A while back when I was working on retrofitting a GR telescoping steering column in my GD WRX, I thought about converting over to an electric setup and ditching the hydraulic power steering system altogether. This would simplify my engine bay a bit, and remove some weight off of the nose of the car. Because +lightness.
There are a few options out there, from running an electric power steering pump from an MR2 and keeping your hydraulic setup, to retrofitting a Prius/Saturn Vue electric column motor, or just going full manual mode and depowering your rack.
Another option is using the BRZ column. I considered using the whole column from the steering linkage to the turn signal switches but BRZ uses Toyota’s spline count for the steering wheel and I wasn’t sure how to deal with the ignition switch so I didn’t want to go down that road.
And after staring at images of the BRZ power steering motor, I was pretty sure the spline count was close enough to take the chance on.
I was also hoping that the BRZ steering link had enough travel to reach the steering rack. If that worked then it would just be a matter of trimming the GR column and figuring out how to mount the power steering motor. It uses a single bolt that passes through a bracket attached to the dash reinforcement bar.
As for controlling the CANBUS electric motor from the BRZ, there is an Aussie company that makes an emulator. You can adjust the level of assistance which is perfect for dialing in the amount of steering feel.
I found a BRZ power steering motor and steering linkage for cheap on eBay. BRZ/FRS parts are pretty cheap in general. My long-term plan is to use a GT86 steering rack (13:1) with this setup instead of trying to find a +2015 STi rack to depower.
The spline count on the upper portion of the GR column is the same as the BRZ so they mate up. This was a huge plus. The difference between the sleeve on the p/s motor and the GR column is bigger than I expected though. We need to make a spacer to take up the gap.
After mocking up the BRZ motor under the GD dash, it’s pretty clear that it will only fit in one location. There’s a couple of thick wiring harnesses in the area, along with the HVAC box.
The harnesses can be unbundled to gain enough slack in them, and there are a few plastic pieces on the HVAC box that can be trimmed to gain more clearance. I also loosened the HVAC box and shifted it over as far as I could.
Both the GR upper column and the BRZ motor need to be shortened to fit under the GD dash. In the photo below, I needed to trim another inch off of the GR column. The process was just trial and error.
The also meant that the shaft needed to be trimmed as well. The shaft has multiple sections to it. There are the threads and splines for the steering wheel. Below that is a solid section (gray) with a tube welded on for the steering lock. The black section is hollow; the shiny section is splined for the slip fit of the lower shaft.
I was hoping I could cut a portion of the solid section and the hollow section, slip it back together and weld it. This almost worked without modification, but the solid section had a slightly larger diameter than the hollow section. I’m guessing that they milled the solid part down a bit to make the slip fit and welding more consistent.
Milling the shaft down would have been perfect on a lathe but I don’t have one. So I improvised with a drill, a grinder, and some sanding paper.
And it worked! I now have a shortened steering column shaft.
The vast majority of the work was test fitting the pieces together to make sure they worked as intended.
Lots of trimming of plastics to get the motor to tuck up as much as possible. Once I got the motor placed I made some brackets with some scrap metal I had laying around (forgot to take pics).
Another problem was getting the headlight/turn signal switches to work. The GR column has a larger diameter so the 2003 WRX bracket won’t work. I bought a GR bracket from eBay but I think they sent me one for a 06/07 STi. But for whatever reason, it fits the GR column. The clock spring is also an issue and I am still researching for a solution (will most likely need an 06/07 WRX/STi clock spring). But the switches have the same mounting points and use the same harnesses. I don’t know if they work the same though.
Also, just an FYI, the clock spring will probably be the second most expensive part of this mod.
One of the biggest PITA was removing the ignition switch from the old column. You have to drill out the security bolts and I broke a couple of bits which makes everything worse.
But it bolts up to the GR column. Ignore my standard hardware, I have the security bolts but I want to make sure this mod is final before I throw them on.
There are a few issues that still need to be resolved. I need the BRZ CANbus emulator. I need to figure out a trim cover fix. I might try the GR column covers. I need a new brake light switch because I broke mine while being careless with the BRZ p/s motor (I may need to relocate it). And there is more angle than I would like on the steering linkage. I either need to make an extension on the rack and pinion or switch to a BRZ rack; which is my long-term plan. I also need to finish reupholstering my steering wheel, which I am in the middle of doing.
But the GR telescoping upper is mated to the BRZ power steering motor which is connected to a GD WRX rack and pinion. I’ve only driven it a couple of miles as my new wheel and tire setup is rubbing pretty good.
If you’ve seen my Instagram feed then you’ve already seen the wheel and tire setup. But I will be doing a post on it here soon.