Underdog Motorsports - 2015 STI Steering Rack Swap

I got the solid U joint as well. best $20 i ever spent on it, I had the Perrin piece and it did the job but i want it to feel more connected and no rubber bushing between. Ill put the perrin piece on my Daughters OBXT.

I got the solid U joint as well. best $20 i ever spent on it, I had the Perrin piece and it did the job but i want it to feel more connected and no rubber bushing between. Ill put the perrin piece on my Daughters OBXT.

I just did the STI link on the outback (subframe spacers removed) wish it was $20 but still the best $60 I've spent

 

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Will be doing this swap! Hopefully this weekend if everything arrives in time.

 

I discovered this morning that my responsibilimobile (2017 Impreza Sport 5spd) has a 13:1 rack - that was the tipping point. No way in heck can my boring car have quicker steering than my fun car!

Edited May 24, 2021 by bubbagump

Got the swap done today! Replaced all pressure/return lines while I was at it.

 

Power steering pump sounds PISSED! Hopefully that will right itself in due time.

 

- Steering u-joint from STI, posted on NASIOC. (This was not necessary, but there was a brand new one up for sale for less than 50% MSRP, it is rare something I need is for sale on the forums when I actually need it)

- Used MOOG outer tie rods. Trimmed 3/4" from threaded end so I didn't have to do the thin jam nut thing. The idea of the thin nut made me nervous. Luckily my good friend has a nice little machine shop. If I were to do it again I would only trim 1/2" off.

 

Everything else :

 

Part Number QTY Part Name

34110VA121 1 Gear Assembly $630.67

34620AC010 1 Pressure Line Bolt

34621AC024 1 Hose & Tube Assembly Gasket

34610AG05A 1 Power Steering Pressure Hose

34611AG22A 1 Suction Hose

34611AG21A 1 Return Hose

010110200 12 Gear Assembly Front Bolt

902380007 2 Front Bracket Nut

901250077 2 Gear Assembly Rear Bolt

901000181 2 Gear Assembly Upper Bolt

901550060 2 Bolt (Used on steering u-joint)

903200005 2 Fuse Box Washer (Used on steering u-joint)

Edited June 7, 2021 by bubbagump

So after really starting to look at things I think I'm not understanding the need to trim the inner tie rods.

 

I'm using the whiteline bump steer kit. Those tie rods have about 60mm of threads. With the stock jam nut, there is something like 52mm of threads on the inner tie rod (I'm remembering measurements I did yesterday, they may not be exact). Essentially the whiteline tie rod will hit the jam nut before bottoming out on the inner tie rod. No cutting required?

 

With the thinner nut, the whiteline tie rod still isn't bottoming out. Still no cutting required.

 

Cutting the inner tie rod threads won't give me any additional adjustment since the length of the whiteline tie rod is the limiting factor with both stock and thin jam nuts. What am I missing?

So after really starting to look at things I think I'm not understanding the need to trim the inner tie rods.

 

I'm using the whiteline bump steer kit. Those tie rods have about 60mm of threads. With the stock jam nut, there is something like 52mm of threads on the inner tie rod (I'm remembering measurements I did yesterday, they may not be exact). Essentially the whiteline tie rod will hit the jam nut before bottoming out on the inner tie rod. No cutting required?

 

With the thinner nut, the whiteline tie rod still isn't bottoming out. Still no cutting required.

 

Cutting the inner tie rod threads won't give me any additional adjustment since the length of the whiteline tie rod is the limiting factor with both stock and thin jam nuts. What am I missing?

The inner tie rods on the sti rack are longer than the lgt ones. We trim the threads to make the inner tie rods closer in length to the LGT.

I understand that sentence. It's just not what I'm seeing on my bench. Are you actually supposed to take the inner tie rod out of the rack and remove the threads from the inner most side of the inner tie rod? Like remove the boot and such?

I understand that sentence. It's just not what I'm seeing on my bench. Are you actually supposed to take the inner tie rod out of the rack and remove the threads from the inner most side of the inner tie rod? Like remove the boot and such?

No. Remove from the outer threads of the inner tie rod.

 

You're seeing that the tie rods are the same length?

 

If that's the case we shouldn't need to cut or use thinner jam nuts.

 

Do you have the racks side by side to compare and post a picture? I'm just curious. I haven't done my swap yet.

Please also keep in mind that I was using Whiteline tie rods sourced back in 2014ish. It’s possible they are drilling and tapping the outer tie rods deeper now than before, which would also accomplish the same job as trimming the end of the inner tie rods. As stated in the original post, trimming has always been optional. I’ve never heard of someone not being able to get their toe in spec due to not trimming.

Thanks for the replies. I suppose the only other alternative is I don't actually have the correct rack. While I haven't actually compared the part label to the known part number my memory can't detect any red flags with the number on the rack. Will double check when I get home.

I have brand new Moog inner LGT tie rods, and a 2017 STi rack with the original tie rods. I can also take measurements when I get home.

So after really starting to look at things I think I'm not understanding the need to trim the inner tie rods.

 

I'm using the whiteline bump steer kit. Those tie rods have about 60mm of threads. With the stock jam nut, there is something like 52mm of threads on the inner tie rod (I'm remembering measurements I did yesterday, they may not be exact). Essentially the whiteline tie rod will hit the jam nut before bottoming out on the inner tie rod. No cutting required?

 

With the thinner nut, the whiteline tie rod still isn't bottoming out. Still no cutting required.

 

Cutting the inner tie rod threads won't give me any additional adjustment since the length of the whiteline tie rod is the limiting factor with both stock and thin jam nuts. What am I missing?

