Subaru Crossmember Information

December 2024 Update: iWire is no longer offering harness merge services so we can focus on other parts of the business, including iDCCD, plug-and-play harnesses, and replacement electrical components. As part of this change, our technical support, wiring guidance, and troubleshooting assistance for harness merge projects will be very limited moving forward.

We appreciate everyone who trusted us with their swap wiring over the years.

These blog posts will remain available as a resource for the Subaru swap community.

To learn more about why we ended our harness merge services, please read the blog post below:

https://iwireusa.com/blogs/iwire-university/why-are-we-ending-our-harness-merge-services

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In this blog post, we discuss the things to consider when swapping the crossmember (also called X-member) during your Subaru engine swap. Learn more about how to do this in our swap guide video on the Buck Yeah Channel

The thing to note here is that the crossmember, steering rack, steering knuckle, and steering column are all connected. When doing a swap you will need to think about all of these pieces. Read on to learn more.

What is a Crossmember?

The crossmember in a Subaru is the mounting point for the engine in the chassis. There are a few different types so knowing which one you have is important.

Turbo vs NA Crossmember

In an engine swap a crossmember that matches the engine is critical. The first step is to utilize a turbo crossmember for a turbo engine or an NA crossmember for an NA engine. If you are going from a NA to a turbo engine, you MUST switch to a turbo crossmember.

There is a U built in to the crossmember of the turbo version for the uppipe which does not exist on the NA cars. We DO NOT recommend cutting your NA crossmember to make it work. Subaru utilizes a uni-body chassis so weakening this point by cutting it could compromise the integrity of the chassis.

Direct Mount vs Non Direct Mount

This refers to how the steering rack mounts to the crossmember.

2005+ STi and 2006+ WRX are all direct mount crossmember/steering rack.

2004 and older STi and 2005 and older WRX are all non direct mount crossmember/steering rack.

The thing to note here is how the steering rack bolts to the crossmember. If a direct mount crossmember is used, the associated steering rack must also be swapped over. Generally you will find that the direct mount rack will be from a STi which means the tie rod ends must be moved in to adjust for the wider track with of the STi. Once that is done the car will need to be realigned as well.

Steering Knuckle Issues if a 02+ Rack is Used

When a GD (02+) steering rack is utilized it creates a problem with the steering knuckle because of 2 things.

The spline pattern between GC and GD racks are different.
The distance between the rack and the column is shorter on a GC than it is on a GD.

Solution 1 (best solution)

Utilize the GC to GD steering knuckle adapter from L&E fabrications so that the lower half of the knuckle uses the GD spline pattern, the upper half is GC, and it is the correct length for a GC chassis.

Solution 2 (works but not ideal)

Utilize the GD steering column and shorten the GD knuckle to accommodate. The problem here is that for 97 and older chassis the column is not going to bolt up or plug in. In addition it creates issues with the plastic surround (clam shell) on the column because the GC and GD don't match and they are not interchangeable. With a GD column the GD clam shell needs to be modified to fit with the GC dash or the GC clam shell must to be modified to attach to the GD column.

Steering Column and Ignition Cylinder with Immobilized Swaps - We have created a resource for this here.

IMPORTANT NOTE - DO NOT ALLOW THE STEERING WHEEL TO MOVE WHILE THE STEERING RACK IS NOT ATTACHED. THE CLOCK-SPRING (AIRBAG/HORN/CRUISE) HAS A RIBBON THAT IF NOT SET RIGHT WILL BREAK WHEN TURNING THE WHEEL TOWARD LOCK! IF WHEEL MOVES WHILE THE RACK IS NOT ATTACHED YOU MUST REMOVE THE STEERING WHEEL AND READ THE INSTRUCTIONS FOR RESETTING THE CLOCK-SPRING.

iWire Suggestion for your Swap:

Put in a non direct mount cross member (turbo or NA depending on your engine) and then bolt on all of the steering parts from the original chassis. This way everything bolts together and you don't have to worry about alignment. Just mark the rack, knuckle, and column with a marker before you remove the crossmember so that the alignment of the steering wheel won't change once it's put back together.

If there is a current issue with the stock steering rack then that might be a reason to change it out with a newer rack (direct mount or non). STi model steering racks also have a quicker ratio so that might be a consideration as well, but just remember the domino effect this change will have on the other parts as described above.

Still have crossmember questions? We suggest checking out the shop helping with the swap for recommendations or if you're going the DIY route you can check out online forums like NASIOC.

Need Subaru DIY Items? Check Out the Links Below:

Subaru Connectors

iWire Wiring Tools

Automotive Wire by the Foot

Updating your Transmission? You May Need our iVSS (Vehicle Speed Sensor Replicator) or our iDCCD (Driver Controlled Center Differential for 6 Speed Transmission).