Investigating the rear axle issue & a potential fix for the LEGO Technic 42129 Mercedes-Benz Zetros
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- เผยแพร่เมื่อ 5 ก.ย. 2024
- As I mentioned in my previous video, the LEGO Technic 42129 4x4 Mercedes-Benz Zetros Trial Truck seems to have a problem with its rear axle. Under constant heavy load pushing the truck beyond its limits, a 5L beam that holds the gear driving the rear differential gets pushed out a little bit, and as a result the gears start to crack and might get damaged on a longer term.
In this video I show you the problem in details, investigate the causes and test a potential fix.
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It's nice of you to remind your viewers not blame a single person, in this case the lego designer which is also a fellow youtuber.
Great video as always!
Nice video and great fix! I’ve just built mine and was worried when building it that the 12 tooth to the diff join looked weak in a few ways! I’ve used the same set up in one of my builds and the strengthening you have to do to get it to work properly is ridiculous. The problem here is not just the beam which pops out but also there a bit of play in the diff from side to side which can’t be eliminated! For this to work the 28 tooth cog(diff) has to be held firm in place with a beam either side but because it’s a diff you can’t. Usually in lower torque builds this wouldn’t be an issue.
I think diffs will be high in demand! Lol 😀
But with this mod, it makes the Zetros even more powerful, so I would think that now the motors would be under more strain, which would be bad long term for them. The PU hub is supposed to shut down the motors once the load is too much, but as shown it doesn't here. I think some kind of string slipper clutch would help, this way there's no cracking but it still saves the motors.
The motors do shut down if they are in danger, don't worry about that
Motors have internal protection but the torque at the rear is so high due gearing that the motors do not see overtorque and do not shut down. I'd have expected lego to use those white clutch-gears to limit the max torque to protect the plastic gearing, though.
@@MikkoRantalainen clutch gears are not effective for driving as they slip under moderate load already.
@@RacingBrick Each clutch gear can output static max torque if I've understood correctly. Let's say it's 1 Nm. Using 5 in parallel results in 5 Nm torque limiter, right?
@@MikkoRantalainen yes, but this is all theory. You cannot identify easily the torque limit e.g. in the case of the Zetros where it should slip versus the number of clutch gears required. Additionally, 5 or more of these gears already require a large space. A more straightforward approach is to tune the output gearing & speed to use the PU system's built in protection to shut down the motors when the load is too high.
i cba to make a long comment let me get to the point, to permafix this axle problem simply replace the *YELLOW 5L AXLE* with a 15462 Reddish brown axle, to do this you have to disassemble the axle a bit and then you need to route it through a 3L beam 32184 so that once reassembling the axle you litteraly cannot pull the axle out. Its a bit hard to explain and it seems complicated but in short replace the yellow 5l axle with a reddish brown one with the end stop bit facing towards the axle truck. ive tested this by making it run into a solid wall and theres ZERO cracking the little black bevel gear never looses contact with the dif. All the zetros does is spins wheels its indestructable.
Thanks Racing Brick! I finally fixed my Zetros.
First Osprey, now this. Lego definitely experiences quality issues
the osprey did not have quality it was just a thing that they missed
@@maxv3450 I think he's talking about the gear crunching behavior of the Osprey :) Have a video about that, too
Those planetary hubs are tough!
Great video. No bashing, just thoughts about a better solution. I love your videos.
I just completed this set today and have spent hours creating obstacles for it. The ground clearance is my biggest gripe. I’d love a good long travel suspension with the same sort of torque this set offers. I may have to get into the lab and see what I can design.
Very smart fix. Great ingenuity there!
Thank you for sharing it with us.
Great work RacingBrick. Does anyone have a list of the Lego ID numbers for the required pieces to do this mod?
That's an interesting aspect of the set, and I have to admit that this didn't happen to my Zetros although I didn't even modify the rear axle. I hold the model in place while driving and no cracking occured. I really wonder if it will crack when I push the truck to its limits in an outdoor test 🤔
You only need to simply drive it against the wall to test it
@@RacingBrick I did and there was no cracking 😅 I couldn't even move the beam with my hands. I send your (really good!) video to a friend who has already built the Zetros as well and he also didn't notice any cracking. I really don't know why some people have this issue with this set and others don't 🤔
Quite interesting, would love to see that video. There's a discussion on Eurobricks, maybe you could share there your experience
@@RacingBrick I can send you a video on Instagram, if that would be okay 🙂
Sure
glad to know this issue happens deliberately as i thought it could be caused by acident
i am going to buy the set online and i am not sure what version of the set i am going to get but i am just going to be carefull and treat it like i treat all my expensive lego sets and not put it through hell for no reason
After all, lego is just plastic, and there will always be problems when facing high torque or struggle. You can decrease the problems, but never fully eliminate them.
