy the complete set.
The new PF motors are also the main innovation brought by this set. Although we would like to see an even more powerful PF L-motor, if we could...
The set itself despite nothing new in terms of AFOL creations, sets a new era in terms of official LEGO Technic sets, thus bringing a lot of innovation into the theme.
Regarding the set design and despite eventual critics on the fidelity to the real world car mechanics, that may appear, the set design is up to the most demanding standards. Specially in terms of hardiness and capability to remain in one single piece under abuse conditions.
In terms of functionality and playability is where there is some room for improvements, if we think about torque, differentials and extreme crawling capabilities.

   as value for the money
   for parts innovation
   for set innovation
   for set design
   for functionality and playability

Overall rate: Highly Recomended  

In general this is a great set that worths the money and very capable to provide you a nice building and play experience. Either if you're still within the targeted age group our already beyond...

Leg Godt!

Read review addendum, about custom tires, here.


Dave said...

Great review! Thanks for the MANY DAYS of work it took to prepare this!

TechnicBRICKs said...

Thanks Dave!

Many days of work, in the middle of many other responsibilities, is the right term!...
But this is no yet the end of it. :)

Allanp said...

I can't say I agree with this overly positive review (i.e. design gets 5/5 JUST for not falling apart LOL!) , but I appreciate the hard work you put into it nontheless ;).

TechnicBRICKs said...


Maybe I tend to be too much positive on my evaluations, but it is not easy to not get enthusiastic about a flagship like this. :)

Anyway it has been great fun to play with this model and we must keep in perspective, what LEGO is all about.
Definitely this is not an RC hobby car, and we should not demand such from it. :)

The design could have been different which is not exactly the same thing as better.
There were here some restrictions to consider and this was the result.
But I'm sure we as fans will have opportunity to come up with something different and better, if we can. ;)

Junkstyle Gio said...

Thanks for this elaborate review. It made me much more enthusiastic about this set than when I saw the first pictures.

But first I want to get my hands on the 9396 helicopter. Hopefully somebody will do a review on that set too soon.

TechnicBRICKs said...

Thanks Hans! :)

We also have a review for the Helicopter, still in draft stage.
Alexandre is working on it. Slowly... ;)

Thomas J Avery said...

Thanks for a thorough and excellent review. I appreciate it!

I'm really excited about the new motors! Those look awesome. Can't wait to get my hands on this set :-)

Alex Campos said...

Excellent and thorough review, as usual! I still don't like the colour scheme, although the introduction of white rounded panels takes the physical implementation of a virtual MOC we've seen a few times here at TBs a step closer to reality. ;)

As an RC vehicle, it appears to me a but underpowered (but then again, this is regular LEGO elements we're talking about here, and there's not much that can be done without breaking their limits or the set budget; for real RC one has to turn to dedicated hobby cars or the Outdoor RC line), but still fun to chase the cats around the house while laughing at obstacles like rugs.

If I get one, it will be for the transmission/suspension elements and the new PF components (and to chase the cats around the house for a while). ;)

@Junkstyle Gio: keep your eyes open for new stuff coming to TBs soon. ;) In the meanwhile, you can check out Conchas' YouTube channel, as there's some new stuff already there. ;)

Junkstyle Gio said...

Excellent movie material indeed!

Pantaleoc said...

I'm building the model with my son. We noticed there is the possibility to increase the speed (probably giving up some torque) by inverting the two first gears that come out from the engines (20:12 instead of 12:20, exchanging the black and beige gears). This should increase the speed by circa 2.8x. Then we also exchanged the four couple of gears coming out from the differentials (again 20:12 instead of 12:20, same colors). This increases the speed by another 2.8x, bringing the speed to some 7.7 times the design speed of the model. I know this is not a car designed for speed, but I like the modification...
Are we the only ones who tried this?

TechnicBRICKs said...


Then you will have much less torque available to overcome obstacles or even a slope.
Tell us how does it behave in that respect.

Pantaleoc said...


Yes with the 7.7x mod the car is much faster but you can see that the engine takes some time to reach cruise speed, and any obstacle becomes a great difficulty. I find the intermediate mod a good compromise, as we found the design speed too slow. In any case we are using it just in the house with no major obstacles or slopes.
I'd like to see a similar model with a gearshift box, to have the right gear for any situation, but perhaps I'm just dreaming. I have not a lot of experience with lego models, but building this one I finally understood how a differential gear works!

Unknown said...

I think the dash is supposed to be held in place with those 3/4 pins. It doesn't say anything specific in the manual, but after I built it I noticed the same problem of the dash rotating down to face the floor. I ended up stretching the hood up a bit and rotated the dash up under those two 3/4 pins and voila! they hold the dash from rotating down very nicely and gives a pretty nice angle to the dash as well.

Kwon8429 said...

Nice, but i afraid you did not attached headlights correctly...please check them again.

kaziutek said...

Outstanding review. My set will arrive tomorrow. It's going to be FUN!

TechnicBRICKs said...


Thanks for the praise! :)

Unknown said...

I'm building the model with my son. We noticed there is the possibility to increase the speed (probably giving up some torque) by inverting the two first gears that come out from the engines (20:12 instead of 12:20, exchanging the black and beige gears). This should increase the speed by circa 2.8x. Then we also exchanged the four couple of gears coming out from the differentials (again 20:12 instead of 12:20, same colors). This increases the speed by another 2.8x, bringing the speed to some 7.7 times the design speed of the model. I know this is not a car designed for speed, but I like the modification...
Are we the only ones who tried this?

Related Posts Plugin for WordPress, Blogger...

© 2007-2014 TechnicBRICKs
TechnicBRICKs contents may be sporadically updated, if the authors finds further relevant info about a certain post, or content/spell mistakes. Hence please don't be surprised if you find few changes at later visits, relative to a previous read.

TechnicBRICKs often shows other peoples' creations and/or images. We always try to credit the author(s) and link to their main publishing website, and if possible with their name in real life.
Since this is not always possible, we request that if you find something here that is yours or from someone you know, you leave a comment on the respective post and claim the authorship.

TechnicBRICKs is optimized for Firefox 16.0 and 1600x1200 resolution displays or wider.

LEGO® is a trademark of The LEGO Group of companies which does not sponsor, authorize or endorse this blog.
LEGO, the LEGO logo, the Brick and Knob configurations, the Minifigure and MINDSTORMS, are registered trademarks of The LEGO Group.
Original LEGO images are copyrighted by The LEGO Group and are used here in accordance with their fair play policy.
You can visit the official LEGO® website at