LEGO 9398 4x4 Crawler MOD Outdoor Adventures

[Kisvakond]

Just another LEGO 9398 4x4 Crawler MOD..

..tested with custom / third party tires and some minor modifications:

Modded config:

- 8878 LiPo battery box for lower center of gravity

- Wheel hub gear ratio changed to 8/24 for more torque

- Third party tires for better crawling performance

- Added extra nose weight for better climbing perfomance

- Modded front & rear axle for higher ground clearance

- Differentials purposely not removed for more realistic & challanging play

Tested third party RC tires:

- Ansmann Crawler 1.9"

- Pro-Line Flat Iron G8 1.9"

Stages:

Stage I: Loose Soil

Stage II: Twisted Trail

Stage III: Rocky Mountain

with Ansmann Crawler 1.9" tires (proposed by efferman):

..and with Pro-Line FLAT IRON 1.9" tires:

"And..?! Who cares, really..?!"

( ..if you can not tease your crawler PROPERLY.. )

So the real question is:

How to torture your LEGO 9398 4x4 Crawler MOD properly..?!

NOTE: Please - in the future - any of you can try testing somehow like this way (and please not e.g. on the flat beach, in the sandy water, etc.), thanks in advance for your set's good health.

Till then, Please Enjoy:

LEGO 9398 4x4 Crawler MOD Outdoor Adventures

720p HD Link:

Edited August 3, 2012 by Kisvakond

[davidmull]

Cool video kisva! What mods have u done apart from tires? Have u locked diff s?

Looks very impressive :) At last we see it on proper off road getting dirty :)

Edited August 2, 2012 by davidmull

[Kisvakond]

Cool video Kisvakond! What mods have u done apart from tires? Have u locked diff s?

Looks very impressive :) At last we see it on proper off road getting dirty :)

Thanks! You can find the list of (minor) applied mods above in the first post or also in my

.

NOTE: By the way it is really nothing special (very simple things), because it was really not the main point of my vid, rather I was interested in scrutinizing the custom tires question, and just secondly the set modifications.

BTW yes, I like proper off-road circumstances and as this set was addressed to able to crawl & climb, etc. I torture it with pleasure..

So, just briefly: despite the relatively high center of gravity (after curing this really big problem..) this set could be able to do some really nice crawling IF you are patient to do some practice with it, as you see in

.

BTW it was a surprise for me too..

(BUT: Of course if anybody want some really good crawler or TrTr, they anyway just rather build a real/better crawler thing with real low center of gravity, proper wheels, like Marceloraus, Yoarish, Zblj, Mbmc, Nico, etc. or any other guys..

* * *

Here you can find some photos on BS (after moderation): http://www.brickshel...ry.cgi?f=508384

Till then:

.. TO BE CONTINUED..

Edited August 3, 2012 by Kisvakond

[davidmull]

What did u do for more ground clearance or is it much higher than standard? Also how does tha Lego tires perform on off road?

Patience is rite :) I'll be leaving my diffs in too!

Edited August 3, 2012 by davidmull

[timslegos]

Nice mods, they sure add a lot to the playability to the model.

tim

[Kisvakond]

What did u do for more ground clearance or is it much higher than standard?

I just changed the 2-2 low positioned grey bent liftarms in the bottom of the front & rear live axle to these ones: after you can see this:

..because the front & rear angle of approach is very impontant even concerning the ground clearance too.

.. Also how does the Lego tires perform on off road?

Yes, definetly this question was also the most important concerning these tests.

I try to summarize my experince briefly:

#1 if you play just in the room/ on the carpet / on the floor inside the house: so on the most artificial surface believe or not there is really no significant difference between LEGO tires and third party tires.

#2 but if you go outside / off-road for some TrTr / crawling on natural surface / soil: it really has significant difference in case of performance, because LEGO tires was NOT ABLE TO CLIMB AT ALL e.g. on this stage:

#3 Ansmann (or any similar type!) performs better than Pro-Line: thanks to the stiffer (but still more softer than LEGO) rubber material than Pro-Line Flat Iron (or similar type) rubber compund, which is extremely soft! (Very-very soft, only recommended for RC Crawlers on rocky surface)

#4 The second important cause explaining Ansmann (or any similar type!): Ansmann (or any similar type!) has optimal hard foam insert, then Pro-Line, which is also too soft for a heavy car..

Softer tire requires more torque from motors and from servo, so too soft tires is rather NOT RECOMMENDED for average playing..

Of course you can build several tire inserts, like these completely made of pure LEGO:

http://www.brickshel...y.cgi?i=4657759

http://www.brickshel...y.cgi?i=3878210

http://www.brickshel...y.cgi?i=4902982

(of course some easier stage would liked more for LEGO tires, but the not rubber material used and the insufficient tire dimension and it's shape and it's pattern is a real shame.. )

Edited August 3, 2012 by Kisvakond

[DLuders]

@ Kisvakond: Nice mods! Could you rank-order the relative importance of your five modifications to the 9398 set? I viewed your High-Definition video in its entirety, and came up with this order:

#1 Importance to 9398's Rock-Crawling Ability: "- Third party tires for better crawling performance"

#2: " - Wheel hub gear ratio changed to 8/24 for more torque"

#3: " - Modded front & rear axle for higher ground clearance"

#4: " - 8878 LiPo battery box for lower center of gravity"

#5: " - Added extra nose weight for better climbing perfomance"

Do you agree?

