[MOC] MM Technology EVO4 Dakar truck

[AdamFMX]

Hello all,

after year and half hiatus of my Lego activities and attached stuff here I got back as I have found finaly time to do even proper building, not just LDD model like last time (ye, that Frankenstein Tatra Pacific). I havent hesistated with thinking what to build as Dakar has just started (I am big fan of truck category, especialy Martin Macík) and also I wanted to finaly use that Dakar tires from Audi RS-Q etron Dakar car which we have ordered with other parts. So I decided to make model of Macík's truck in rough scale 1:12 which off course woulde be powered by Powered Up motors and to challenge my brain I added working gearbox with possibility of "power-shifting" as side goal.

To introduce inspiration: Dakar itself probably doesn't need introducing, same as truck category. Last two editions has won Czech team MM Technology with Martin Macík Jr. behind wheel of their own truck called EVO4 and with nickname Bohouš. This year they have updated version nicknamed Pepa, but both are based on Iveco Powerstar. Only bonneted Iveco today. Bonneted trucks slowly showed to be better due better weight distribution and this Czech team, which started with cabover Liaz, has switched to bonneted Iveco.

Last year truck Bohouš

Regular Iveco Powerstar

They started as family team and now they are in fact biggest truck team on Dakar-9 trucks, from which 5 were made last year. Enough was said about inspiration, let's pull out some bricks. After dedusting and disassembling legendary John from even more legendary Grand Tour to source H and rectangular frames and also Xerion wheelhubs (my first contact with them was Claas Xerion set, since that I use this name for them), as first I made front and then rear axle.

Legendary John built by R. Hammond, J. May and kinda J. Clarkson

Half-done front axle, I still was not sure about steering mitor placement

Finished front axle (sadly no photo of rear one)

After axles were done, I moved to most difficult part-gearbox. I wanted at least 2 speed one with big reduction and fast gear, to prevent Zetros-like outcome (great set, insane climbing abilities but insanely slow for everything else). And also ability to shift under load/almost under load. My head for designing such thing was too much exhausted, so I decided to look on Rebrickable for some inspiration, but nothing was appealing to me. However, then I remebered on Volvo dump truck, which had quite complex gearbox and when I saw, how it is done, I said to myself that I will do 4 speed gearbox.

At start was tricky to make some holding frame for it, but slowly I somehow made quite compact gearbox, which even worked when operated by hand. However, after addition of motor combiner (just two beams and some gears) I found out, that my design has some flaws-4th gear was non-shiftable due colliding stuff, whole gearbox was twisting and few others.

Gearbox v0.9-without any frame, just demo

Another day gave me some ideas (and my dad too) to fix issues and afyer few hours of coursing how stupid I was final product was born-working 4 speed automatic (not entirely, kinda like sequential) gearbox compact, sturdy and light enough to hide in truck frame (or superstructure-anyways it will be empty box to minimize weight). I dedusted also my coding skills in Powered Up app and made controller for shifting. I tested result and I was quite satisfied.

Completed gearbox before fixes were implemented-v 1.0

After that I made descent gearbox with integrated interaxle diff and quite ridicolous total gear ratio (around 6:1 if my memory is right). "New" diffs and "new" cv joint shafts are gift from god-they are perfect for this use. I tested gearbox once again and measured some things, which forced me to flip descent gearbox due total length. But after that everything was perfect. Only one thing was bogging my mind. How that thing attach to frame.

Gearbox demo run

Size and stuff position approximation (panels are marking 7.5m length as real thing)

That was Saturday state and today (yesterday I was working on something different) I made frame (once again I saw opportunity where to fit it) for rear axle first, as it was easier-front axle has integrated steering motor and drive motors were at front too. It was quite easy to do-I was actualy pleased with quick progress and then I got even another idea-flip motor layout-shift motor will be in front and drive ones in rear. Why to bother? Well, if drive ones would remain in front, then would be almost impossible to make correct bonnet (which will be anyway fun to do due curvature). To my luck, I was kinda future-proofing gearbox and I counted that layout could be changed in future, so it was not problem and also in reality thus way was easier to pack drive motors into frame and also to make frame merged with shifting motor for front axle (due steering motor). Suspension was fun part-at start I didnt know how to properly attach shocks from live axle to frame, as my every older model was independent double wishbone, but after while I figured it out. Front was little harder due to already mentioned steering motor, but also this went suprisingly fast. I made some quick cable managment (not much, just one cable was moved and clipped to not get eaten by gears from gearbox), added Panhard's link to rear axle and two links to front axle as well. Only structural thing missing is hub holder.

