8081 RT


I have said it before; I really like set 8081. It has so many possibilities for improvement. After talking a look at RM8‘s design, I thought I should do a street version of the 8081 to follow up on the 4×4 8081 I built a while back.

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

8081 RT Front

I took the existing bodywork and frame of the 8081, and chopped out the rear suspension unit to revise the rear suspension design. I wanted an independent setup with a differential. As I have used a couple of times before, I used a floating differential design. The differential is attached to the driveline much like a live-axle set up, but is connected to two independently mounted wheel hubs. I have used this before, and I like the way it works. It allows for a driven axle with independent suspension in a very narrow setup. This way each wheel can move independently, but it does not require two universal joints on each side of the differential. Since the differential is not fixed to the chassis, it has to be braced to the driveshaft. While this set-up is not often used in real cars, it works well for LEGO designs. I used the new wheel hubs, and attached them via a short upper arm, and a long lower arm so the camber would change through the suspension travel.

Moving to the front, I kept the V-8 as in my 4×4 8081, and built the rest of the front around the motor. I used a suspension design similar to 8081, where there are two equal length arms holding the steering pivot. A single shock absorber is used for each side. All told, the car is about two studs lower, due to the new suspension, and the new tires.

It is not much of a redesign, but sometimes I need a project that is not a significant, and allows me to just build something simple.

Happy Building.

Talon Track


Every once and a while I see something so creative I have to build something like it.  I happened with my HH-65.  It happened with my Zil 132.  And to some extent it happened with my Spitfire.  But when I saw the Urban Buggy from Chrismo, I though I have to make something like it.  It was such a fresh and creative design.  It had such great lines, a perfect stance, and a unique driveline setup.  But while imitation and outright plagiarism are the most sincere forms of flattery, I thought something of my own design would be a better contribution to the LEGO community.  I present my Talon Track Car.

You may find the full gallery here, and the instructions here.

I designed this car to be fast and stable, just like a track car.  I started with a drivetrain that would be reliable and effective.  A PF XL for drive, and a PF M for the steering.  I placed the PF M in the front mounted directly on the suspension unit, with a return to center spring in the middle of the mount.  The system is set up differently than in my Rumble Bee, but uses the same return part.  Each suspension arm would have a single shock absorber.  Directly behind the steering motor was the XL for the drive.  It was geared up with a 20z/12z ratio, with the driveshaft connecting directly to the 20z gear that turned the differential.  The rear suspension used an independent setup that was developed a long time ago for my Red Car Bigger (great name, huh).  If it’s not broke, don’t fix it.  The suspension was planted.  I placed the rechargeable battery box and the IR receiver behind the rear axle.

The car was quick, and didn’t have any problems, but faster would have been cool.  The return to center system worked well, especially for the quickness of the car, and the quickness of the steering.  It was easy to control.  The car was robust, and crashed well.  So go ahead and build your own.  Enjoy.

Flat 6


thirdwigg:

Every once and a while I get picked up by another LEGO blog. I am honored when it happens as it show others value my work. However, it seems to happen when I lease expect it, and in creations I find fun, rather than significant.  Thank you none the less.

Thanks to the Lego Car Blog for posting my Dune Buggy and my Zil 132, and The Brothers Brick for Posting my Rumble Bee.  Spreading thirdwigg is deeply appreciated.

Originally posted on The Lego Car Blog:

Technic Dune Buggy

Porsche Powered Dune Buggy

This monster dune buggy was unearthed by the Elves on MOCpages. K Wigboldy has included steering, all round independent suspension and, best of all, a huge six cylinder engine hanging out the back.

View original

International FTTS


It has been a little quiet in Thirdwiggville for the last month.  I have been working on a project that is taking a lot of time and resources, so my posts have slowed, even though my building has not.  But just wait, it’s going to be awesome.