but you can eliminate it its just this one piece in the rear axle
Not only one piece unfortunately. But the problem can be eliminated with a redesign, if the structure is rigid enough then the motors simply stop if the wheels are blocked
@@RacingBrick Yes that is true
You forgot another simple fix: Superglue! ;)
My theory would be, that the new pins TLG introduced this year are softer and can slip out easier compared to the inventory parts the Designers use to test their builds. The new pins don't make the same clicking noise as before, the nr. of friction grooves/holes changed. Can you check if the red pin used is 6209519 or a new element Nr.?
Same ID, you can see the full part list in my review video
I've heard that the superglue solution may cause some problems for the later tearing down process.
You are so silly! May be it will be stick, but you can't fix the the gear box with that :)
I hope they add a fix or some sort of accessories do add to that assembly so no one would face the issue..sonce the set isn't out in all markets yet
Great clip!!! Good idea to fix this problem!
I think, you alone have already made more videos with this set than there are reviews with it on TH-cam)
I follow your modification at rear axle sytem and i made modification on rear link also thank you
I havent tried but cable ties (nylon zip ties) might be a low profile solution less permanent than glue.
Would putting one of those green rods in the middle of the red peg that pops out work?
05:22 this is really impressive! Thanks for the video
The easiest way to fix: glue it ^^
Just save your money until the Zetros goes down in price. In the meantime the Heavy Duty tow truck is ALOT of Lego and functionality for the price. Especially when you compare it to, say, the Porsch 911 RSR or similarly sized/priced sets.
Where can I find some more details about your friend's red 4x4 you had on your desk? Has he published it on rebrickable?
Hi, it's the friend here. Not much on rebrickable, but here's my youtube channel: th-cam.com/users/Attikavideos and here is a forum link for the pickup in the video: www.eurobricks.com/forum/index.php?/forums/topic/173533-moc-the-ultimate-pickup/ on the bottom of the 2nd page you'll find a link for the stud.io file that includes the instruction as well. Good luck ;-)
@@Attika Cool! Thank you very much!
LEGO Group: We have gone too far. Back to Galidor!
Thank you, great video as always
@5:55 time for Lego to bring out some bead lockers!
Kragle!
i can't get the 4WD function to work on mine. When I engage it, the motors spin but none of the wheels move. 2WD works fine (although the truck is VERY slow - is this normal ?)
Why do the modern lego Sets have such issues, I can't think of an old lego set which had such a severe issue.
Because old lego sets did not have such complicated mechanisms using gears
Old Lego sets with motors used elastic in order to have the "necessary" torque, but if you blocked it, the elastic would be slipping easily... Try to do a trial truck with old 9V systems, only using PF ir receiver and extension cable to connect to motors, and you will see... At the first ramp over 10°, you won't climb anymore XD
@@pranava8185 By old I didn't mean Sets from the 9v, none pf era, but rather Sets like the 42009, which has a complex gearbox and works perfectly, if assembled correctly.
@@richardjulien1329I didn't mean that old, I rather meant Sets like the 42009.
A buggy motor is count as a 9v motor and I can assure you that the buggy motor can climb more than 10°. And with the right reduction, any motor, even the oldest lego motor can climb until 45° without any problems.
@@b3for354 Driving is the only motorized "function", that is usually build without a clutch gear (exception: tracked vehicles like the 42100, because the tracks can get loose if the force is too high, and realy old vehicle use the mentioned elastic...). everything else "works perfectly" because it cannot be blocked completely. If you block the wheels in 'older' Lego sets, the differential will just slip through with the usually sound... And I don't think anyone ever tested the behavior of every transmession ever build when it is blocked completely .
Hello sor i habe a problem with the zestro only 3 wheels work when switched to 4x4 what can i do to fix it
BRO, I FEEL YOUR A BIT EXTREME OF YOUR EXPCTATIONS OF THIS KIT?! REALLY WOULD ANYBODY RUN IT LIKE THE WAY YOU TEST IT OUT ???? CMON MAN....REALLY????!!!!! HAVE FUN MAN....GMAN 305
Bro, it's an RC toy for kids. Do you expect them to play only by the rules and never stress any components? Really, the key feature and selling point of this set is the ability to climb. Yes, running it against an obstacle is extreme, but if the issue happens there within a few seconds, then it will surely happen with a few days or weeks of moderate usage.
