Retrofits

GD WRX Electric Power Steering Conversion [Part 4]

Finalizing the GR column, BRZ powered, VA rack steering retrofit in a GD chassis.

The next step in the process is to remove all of the hydraulic power steering system parts. The power steering pump, the lines, the reservoir, and the old rack. I wasn’t sure if I wanted to reverse this process one day so I decided to be nice to the parts as I removed them.

I did weigh the OEM p/s parts. The system as a whole was approximately 10 lbs. The p/s pump bracket is 1.7 lbs and it is staying on the car. I may remove unneeded material off of it one day.

PartWeight (lbs)
Power Steering Pump5.0
P/S Hoses (to/from Rack)1.7
P/S Reservoir & Hose to Pump 1.1
P/S Pump Bracket1.7
Fluid??
Note: The depowered VA STi rack is 2lbs lighter than the 2003 WRX rack (both had inner tie rods attached without outers).

With the 2003 WRX rack out of the car we can compare it to the VA rack. We can see that the LH side of the rack has different attachment methods. Thankfully, the VA mounting points line up to the OEM subframe.

We need a spacer to accommodate the offset mounting points on the VA rack. I ordered these 1-inch OD, 3/8-inch thick aluminum spacers from McMaster-Carr. The OD is a little too small and they want to pull the bushings through the rack so we had to add a slightly bigger washer to them. We need longer bolts too, so I ordered two JIS M10x1.25x70mm bolts from Bolt Depot; 65mm bolts would probably work better, 70mm is a little long.

One day I will to a write-up on measuring and selecting hardware.

P/N – 92510A817

The biggest issue is opening up the subframe to accept the larger control valve housing on the VA STi rack. A 3-inch cutoff wheel or small reciprocating saw would ideal here. It is a tight space and it is difficult to see what you are doing. I managed to cut a few slots in the subframe and then break the tabs off with a vise grip. Then test fit again and cut some more. It is tedious as hell but it worked.

Eventually, we got the rack bolted up. I reused the passenger side bushing from my SuperPro Rack bushings.

And then ran into a new problem.

The BRZ steering linkage won’t connect to the rack as it is bottoming out on the firewall.

To fix this, we could either make an extension on the rack input shaft and hope it gives us a better angle or we can cut the firewall. Looking at BRZ firewalls, the steering shaft opening is kind of oval since the BRZs have telescoping columns. Cutting the firewall is kind of a point of no return, so of course, we cut the firewall.

Ignore the grommet-less wires on the left.

With the firewall modified, the steering linkage bolts up.

The next major issue is the inner tie rod ends. Below, we can see that the VA STi inner tie rods are longer than the GD sedan units. I initially wanted to use GD STi inners with thread adapters, but this project is way over budget and I just want to get this thing running for the summer.

So, we are going to cut them.

If we thread the outer tie rods into the inners, the outer bottoms out with no space to place the lock nut. Some people use a narrower lock nut, but we are going to make use of what we have and just trim the tie rod ends down a bit.

I used a roughly a lock nut’s width to remove from both the inner and outer tie rods. Since at a bare minimum that’s how much space we need.

I was in a hurry to get this part finished so I just went ahead and reassembled the rack and other associated parts.

Since we no longer have a power steering pump we need a shorter belt. I have yet to find a 5-rib 27-inch belt but the 4-rib works. It just looks weird.

With the car on the ground, we can adjust the toe. I use cardboard underneath the tires so the tires can slide easier. And I take the front bumper off so that I can reach the inner tie rods to make the adjustments.

After this, I tested the system by turning the key on, and the steering was very inconsistent at first. It would go from almost no assist to full assist (in failsafe mode) while parked. Even after starting the car, it was still inconsistent.

However, after driving it, things settled down. I wonder if my battery voltage was too low or the alternator couldn’t keep up at low rpm. Either way, the inconsistent feel seems to happen at the first start of the day and then goes away.

As far as how the new setup feels, I haven’t driven it a ton yet. It has been raining for the past couple of days, so it is hard to say. Steering effort is heavier but not by a lot. The steering is quicker, and the on-center feel is tighter. I would need to take it to the Dragon or somewhere similar to get a better sense of the changes.

I noticed that my parking lights didn’t work anymore. After checking all of the fuses, I remembered that I removed the parking switch on the top of the steering column cover. There is no opening for it on the GR cover, and I don’t use the switch anyway.

So I made a kind of jumper for the switch from the harness unused harness. The red and green wires need to be connected.

I have a few other odds and ends to attend to, but overall I am pretty happy with how this turned out. I wasn’t even sure if this was even possible, but it seems to be working. We have a GR steering column mated to a BRZ power steering motor, connected to a VA STi steering rack in a 2003 WRX. Crazy.

Cheers!


References

Install: 2015 STi 13:1 steering rack into a GD
https://forums.nasioc.com/forums/showthread.php?t=2679348

Toyota FRS Electric Power Steering in an A Body
https://www.pro-touring.com/threads/130064-Toyota-FRS-Electric-Power-Steering-in-an-A-Body/page2

1 comment on “GD WRX Electric Power Steering Conversion [Part 4]

  1. Hmmmmm reading over this has sparked my curiosity for ding the VA steering rack swap on my car, especially since my rack is leaking far worse than before.

    Nice work on the install, I’m interested to hear your thoughts once you’re able to actually get the car out and test it!

    Like

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