Sariel

Here is a video with the 9398 with differentials removed, doing fine with Power Puller wheels on. It's almost unstoppable in this set-up, and does way better off-road than it did with differentials. Of course, removing the diffs leads to tire wear and parts wear, but I have noticed that the transmission pieces in 9398 are getting worn even with the differentials.

Sorry, I had to.

I wish it was true. I bought mine at eBay.

May I suggest sheep? I have already swapped differentials for knobs and increased gear reduction in my 9398. Seeing as you continue to discuss the limited slip differentials issue, I guess I'll film how it handles without any differentials whatsoever - it's practically the same, even with PP wheels. The only noticeable difference is that when turning, wheels on the inner side lose some grip.

Not every. Also, by taking a different line I need a lot of time and a lot of space for each obstacle. Differentials suck big time. And you only have power on the wheels that do nothing at the moment - like, rotate in mid-air. I don't think you can get enough power to drag anything round if you don't have enough power to drive through an obstacle in the first place. I strongly disagree. When both motors drive both axles, then every single axle can receive the total power of two motors. With separate motors, you can't have more than single motor's power per axle. Consider a simple situation: one of your axles gets stuck with both wheel in the air, as it happens with small ground clearance sometimes. The motor on this axle does nothing then, and the other motor on the other axle is your only hope. So you depend on the power of a single motor, even though you have two. I believe I've seen over a hundred TrTr vehicles and a drivetrain that connects motors together always works better, simply because motors can help each other.

It has the LEGO 8878 battery, running at 7.4V. Not without a major redesign of the whole model. The axle's structure is very compact, with no space to really add anything, and you would need another IR receiver + a motor to lock & unlock the differentials. I honestly think you'll be better off by removing the differentials completely and inserting knob wheels instead - this will keep all wheels under power at all times, while impairing the handling - but it's one or the other, really.

It sure could. A quick way to make it more stable is to use the Power Puller wheels, which are wider and heavier, so they lower its center of gravity. But they also eat more torque than any other wheels.

Less weight = worse grip. No, the performance with another battery box is just as good as with 8878. It was apparently just one box what was faulty. I'll be uploading an outdoor Crawler's video in a moment. Here it is. Besides improved performance, this video demonstrates why differentials are so bad:

I have noticed that my L motors perform much better when powered from 8878 battery than when powered from a battery box. So I tried swapping Crawler's battery box for another one, and it worked.

Yeah, I'm not really into electrics but it looks like the power was coming from 5 batteries instead 6.

I finally found out that my Crawler came with a faulty battery box. The same batteries with another battery box give it much more power. My apologies for misjudging this set. I have never come across problems with the battery box before.

You mean the small pump, easily mistaken for a cylinder.

I guess I won't be finding out anytime soon :(

I tried both, actually. This week I will have a chance to take Crawler on a TrTr course to see how it does there. I'll probably film it too.

Technically, batteries don't affect torque of a motor, only speed. Torque depends on internal gearing and is therefore constant for a given type of a motor. With more voltage from batteries you can drive faster though, and build a higher momentum, that helps against obstacles. Anyway, my batteries were fresh. Note that I was driving Crawler head-on against obstacles, in other videos it usually approaches them at angle.

Yes. XL-powered vehicle would have no problem with my hand or the box, that's my point. If could attack any obstacle if reinforced and geared down enough. As for my Jeep, the comparison is unfair in general, as the Jeep was lighter, with stronger motor and more geared down. But the point is - you can get so much more out of LEGO even without the need for new motors or new IR receiver. Hence my disappointment - LEGO designed some new parts that can be beaten by the old ones. Yes, I like to think it was him ;)

I think a little washing wouldn't hurt these pieces.

A little video of mine, with Unimog wheels, PP wheels, time lapse build and vanishing torque:

Good point. We model our races after real Truck Trial races held for example in Czech Republic, where you have to go through the gates, but you are free to drive as you like between the gates. Example: That inevitably makes torque more important than handling. We simply try to be accurate not only with vehicles, but also with courses. But leaving the torque aside, the Crawler handles very, very well and has an excellent, very stable suspension - as Anio's video shows.

It's a great video, but what's the single tallest not-sloped obstacle there? 2cm, 3 maybe? That's less than half of the Crawler's wheel diameter. Also, all obstacles shown there seem to provide excellent grip, there's no opportunity for differentials to show their worst.

That makes things slightly better - the default gear reduction is minimal, to be honest - but it's nowhere near the performance the XL motor provides. I'm just finishing the video that shows Crawler struggling in many situations where XL-powered trial truck manages. I expected better from a set that comes with "Extreme Off-road Performance" on the box. IMHO a car that can't climb its own 8 cm thick box is hardly extreme. If you wait for my video, you will see it stopping dead when a single wheel meets my fist resting on the floor. Then again, I may be expecting too much from it, because I'm used to watching top-notch Truck Trial vehicles. The 9398 comes with a great suspension and some clever building techniques that many people will enjoy. I'm just disappointed with the motors that stop fairly easily. Look at it this way: Crawler weights nearly 1.6 kg and has two motors, each with some 150% of Medium motor's torque. But the motors are not connected and there are situations where their torque doesn't really sum up. For example when climbing uphill, most of the weight rests on the rear axle while the front one doesn't help much because it loses grip. So you get 1+ kg on a single axle with small gear reduction to be handled by a motor not-so-much stronger than the Medium motor.

After playing with the Crawler for a while, I have to confess its performance disappoints. It's got a nice suspension and everything, but it lacks torque so desperately that it can get stuck on a thick carpet. LEGO advises you not to use it outdoors, probably because it would get stuck on grass. Also, differentials. Sorry, but anybody who claims differentials are OK for LEGO Truck Trial has not enough experience. Differentials kill in Truck Trial. Even when all your wheels are on the ground, it's enough for one of them to slip e.g. on sand - and you're done. In heavy-duty TrTr you don't need good turning radius - you need a drivetrain that stop only on walls.

I don't have to film it to tell you that it will work.

Perhaps this will help too:

I'm amazed at how good and complete it looks with primarily studless pieces used for the body shell.