Rally Car (LEGO Technic 42077)

by ReDo.Bricks (@ReDo.Bricks)

Rally Car (LEGO Technic 42077)

Description

LEGO Technic set 42077, the Rally Car from 2018, built in ReDo from LEGO Technic parts by their part numbers: 1004 pieces, each one the real part in its real colour, every pin and axle joined into the holes it goes through as the set is built. The knob on the roof steers the front wheels through its bevel gears and the steering links, the rear wheels turn the engine's crankshaft and pistons through the differential, and the doors swing open on their hinge pins.


## Where it comes from


Each piece is placed where the LDraw community's model of the set puts it: *42077 - Rally Car* by Philippe Hurbain [Philo], from LDraw's Official Model Repository, redistributable under CCAL 2.0 (CC BY 2.0). The parts are ReDo's own parametric LEGO parts and meshes made from LDraw's drawings, not LEGO's CAD.


## What is different from the box


- Some pieces are built as LEGO's current mould of the same part: the black friction pins (2780) as 61332, the blue 3L pins (6558) as 42924, the pin connector hubs (15100, 87082) as 65487 and 44874, the towball pins (6628) as 66906, and the tan 3L pins without friction (32556) as 39888.
- The model leaves out a black pin the set has, placed here where LEGO's own booklet puts it: through the middle holes of the front axle's two white thin liftarms into the T-beam (step 101).
- The model paints two round pin connectors and the two ribbed hoses Metallic Silver; the set's are Flat Silver, as here.
- The model draws some gears tooth on tooth. Here the rear drive shaft's 20-tooth bevel and the steering knob's shaft with everything on it are turned half a tooth, so every pair, the steering pinion and its rack included, meshes tooth in gap.
- The ZR tyres are drawn 1.2 mm off the middle of their rims, so their beads miss the rims' flanges; they are centred on the rims, as the real tyres sit.
- Pieces the model draws a fraction of a millimetre into their neighbours, or off the holes they go through, are set where they belong: two pins 0.4 mm off their beam holes, two axle pins 0.8 mm too deep in their stop bushes, the right floor panel with its pins, beam and fairing (0.8 mm in from where the left one mirrors it), a 1 × 7 beam and the right rear fairing with its pin hub (each set where its left twin mirrors it), the two 2 × 2 plates with pin holes and the tiles on them (1.5 mm off their pins), two curved slopes sunk a plate's height into the plates that hold them, two axle pins rolled 3° across the cross of their axle holes, the left rear CV joint (square while its half shaft leans 13.6°), the front toggle joints (3.6° off the pin hole they close on), and the seats' Axle 3 (0.05 mm off the line of the beams it runs through).
- The front steering links stand over towballs 0.34 LDU further apart than their sockets; each is turned onto the line through both balls and set midway.
- Each door hangs on one long pin. The model swings them shut until their fairings cut 1.5 mm into the A-pillar's axle 10; here each stands 4° open on its hinge pin, where its fairing clears the axle and the rear fender.
- The rear wishbones are held by their pivot pins and a 1 × 7 strut each, so they do not swing, and the fender hinges at the other end of the rear links 1 × 6 cannot bring their towballs closer than 40.1 mm, while the links' sockets stand 40 mm apart and the model draws the balls 41.7 mm apart. Each link is set midway on the line through its two balls and recorded as a flex: the real link stretches over them.
- A few joints close in the real set only because the plastic gives, and are recorded as flexes: the seat backs' pins (0.95 mm off the double-bent beams' holes), the rear suspension links 1 × 16 and the shock bar's pins and connectors (0.2 to 0.8 mm), the front bumper's angled connectors on their pin hubs (0.65 mm), the notched axle in the rear crankshaft (0.05 mm), the rear links 1 × 6 (0.85 to 0.9 mm), the doors' fairings over the ends of the pins in the doors (0.8 mm), the hood's curved panel on the two small fairings at its front (0.85 and 0.9 mm), the hood's 1 × 13 beam against the connectors and the 1 × 9 beam it crosses (0.3 mm), the red 1 × 2 beams against the round pin connectors at the front (0.35 mm), and the engine's crankshaft and connecting rod on the axle with stop, whose end the model sets 0.8 mm past the crankshaft's axle hole. LEGO's booklet builds each of the last five as the model has it (the doors at steps 228 to 240, the hood panel at step 205, the engine at steps 38 to 43), so none is a fix to the model.
- Where a flex is a pin in its hole or a towball in its socket, it stands in for that joint, held where the model draws it, so the whole car is one piece: the two rear links 1 × 6, the two rear suspension links 1 × 16 with their pin hubs, and the shock bar's axle and connectors with the pins the links hang on hold to it, in a drag and in Simulation.
- A few faces LDraw draws touching come out a few hundredths to a tenth of a millimetre into each other in ReDo's meshes: the bumper's angled connectors side by side, the differential's 12-tooth bevels in its cage, the rear bent beams on their L-beams, the front pin hubs on their 1 × 3 beams, two half pins end to end with pins, and the left door's long fairing against the pin beside it. They are recorded as flexes too, until those meshes are made closer.
- The parts leave out what does not change how they fit: the hollows under a beam, the engine's moulded detail, the tyres' tread pattern.


## Try it


Turn the knob on the roof in Simulation to steer the front wheels, open a door, or select any piece to see its part number.

Bill of materials

Licences

Open in the ReDo Playground