When I first built the set I did not do any extreme tests, simply was running it over some obstacles and made it climb slopes. Still, the cracking appeared in like 2 days.
Calm down calm down!
Me:*confused screaming*
Hi. My son and I are at a loss with the issue we are experiencing with this truck. We've tried switching the rear diff lock orange piece and tried completely rebuilding the rear end. When we lock the rear diff, the driver side rear wheel will not turn and just drags on any surface. Any solutions? Your help would be much appreciated.
WOW, 55 degree is crasy...
I just had to replace one part on the rear axle and there was no problem at all, not even when i hold both wheels
Just finished building this set … problem is that on the remote app ( Apple iOS ) the accelerator makes the steering turn ? and the steering makes the truck go forward and back, but only for a few seconds ? All connections are correct, have done mechanic trouble shooting, will not drive forward and back, any suggestions from viewers ?
I never had this problem ..however I have power issues when steering
Can you make ANOTHER video 'cause it's kind of hard to fix it! I don't know what to do with this part! (I think I'll understand if I have the set.)
It'll be definitely easier if you'll have the set
Hello, I really need help to calm the sadness of my children. I have assembled the truck but when I run the engine the front wheels spin forward and the rear wheels spin backwards. How can we solve the problem?
Normally you shouldn't be able to install the differentials incorrectly in the axles, but that can cause such issue. I would suggest to double check the orientation of the differentials, also the whole front axle, something should be the other way around as it supposed to be.
With great power... ;) Thx for the video and small guide.
One question: If it cracks with every gear locked in place, doesn't this damage the gears immediately?
Are we nice guys and record that under "very clever clutch to prevent broken U-joints"? I'm not sure we are :D
Maybe it helps a bit to use a 11 liftarm, two pins with pinholes and Bricklink Item 42003 to connect the frame and the liftarm for the gear to the angular liftarms on the sides from behind (if I did not count wrong...)
The structure is not fully rigid even with the half beams, in this case there are still other support points that can move a bit but that really requires a high resistance (grabbing both wheels). It is certainly possible to build a structure that has support points for all gears that cannot move relative to each other, but for that the best is to start from scratch :)
@@RacingBrick Hold my beer! :-D
Wouldn't it simply fixed by a White Gear with 24 Teeth and Internal Clutch?
Hey, the extra parts you used for the fix, did they come from the 42129 lego set? Also, do you have a step by step guide on the gear fix? In the video, its not very clear on exactly what was added / replaced modified.
Nope, not all parts are from the set. There'll be a guide coming soon.
@@RacingBrick One more question, after i completed the zetros build / started the control app on ios / my diff lock switches opposite to what the app shows. So when the app switch is in locked position , my diff is open and vice versa. I was under the impression that it will reset to a default position after the calibration process on the app, but thats not the case. Any ideas on how to fix this?
@@marcinlimanski not sure about this one, the calibration got it right for me. Are you sure everything is built according to the instructions?
Amazing fix! Is it normal that rear wheels are slower than the front wheels?
Normally they shouldn't be
@@RacingBrick Thanks. I didn't put on the tire and I observed rear wheels are little slower.
Dear racing brick,
Great video, thank you a lot. Last week I completed full assembly but when I lock the diffs, only one wheel of the rear axle rotates. This happens when I have the zetros upside down or when I lift the rear part of the zetros and rear axle not touching the floor. When I'm driving the zetros I can see both wheels of the rear axle turning normally. I fully dismantle the whole vehicle, assembled again, issue remains. please help!
You should check if the axles are properly connected to the gears inside the differential on both sides
@@RacingBrick thank you for replying! so i have to dismantle the whole rear axle and to check if the axles are properly connected and aligned as described in pages 125-126 and 127?
А сколько стоит этот набор
My back left wheel don't moving ;x
The next fail, after the Osprey?
Just built this set with my son (took us 4 days). On the app we move the throttle forwards. The front wheels move the truck forwards but the back wheels move in the opposite direction. Spent 1.5 hours talking to lego on the chat, but no resolution and then app crashed and lost the chat and call number. I was told that rechargeable batteries in the hub can cause issues to we've just tested it with non rechargeable batteries (more expense) and that hasn't solved it. Any ideas how to get all the wheels working in the same direction?
One of your differentials should be placed icorretly, with the wider red gear part placed on the other side. Since the rear differential would not fit in place in the other direction I assume it will be the front one. Compare your build with the manual from step 232. There's no clear image from below once the front axle is completed, but e.g. in step 271 you can see how the differential and the red gear of it should be oriented, it should be on the right side of the vehicle where the duck sits.
