2GodBDGlory

Yeah, I agree that it's an odd issue. Granted, I was testing on a slope of loose sand, which is a pretty worst-case scenario. The center of gravity is worryingly high, which could have some impact on it, but the suspension was easily keeping all the wheels on the ground. These tires aren't the stickiest out there, but they are nice and big, with helpful lugs on them. One thing I've done in the past on similar models is to stuff the tires with marbles, which adds lots of weight right where it's needed for maximum traction. I think that's not really purist enough to use for this race, though!

Well, I finally got around to taking an outdoor test drive, and immediately some major problems came to light. For one, the 11L axle in the gearbox is getting extremely twisted, and there isn't really anything I can do about it, other than scrap the gearbox. Additionally, the 20:12 upgearing in the rear axle began skipping like crazy, ruining the 12T gear. I'm not sure what I'll do at this point, but it seems pretty clear that I'll have to make some dramatic changes to the drivetrain... Removing the gearbox would really be too bad, but I'm starting to think it might be required in order to safely run the amount of power I'm wanting to have. It also has a worryingly high center of gravity, and worse traction than I'd hoped. That'd be harder to fix without essentially building a new car, but it would be good if I could come up with something to do about it. Anyways, I'll be thinking about what needs to be changed on this going forward!

I've been using a standard Ender 3, and it's a very solid printer for the price. However, my recommendation would be the Ender 3 Neo, which is only $20-30 more than the standard one, with some important upgrades like a silent motherboard, auto bed leveling, a better buildplate, and a metal extruder, all of which are upgrades that I did, for much more than that $20 to 30.

Wow, nice job! I don't think I've seen any Technic T100s before, and that race livery looks very nice! Overall the model just looks good and clean.

Thanks! I do plan on sharing video of it at some point, but I haven't actually done much testing yet, so I don't have any film yet.

Thanks! It's true that it could look better with more normal fender placement, but I had a really hard time finding any placement that would work with massive tires, a fair bit of steering offset, and lots of suspension travel, all without sticking the fender out past the front of the car, so I'm not thinking that would be an option. I'm looking forward to doing some off-road tests, but right now I'm just waiting to get my real car on the road so I can get it to places more easily!

I'm a little tardy in posting this final update, but I got the bodywork finished up last weekend, and added LEDs and an old Canadian flag piece from my Dad/Uncle's '70s Lego collection. I'm pretty happy with how it looks! I also reinforced the portal axles, and added skidplating on the bottom, so really all I have left to do is add some bumper stickers, and then test it out and make whatever changes are necessary!

Nice job! I saw this on YouTube the other day, and was pleased to see a model of this interesting, niche car!

Ooh, nice work!

That's pretty cool, and impressive that you were able to build it around standard size cylinder elements!

So, the first thing I did after my last update was to start changing gearing to make this truck faster. I added an extra stage of gearing in the axles after the ball joints, with a 20:12 ratio being the largest I could fit in. This gearing also allowed to keep my axles flatter, with the advantage of giving me neutral castor angle and even ground clearance, rather than backwards castor angle and uneven ground clearance. The second gearing I was able to change was switching the portal axles from 1:5 to 1:3, with 12:36 gearing. This was a bit disappointing to have to do, since portal axles are really where you want to keep as much reduction as possible, but I didn't see anywhere else where I could change gearing without compromise. If I decide I need it still faster, I'll probably have to find a way to increase the drive ratio of the bevel gears in the axles, but that would either require a lot of rebuilding, weaken the components a lot, or introduce unevenly operating knob wheels. After getting that done, I moved on to bodywork! I had decided that I wanted to use these custom-painted 1:8 car wheel arches, but mounting them normally in the front would result in them sticking out two studs farther than the front, because my Niva has the wheels pushed out to a non-stock location in the extreme front. Rather than forget the wheel arches and bore myself building another 4x4 with basic beam-stacked sides and slope-brick wheel arches, I decided to mount the wheel covers at an appropriate angle to still cover the wheels. It looks a little odd now, but it allowed me to use some panels to fill in gaps, which looks fairly nice, I think, and at least different from my usual! I've started trying to find a place to mount the rear wheel cover, but my rear-wheel-steering system is complicating this. After getting these wheel arches figured out, I moved on to the front. I'm super happy with how the orange/white secondary lights turned out, fitting nicely into some black System panel pieces to provide a realistic black rim around them. The grille wasn't too complicated, but the bumper unfortunately couldn't reach the full width of the car for fear of colliding with the wheels at full steer and suspension travel. I'm quite happy with how it's looking so far, though, and I think this should become something that's both fun to drive and fun to look at, which isn't something I could say about a lot of my off-roader models!

Looks fun! Are you planning on making it RC? If so, you're going to have to be very careful with bracing that gearbox, because 6-speeds add a lot of friction, which makes skipping gears a very attractive alternative for the motors to take if possible!

