Unimog U90

About 3 months ago I purchased a set of four Fischertechnik tires from ebricks.ru. After seeing a review of them by RM8, I reached out to him, and he mailed me a set. After a little time, I finally have something to show with them.

Unimog U90

After playing with a number of ideas, I decided to do another Unimog. It’s easy to motivate myself to build a vehicle I love. This time, I wanted to do the unloved U90 (418) version. It was not a terribly successful version, as many find the hood…not one of the best. But few people have built this version, so I was up for it. I put to to a vote on Eurobricks, and the decision was to build it in green. Off I went.

The scale required a 27 stud wheelbase and a 19 stud width. I built the front and rear axles and tied them together. Through a couple of edits, I finally added the suspension and figured out how to get portal axles into the truck. The Power Functions XL motor was mounted just over and in front of the rear axle driving power to all four wheels. The Servo motor was placed directly ahead of the XL for the front axle steering. I added a four cylinder fake engine over the front axle. The rechargeable battery box was placed over the rear axle.

Unimog U90 Driveline

The suspension is a live axle setup, with four hard shock absorbers at each corner. Each wheel has about 2 studs of travel. Not much for a Unimog, but enough for a 418. At this point I started a draft of the cab, and a draft of the bed. At this point the truck had an identity crisis. Move forward with green or find another option.

Unimog U90 Bed Tilt

Building LEGO Technic with green is not the easiest. The color lacks 1×5 and 1×11 beams. Both of the these parts would be needed for the bed and the cab. I could make some things work for the 1×11 in the hood, but there was no other option (read, inexpensive option) for the 1x5s needed for the bed. I toyed with other colors for the bodywork; orange, white, blue, yellow. None of them had the right pop I was looking for. Other than the orange, but, as other have said, orange has been done too many times. Then it dawned on me, “why not use plates?” I had my solution. With one bricklink order, I was done.

The truck drives well, and is easily controllable. The front portal axle can use a little strengthening, so serious trial abilities are lacking with this truck. Both the bed and the cab can be easily removed. I ran out of space for a ram to elevate the bed, but it can tilt three ways. I was pleased with how the truck turned out. It looks great. The driveline coule use some improvements, so I will make those improvements on the next truck.


Mack Marble 5T

I confess.  I took the bait, and started on the 2012 You Design It, We Build It before the final rules had been confirmed.  I should know better.  After all my schooling, you would think I have a good idea about how to follow directions.  The first direction is, wait for directions.  But, with all LEGO building, I enjoy what I am creating, and so even after the rules and directions have been given, I still want to contribute to the LEGO community.  So, my next MOC is another Trial Truck, built with the intention of being easy to play with, easy to build, and tough enough to handle child play.  All with instructions, so you can build one.

See Instruction Page

I built this model based on what I thought could be improved on set 9398.  While this new set was a great step forward for the LEGO company, I felt there where a couple of changes that should be made to make the model a better off-roader.  Because I was working with the assumption that this would be something LEGO would produce, I gave myself a couple of constraints.  First, the model had to be less than, or equal to, the cost of 9398.  Second, the model had to have improved off-roading skills.  Third, the model had to have easy playablity, so the drivetrain had to be reliable, the battery should be easy removable, and it should be easy to drive.

I started the frame before the axles.  I placed the battery box directly over the driveshaft.  An XL motor was place behind the BB and three 16z gears above the driveshaft.  One 16z gear went up to the fake motor shaft.  The driveshaft would connect front and rear to the two axles through the new ball joints from 8110.

I then built the two axles, starting with the rear.  To keep the speed of the Mack similar to the 9398, I would gear down the XL motor to about 1:4.  The driveshaft came out of the ball joints and connected to the differential.  I chose two 12z/20z gear sets as the final reduction.  This would keep the driveline a little stronger, and help keep various axles from working their way out of the gears, much like the design of the 9398.  The final gearing was 1:3.89.  It’s not a stump puller, but it could still move up most hills.

The front axle was a little more tricky.  Basically, it had a similar setup, with a PF M motor placed on in it to work the steering.  This was by design.  To keep the driveline reliable, and limit the failure of steering, I kept the steering part of the axle, rather then having components placed in the chassis, and then connected via a shaft to the front axle.  The steering is a little quick for my liking, but it works flawlessly.  To understand more about the axles, check out the instructions.

Through a little trial and error, I connected the suspension, and tweaked it so it would function in a way that was robust, and allow for great movement.  I am still not pleased with how it turned out aesthetically  but it functioned without problems, it supported the model well, and allowed for sufficient articulation, so I left it.

I then added a simple body, a basic rear bed, and added some engine components such as exhaust,  intake, and a simple turbocharger behind the fake motor.  When I was done, I noticed the cab looked a little like an old Unimog.  This seems to be a theme with me, as I love the look of the Unimog.  On the other hand, I do not like the look of too many cabover truck designs, as such, many of my trucks have the slight setback cabover design that is very similar to the Unimog.  My T55 is like this, and this is why I have built so many Unimogs.

The model worked well.  the suspension and stability was perfect.  The truck was stable, and did not roll over, all while being able to handle various terrains.  The gearing was sufficient and would be great for a playing child.  It was easy to change out the 12z/20z gears in the portal axles to a 8z/24z setup which made the truck a little more strong.

It would be a great model for many LEGO fans due to cost, reliability  stability, and playability.  So I have posted instructions for people to enjoy the model as well.  I think it would have been a great LEGO set, then the rules were released.

Next time I’ll wait for the rules.  Thanks for reading.

Full gallery is here.

Freightliner M2

For some reason, I often find myself building two trial trucks at the same time.  While I was building my ZIL 132, I also wanted to try something with floating axles.  The model would use 6 wheels, a 3 speed transmission, and fully suspended live axles.  I also wanted to model the Freightliner M2 Business Class truck as closely as I could.