Can you pls help me my zetro always goes right but i dont press anything pls help
Looks like you have a mechanical problem at steering
@@catzzzz1450 its already fixed the app was bugged just had to reinstal everything works now👍
Yay =D
If i can do the apple on the bin on my 42129 yes
Imagine if Lego made some technic gears, axels and lift arms out of metal. There wouldn’t be any of these issues.
At some point the metal should connect to plastic pieces, and that's where the trouble would happen
On one of your previous videos on powered up where you showed how to unlock the secret code blocks, what text editor did you use? I tried Zarchiver pro for the file manager and Simple Text Editor by MaxiStar and when I taped "open" it went to the text editor and nothing showed up. Can you please help me?
I used the default text editor on my phone. You can download a json editor if you prefer
I don't have a default text editor :(
I know this is a older video, but does anyone hear a click when switching modes with this set? It does not happen all the time, but sometimes I hear a click sound when switching to the other mode. I am not sure how worried I should be.
There's a clutch built in, you should not be worried. Check my other video about the set where the gearbox is explained
8 Lego employees disliked the video.
differential lock is not made for solid surface like in real life
Wheels not turning on mine anyone know why
Hi guys. Can someone please help me? I have finished building this set a few days ago and I have a problem. When I drive with locked differential the left back wheel is somehow blocked and it doesnt move but when I open the differential (4x4 is active) all the wheels are moving. Please help I dont want to rebuild the whole set. Thanks!
It sounds like the small tan gears are not rolling freely inside the housing of the rear differential. I suggest to take the rear axle apart and make sure all 5 gears roll smoothly in the differential housing.
@@RacingBrick Thanks for the fast answer! I will try to investigate whats wrong and I hope that I will get it to work. Building the these sets is so much fun and I feel like a kid again when building them :D anyway great video as always thanks to your videos i have bought my first technic set :D and when you will have nothing to do you can make a video how to detach the axles the easiest way so everyone who will have the same problem can fix it without rebuilding the whole set :)
ahoj rené , chtěl jsem se zeptat jestli ti pomohlo rozebrání zadního diferenciálů . Mam úplně stejný problém jak popisujes . Když mam zamčeny diferenciál tak LZ kolo je zablokované a neotači se . Když otevřu diferenciál tak vše funguje OK . Dekuji za odpověď
@@marekelias4721 ahoj Marek, áno pomohlo aj keď neviem presne čo to spôsobovalo ale už som to neposkladal tak napevno k sebe a bolo to lepšie… takisto som si všimol že som jedno koleso založil naopak (myslím normálne koleso s pneumatikou :D)
@@renco02 diky za rychlou odpověd , tak ja to znova rozeberu :-)
Ciao ti seguo da Italia!riesci a darmi le istruzioni dettagliate x sistemare bene il differenziale posteriore e quelli centrale se mi mandi le istruzioni ciao grazie saluti Gianluca
One word "glue"
New sub :D
Does anyone have a problem where if I try to climb some blankets or books the back axle cracks even when the differential is open or locked? Is this just me having the problem??
This is exactly the issue I am talking about in the video, check your rear axle and push back the beams in place
@@RacingBrick I mean’t when I Drive it, it cracks even with a Differential open, and when I am driving it on top of blankets or if the front axle is off the ground it still cracks with the differential open in the bottom right wheel it stalls every single time when there’s a crack
@@n64omighty89 if the beams separated once then it does not matter if your diff is open or closed, in can crack on a plain flat surface as well. Verify your rear axle assembly.
@@RacingBrick ok thanks for the advice =D
When you hold the tire, but the rim still turn : O_O Nani?
when the tire grips the ground stronger than it grips the rim
Put rubber bands on the rims in the groove where the tire goes. Adds grip between tire and rim without having to glue it.
Gentilissimo mi puoi dare le istruzioni x risolvere i vari problemi in italiano grazie ciao
I paid for this lego 180 €
problem solved!
Mine is good just seems slow
Bel problema ma credo che lego saprà risolvere questo piccolo intoppo comunque sempre forza lego technic.
hi
Great upgrade ! (Like always) Lego is now to poor to make good set !
So I pay €300 (which is much more than $300) and have to fix several problems myself: gears, doors, the hood, all the parts that fall off far too easily (and you did not even mention that the front gears are prone to eating grass) - great. Sounds like another Osprey. I can only say: Welcome to the Lego world of total ignoramuses.
Фирст
One could just use GLUE to hold the parts together.... :)
yeah but
Lego not for afols✌️😃
3rd
Lego quality control is sucking nowadays
So ugly set and also ill-considered