Clutch Fork Evolution: How We Made A Great Part Even Better

September 6, 2024 by
Clutch Fork Evolution: How We Made A Great Part Even Better
Eric Hazen

Responding to an overwhelming need, Verus Engineering came to the rescue of Subaru enthusiasts worldwide by creating a machined clutch fork that far exceeded its OEM counterpart. By vastly improving the material's yield strength, we created a more durable component resistant to the cracking and breaking drivers experienced.

As orders for the clutch forks continued to pour in, we decided to develop one of our most popular Subaru aftermarket parts even further. Here’s what we did and why it’s a superior product.

Forged In The Fires Of Aftermarket Excellence

We completely changed the manufacturing process to create an even more resilient part. Forging became the answer. Our new forged clutch fork is squeezed into shape, which leads to superior grain properties. 

Comparison of grain properties with different manufacturing methods

Here's a visualization of grain structure comparing casting, bar stock (machining), and forging.

Our clutch forks go through the following:

  • Heat treatment to a hardness level of 26-32 HRC (very hard)
  • Cryogenic treatment to ensure superior physical properties
  • Black-oxide coating for rust resistance

Instead of machining the unit from a solid piece of material, an ingot is heated and formed into shape under extremely high pressure. Forged cranks, rods, pistons, and more are all produced this way.


Squeezing a metal piece into the desired shape as part of forging process

This process improves the physical properties of the product through the microscopic grain structure, which is invisible to the naked eye.

The process makes sense from a business perspective, as it is less wasteful in the long run when manufacturing a large number of parts. We justified the significant upfront tooling costs because we expected to sell this component for decades. 

What Does This Mean For Your GT86, WRX, Or BRZ Clutch Fork?

It’s all about yield strength and making the component stronger and more suited to handling the added horsepower and torque enthusiasts desire. Yield strength indicates the maximum stress a material can withstand before permanent deformation occurs.

In the graph below, you can see the decrease in stress concentration as you move from OEM (left) to machined (middle) and finally to forged (right). Warmer colors like red and purple show areas of yield strength. Cooler colors like deep blue represent areas of low stress. As you can see, the clutch fork’s properties improved as a result of the forging process,

Yield-strength comparison of clutch forks

You can see the improvement in yield strength from OEM to forged as the warmer colors give way to cooler ones.

Why Upgrade the Subaru Clutch Fork If Machined Units Were Fine?

Absolutely nothing was wrong with the machined unit, and we haven’t had a single instance where one failed. We made the decision because we had a hard time keeping clutch forks in stock. In the end, we switched to forging to alleviate stocking problems. It benefitted everyone, including our loyal customers, as you get a superior product!

Verus Engineering clutch fork ready for shipment

Order your forged clutch fork from Verus Engineering today!

Order Your GT86, BRZ, Or WRX Clutch Fork Today 

Shift gears confidently and keep your GT86, WRX, BRZ, and other models on the track or street longer with forged clutch forks from Verus Engineering. You will appreciate the peace of mind and performance this part delivers. Browse our online shop today

Clutch Fork Evolution: How We Made A Great Part Even Better
Eric Hazen September 6, 2024
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