Hrafn

That's great! It sounds like both of these designs are true Torsen diffs, which is exciting. Some of the other LSD-type designs using worm gears have a sort of hysteresis or memory due to the way the worm gears travel.

Beautiful! Thanks for showing us the photo of the underside, too. I'd love to see more, especially to see how you crammed studless PF and semi-studless RC motors (with their strange shape and dimensions) into a studded vehicle.

I'm excited to see it! A lot of Technic LSD / Torsen / etc. diffs seem to have structural flaws, and some even tear themselves apart when subjected to large torque. Have you managed to avoid those problems?

Megablocks?

Very nice! The solution for the two-speed wipers is clever.

Either mudguard is good; the one piece one is a little better IMO but its color doesn't match the rear mudguard. Do you have enough black liftarms to redo the rear one in black to match?

I really, really need to stop posting before I have my coffee. This doesn't make any sense at all. That said, as others have written, it can work to take the gear off and put it on again if in doing so you also fix whatever misalignment was causing the problem.

Take the 12t gear off the axle, turn it 90 degrees, and put it back on. Unlike with the other gears that have a number of teeth divisible by 4, the orientation of the 12t gear matters.

Those are both clever, thanks! Lipko's is particularly compact.

I like the arches, actually - I think they look better than the flex axles or bent liftarms people usually use.

Woo! Your Fulvia is what inspired me to work on a rally car, though since it's my first Technic MOC it's going veeerrry slowly. I'm looking forward to seeing your new one!

After seeing the comments here, I wondered what process others follow in building cars and other vehicles. My approach thus far has been: 1) determine what vehicle to model 2) figure out the scale 3) determine the wheels and tires used, to match the intended scale [this may actually come before 2) - in my current effort I picked the tires first, then determined the scale] 4) figure out roughly what features I want: suspension type (if any) per axle, which axles are driven, which ones are steered, whether there will be a gearbox, whether it will be motorized, etc. 5) build the axles 6) build a chassis and fit in the other features (gearbox, motors, etc.) desired 7) bodywork (not that I've gotten quite to this step yet...) So far I've had to go back and revisit earlier steps a number of times - for example, I thought I was done with my axle designs but then found out that the motors I wanted to use were so strong they were tearing the rear axle assembly apart. Preliminary bodywork showed me that the shock towers were too high, so I had to redesign the front axle. And so on... Is this similar to what you do? I was surprised to see Doc_Brown say he started with the bodywork (gorgeous though it is!) for his GTHO.

That's a neat design, but I am skeptical that 3D printing it at Technic scale is going to work well. It would be a lot of small parts, all of which need to be made to close tolerances. The "claw" part presumably also needs to be fairly firm so the "fingers" don't bend out. Also, what keeps the balls from simply falling out when the joint is straight?

Beautiful work as always! I'm eager to see more photos of this thing.

Sorry, I don't know what I was thinking. You're right, the AA pack has the same issue. It's easy to open and hack that battery pack, though, and not too expensive a mistake if something goes wrong - in comparison to the very expensive LiPo battery. I'm not sure I understand about the M and Servo - do you have a photo of what you're trying to do?

The overload protection you're having trouble with is probably the one in the battery, not the motor or receiver. Take a look at Philo's video. The two main solutions I know of are either to modify the battery pack itself by short-circuiting or replacing the overload protection chip (which runs the risk of damaging it permanently) or to use the AA battery pack. The latter adds a lot of weight, though.

Very nice, and an unexpected use of Lego! In English (approximately, since my German is very rusty): Unfortunately it's not only the walnut that was cracked, some gears broke as well. Since breaking gears is no fun, I've put the project on hold. Uefchen, have you considered using worm gears instead? They are less likely to break. (Koennen Sie Schneckengetrieben nuetzen? Sie sind stark.)

That looks great, and you really squeezed a lot into a tiny space. I love the claw parts used as a skid plate in the front.

