amorti

Another zombie post, but maybe I have another angle, as a motorcyclist. You can shift a motorbike's sequential gearbox up without the clutch, as long as you dip the gas at the same time to allow some slack into the system. Quickshifters do the same, by sensing an input on the gear pedal and cutting the spark for a few cycles until the next gear engaged. You can also do it on the downshift, and quickshifters can do this. However, it's a much more tricky operation and more often results in grinding gears... You don't tend to try it too many times more after that. It would be considered very lacking of mechanical sympathy to attempt a gearshift without introducing that little slack in the system. Indeed most times it's not possible as the dogs on the gears are slightly tapered to pull themselves tighter under load. Can you solve the shifting issue by software? Can the app cut drive to the XL motors for the briefest moment just to introduce some slack, then the shift goes easy?

Looking awesome as always, diederik. Grats!

What kind of animal must I be to look at that and wonder, not whether you'll hurt the wishbone by bending it like 0.2 studs, but whether it would be stronger I'd you put a normal black pin between the two 5L liftarms, and pulled the wishbone open around that...? Sorry for zombie quote. Props going out to didumos. Outstanding work, genuine top drawer stuff. The videos of it whizzing about look like a real RC buggy, it's just amazing

Of course you're right - it can't hit the inside edges of the frame. There was maybe a little surface drag against the uneven face, but it wasn't the problem. I have been working on the problem of excess friction in the bodywork differential, and I am pleased to say I have solved it. With the following solution you can literally pick up the model by the middle, and use light pressure from one finger to rotate the bodywork as the designer intended. Here's how: https://photos.app.goo.gl/Z8L35pHVhkRgDXtD9 (Not sure if possible to embed Google photos?) You can bench test the two solutions shown in this picture, and even unloaded mine has noticeably less friction/jerkiness but the difference comes when it's all loaded with the weight of three motors twisting around. The pieces remain all from the original kit: 4x black pins can come from the yellow "coat hangers" on the front wishbones. They are there to stop the wishbones separating and the steering knuckle coming out, they don't need those pins. Swap 2x 3L axles without end stops into the coathangers (the end stops aren't really needed here), then from there 2x 4L with end stops inside tie rod construction, giving you back 2x 3L axles with end stops. These stop the gears falling into the gearbox, which makes friction (try it!) The 12T bevel gears are already available assuming you're building the locked differential version of the model. It's not so easy to assemble the 4 gears inside the frame, but you can do it with patience. Put the side gears in at the same time, one from the top, one from the bottom. Check it has very low friction when finished, if not then you may have one of the gears a tooth high or low; just keep trying til it all moves easy. Good news is you can now skip the alignment procedure in the instructions, just ensure both turntables are 100% perpendicular when you put the second of their tan driving gears on. A good part of the benefit is because I've also lubricated the two turntables, which had a fair bit of plastic dust inside them, with this: https://www.granvilleoil.com/prodInfo?pID=170 I happened to have it in the house, from my dad who's an electrician. He has it as it's safe to use on electrical wires, it doesn't eat the insulation like mineral oil does. I've looked at the specification sheet on the website, it contains no solvents but an "inert thickener". No guarantees of plastic-safety here, but I'm happy to give it a try. Of course everything has a compromise. You now have to use a flex tube (from the original kit works well) to access the "connect" button on the hub. I'd also point out there is a little wear evident on my CV joints. Considering what I've been doing with the model (see video above) and on locked differentials, I am not upset by it. Just know that if you do the locked diff version, there are no Cardan joints to snap, but there will be wear on some pieces.

I think once you've committed to making the locked differential variant, you can swap those 2x red 2-links employed as spacers for bevel gears. The 2-links can get caught up on the uneven surface of the frame, the bevel gears don't have that problem. Does mean the bevel gears are no longer available if you decide you chose wrong, but having tried crawling on both open and closed diffs, I don't see a need for the open diff version unless you're driving around on a high grip surface, otherwise just let the tyres skip.

If it's a democracy, I'll take instructions for 42099C before incorporating these mods ?

Yes, it's just what I meant. I did use two pairs of pin/bushes but it's the same. Wouldn't want to invert the hub myself, but there's probably a way to invert the frame of it right at the start of construction. Technic function same, toy function improved :)

Does the angle sensor still work right? No idea, guess I'll have to look if it has ingredients listed. I saw wd40 PTFE spray recommended, but haven't spotted any locally. Will keep hunting.

If you don't bite your nails it's tricky but quite possible, but yes if you've not built Rocky yet you could flip the battery box for an even bigger usability gain. Wouldn't that mess with the angle sensor though, make it think it's going downhill when it's going uphill? I really liked how didumos kept that functionality, and especially how the steering drives the front of the rack to keep that correct. Actually I might pull it apart and build it again, with that in mind. And use normal pins from my stash where didumos had to use 1.5 pins within the constraints of a B model. I'll put some silicon grease in the turntables at the same time. Any tips what's safe on Lego? I have a little red grease used on rubber brake seals (car) and some dielectric (silicon) grease usually used for plastic and rubber parts. The dielectric grease is much thinner/lighter so would seem a better choice.

As you geared down 5:1, which is the same as the new hubs on 42099, would using those allow the build to be simplified further? I'm enjoying didumos Rocky crawler but this build looks cool also, it's lighter and won't have the same issues with the turntables differential getting caught up. Might try building your crawler from (mostly) 42099 parts. I also have the Street Motorcycle set from years ago so I'm part way there for long soft shocks.

Thanks didumos for your work! I used to love Lego as a boy, but my last big Christmas set before 42099 was 8868, so now you know about me. The Rocky is far more capable than the original model. If anyone is here wondering whether to pay 15e for the plans, stop wondering and just do it. I've been out this evening driving it on some terrain the original wouldn't have a hope on. It's a shame to bang up the motors as they're the lowest point now, but it's fun doing it - I can't believe this is Lego :D Suggestion: if you swap two of the 3-long pin/bushes from inside the doors and use them to hold the bottom L beam of the chassis, it becomes a flip open cover for the battery box. Muuuch easier to swap batteries that way! I've been using an open front and closed rear differential so far, by I think I'll try it with both closed. The extra traction should be worth any tyre skipping. The one thing I wish for is a bit more steering lock. I dropped the parts locking the front wishbones as noted above and it does help, although in one crash/flip that did allow the whole steering knuckle to pop out of the wishbones. There's some more angle available on the CV shafts, but the steering rack isn't long enough. I can't see any way to do it without a ground up redesign which not to mention being outside my comfort zone, would definitely need parts not included by Lego, so I think it's best just to live with it. Guys, what RC tyres could you use on this model? For a bit more grip and/or "suspension".