The model started as my trucks usually do; with the axles.  The second and third axles would be identical, and would be connected with a simple pulley wheel universal joint between the two.  To keep the speed through the universal joints high, and the torque low, I used as 12z/20z gearing after the universal joints, then the knob wheels to rotate the axis, then the normal 8z/24z gearing on the portal axles to finalize the drive.  This also allowed me to keep fewer knob wheels as the second axle had the drive shaft from the transmission pass uninterrupted to the rear wheels.  The final drive ratio for the two rear axles were 1:5.

The front axle was a little more work.  I wanted to have the steering motor mounted on the axle so I would not need to have a steering shaft connect to the front axle.  This proved too difficult, as it would raise the PF XL motor that I was going to use for the drive to high on the truck.  I decided it would be better to mount the steering motor on the frame and connect to the front axle via a CV joint.  Once I made this decision, the front axle became easier.  I used a 1:3 gearing on the portal axles, a knob wheel, and then a drive shaft back to the transmission.  The steering axle would exit just above the drive shaft on the axle to move to the right for the steering motor.

The frame was pretty simple.  Once I had the transmission placed, and the axles spaced, it was simple to place the suspension components, and the shock absorbers.  Each axle had two steering links mounted vertically which connected to a 3×5 liftarm which would activate a shock absorber; very much like Lyyar’s design.  Each axle had a steering arm to keep the axle from swaying laterally.  Finally, all three axles had a number of 9L links to keep the various movements maintained.

The transmission was going to be placed behind the PF XL motor which was under the hood.  The changeover mechanissm would be placed in the center of the truck with the changeover motors mounted longitudinally, on both sides of the truck.  The PF XL motor was place directly above the first axle, and was mounted on a moving frame that was moved by the changeover.  This allowed a moving frame to work its way through the three gears.  The ratios were 1.25:1, 1:1.25, and 1:2.  This allowed for final ratios of 1:4, 1:6.25, and 1:10, which was more than capable for most terrain.  The drive and steering Battery Box was mounted over the second and third axles, and the gearbox 8878 battery box was just behind the changeover in a little box on the bed of the truck.

Finally, like always, a simple body was mounted.  I had a little trouble getting the look I wanted on the front of the hood, as the suspension components kept getting in the way.  I added a bed, covered the changeover and motors, and a couple more details and everything was finished.

The model was not my best driving truck, as six axles do not want to always work together.  The suspensions was supple, and I was getting no drive or steering input on the suspension.  The truck worked well over various terrain, but struggled on some on step obstacles.  The transmission mounting worked well at changing gears, but gears did not have a strong support, and I found they liked to skip at times.  I liked how the suspension worked, but I do not think it brought enough of a valued to use this system again.  It had moderate improvement on dealing with terrain, but it placed a lot of stress on a number of parts, such as the frame, the axles, the driveshafts, and the universal joints.  The next truck will use a pendular set up again.

The full gallery may be found here.

Power Functions 4×4 8081

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.

Zil 132

A couple of months ago I was struck by a new design by Waler.  It was refreshing to see a well made Trial Truck based on something a little different.  I wanted to make a model of my own.  Thanks to him for the inspiration, and for the great ideas on the cab and the fenders.

From the beginning I knew this truck was not going to be a serious off road contender, but I wanted to redesign the whole drivetrain.  I decided to go with a pendular suspension for the first and second axle and a trailing live axle for the third axle.  All three axles would have a differential and a a set of portal axles.  The first and the third axle would also have steering linked together.  As is often the case with my trucks, I had the pendular axles held by a turntable with the steering function passed through the turntable by use of a differential.  The second axle was held by a turntable in the front, and the steering differential passed through to provide steering to the final axle.  The drive function powered all three axles and would connect to the transmission and motor in between the first and second axle.

The third axle was a suspended live axle that had a trailing setup created with the new 8110 pieces.  This would allow for rotational and vertical articulation while connecting the drive shaft and giving space to the steering function above.  The steering shaft would allow for movement via a CV joint.  The Power Functions M steering motor was placed in the rear, and used a simple 1:9 reduction.

A Power Functions XL was used for the drive funtion and was placed between the front two seats.  The motor was mounted on a sliding assembly for the gearbox function, much like the design pioneered by ATRX.  I used my three speed changeover design to move the motor through three gears, for a final ration of 1:7.5, 1:4.7, and 1:3.  The gearshift worked perfectly.  While the drivetrain was a little complicated, the gearing was rather simple.  The battery boxes were place above the second axle side by side.  This kept the weight centered, and as low as I could get it.

Finally I added a cabin and a cargo area.  The cabin was straight from Waler’s design, as was much of the fender area.  I used technic panels to create the cargo area, which also gave me a space to place the two IR receivers.  This also hid the two battery boxes, and the wiring, and generally cleaned up the truck.  I created two small doors in the top to assist with picking up the ZIL.  I was done.

Over mostly level ground the ZIL was one of my better designs.  The differentials and steering worked flawlessly to make the ZIL drive easily.  The gearbox worked well and eased the drivetrain over slight irregularities.  But once the  pavement turned to dirt the ZIL struggled a little more.  It was not designed to have too much suspension travel, and this showed.  It struggled on some of the bigger bumps, as the tires would scrape the wheel-wells.  Overall, I was pleased with the design, and was happy with the way it turned out.  It looked great, it was fun to build, and it was a blast to drive.

The full gallery can be viewed here.  Also, a big thank you to The Lego Car Blog for posting this model on their blog.

4×4 8081

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.


Instructions can be found at Rebrickable.com or here.

Full gallery is here.

I also created a motorized version after a number of requests.  You may see the gallery for that MOD here.