Maintaining Performance Cars with 3D Printing

Maintaining a 25-year-old car comes with its share of challenges. Maintaining a modified one car comes with even more. The 1994 Nissan 300zx that I own is particularly infamous for these challenges. When I first got this car, one thing I needed to do was secure the coolant cold return hose. This part was originally a long L shaped rubber hose that was thankfully replaced by an aluminum pipe and silicone connectors by a previous owner, a common upgrade. The solution that virtually all 300zx owners seem to take here is to zip-tie the aluminum pipe to the sway bar because it’s conveniently close, simple, and secure. This solution has never sat well with me so I decided to take a closer look at this problem and see if I could do better. Fundamentally what I wanted to do was replace this simple Zip tie with something that would fit between the coolant pipe and the sway bar securely, and lock onto both pipes.

Under Shot of the Original Zip Tie. Blue silicone sleeve used to help buffer it.

Enter 3D Printing

I’ve never designed anything to be 3D printed before but was familiar with the concept. It was a fairly simple idea that I had in mind so I decided to give it a try. I quickly discovered tinkercad.com, a web-based CAD software, that is free to use and had plenty of functionality for me to get started. The design I had in mind was a basic “egg” shape that would capture both pipes as well as capture a zip tie that would be used to secure all three together. A quick search in TinkerCad’s shapes gave me pretty much what I needed right off the bat.

Half the designing was done for me

From that basic shape there I was able to make just about everything else pretty easily. A couple of guides for the zip tie, a couple cutouts for the coolant hose and sway bar, and clipping the ends to allow it to clasp them. I added some cutouts to remove material. The last feature I added were angled cuts to the pipe cutouts themselves. This allows the whole piece to twist +/-3 degrees without binding and still holding each pipe tightly. After a few revisions, I finally came up with the design below.

Version 1.3

When picking which Zip tie to model my design ff of I chose the giant 2mm x 8mm because it was easy to use just one for the whole installation and you could always use a smaller one in its place.

Material Selection

Now that I have a design I had to make an actual part that will stand up to the punishment of being in an engine bay, exposed to the heat of the engine coolant over and over. There are many different plastics out there for 3D printers but the one that I landed on for this application is Acrylonitrile-styrene-acryl or simply ASA. ASA is a close cousin of ABS plastic which you find in engine bays already. What primarily differentiates it are some added changes to the chemical formula that gives it additional UV protection. It is very strong, great for mechanical pieces, and impact pieces. The heat resistance is also very high. The filament manufacturer (Prusa) states

“there are no signs of deformation up to temperatures near 93 °C”

The VG30DETT in the 300zx operates at~82 °C when warmed up. My hope is that being on the cold return side of the radiator this part will stay well below 93 °C under normal conditions at all times. ASA tends to be more difficult to print well but I think worth the extra effort here. I was able to get a hold of some ASA in a wonderful “Galaxy Black” color.

Galaxy Black test print

Printing

Now came the actual printing. The printer that we have on hand was an Original Prusa i3 MK3. It had an enclosure built for it to help maintain a more consistent temperature when printing difficult materials such as ASA.

Prusa i3 MK3 in the IKEA based enclosure

After a couple mistakes and failed attempts I finally got a physical copy of the design I has started from.

Final print of the clip

After some light cleaning of the support material, it was ready to install.

Installation

Installation is as easy as is sounds. Clip both ends around the appropriate pipes and center it up where the two pipes cross.

Then add a Zip Tie and secure it.

Final Installation of the clip

Conclusion

In the end, this was a very fun and rewarding challenge. It is a whole new world of techniques, materials, and challenges and I found a wonderful community of people volunteering their knowledge and time to help make it better. I’m interested to see how ASA holds up in the long term and will try to update you all how things progress. I will be trying my hand at a few more pieces soon as well. I’m sure it will be a lot quicker next time around.

If you would like to give this part a try for yourself in your Z check out the links below.
Thingiverse link: Get It Here
Prusaprints.org link: Get It Here

If you don’t have a 3D Printer you can still get a copy printed by Shapeways at this link: Get It Here

Sports car enthusiast stuck in the 90s. Current project is a 1994 Nissan 300zx TwinTurbo.