Underdog Motorsports - 2015 STI Steering Rack Swap

[amm203]

From the first post of this thread courtesy of Underdog:

 

https://www.mcmaster.com/91938A130/

[iNfEk]

Oh. That’s what you mean. Gotcha. Thanks, the way I read it was you used something else and not the one he had mentioned.

[Code]

I think I have a few left from my 5-pack somewhere. I’m happy to send them your way if I find them.

[Smithcraft]

Didn't know how many of the slim jam nuts would be needed so I ordered 2 packs, so I have a bunch to send if someone needs them.

 

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Edited March 14, 2022 by Smithcraft

[ViscousSquirrel]

Just wanted say thanks for the write up. I did this job today on my 2006 OBXT. WOW what a difference between the old leaking OBXT rack and the new STI rack. It has a nice solid feel to it and really firmed up the response and on center feel.

[ViscousSquirrel]

Didn't know how many of the slim jam nuts would be needed so I ordered 2 packs, so I have a bunch to send if someone needs them.

 

SC

 

Hey I could use a couple of those to get my toe in. I tried to order them online but they were 32 bucks to ship to Hawai’i. I would be happy to purchase yours if you have spares! Thanks!

[elomo64]

Finally did the plunge! Was very lucky and found a new STI '15 rack for $450 here in Mexico, where the used ones would not go any lower than $600.

Installed with no issues, I did have to slightly file the engine cradle opening as it's my 3rd time doing this and it's always a pain trying to get the pump through that small opening.

Only thing I'm experiencing is the steering wheel will shudder if I turn too quickly, but I believe this might be the belt slipping (some ATF fell on it which I did clean but maybe not enough) and not the pump not keeping up. I'll probably get a new PS pump in a few months anyways.

Driving difference is night and day, even though I didn't get the STI u-joint, the wheel feels SOLID, so the STI joint might be entirely a placebo effect.

Edited October 10, 2022 by elomo64

[ckwaters]

On 3/14/2022 at 1:04 PM, Smithcraft said:

Didn't know how many of the slim jam nuts would be needed so I ordered 2 packs, so I have a bunch to send if someone needs them.

 

SC

PM sent

[ckwaters]

I just did this swap about a month ago on my Outback 3.0R. I used Whiteline outer tie rods, bushings and Cusco brace. You DO NOT need to cut your inner tie rods, they did not bottom out even with jam nuts removed.....plenty of depth in the Whitelines.

At full adjustment I was slightly toe-out. I purchased thinner jam nuts and now there is plenty of adjustment. I bought a toe measuring tool and I got to 0 degrees toe and have more adjustment to spare if needed.

VDC is giving me a little trouble. It's kicked on 3 times so far. Each time was in a medium speed right bend in 3rd gear off throttle. One time a car was following me pretty closely through the turn and that was not a situation I want repeated so I plan to disable it one way or anothe as soon as possible. 

I'm re-reading this thread and checking out the linked STi threads but so far I don't see a full workaround for the VDC. Is programming an Ardurino an option? I already have one for my 6MT swap so throwing a few more codes in there might not be difficult. Or can a tuner do something to fix or disable it? I don't want any dash lights on long term.

[Febreze Mee]

On 11/14/2022 at 8:54 AM, ckwaters said:

VDC is giving me a little trouble. It's kicked on 3 times so far. Each time was in a medium speed right bend in 3rd gear off throttle. One time a car was following me pretty closely through the turn and that was not a situation I want repeated so I plan to disable it one way or anothe as soon as possible. 

I'm re-reading this thread and checking out the linked STi threads but so far I don't see a full workaround for the VDC. Is programming an Ardurino an option? I already have one for my 6MT swap so throwing a few more codes in there might not be difficult. Or can a tuner do something to fix or disable it? I don't want any dash lights on long term.

Bump! I'm would like to know as well.

[livinon2wheels]

Im curious, I have an 05 Leggy wagon 2.5i that I am using part time as a track car and it still has the original rack in it. What would be a bolt in upgrade for that car? And would it be possible to just change the steering knuckles at the wheels to quicken the steering without a rack change?

[Underdog]

The ‘15 STI rack should bolt right in for your 2.5i wagon. Might need to look at upgrading the pump for good measure. The knuckles will not affect your steering ratio. 

[livinon2wheels]

thanks for the info underdog...when the time comes thats what I will do.

[subaru-tech]

When I did my swap I used a 2015 sti power steering pump. The pressure is a little higher and aids in the judder when turning fast

Edited January 29, 2023 by subaru-tech

[Underdog]

Fixed the images in the original post. @subaru-tech can you verify that you used P/N 34430FG040 for the pump? Did you need any other hardware for the install?

[willisdaye]

On 11/30/2022 at 12:58 AM, Febreze Mee said:

Bump! I'm would like to know as well.

