Wheel_Nut

I always found that 1:10 scale models were a lot easier to store. The other benefit is they don't need registration or insurance.

It probably answers the question why production runs are limited. When Tamiya run the injection moulding / dies for a particular kit, they would make enough for the production run they have planned. The unit cost for each plastic sprue will typically be very low, but a lot of the cost is in the time needed to change over dies, do maintenance and also testing the setup between production of different mouldings. The warehouse probably doesn't have space to keep high stock levels as that would be costly as well. I don't know how big an issue tooling cost is these days. AFAIK the tooling cost would be about 10% of what it used to be back in the 80s due to far better technology and automation. I don't think the unavailability of tooling is a major obstacle if there is sufficient demand for the product, but again it takes time to test-run and revise new injection moulding tooling. Its pretty obvious that Tamiya don't plan to sell a lot of spare parts. It seems like they use the entire production to go in the kits, and when that is finished (I guess) there won't be any more until they decide to do another re-release.

The Cat XLS was completely dominant after its release. It was light weight, well balanced, and had surprising amount of grip. I never raced a 4WD car, but about 50% of the cars racing were cat XLS, especially the guys who were the most competitive. Yokomo YZ870 was also competitive, but not as popular as the high cost and limited parts support put many people off. Kyosho Optima mid had a very loyal following, and there were guys who got really good performance from it. Avante was very much obsolete from a racing point of view, although it was only the new racers who ever attempted to race one.

As I recall "Peak Tamiya" coincided with the release of the Hotshot. After kids began breaking their Hotshot models, it was probably the start of the decline. Some went on to more advanced models that were better quality, and the younger kids probably didn't take it up at the same rate as the first generation during the craze of 85.

The correct answer is the "Super Champ"(!) Actually any of the SRB buggies will qualify. They are iconic because of the way Tamiya replicated many scale features of the VW based chassis. They are also the most durable for long term collectors because they have the high proportion of alloy parts. Although not necessarily the best for actually running the buggies. Hotshot and Boomerang are also iconic because they were sold at the absolute peak of Tamiya's popularity in the 80's.

To me it seems the MIP upgrade would be worthwhile if it stops the Boomerang from making crunch-crunch sound on the exit of every turn.

Thanks for the kind comments. Good question about the reason for 4 link beam axle! The main reason I chose it is because its very simple to make, and it has a high proportion of parts than I can make myself from metal extrusions and FR4 fiberglass sheet. I also believe it will serve well for this design without major issues. I actually like the panhard-rod used to locate the front axle because it determines the height of the suspension roll-centre at a well fixed location. There are some disadvantages for the rigid beam axle compared to a double wishbone setup, such as limited suspension travel and increased unsprung weight. If getting really technical, there is potentially some gyroscopic reaction force when left and right wheels are coupled on the same rigid axle. Let me know if there is something I have missed, or other reasons why I should consider a different approach.

In this case I'm also not replicating parts. For my chassis design it is just a CAD "component" that is created to look like a gearbox and have the mounting screws in the correct location. It wasn't really necessary for me to create a CAD model of the entire TA01 gearbox. I did it partly so I could create a realistic looking image on the CAD screen. Of probably greater benefit, it helped me practice CAD "extrude" functions such as Cut / Join / Intersect operations, and also make design revisions using "timeline" functions in Fusion 360. If I want to actually make a 3D printed gearbox there are many details that need to be checked and added. Its almost certain that some of the detail dimensions will have errors, but hopefully it will not affect my chassis design. The stock TA01 gearbox comes in 3 pieces, as it has a top cover and rear cover. My CAD model has gearbox and top cover in one CAD "Component" but even still it has many simplifications compared to the actual mouldings. I have attached the 3-view of the sketches I created in CAD for anyone how cares to see them. From these drawings all of the 3D features were created using extrude functions in around 10 steps.

That would be great to replicate parts. The issue I have is that printed parts are unlikely to match the strength and quality of Tamiya ABS injection moldings. Unless there is somewhere I can get the parts professionally made from ABS. Is the difficulty mainly about creating the correct 3D design? Otherwise are there manufacturing issues to be concerned about?

Since July I have been busy learning to use CAD. I have created a new thread for my next project.

This video shows the chassis design. This video shows the fitment of the VW body and suspension movement.

This build is a sequel to my previous 2WD Truck using a Lunchbox gearbox. The new project follows the same lines, but uses a Mantaray rear gearbox instead! Its designed using Autodesk Fusion 360 CAD, whereas the earlier project was designed on paper. The wheelbase is shorter at 243mm. I tried to improve some weakness such as the steering linkage and get a bit more suspension travel. The body is Tamiya 11825147 VW Beetle body from M02L and possibly others. Wheels and tyres are from Tamiya Comical Buggy. The design is completed and I have most of the parts. I have a Mantaray rear gearbox that I've been keeping from another project. Its still going to take several weeks until I start the actual build. You are welcome to make any comments, no matter how harsh!

The lowered motor position in the Mighty Frog seems a good idea, but IMO he should have done rear motor conversion for more grip. Grasshopper conversion is awesome.

I've been trying to learn Fusion 360 CAD. I download the software and it allowed me to registered as free for personal use. I'm really a beginner when it comes to this CAD system. What I'm planning is a similar 2WD truck with bigger tires. This time it will be using the rear gearbox and suspension from the Mantaray. Wheelbase will again be 260mm but the track will be wider. Its going to be a while before I'm ready to actually build. The pic shows what I'm up to currently, so there is a lot more work to do. Let me know if you have suggestions.

Not particularly amazing, as the concept was to combine a rigid front axle with the lunchbox rigid rear axle. My approach may be different from typical rc car modification because I took my time for planning and working on the drawings. In hindsight using a CAD system such as Fusion 360 would have been easier. I'll be using CAD from now on. In my past hobby I designed some radio control airplanes and built them from balsa wood, so there were a lot of design drawings done for those.