[Kisvakond]

@ Kisvakond: Nice mods! Could you rank-order the relative importance of your five modifications to the 9398 set?

Importance to 9398's Rock-Crawling Ability:

#1 "- Third party tires for better crawling performance"

#2: " - Wheel hub gear ratio changed to 8/24 for more torque"

#3: " - Modded front & rear axle for higher ground clearance"

#4: " - 8878 LiPo battery box for lower center of gravity"

#5: " - Added extra nose weight for better climbing perfomance"

Do you agree?

OK, I've got it.

Well, to tell you the truth, my opinion is:

- there are many different factor concerning "rock-crawling ability" if we use your phrase. >> (#1-5)

- these factors are mostly independent from each other, but not always:

- if we try to separate them we see:

#1 is relative with #5 as both depends on Axle Load/Weight, these have effect both on "static" & "dynamic" Stability as the part of the suspension system(!)

#3 is completely in contradiction with #4 >> as trying to improve low Center of Gravity is the "enemy" of higher Ground Clearance, these factors mostly depend on Design/Geomerty, it has effect mostly on Stability.

#2 and finally gear ratio concerns the Force/Torque/Power of the system, it has effect on "dynamic" properties of the drive-chain.

#6 we not mentioned a well-tuned SUSPENSION(!) system yet, which is the most important part in case of AWD/ATV performances.

(Fortunately the 9398 owns a quite good suspension)

Conclusions / to answer your question:

- all of these factors is approx. equally important concerning "crawling ability" because the original design is not really a crawler design, than a "Bigfoot" or a "Monster Truck"..

A real trial / crawler thingy looks like this: >> rc crawler thingy

(BTW the 9398 is really exceed my expectation, so I appreciate the designers good work, nicely done! )

* * *

The main problems with 9398 set:

- relatively high center of gravity(!!!) >> change to 8878 LiPo OR rebuild it.. :)

- it is slightly bottom-heavy(!!) >> add some nose weight on the front as low as possible (approx. 100-150gr is enough)

- other things: at your taste..

I really don't want to make anybody to buy third party tires.. (just if they really like they nice profile, like me! )

I hope it was helpful..

Edited August 3, 2012 by Kisvakond

[DLuders]

Hmmm, if you suggest people to "add some nose weight" to the 9398, perhaps the B-MODEL is a better crawler than the A-Model, due to its nose-heavy design. Have you built it and tried it on your "rubble mountain"?

[Kisvakond]

Not yet, but I think it is not my favourite design.. (moreover it is really exrta high, too high..)

The point is (to be exact):

- as I said the Crawler is slightly bottom-heavy.

- if you balance it with some extra weight, it will cure this problem.

- but if you add more weight than it is needed, it will be nose-heavy, which is aslo not so good..

- if you think, when you drive forward: you will need more traction on first axle , so nose-heavy config win, when you drive reverse: you need more weight on the rear axle to climb easily..

- of course when you have nice, big & heavy machine (like LUGPOL trucks) you will not need to mess with so "exact balancing" because you have the proper traction / grip by weight..

- only in case of these "easy thingz" (like 9398) needs this messing

Anyway: as we mostly drive forward during a Truck Trial / Rock Crawling, etc. and just rarely backwards, we rather need the slightly nose-heavy config..

I hope it is clear now.

Edited August 3, 2012 by Kisvakond

[Tamas Juhasz]

Cool outdoor crawling, and very nice publication! Good to see you also here.

- as I said the Crawler is slightly bottom-heavy.

- if you balance it with some extra weight, it will cure this problem.

- but if you add more weight than it is needed, it will be nose-heavy, which is aslo not so good..

- if you think, when you drive forward: you will need more traction on first axle , so nose-heavy config win, when you drive reverse: you need more weight on the rear axle to climb easily..

Yes, I agree: a crawler should be bottom balanced, but if it's nose heavy a very ittle, imho that's optimal.

I know it's not possible with 9398, but I thought earlier about an off-road vehicle with motorised balancing, for example the battery box could slide from bottom to front/rear, depending on the terrain.

Edited August 3, 2012 by Mbmc

[Kisvakond]

Cool outdoor crawling, and very nice publication! Good to see you also here.

Yes, I agree: a crawler should be bottom balanced, but if it's nose heavy a very ittle, imho that's optimal.

I know it's not possible with 9398, but I thought earlier about an off-road vehicle with motorised balancing, for example the battery box could slide from bottom to front/rear, depending on the terrain.

Thanks Tom! Same here..

Yes, your idea would be a perfect idea: a remote controlled sliding heavy thing (e.g. PF battery box) depending the position of the truck/car will suit for this mission.

Edited August 3, 2012 by Kisvakond

[Kisvakond]

Finally public, all photos (3 page..) available now:

LEGO 9398 4x4 Crawler MOD Outdoor Adventures BS

Edited August 3, 2012 by Kisvakond