Developing WangSpec’s Brake Duct Shields: From CAD to Prototype (Part 1)
Intro
The Braking System is one of the few, if not, only other components of a car that can rival the temperatures of an internal combustion engine. Keeping brake rotors cool isn't just about performance - It's about longevity and safety.
Here at WangSpec, we saw an opportunity to improve upon one of the best performing brakes of mass produced vehicles (Up until about 2004).
We love motorsports inspired builds, and the development of this part primarily benefit those builds, but we are also aware of how high speed braking can also massively benefit from this cooling kits, such as half mile racing events.
Research
First, we have conducted research and observed the approaches and solutions that others have successfully implemented in their brake cooling solutions via hand fabrications.
We have found that central air channeling through the center of the brake rotor, and having air flowing outwards of the cooling vanes usually produces the most even cooling across the rotor, thus reducing the probability of cracking from concentrated cooling of the rotor face - This is generally accepted to be ideal by many if this was possible.
However, packaging is usually the challenge, especially as the rotor get's smaller and smaller in diameter. This usually forces transitions and shapes to be sharp, and complicates fabrication.
Material Selection
The stock Toyota shield is stamped steel, and slightly encloses the outer circumference of the stock brake rotor. This was designed to help partially contain brake dusts, and also features vents to help reduce some of the heat that can be generated by partially containing the rotor as well.
Since we are working on the unsprung weight of the front suspension, we have first considered lightweight materials such as carbon fiber and aluminum. We have considered the results under extreme conditions across other platforms, and have observed heat related failures between these two under the most extreme conditions.
This has lead us to explore other materials, such as Stainless Steel & Titanium. Both of these materials offers improved heat resistance, longevity, durability, and excellent corrosion resistance.
Phase 1: Concepts & Failures
Development started using my own Personal JZA80 Mkiv Supra as the fitment mule.
I have started by taking a 3D scan of a brand new Toyota Steering knuckle, and started modeling a flat shield type shield. 3D scanning allows us to achieve a very accurate approximation of the factory bolt hole locations (Up to 0.1mm!)
During it's early iterations, we have considered a multi-piece option, by having the flat shield laser cut, and then having the transitional piece fastened or riveted onto the shield.
For our fitment tests, we were 3D printing the model out of PLA in the beginning.
However, when we have mocked it up to the car, we have observed 2 problems. First, we have observed a large gap between the rotor and the shield. A small amount is generally acceptable for debris and material growth due to heat, however this wasn't what we saw from photos shared online.
Second, we have initially modeled the hose entry to be above the steering arm of the knuckle. This was our first choice, as this was the most simplistic channeling and transition of air flow, and allows for simple manufacturing.
However, this was a failure, due to the fact that the hose entry would run into the sway bar, and sway bar end links along it's steering arc. Additionally, most aftermarket (Even OEM) sway bars are not locked in place horizontally by it's sway bar mounts, so it can also move and contact nearby parts. I,E the old school TRD (Big-Ass) Variant of their Sway bars, were reported to break Wheel Speed Sensors, and owners were remedying this by cutting off a part of their adjustment ends.
Phase 2: Attempts & Iterations
After seeing the sway bar interference, I pivoted to placing the duct entry below the steering arm - Something I had tried to avoid.
The Supra’s double-wishbone short knuckle design gives it sharp steering response, but leaves very little packaging room for anything else. That forced compromises I didn’t want to make, but it also opened the only realistic path forward.
Back to the drawing board, I modeled the duct entry from the bottom. This introduced new challenges, since the transition was more complex. After several iterations, we printed a version with a straight inlet and mocked it up on the car.
At full lock, the hose contacted the lower control arm in one direction. To solve this, I printed a few more variations until the hose ran parallel to the control arm at full lock. That solved one issue, but we have found another: on the opposite lock, clearance against the outer tie rod became a problem. This was exactly the kind of interference we were trying to avoid by originally attempting the above-arm design.
So another compromise was required - route the hose above, or below, the outer tie rod end. Using a brand-new stock tie rod (after removing my bump steer correction kit), I found that routing under the stock tie rod was the only viable solution.
Unfortunately, this confirmed that the duct design would not be compatible with bump steer correction kits. With the tie rod dropped 25 mm, there’s simply no way to achieve clearance without pointing the hose entry nearly 90° downward, which would increase manufacturing costs and destroy airflow efficiency.
Lesson learned: the Supra’s factory geometry left us just enough room to make a bottom-entry duct work - but only for stock tie rod setups. This became a hard design constraint going forward.
Phase 3: Finalized Design
Spacer Integration
Early mockups revealed how difficult it was to keep the duct shield consistently positioned relative to the rotor. The goal was to place the shield close to the rotor’s hub so air could be contained and directed into the cooling vanes, while still leaving a slight gap to allow debris to escape.
Two approaches were considered:
1. Curving the shield continuously toward the rotor’s center.
2. Running spacers on the back of the shield to bring the face closer to the rotor.
Because of the constraints of additive manufacturing, we chose the second option. By integrating the spacers directly into the back of the shield, surface finish and print quality improved dramatically. Support scarring and delamination were greatly reduced, since fewer internal supports were required.
The spacer’s profile was modeled to match the knuckle’s factory mounting surface, which reduces cantilever stress from the added height and locks the shield into place more securely.
Weight Reduction Pockets
On the backside of the shield, we incorporated weight reduction pockets between the integrated spacers. These cutouts remove unnecessary material, shaving weight without sacrificing strength in critical areas.
The FEA simulation confirmed that stress levels in these pockets remain very low, with the primary load paths running through the duct transition, and spacer structures. This gives the shield a lighter footprint while maintaining the durability required for motorsport use.
Safety Tab
During the final design stage, we added one last feature: a safety tab. This small loop gives the option for a safety wire to be tied into the steering arm of the knuckle. In the unlikely event of a failure, the tab provides a way to secure the duct inside the wheel well rather than allowing it to fall onto a rotating component.
Most users will never need it - but motorsport teaches a hard lesson: parts can fail in ways you’d never expect. Having witnessed components break that “should never fail,” we prefer to design with those possibilities in mind.
The safety tab is our way of offering an extra margin of protection - A last line of defense for those pushing the ragged edge.
Phase 4: FEA Simulation & Stress Checks
Simulation & Stress Checks
Before committing to metal prototypes, we validated the design with finite element analysis (FEA).
In this particular simulation map, the blue arrow shows where the force was applied. The blue regions represent the least amount of stress, while the colors shift toward red as stress increases.
The heat map showed stress concentration exactly where we expected - around the duct exit and mounting points. To account for this, we thickened the duct walls to add an extra margin of safety and longevity.
We also exaggerated the test conditions far beyond what the part will see in real-world use. While hot spots appeared in localized areas, they stayed well within acceptable ranges for stainless steel under repeated thermal and mechanical cycling. The end result: minimal deflection and confidence that the shield will stay locked in place even under heavy vibration, clamp force, and track abuse.
What’s Next
With the design validated in CAD and stress-checked in simulation, the next step is real-world testing. Our first stainless prototypes are already in production and on their way to us.
In Part 2, we’ll share hands-on photos, actual weights, and fitment notes from installing them on the Supra’s front knuckle. That’s where theory meets reality - and we’ll find out if all the compromises and late-night iterations paid off.