Last summer I wanted to do another Trial Truck that would utilized some features I have never used before.  I wanted something complicated to see how it would work.  I wanted a model that would use four wheels steering, independent suspension, and have a simple two speed gearbox while being low to the ground.  After spending some time at the Chicago Autoshow, I saw a FTTS concept, so I thought this would be a great vehicle to model for this next truck.

This model would be built around an independent suspension.  After seeing it used so effectively in a truck by ATRX, I wanted to give it a try.  Each of the four wheels would use a simple double a-arm set-up with a wheel mount attached at the outside.  The wheel mount would house the portal axle and connect the steering linkage.  After a couple of different designs, I also decided the wheel mount would also connect the the shock absorbers.  This was a little unorthodox, as most independent designs mount the shock absorbers directly from the frame to the a-arms.  I did this for two reasons.  First, the model would be heavy, and I could not get the support I needed when the shocks were connected to the a-arms.  Second, and most importantly, I noticed too much suspension flex when the shocks were mounted to the a-arms.  The force applied to the wheel would go up the wheel, to the wheel mount, through the pivot, halfway down the lower a-arm to the shock.  LEGO is relatively stiff, but all these steps complied too much flex.  I would not have it.  I mounted the shocks on the wheel mount, and created a simple MacPherson strut set-up.  This worked well, as it allowed for full steering movement, long suspension travel, and adequate support of the truck.

The front and rear suspension axles both had a PF-M motor driving the steering.  Each were on independent PF channels connected to a single 8878 Battery Box to allow for individual steering, crab steering, and to solve steering drift commonly problematic with four wheels steering vehicles.  Both axles were connected with dual drive shafts running the length of the truck.  One drive shaft would then connect through a simple two speed gearbox to the PF-XL motor.  The final gearing was 1:6.2 and 1:10 for the truck.  This gave the truck sufficient top speed, with an effective crawler gear.  The Battery Box used for the drive motor and the gear shift motor was placed directly behind the front suspension, and in front of the drive motor.  This placement was perfect for stability.  It helped give great traction to the front wheels, kept the center of mass low and to the center with a slight forward bias.

I then finalized the model with a simple removable body built on a Technic frame.  While the hood was little high, and the rear body a little too short, it looked pretty close to the rear FTTS.  Fans seems to like the look, as it is still one of my more popular model.  See the full gallery here and the Work in Progress gallery here.

The model was a lot of fun to drive, and due to its squat design, it was very well planted.  The truck did not want to role over.  I think it could have used a little more suspension travel, and having four wheel steering was crucial to give it some maneuverability that was lost due to the suspension design.  The gearbox was flawless.  The truck did have some trouble skipping gears at the portal axle.  It seemed to happen when a single wheel was over-stressed as the driveshaft could have used stronger bracing in each suspension unit.  This placed a lot of strain on the particular wheel.  So would I do the independent suspension again.  Maybe, but it would need some strengthening and redesign.  Maybe it’s time for another truck like this.

Thanks for reading.  Something big is coming.

T-72


As a child I always wanted a model of the Russian T-72, so I decided to create a version of the tank out of LEGO bricks.  As is often the case, the model started with wheels.  This determined the scale, and from there, I was able to determine the rest of the tank dimensions.  This gave me very little room for all the functions of the tank.

Instructions are available for $5 USD.  Buy Now Button

Model of the popular Russian T-72. View the full gallery here.

The tank includes independent suspension on all 12 of the drive wheels.  6 are suspended with 6.5 length shock absorbers, 4 are suspended with rubber connectors, and the final two are not suspended, but move freely with the track.  The tracks are driven from the rear by two longitudinally mounted PF M motors.   These are connected 1:1, through double bevel gears to the 24z sprockets.  The battery box is place in the front of the tank, with the IR receivers placed over the drive motors.  The final PF M is mounted vertically in the turntable, to rotate the turret.  It could use another reduction, as the rotation is a little quick as you can see below.

I was pleased with the way this model turned out.  While the functions work alright, the aesthetics of the tank represented the original well.

The full gallery may be found here.

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