Classic Land Rover Defender, v1 (with 4L motors and RC electronics)

2024-09-08

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I didn’t originally plan to build a Land Rover Defender model. My idea was to build a chassis with a 2-speed gearbox, locking center and rear differentials, suitable for an off-road vehicle. Something similar to my Unimog, but a car, not a truck. And once the chassis is ready, I would only need to find a suitable body.

Video

Drivetrain & gearbox

For propulsion, I used 4 L motors connected in pairs. The motors are geared up and then connected to the gearbox.
In the first (low) gear, the movement goes to the 12:20 gears and then directly to the drive shafts, the center differential is locked.
In the second (high) gear, the movement goes to the central differential through a pair of 16-tooth gears with a clutch.

The idea of the gearbox layout is taken from this MOC by Superkoala.

Motors gearing

There are two options here:

More torque	More speed
20:16	24:12

Gear ratios

Gear	Central diff	Gears	Final ratio
1st	Locked	20:16 (or 24:12) -> 12:20 -> 14:22 (diff in axles) -> Planetary hubs	11.33:1 (or 7.08:1)
2nd	Open	20:16 (or 24:12) -> 16:16 -> 14:22 (diff in axles) -> Planetary hubs	6.78:1 (or 4.25:1)

Front & rear axles

The front axle was inspired by the Jeep Wrangler model by gyenesvi. The differential here is always open.

The rear axle has a locking differential, activated by a GeekServo motor.

I experimented with the 9.5L shock absorbers, but they were too long for this model, so I decided to go with the standard 6.5L shocks with a hard spring. The suspension is soft, with good travel.

Bodywork

Once the chassis was ready, I started to choose the body - after several attempts I found out that the classic Land Rover Defender 110 was the best candidate!

Even though the reference image I found shows a 5-door version, I decided to build a 3-door version to simplify the body and reduce the weight.

The bodywork design was heavily inspired by the Land Rover Defender 110 model by Sheepo. I decided to build it in red, luckily LEGO has enough red parts to build the body.

I made the body modular, so that it can be quickly disassembled into large pieces for maintenance or modifications.

The largest pieces are the left and right sides.

All 3 doors have locks.

I was primarily focused on playability, so I decided to sacrifice the fake engine and place the battery under the hood for better weight distribution. The curb weight of the model is 2.40 kg.

In order to have a working steering wheel, I used a second GeekServo motor. It’s connected to a separate receiver channel, which mirrors the 1st (steering) channel. The gearstick also works - it’s connected to the gearbox with a technic link. The interior is simple, the seats are taken from the 42110 LEGO set.