Rear axle succesfully attached to frame, font one demo fitted and already swapped motor layout

Rolling frame done, note driveshafts-exactly placed as on real truck

Top view

Driveline detail

I have made some quick drive testing, but due poor battery condition (rechargeables) test was short and not final, but already with almost dead batteries it climbed smooth plank at 35° angle in 1st gear without bigger issues-initial accel was on flat and on 4th gear, after half of chassis was on slope I downshifted to 1st without releasing throttle (autoshift and throttle reduction are not programed yet but layter one will not be needed as test showed) and it smoothly continued forward without stopping. Speed in 1st gear is bit slower than Zetros, 2nd is comparable (if memory serves right), 3rd is 1:1 in gearbox and 4th is slight overdrive in gearbox. That all without planetary hubs.

And also thats all for today, see ya later

[bruh]

Wow! Very nice. I'm interested to see how it continues to perform, especially with a body.

I don't know if you have it, but buwizz would give you more power, with the same motors (different voltage). 

[Jurss]

Good progress so far. Proper model for these tires. And prope timing for this build. Will You finish tMOC together with rally?

Is gearbox automatic somehow, or what? Was not shure from text.

[AdamFMX]

6 hours ago, bruh said:

Wow! Very nice. I'm interested to see how it continues to perform, especially with a body.

I don't know if you have it, but buwizz would give you more power, with the same motors (different voltage). 

Thanks, bonnet will be kinda tricky but doable. Also I know about buwizz, however I don't have it.

3 hours ago, Jurss said:

Good progress so far. Proper model for these tires. And prope timing for this build. Will You finish tMOC together with rally?

Is gearbox automatic somehow, or what? Was not shure from text.

Plan is to finish it this week so yes, it should be done when rally ends.To gearbox: it is hard to properly classify it as it is controled by motor, so technicaly automatic/automated transmission, it has two gear selectors so technicaly double clutch and you only give it order to upshift or downshift so sequential. That concluded, I honestly don't know how to properly call it. However there are plans to make it automatic, but only if Powered Up app will support it

[Jurss]

To make it automatic, You need some input. Don't know what that could be, or even if powered up can read something from motor. I think, it knows motor speed, but that may not be enough. Maybe to compare selected gear and motor speed, then set for each gear allowed speed.

[AdamFMX]

1 hour ago, Jurss said:

To make it automatic, You need some input. Don't know what that could be, or even if powered up can read something from motor. I think, it knows motor speed, but that may not be enough. Maybe to compare selected gear and motor speed, then set for each gear allowed speed.

Ye, I was thinking about similiar system, but I really dont know if it is possible to make that logic part in Powered Up app.

Anyways, this morning I have started to work on bodywork and bonnet is slowly shaping but it is pain to do due curves

Bonnet slowly taking shape

Also I made cable routing and hub mount

[AdamFMX]

Status update: bonnet is complete and it looks quite good

But bad news is that I have run out of white parts entirely, so result will be mashup of different liveries. Also it can be only yellow, because even from that I don't have enough parts, especialy panels

And if it looks weird then trust me that it is in scale (maybe I will lower roof by 2 studs but no more)

EDIT: I lowered it by that 2 studs and it is way better (sometimes I am really suprised how little change can do such difference)

Edited January 5 by AdamFMX

[AdamFMX]

Extremely bad news: I was moron and I forgot to exchange crossaxle pin to axle and this gearbox is so tight that there is literalyno space how to get that axle in with fingers. Luckily I am bit of amateur kit modeler so I have some tools for work in small spaces. I am sure that I will be able to get that axle in, only question is if I wont be doing it till midnight or more

Gearbox after quick bodywork de-mounting. Note grey tooth gear on dark grey beam-this is that problematic bit-3 studs long axle but space is big only 2 studs. Damnit

EDIT: IT LIVES!!!! Everything works, shifting under light load works (on flat surface or slight inclines), it drives nicely. Also repair was quite easy-what suprised me. As first I removed hub and structure around it, then mid-frame adapter (adapter between main frame and hub holder), descend gearbox with output collector gearbox and I had access to site in question. From here it was quick-gear with axle took 1 minute, assembly roughly 5 minutes (disassembly took around same time, most time was spent when I was trying beam together with gear while everything was mounted). Now I can get back to superstructure

Edited January 5 by AdamFMX

[AdamFMX]