I'm thinking about lumping a rack swap in with other suspension upgrades I'm doing soon on my OBXT, and am also interested in not having to gut VDC. I already have an Arduino mounted near the steering column that controls my diy boost gauge, so it seems like this could be a two birds one stone situation. I think it would be as simple as using the map() function to scale the sensor signal to the original range, and using a DAC shield to output the signal to the VDS module. If I end up pulling the trigger on the STi rack, I will definitely take a stab at this and post my updates here.

[Karlor]

I'm considering to take this plunge as well, however just last year I had a new pump put in for my 06 OBXT, and I think the refresh must have blown out a seal because now my drivers side boot developed a steady trickle of PS fluid. The rack was replaced by the previous owner at 185K, I'm now at 205K.... bummer. Two questions I have:

-Will my 2006MY brand new pump (34430AG0419L) be enough to handle the new 2015 rack? A comment in this thread above was mentioning judder in the feedback and I'm curious if this is what can be expected running the 2015 rack with my new 2006 pump.

-Is it possible to use OE 2006MY OBXT tie rod ends? I have stock height suspension and no plans to lower the car, possibly may consider a small lift in the future. I have seen numerous mentions of the Wihiteline rod-ends bump steer kit, they are expensive. Any alternatives to the Whiteline kit?

 

Many thanks from forum noob Karlor for this epic thread!

 

Edited June 18, 2023 by Karlor

[ckwaters]

I’m using an OEM Outback pump without issue. Using Whiteline isn’t a requirement but you’ll have to see if you have enough toe adjustment when you put your tie rods on.

[Febreze Mee]

I, too, am using a factory 2006 Outback pump with no issues. I can't speak to the tie rod ends. 

[shandalo]

Curious to know if anyone learned a good workaround for VDC. I like the idea of this swap but would like to avoid another permanent dash light. 

Since this is only a documented issue for OB owners going to the STI rack, wondering if OB owners could step halfway to the LGT rack and not have the VDC issue.

[ckwaters]

I’ve been wanting to try a couple things but don’t have the time. Maybe someone else can try. Try disconnecting the G sensor located behind the shifter. Or disconnect the steering angle sensor behind the airbag. Not sure what other systems get input from those sensors but disabling either one should definitely kill VDC. And to get rid of the light, remove the bulb would probably be the only way. 

[Febreze Mee]

I wonder if you could some how attack the connectors with a resistor, like you would with the airbag light after a seat swap. Worth a look!
 

 

[iCruess]

I swapped a brand new LGT rack into my 2009 OBXT today, yielding a "disabled traction control" dash light and steering shudder left and right. I hoped the less extreme steering ratio of 15:1 (as opposed to the STi 13:1) would not trigger the VDC, but it seems likely. The other thing I can imagine is that my steering wheel is 5 minutes to the left while the wheels are straight, so maybe that's throwing the sensor off. Maybe I did not align the steering wheel center with the steering rack center, IDK.

Any insight would be helpful. Going for an alignment tomorrow...

 

UPDATE: The shuddering was due to microbubbles of air still trapped in the system. We cranked lock-to-lock for 15 minutes, and it smoothed right out! The belt on the power steering was squeaking when we cranked the wheel, so we tightened it to deliver full power from the pump throughout the entire turn in both directions. We wedged some rubber shims between the steering column plastic cover and steering wheel to hold it in the center position while I loosed the u-joint and realigned everything as best I could. 

I had an alignment done at a local garage and the steering wheel was .38 degrees off-center. They reset the ESC, completed the alignment, and I drove 100+ miles with a few hard turns at high speed, firm braking, coupled with a few lock-to-lock figure-eights and all I have to report is smooth steering and no dash light!

So far the LGT rack is a success.

Edited September 29, 2023 by iCruess

[Kaos22B]

Related but semi-random question.  Has anyone thrown in the matching PS pump for the 13:1 rack, ran that for a bit until they later installed the rack itself?  If so, did you have any issues?

It would be nice to tackle this in stages and not  have the car down and sitting waiting for me to get to it.

[willisdaye]

Update for OB XT/3.0R owners looking to have the STi rack and keep VDS:

I still have not installed the new rack since I have higher priority projects on this car (and bikes ). That list is finally dwindling however, so I did more digging on this and found this really good writeup on steering angle scaling in the Forester forum. It's a comprehensive guide and a pretty straightforward project, assuming you've messed with arduino before. The github code is linked in the guide, and the only change it needs for use on an OB/LGT is to update the steering ratio. In my case since I already have an arduino on board, I'll just have to rehash my existing boost monitoring code to add SAS scaling, and add the CAN-BUS shields. Other than that, it'll probably be sometime next year that I do this upgrade, so if someone beats me to it, let us know how it goes!

If that link is broken DM me and I can send the .pdf and .ino files

Edited October 31, 2023 by willisdaye