"Mechanix Menace": An LS7-motivated, chopped and heavily modified 1973 Datsun 240Z

[chevyz240]

The car has been bolted down to the garage floor for almost 12 years! Now it was finally time to put it in a rotisserie to simplify the seam welding of the cabin part of the chassis. I modified the rotisserie stands I used 19!! years ago on the car! They have to be able to straddle the centerline reference ruler on the garage floor.







More pictures at https://www.facebook.com/MechanixMenace

[chevyz240]

This time, the post is not about Mechanix Menace, instead it covers the design and manufacturing of a carburetor plenum for a friend's road race Corvette. He wanted a low design to not reduce visibility out of the car too much. I used my airflow experience from a previous job to design a sleek plenum, but still with low restriction. A mold was 3D printed by me, and then he made the plenum out of carbon fiber.

[carbuff]

That is very interesting. I would also be curious about the CFD effects in the rear which you noticed and asked about. I would also wonder if the rear barrels would run richer due to being more air starved vs. the fronts.

I'm curious - did he just turn the linkage arm upside down, or was there more to it? I'm not a big carb guy, so it's not obvious to me. I like the wheel he added...

[dhutton]

This time, the post is not about Mechanix Menace, instead it covers the design and manufacturing of a carburetor plenum for a friend's road race Corvette. He wanted a low design to not reduce visibility out of the car too much. I used my airflow experience from a previous job to design a sleek plenum, but still with low restriction. A mold was 3D printed by me, and then he made the plenum out of carbon fiber.

Wow!

[chevyz240]

That is very interesting. I would also be curious about the CFD effects in the rear which you noticed and asked about. I would also wonder if the rear barrels would run richer due to being more air starved vs. the fronts.

I'm curious - did he just turn the linkage arm upside down, or was there more to it? I'm not a big carb guy, so it's not obvious to me. I like the wheel he added...

I think the difference in airflow between the different barrels is very small. If you would CFD other air cleaners and plenums, I am sure you would see much worse results.

He used the downwards pointing part of the throttle arm and had to create the wheel for the gas wire to reverse the rotation, since the lever now needs to be pushed instead of pulled.

[chevyz240]

I have now seam welded all the tubes in the cabin part of the chassis. The rear shock towers are also fully welded. Most of the rear wheel wells are done too. The weld quality goes from decent to pretty bad. Some of the places were really hard to reach, even with the rotisserie, so the ergonomics didn't help. And in some places the welds started to bubble from some contamination, luckily almost only in the sheet metal joints. Some of them have been sitting for some time, so I don't know if there was a bit of rust in there. Unfortunately, TIG welding is very sensitive to contaminants, compared to MIG. In the YouTube video, I also explain some early design decisions.

I am very happy to have come this far!

More pictures here: https://www.facebook.com/MechanixMenace

[jaybee]

That's a sturdy chassis indeed. The backbone is going to make it crazy stiff.

[chevyz240]

That's a sturdy chassis indeed. The backbone is going to make it crazy stiff.

Yup! With the sandwich panels, it'll be stiff!

[chevyz240]

I have cut away the outer part of the stock rocker panels in preparation for the new ones I will build. They will consist of a widened version of the stock rocker panel, that probably will be filled with construction foam, and an upper part that will have an aluminum honeycomb core. These cores will increase stiffness and strength, which will benefit both chassis stiffness and impact protection.

I have also worked on the brake bells (hats) and the caliper adapters. Initially, I sent the brake company models with the calipers in the correct positions in relation to the spindles (uprights), and they were going to design the bells and the adapters. For some very strange reason, they haven't managed to get the dimensions correct. After several attempt, my contact person (the CEO) said that I can design them myself. So, that is what I have done!

While doing so, I also found out that some dimensions for the AP disc (rotor) attachment hardware wasn't correct either, so I have corrected this as well. Now I just hope that they will produce these parts to my exact specifications. I have not had that discussion with them yet! We will see what happens!









Many more pictures here: https://www.facebook.com/MechanixMenace

[chevyz240]

There has been a pause in the garage work due to some issues with the physiotherapy of my shoulder after surgery I had in November. I am supposed to basically not use the arm at all. For that reason, I have gone back to the modeling in Blender. The shoulder (haha!!!) and character lines have been tweaked to try to get a more aggressive look. In the video you get more info on my thoughts and lots more views and alternatives.

Please let me know what you think!

[chevyz240]

I have suffered from lumbago for almost two weeks, so no work has been done in the the garage. Instead I have continued working on the Blender model. Just for fun, I also made this little film, that starts with the car dragged up on the street, 15 years ago, followed by the steps I took in Photoshop to visualize the car. It ends with the current Blender model.

[chevyz240]

This video shows many of the steps I’ve taken while modeling how I want the car to look.

The video is divided into two parts. Until 01:42, the car is shown from a single angle while I move quickly through the different stages and changes. After that, you’ll see the car from more angles and have more time to look at each step.

Early in the modeling process, I considered changing almost every line of the car except for the already chopped roof. After thinking it over for a while, I decided I wanted to keep the car looking more like a classic Z. I also didn’t want to spend too much time reshaping the body, so the idea was to keep it mostly stock (aside from the chopped roof) and add some wide fender flares.

Pretty early on, I had the idea of widening the entire body, but I never really thought I would go through with it since it’s such a big undertaking. However, since the project has already taken so long, I finally decided to commit to that idea. The body will now be made of fiberglass, except for the steel roof, which is welded to the roll cage.

As you can see, there are a lot of small changes throughout the process, and I’m not done yet! But I think the final shots are pretty close to what I’ll end up with.

What do you think? Anything you would change? Feedback is welcome!

[chevyz240]

I have just started my summer vacation, which will continue all the way to September 20th!!!! 🙂 And then on October 1st, I will go down to 30% work hours! This will hopefully mean that progress on Mechanix Menace will hit a higher gear! Today I have hand shaped the last corner piece on the driver's side rear wheel well. Check out the full process in the video! 🙂

[chevyz240]

A little while ago, I welded in the last pieces of the hand shaped rear wheelwell corners.

Today I went to https://www.autocut.se/. There, Håkan helped me bend the three different pieces needed to create the new rocker panels. The top part will be filled with aluminium honeycomb and the bottom part will be filled with polyurethane foam. This will create an extreme stiff, strong and crash safe rocker panel.
I was a bit worried that the parts wouldn't come out the way I wanted, but Håkan nailed it! (With a little help from me...) 🙂

On the way back home my daily driver 2004 Audi A4 reached 510.000 km (317.000 miles).

When I got home, I had to celebrate both things with a pizza and a couple of Hefeweizen in the sun!

Thanks a lot, Håkan and Martin, for helping me out! Much appreciated! 🙂







Many more pictures at https://www.facebook.com/MechanixMenace

[chevyz240]

The summer weather has been very good so far, so I haven't been in the garage as much as planned... But I have gotten some things done at least.
I have made some jacking points and tacked the first lower rocker panel piece in place. Today, I will work on the second one.

In the YouTube video you get detailed explanations on the jobs above, and the thought processes behind them.

Questions and comments are welcome! 🙂

Many more pictures here: https://www.facebook.com/MechanixMenace/

[chevyz240]

A major job has been accomplished! I have made the first aluminum honeycomb filled upper rocker panel. I expected it to be complicated, but it was even trickier than I thought! 🙂
Everything can be seen in detail in the video.











More pictures at https://www.facebook.com/MechanixMenace