8297 Revamp

A full rehaul of the 8297 Extreme Offroader.

Features:

• 2 L-Motors for drive (4WD)
• On-axle steering motor
• 4-link suspension
• 3rd party Axial Ripsaw 1.9 tires (R35 compound)
• Extra roof lights

I've owned the 8297 set for quite some time, and after browsing a post on the EB forums, I came up with the idea to finally motorize the Extreme Offroader. The final product ended up with a fully rebuilt chassis -- 4-link suspension, portal hubs, 4WD, and a functioning dummy motor. Unfortunately, the winch needed to be removed because of a lack of space.

This model was built from the axles inward, with simplicity as the key. There are 0 differentials in the entire drivetrain, and only 2 universal joints. Link mounts were another key part of the axle design, and I managed to include a caster angle on the front axle. In retrospect, a caster on the rear axle would have been nice as well, but the axle performed fine as-is. Overall, the chassis functioned extremely well, with full suspension articulation and 0 gear slip achieved.

The steering system was an interesting aspect of the revamp. Originally, I wanted the motor to be mounted on the chassis, with a 9L link connecting the steering arm on the axle to a crank on the chassis. Eventually, I ran out of space in the chassis (especially since I wanted a working dummy motor), and I redesigned the front axle with the motor mounted on it. This resulted in a very simple setup, albeit with some occasional steering slip. The slip only happens while standing still, so this is a minor problem.

The performance of this model is pleasing, to say the least. The combination of the tires and the very simple drivetrain makes for really powerful crawling. The soft suspension also allows for all four tires to maintain contact with the ground over most obstacles, and since the tires are made of an R35 compound, the traction is beyond that of any LEGO tires.

Overall, this is one of my more successful models. As the first model of the new year, I'm reviving this blog and bringing you all a video and a free LDD file to download (links below). Enjoy!

More pictures on Flickr

LDD file and pictures on Brickshelf