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Power Functions 4×4 8081

May 18, 2012 4 Comments

For most LEGO enthusists, when they purchased the set 8081, they quickly modified the set with a Power Functions drivetrain. It makes sense. LEGO models are a little more exciting when they are motorized. But I guess I went a little backwards. I wanted to do the fun stuff first, and make the most complicated and compact drivetrain I could make. I posted the instructions here, and they can also be viewed on Rebrickable.com.

But the comments kept coming from people who wanted to see my model motorized. So I thought it might be a fun addition. I added a two PF M motors, a 8878 Battary Box, and an IR receiver. I tried to keep the modifications simple, so I could easily add the motors to the MOD, and take the system out if I wanted to. The drive motor was placed on a simple mount that connected to the frame. The power was fed thought a 8z gear to a 24z gear which then connected directly to the V8 driveshaft. The driveline was unchanged from the V8 down. The steering motor was mounted laterally in front of the rear seats. A 20z double bevel gear drove a 16z gear, then a worm gear moved the final 8z gear which was mounted on the existing HOG steering axle. I removed the passanger seat which is where I placed the battary box, and created a simple mount for the IR receiver. The added weight required a new shock absorber, so I added that as well.

The model worked alright. The drivetrain did well to handle the new power, and I could easily control the Crusier. The steering motor was a little too powerful for the upside down facing steering rack. It skipped a little under load, which was a problem over rougher terrain. The drive motor was a little taxed, so a PF XL would have done a little better. I guess I could add that, but I am ready to move on to my next model. Stay tuned.

The full gallery may be found here.

Filed under MODs Tagged with 8081, 8878, Cylinder, Differential, Instructions, live axle, MOD, Panhard, PF M, power functions, remote control, steering, suspension, technic, V-8, Worm Gear

Red Sedan

May 13, 2012 2 Comments

When I got out of college, I started getting back into LEGO; the end of my “dark ages.” I wanted to make a large supercar, just like everyone else. But after my first attempt, there were a couple of things I wanted to improve, and the first car did not really look right. OK, so what needed to change? I needed to stretch the car, and make the stance a little better, add some features, and make it as real as possible.

See full gallery here.

I used the dementions of the 2005 BMW 5 series as my template. From these demensions I used the F1 Racer wheels and tires to set the scale, then I determined the wheelbase, got the width, and I went to work. I first made the rear suspension unit, and then the dual cam V-8. Then I linked the two with a 4 speed transmission, and a long driveshaft and added a simple parking brake. It took a little work, but I then added the front suspensions. I have found it best to use technic beams to mount the front suspension. The A-arms are then attached to this structure, with the shock absorbers placed on this structure and braced with liftarms. I then connected this directly to the front of the V-8, and connected it to the rest of the chassis with a simple frame. I used the old steering mounts of the old 8865 supercar, and connected them to the steering wheel through an upside down mounted steering rack. Of note, the car was going to be big and heavy. I had to find a way to get two hard shock absorbers at each wheel which limited the suspensions options I had. In addition, I added a front and rear sway bar, which took a little more space, but it worked.

Then the body. I worked first on the doors, and the front bumper. I used a dual pivot design for the doors so they would open even though bricks do not work well with pivots. Then I did the front and rear quarterpanels, and set the rear bumper in such a way that a full size spare tire would fit. I then worked on the interior. I designed a simple tilt steering using a worm gear, and a universal joint. I made sure to use the great front seat design by Pixsrv, added a rear bench seat, funished the trunk and added all the little compartments in the center console and glovebox.

I finished with rest of the body work. The roof had a sun roof, and the trunk would have a damped shock to hold open the trunklid, and added small details and some mirrors. It was big, and it was done. I was pleased with my first large car. It still my most popular on Brickshelf.com.

All in all it was a great experience to learn about how to make a large car, and all the challenges that go with that. Frankly, since this design, most of my cars have been a little smaller, as it makes the suspension and steering work a little bigger. Lessons learned.

The full gallery may be found here.