Good news! No, it ain't related to Dacia Sandero. I have made quite progress and now I have frame and top paneling of superstructure done, tyre holders as well. However model will not feature any deco interior, as cab is filled up by gearbox. Access to hub button is either through first roof panel with intake and exhaust or through sideboards. Access to battery is bit worse but still quite quickly accessible-remove rear superstructure panel (not build yet), push out axles in top corners, release cab rear wall safety pins and slightly pull cab apart from underside. Tomorrow it should be fully done

[bruh]

Very nice! I'm excited to see the finished project and what it can do

[Jurss]

16 hours ago, AdamFMX said:

but it is pain to do due curves

Technic/lego doesn't have to be so curvy ;)

11 hours ago, AdamFMX said:

Note grey tooth gear on dark grey beam-this is that problematic bit-3 studs long axle but space is big only 2 studs

Lego is pretty elastic, sometimes You just need to remove something, then other sections are stretching, and it is not always needed to disassemble. Yes, there are risks braking something.

[AdamFMX]

7 hours ago, Jurss said:

Technic/lego doesn't have to be so curvy ;)

Lego is pretty elastic, sometimes You just need to remove something, then other sections are stretching, and it is not always needed to disassemble. Yes, there are risks braking something.

I know but I am sadly detailist so that wont work. And also I know that Lego is elastic, but it was already on edge and I didn't want to break anything.

And I have even better news: again not Dacia, but it is done! Livery is kinda color mashup due to par limitations but I tried to minimalise consequences and made it at least somehow "ordered" and symetric on both sides. Front doors are not much openable due their thickness (literaly armored doors lol) and the fact that mirror is not perfectly placed, but at least they wont open themselves. Sideboards are also openable but now without problems and they hold in place actualy. Now just tailights and maybe rework grill as doors needed slight bonnet change which influenced grill (narrower inner space-grill was inset)

Opened sideboards

Hub power button access panel (opened)

Now with opened doors

[Guest]

 Oops, wrong account (this one was supposed to be deleted

 

Edited January 7 by AdmFMX

[AdamFMX]

Finaly from proper account (previous one is technicaly unusable due lost access to email and before I saw option to change email I have created this one)

Since I am detailist and also I had another look on sideboards I decided to redo them to be closer to real thing (rear overhang is not so long and smooth, it is shorter and steeper. And this time I am writing from PC and realised that what looks on phone perfectly (text formating), on pc it is totaly boinked. To details-I have added front turn lights, rear lights, redone grill and already mentioned sideboards. Oh, and also I have moved rear axle bit due new wheel arch position. (I have almost forgot most important thing, hehe). Now it is perfect and finaly and really done.

So please enjoy this nice result together with me

Cheers, Adam

Edited January 7 by AdamFMX

[bruh]

Looks great! Could you make a testing video demonstrating how well it performs on obstacles? I'm curious about climbing ability and suspension travel.

[AdamFMX]

1 hour ago, bruh said:

Looks great! Could you make a testing video demonstrating how well it performs on obstacles? I'm curious about climbing ability and suspension travel.

No problem but to be honest there is not lot of suspension travel. Also no diff locks at all, only insane reduction but I can try to make some course

[AdamFMX]

Status update after 2.5 week: Well looks like my fix of 3rd gear caused domino effect and whole new list of issues appeared. I got to them now thanks to half year on school (load of tests previous 2 weeks, now just relax), although maturita exams are even closer so situation is not much better.

But to the topic: I wanted to make video of driving it through various stuff but that plan crashed immediatly after I tried to cross seam between carpets on 3rd gear-something got crackin. I have stopped, checked everything and tried to get going once again. And guess what? Again cracking.

I did another check and decided to do hill test (other gears were ok, even 4th which I was expecting to be more problematic, in reality troublemaker is 3rd) in 1st gear. 40° was limit-frint didnt had enough traction and when slightly pushed into plank, cracking once again reappeared. I did more runs and every time cracking noise but from different places.

First culprit was step-down gearbox, especialy central diff. Despite using new one, it somehow kept pulling appart. After diff switch (probably this one was weirdly assembled) cracking continued but now not from diff inside but from gear powering diff. I confess, this part of gearbox aint as sturdy as could be and that immense torque was twisting it. When it was twisted enough, tooths jumped and cracked and whole thing repeated.

Tomorrow I will send more images as I am now already in bed. But I am not sure if it is in my ability to solve any next issues after step down will be fixed. Because there is whole A4 page what next can go wrong, while 90% is related to gearbox, which will be pain to fix as it is integrated into frame. For those willing to help I could send LDD/io file, but only probably after 2nd February