Mine had a sequential, but if I were to build one again today, it'd probably have a remote-controlled 6-speed manual, using two servo motors to allow for joystick control from a remote (This is a system I've used on my most recent Ford Mustang and Ford F-Series MOCs, and it's very fun to operate!).

I actually did make a 1:8 one a few years back, but I'm sure a lot could be improved, so good luck!

Nice! It's always interesting to try FWD cars, so the Type R should be interesting.

Yeah, that's strange! You can see it at 0:33 too.

That's neat that we get that gear in black. I wonder why they needed it, though! It's certainly one of the gears that didn't need a recolor into a more inoffensive color, but it's nice. I'm really glad to see those Technic baseplates there! It's a better color, and will hopefully make those things cheap enough that I can finally justify buying some!

Do you have to have a 9-speed? By the nature of Technic gearboxes, it's usually very difficult to go beyond 8 speeds, and 9 would be a real challenge. If I were building a car and really wanted to have a realistic 9 speeds, I'd probably try using something similar to this old 12-speed design of mine, and then just ignore/block out three of the speeds: A great tool for calculating gear ratios is Sariel's Gear Calculator app Good luck!

The need for the brackets probably just went down a lot when the longer cylinders came out, I'd guess

Thanks for posting this! I recall seeing it on YouTube, but it's always nice to read some more details!

Thanks! Yeah, I realize that I have excessive gear reduction at the moment. I have as much as I do in the gearbox just because I wanted my two ratios to be as different as possible, but now I'm going to have to change my gearing down the line to be faster. I've built several heavy-duty off-road models with brick-built hubs before (though of a different design), so I'm hopeful these can work, and will provide much better ground clearance than planetary hubs.

After determining that my method of bevel gear power transmission was a dead end, I felt stumped for a while. How could I eliminate those bevel gears while keeping reasonable suspension geometry and the gearbox? In the end the solution I struck on was to design a gearbox based on a 5 stud spacing rather than the 4 stud spacing of the earlier design. There aren't many gear ratios that work at this 5 stud spacing, with the only options I know of being 56:8, 40:24, and 36:28. [Well, I just checked and 9:15 (with old, pre-Technic gears), or 6:10 (with splat gears) both work, but are both actually identical gear ratios to 24:40] This was probably the time when I most wished the 48T spur gear from the The Lego Movie version of Emmet's Super Cycle had made it into production, since a 48:16 ratio would have been great! (According to something I read somewhere sometime, it was planned for production, but budget cuts forced them to use a standard 40T gear in the official set) I actually didn't realize 56:8 was a possibility until later, but I'm sure I wouldn't have tried it anyways due to impractical size and pathetic 8T gears. That left 40:24 and 36:28, but wanting the largest possible ratio spread, I opted for the 40:24 ratio and its opposite, 24:40. This meant that my already unsynchronized gearbox would have the added disadvantage of straight-cut gears trying to slide into each other, but so long as the drive motors are turning, it hasn't had trouble engaging. The spur profile also allowed for a neutral gear to exist in between the two speeds, thanks to the two 1/4 stud spaces between teeth and the edge of the gear adding up to the 1/2 stud of the width of the gear teeth, which prevents jamming when shifting. Anyways, this gearbox was able to fit into a space only three studs long, which was crucial, and it allowed the XL motors to be mounted linearly with a three stud space between them--perfect for fitting part of the suspension ball joints between them! This gearbox is shifted by a PF M motor through a large linear actuator, through a 4-bar linkage, which I found to be the best way to transmit the linear motion of the actuator down ~6 studs to where the gears were without losing motion to part bending. Redesigning the gearbox also meant redesigning a fair bit of the frame, but other than that not much has changed. The new gearbox has a much lower high gear, though, and it was already slower than I would have liked, so I'll probably have to find a way to add significant upgearing later! It'd be easy to swap the portal ratio from 1:5 to 1:3, but I'll probably have to dig into the axle drive ratio to get the change I desire. I've already snapped this 8L axle simply by its twisting in the ~1/2 stud space between the 40T gears and the wheel hubs in the portal hub assemblies (in high gear!), which seems like a good indication that I have abundant torque to trade for speed! Also, I finally took a look at that video you linked, @Daniel-99, and those are some pretty extreme machines! I thought my 8:40 portal axles were the craziest anyone had done, but those 8:56 ones put me to shame! It's a really great idea, though, and one that just might convince me to buy a couple more 56T turntables sometime so I can try it!

Hmm, that sounds like a challenging, though interesting, project! If modified valves are too expensive for you, have you thought about modifying them (even starting off of clone ones) yourself? That could save you a lot of money, and still probably be less effort than 3D printing.

True, I wouldn't really call it a truck either, but to me "Trial Truck" is just terminology that I slap onto anything I build that's intended for heavy off-road use, and it's especially fitting for this one, since I plan to enter it in a "Truck Trial" event. Yeah, it will look a bit like a monster truck I think!

I love that strategy for combining the small LA with that bevel gear frame! It's something that looks super helpful, and makes me wonder how I've never seen it or thought of it before!