Ask and ye shall receive! Here's a top view with the wheels at maximum steering lock: The front axle structure is totally different than before in order to make it really robust, but the basic geometry is the same. The shock tower tops are not properly connected yet because I plan to integrate them into more reinforcements for the area in front of the front axle. I'd like to have a fake steering wheel connected to the servo and geared up, but I'm having trouble finding a way to route the connection without having the front axle assembly get too tall. The hood will be no more than a stud or so above the current axle assembly, so I don't know if there will end up being enough room for the steering wheel to be connected properly. EDIT: Or I could do the simple thing by moving the servo back 2 studs and gearing the steering wheel from there. EDIT 2: I just moved the servo forward of the front axle, which freed up a lot of space in the middle of the car for a transmission. Two cranks form the long sides in a parallelogram four bar linkage; one of the short sides is driven by a rack. The steering tie rods attach to ball joints on the long sides of the parallelogram. The Ackerman effect is actually exaggerated in this vehicle - when turning, the lines of the front axles intersect well in front of the car's rear axle. This was driven by a number of considerations when constructing the front axle (overall size, avoiding wobble in the tie rods, etc.) but ends up having a beneficial side effect: at high speeds, if the rear wheels are suddenly stopped, the car loses rear traction and goes into a sort of handbrake turn. Well, it did with a lighter-weight dummy chassis; hopefully that will still happen when the car is complete. The same area, from below: The rear axle, again, is your design with only small changes: The motor locations are tentative at this point. On the plus side, having them here opens up a space for a gearbox (if an odd-shaped space) and uses the rigidity of the motors to strengthen the chassis. On the negative side, I'll have to do a 90 degree connection with gears or knob wheels to get drive to the rear wheels. My hope is to have a low-profile gearbox in the space between the motors, and then put the battery box on top of the gearbox towards the rear axle, to keep the center of gravity low. EDIT: after moving the servo I will probably reconfigure the motor setup, turning them 90 degrees, putting them near the rear axle, and hard-coupling them. The driveshaft could then go forward to a transmission, then up and over the motors to the rear axle. Hopefully that will work. The car itself will end up very low-slung so I'm trying to keep everything as low as possible. Right now the front of the car is up too high, but with the added weight of the bodywork etc. it should drop down so that it's even with the rear, with 2-3 studs' ground clearance.

Thanks guys! Sariel's gearbox is definitely one I'm going to test out. I may put a spring-loaded bumper on the front to help with crashes, but the chassis still needs reinforcement. Right now it's a basic double-rail system with some 5x11 plates between the rails; I'll need another set of longitudinal beams higher up and some sideways and torsional stiffing. It's definitely doable. After the amount of effort that went into the endless redesigns of the front suspension, everything else seems relatively easy!

That must be very frustrating. I hope you persevere, though - you've put a lot of good work into this project. For the leaf springs, as long as you're going the non-Lego route, have you considered brass? Hobby shops sell thin brass sheets and strips, and I suspect you could bend the ends of a strip into loops using needle-nosed pliers.

Thanks! I definitely want to do a video, but it'll be a while since there's a lot to get done - fully integrate the motors and battery, finish building the chassis so it's strong enough to endure crashes, do the bodywork, and figure out how to do decent videos. Right now I can just about squeeze in the motors and battery with some effort, but that leaves no room for any gearbox. Initially I wasn't planning on a gearbox, but I might want at least a manual 2-speed one since the high speed is so fast and hard to control. The chassis also needs to be very robust to withstand the inevitable crashes - my test chassis splintered every time I hit a wall, and the lack of a bumper meant that glancing blows to the tires tended to tear the tires off or detach the steering links. I'm concerned that in order for the bodywork to hold together in crashes, I'll have to make the model pretty heavy. I got the snowmobile parts straight from Lego, since the set isn't available in the US yet, and they're really nice to have. With some modifications, though, I could probably have done this model with just the old 6L ones. I got some 5L axles with stop in the same order, and those have also come in really handy.

Thanks! The rear suspension is a variant of Thirdwigg's floating differential double-wishbone setup for narrow vehicles, widened to 21 studs and using to hold the differential. Thirdwigg's original design was good but not quite up to handling the power of 2 RC motors; the L-liftarms slid on the 5L axle and the 20t gear started skipping. Like the front suspension, it's a short / long arm suspension, but with less travel and a stiffer spring configuration. I'm hoping that I can keep the current performance when I add weight. Right now the turning circle is 105cm, which is good for 1:10 scale. Moreover, right now I can do really tight handbrake turns (by using engine braking)! Front steering is with a servo, driven by a bang-bang remote, which gives fast steering and a maximum steering lock of more than 45 degrees.

Thanks! I'll definitely have to use an AA battery box, as the rechargeable one gets overwhelmed after a while. I don't know if the car will demand enough current for me to need to modify the AA box. Right now, the test chassis performs amazingly well (and drives incredibly fast) with either the rechargeable or (unmodified) AA box, but I expect to add another 400-500g of weight before I'm done.

Outstanding! If anything it looks better than the real vehicle. I'm looking forward to seeing your continued progress and the final result!