 

Yea I trimmed inner just to be safe incase something about my setup with the Moog outers was a little different, like maybe my Moog's weren't tapped quite as deep as other options. After the job was said and done my inner tie rods are pretty far from being bottomed out, much further than the 2 or 3 threads I trimmed off.

 

Reason I trimmed outer rods was just for aesthetics. The place next to my work where I get my alignments done out of convenience gave me crap last time I brought my car in because I work on my own car. They almost refused to work on my car because they didn't want to potentially be held responsible for something stupid I did. After inspecting my work they agreed to work on my car. I did not want them refusing to work on my car after the steering rack swap because it "looked weird".

I trimmed mine to be safe. It's probably not needed.

https://legacygt.com/forums/showpost.php?p=5378160&postcount=198

 

You can see how little I cut off.

Thank you Underdog and Rhitter for all of the info! I got my 2015+ STi rack in finally.

 

Can confirm that the 2015 STi solid steering u-joint will not fit on Outbacks. I do have my subframe spacers in still, so maybe those of you who've removed them can try and update this thread. I'll be posting a 2015 STi solid steering u-joint up in the classifieds here soon.

Subbed to get back to this mod in the near future...

Thank you Underdog and Rhitter for all of the info! I got my 2015+ STi rack in finally.

 

Can confirm that the 2015 STi solid steering u-joint will not fit on Outbacks. I do have my subframe spacers in still, so maybe those of you who've removed them can try and update this thread. I'll be posting a 2015 STi solid steering u-joint up in the classifieds here soon.

 

I’m interested I. The steering knuckle if you havent sold it yet. Im looking to swap my rack in the next month or so.

Stupid question but I checked on parts.subaru.com and starting in 2018 the rack and pinion parts number changes as well as version, ie; Type RA is not same part number as premium. So, in order for me to swap in a 2008 spec.B, which years are bolt on? (Except the tie rod mod etc.). I don’t want to order from a 2019 STI for example and not have it fit at all.

Thanks in advance

I just finished this install but on a swapped GC, which was a bit more work.

New crossmember, new column, custom adaptor for column to rack, modified thread adaptors to use factory ITRs, factory 15+ lines and pump.

Waiting on a driveshaft and finishing up some other driveline parts to drive it and compare it to my swapped RS that has a GD STi 15:1 rack, to see if all that work was worth it. I'm thinking on a super light and small GC, it may be too quick for a street car. It will be nice to compare and give an idea of what the Spec B would be like with it however, and the install on that should be easier.

 

A (belated) follow up. Let me start with the following caveats before I describe how it felt when I drove the car around.

 

1) Car wasn't properly aligned yet

2) Breaking engine in/getting miles on it at low-med throttle/boost/rpm.

 

That said... it's very fun. I always describe my own RS with the GD ratio STi rack (15:1) as feeling go-kart like. This RS with the 13:1 rack is far more deserving of that comparison, and wicked fun around corners even at moderate speed. I barely have to rotate the wheel and it goes where I want.

I truly cannot wait until we finish this thing and get it trackable. I was concerned it would make the car twitchy at speed and even less desirable to drive. Wrong. I want to drive it more because of this, just not as a DD (which, for me isn't what a swapped RS is for).

 

Seriously considering doing this to the Spec B or my own RS at some point (Spec B, if there are truly no issues with the VDC. The RS if I decide to go with the aftermarket x member, which is an additional consideration as far as cost/fitment). Not sure how much that helps anyone technically, but just another "I very much enjoy the faster rack" review.

Edited November 2, 2021 by Kaos22B

I've got every part needed for the swap,including a new aftermarket braided high pressure line and I'm simplifying the return line from the rack. Do the stock lines that mount at the rack use O-rings or do they bolt up like a AN line? I want to make sure I've got everything covered before I get a nasty surprise once everything's apart,lol.

 

Thanks,Zack K

It looks like 34110VA120 has been replaced with 34110VA121.

 

Does anyone know if it's very different or should it be ok to go ahead and use?

 

SC

I just recently installed a new rack with P/N 34110VA121 and it went in perfectly. Used the thinner jam nuts and didn't have to trim any threads (using the WL bump-steer tie-rod ends). Alignment on my setup was no issue for the alignment shop (-1.2° camber). Only thing I can guess/hope is they revised it to fix the known issue of these leaking relatively quickly near the input shaft

Subaru OEM steering rack from a +15MY STI (p/n 34110VA120 was super-seeded by 34110VA121)

I just recently installed a new rack with P/N 34110VA121 and it went in perfectly. Used the thinner jam nuts and didn't have to trim any threads (using the WL bump-steer tie-rod ends). Alignment on my setup was no issue for the alignment shop (-1.2° camber). Only thing I can guess/hope is they revised it to fix the known issue of these leaking relatively quickly near the input shaft

 

Good to hear!

 

I figured I would go ahead and order it since there isn't an option at this point.

 

SC

A comment from solidsnake from another thread about the 120 vs 121.

 

The 2015+ rack fits fine on a spec.B (same as the regular LGT). The part number for the new rack was superseded in 2019, but I think they're effectively the same. Not sure about the 2020. I've fit both 34110VA120 and 34110VA121 on my '07 spec.B.

I just recently installed a new rack with P/N 34110VA121 and it went in perfectly. Used the thinner jam nuts and didn't have to trim any threads (using the WL bump-steer tie-rod ends). Alignment on my setup was no issue for the alignment shop (-1.2° camber). Only thing I can guess/hope is they revised it to fix the known issue of these leaking relatively quickly near the input shaft

What thinner jam nuts did you use. I plan to do this on my 2005 LGT. steering rack is creaking and needs replacement.