Series: 2015+ Subaru WRX Modification (Pt.8 - Transmission / Clutch)
Series: 2015+ Subaru WRX Modification (Pt.8)
Hello and welcome to my Op-Ed on the 2015+ Subaru WRX! This is part 8 of a 10 part series that plans to encompass all of the information you will need to make informed decisions regarding the best upgrade path for your vehicle.
This week, I will be giving an in-depth overview of Transmission and Clutch Upgrades. This overview will consider the purpose of each component as well as what specific brands I recommend.
Disclaimer
The statements made in the article below are subjective and based on my knowledge and experience gained from working with the VA WRX platform. Please refer to your preferred tuner, or a trusted vendor, for recommendations on your specific set up.
Intentions
This Op-Ed is intended to help the user better understand how certain modifications affect the engine and performance, what tuning changes are necessary to account for these modifications, and what brand(s) I recommend for each modification category. This is NOT intended to be a tuning guide. I am NOT an expert in ANY category that will be discussed.
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Modifications and Preferred Brands
Transmission
The transmission is the essential assembly that transfers power from the engine to the wheels. The OEM split-case 6-speed cable-style transmission in the VA WRX is perfectly capable in most cases. However, under heavy abuse or high torque applications, problems may arise and components may fail prematurely.
When debating a transmission upgrade, bear in mind the torque goals. Some transmissions aren’t designed to handle well over factory power levels. Some transmissions aren’t meant to handle aggressive driving at factory power levels. All of these factors come into play when deciding what transmission is best for your specific situation.
In any case, if a transmission upgrade becomes a necessity, the best option is usually to source a 6-speed linkage-style drivetrain swap from a VA STi. Certain gears in the STi transmission are considerably thicker than their split-case counterparts; this aids both in power delivery and longevity. Seeing as most components are drop-in ready, there is typically no better way to ensure power is transferred safely to the ground.
Clutch
The clutch is a critical power transmission component as it regulates the torque delivery to the transmission. In most situations, the OEM clutch is perfectly sufficient. However, if the vehicle sees frequent launches, heavy abuse, or an abundance of extra torque, the factory clutch may begin to slip.
As a tuner, I have seen many clutches fail when torque rises well above factory specifications. It’s not as much a matter of if, but a matter of when. I always recommend installing a clutch that can handle 25% more torque than what it will be subjected to. This will ensure a sufficient factor of safety on all torque transfer components.
With so many solid clutch options out there, it’s really best to contact your preferred tuner, or a trusted vendor, when sourcing an aftermarket clutch, flywheel, or combination of the two. Just make sure that the components are rated above the amount of torque you plan on producing. That way, you can ensure longevity of the assembly in all circumstances and situations.
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Tune in next week (03-29-2021 @ 12:00 EST) where I will be giving an in-depth overview of Alternative Fuels. This overview will consider the benefits and drawbacks of certain alternative fuels as well as how to account for them during the calibration process.
Cheers!
-Clint
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