Hrafn

I hope your leaf springs work out! I know a couple of people have used 2791 as a leaf spring, with 2790 in the middle to connect to the axle being suspended. It sort of works but isn't ideal.

Amazing! The only thing I might change is with the light gray parts. I would move the light gray 'cheese slopes' back 1 plate so they're flush with the trans-clear ones, and then maybe replace the gray plates that run along the top of the grill with 'plate, modified with door rail' if you have them. Right now the cheese slopes don't quite align with the plates. That's a tiny detail, though - this is easily some of the best bodywork I've ever seen in Lego!

Part 2695, which is inexpensive on BrickLink.

Welcome! One note on terminology - RC is usually used here to refer to Radio Control; if you're looking for remote control via infrared (IR) systems, people on this forum generally use the term PF (for Power Functions) for that. Lego put out a couple of types of actual radio-controlled vehicles in the early 2000s, but the motors used for those, while powerful, are rare and expensive and a bit hard to work with, and the receiver / battery box units are very large. PF is easier and less expensive to work with, though it doesn't have the range of RC stuff. That digression aside, what are you looking to build, and how large? Other than the 42009, do you have any Technic parts already?

Looks good! I know it would throw the geometry off a bit, but have you considered moving the top axle slightly and using 12t double-bevel gears on it? Those would mesh a little more smoothly with the 16th clutch gear.

Very nice, thank you for sharing it with us! How much is the final vehicle slowed down by the additional weight of the bodywork?

I'm so, so sorry to hear this. I hope that your family, friends, and community will be there for you to provide whatever support and solace they can.

Yellow supercar by VK (2013): which was based partly on Madoca's red supercar: Frankly, I think all l of Madoca's stuff belongs in this list; all of it is from 2013 and 2014:

The reverse gear can be switched to a 5th gear. The one downside is that it's not much of a change from the adjacent gear; for a smooth gear ratio curve you'd want a further 20:16 gearing or something similar. Rather than a dedicated reverse gear - which could be slow to switch to if you're on the fastest gear - it might make sense to use a variant of Sariel's direction sensitive gearbox. Instead of having the output rotate in the same direction no matter the motor input, you can use the ratchet to select between reverse (which goes through a dedicated gear train to gear down the motor) or forward (which then goes through whatever gearbox you're using, in this case a 5-speed). That way you get 5+R but the ability to switch into reverse quickly. If you put a spring on the ratchet that tends to return it to a neutral (disengaged) position when the motor is off, you've also got a clutch built in. As soon as you stop driving the motor, the clutch disengages and you can (theoretically) more smoothly shift gears. EDIT: you'll need brakes if you implement this, but you already did so in the Fulvia. Of course, actually putting all this together is the tricky bit. In particular I think it'll be an interesting challenge to create a gear selection mechanism that is fast, accurate, and strong.

Very nice! I look forward to seeing the completed version.

Thank you, that makes sense.

Very nice! I think the axle might need to be a bit longer, though. If the hub connection is 1 stud thick where this axle goes through it, there might not be enough of the axle protruding on the other side for a wheel to stay on securely.

You can buy individual parts from Lego now - take a look at this thread. The part selection is somewhat limited, the system is clunky and slow, and some of the parts are priced well above BL prices - but it does work, and can be a good way to get some specific parts.

Could you explain how that works?

Interesting. Do you have a link to the older discussion, or force diagrams? Thanks!

Nope. I don't have the oldest style diffs so I can't try this, but I always put 4 bevel gears in my 4L diffs to strengthen them. In order for the 4th gear to fall out, the two gears it is meshed with would have to rotate in the same direction, but they can't because they're both meshed with another gear. The advantage to having 4 gears instead of 3 is that it balances the forces on the two gears that are connected to the half-axles.

Rubbing alcohol might work, though I'd test it on one part first to make sure it doesn't melt the Lego. The same goes for acetone (found in some nail polish remover) and mineral spirits.

This is extraordinary. Bravo!

The rear suspension will have limited travel, so I don't think it'll be an issue. I know what you mean, though - I've had those bind and pop out, or grind against other parts, when the suspension moved too much. The new steering setup doesn't wobble at all. I thought about having longer steering arms, but then to get Ackerman steering the arms also need to come 'in' more - which means the steering rack is placed further back, is even shorter, and (as you point out) has to move a lot more. The other thing is that with kingpin inclination, the end of the steering arm moves up and down as the wheel steers. The longer the steering arm, the more this is an issue. The current setup is a pretty good compromise, in my opinion, between all the various considerations (size, travel, steering lock, Ackerman, kingpin tilting, etc.)

Right now I'm looking at loosening my scale standards and going with the usual 23-stud-wide double-wishbone setup. It's only 1 stud wider on each side and it has a LOT less friction. I have tried that, but the friction in the axles still dissipates power, no matter how the motor is geared. The differential probably drains some power, too, but I'm reluctant to give that up in the name of more power since I also want maneuverability.

Time for an update! Any suggestions or advice would be welcomed. For the rear axle, I'm using Saberwing's design. It works well, with two caveats. First, after a few crash tests (running into walls), one of the bevel gears fell out when the 2L axle it was on slipped into the CV joint. I had been careful to use an old 2L axle (with no notches) in hopes of avoiding this, but I guess it's just an inherently weak connection. Second, the vehicle moved a LOT more slowly than when I tested the same motors on a somewhat lighter and much simpler dummy chassis, so I think I'm losing a lot of power to friction in the rear axle. For the front axle, I abandoned caster angle but kept the short-long-arm suspension, kingpin inclination, and pseudo-Ackerman steering. Including caster just made things too complicated. The kingpin inclination is 18 degrees, which is not as steep as earlier designs, but because the lower ball joint is tucked inside the wheel, the scrub radius ends up being near zero. The front axle still needs some work - I haven't fully integrated the steering motor, figured out the shock mounting locations, or gotten the ground clearance quite right (it's currently much higher than the 2.5 studs or so the rest of the vehicle has). I've been using 2 RC buggy motors to power this, directly coupled and with no gearing from the fast output on the motors. Unfortunately the motors are not delivering the kind of performance I was hoping for, or that tests of a simple chassis led me to expect. I suspect I've got a lot of frictional losses. Also, I'm now seeing the overload protection on the 9V battery box kick in after the motors stall half a dozen times or so; with the simple chassis that didn't happen. I'm very reluctant to use the RC receiver / battery / steering unit, since it takes a huge amount of room, so I'll keep working to see if I can improve the drivetrain

Three 12t single bevel gears in an 87408 or 48496 ?

Are you doing rear or front wheel drive? Rear will probably be easier - that way each axle only needs to accommodate one function. The three simplest, common steering setups (all using rack-and-pinion steering) are 1) servo plus the 'train remote' 2) M-motor with return to center (using the 'hockey spring' or rubber bands) 3) M-motor geared down 9:1, including a clutch gear (the white 24 tooth ones) to prevent the motor from stalling Either of the M-motor designs should work with an L-motor. Return-to-center is good for fast vehicles but limits you to steering all the way left, all the way right, or straight ahead. A geared down M-motor (or L-motor) is slower but offers more control.

Yes! Though with a chamfer.

The RC motors were designed for use with the RC reciever / steering unit, which is also 9V and powered by 6 AA batteries (each of which is 1.5V). The issue with the 9V battery box seems to be that it, like the other boxes, has a current limiter in it to protect against overheating. Presumably the RC unit does not, or has a higher maximum current limit.