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Power Functions 4×4 8081

May 18, 2012 9 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

4×4 8081

April 26, 2012 9 Comments

Truthfully, I was excited about set 8081 when it was first announced. I liked the size. I liked the coloring. I liked the stance. But mostly I liked the potential. Most of the Technic community dismissed the 8081 because of its watered down functions, but I was interested in making some changes to see if I could make the Cruiser Extreme.

The full gallery can be found here, and instructions here.

I first added a V-8. There was plenty of room, and after seeing a great modification from Efferman, I had some ideas. It was a simple addition.

Next was the drivetrain. This was a little more complicated. I wanted to make it four wheel drive, and I wanted to make sure there were three differentials. I rebuilt the rear axle, so It would have a more active setup. I put in longer shocks, and added a Panhard rod, and two stabilizing links. It worked well. The front axle was more challenging. The new CV joints made the project a little easier. Once I had the differential place, I had to fit everything around it. The steering rack was placed upside down, and was connected directly to the existing steering link in the original 8081. Then I added a Panhard rod on the front of the axle, and rebuild the front bumper, and everything was set.