Underdog Motorsports - 2015 STI Steering Rack Swap

Here is a GR steering coupler compared to mine, the major difference is the lower spline clamp; the picture isn't the best, when the ends are lined up the lower mount side is obviously longer. I'm going to try to take apart the universal joint this week and swap ends, it *should* be simple...

http://farm7.static.flickr.com/6088/6160339125_350e41bdf8_z.jpg

I found a rack but it is slightly damaged. I have not seen it in person yet. These are pictures that were sent to me.

Is this something that could be repairable?

Just did this swap after having the rack sitting around for almost a year.

Everything went smoothly, although getting the universal splines to re-engage on the rack took a bit of fiddling. I went to the thinner jam nuts right off the bat and had no alignment issues. Also took awhile to fully bleed the power steering system.

Night-and-day difference in steering feel, though. Probably the best single mod I've ever done in terms of feel.

Those pinch bolts tho

Not technically part of this job!

I kind of want one now.... anyone decide to give up and sell theirs?

Put a search on ebay for the part number. I just picked one up a few weeks ago. Just be sure that they say it came off an STi, I did find some that had the part number but said they were off a WRX and the seller didnt respond to e-mails so I didnt risk it.

Put a search on ebay for the part number. I just picked one up a few weeks ago. Just be sure that they say it came off an STi, I did find some that had the part number but said they were off a WRX and the seller didnt respond to e-mails so I didnt risk it.

Yeah, no good prices at the moment. I'd just as easily buy a brand new one from my dealer.

I upgraded mine in the Outback (which has a slower rack than the LegacyGT)

- Basically my thoughts are, At lower speeds (less than 40) it didn't make a huge difference.

- at higher speeds it makes a small but noticeable improvement. It's one of those pieces that I essentially see as why not do it if the rack is off. It all helps.

Can't remember but did you remove your body spacers? Curious because it does mention in the first post that we need to remove the body spacers on OBXT's. Wondering if actually need to get those parts in order to make this work.

This is going to be my next mod since my leaky rack has nearly 300k on it and would never be allowed on track with that thing lol. Figured it would be a perfect time for this swap.

Recently, I installed the 2015+ STI power steering rack, and aside from having to repin it (oops) the issue I ran into was wider track. If you follow this thread, you'll see Underdogg says to cut the INNER tie rods, leaving 3-4 threads more than the Legacy inner rods. Well...sorta makes sense, sorta doesn't, because the OUTER tie rods have about 4" of available thread space, whereas the INNER tie rods have about 1-2" of thread space. So really, you'll run out of INNER tie rod by the time you thread in the OUTER tie rod all the way in. Sooo..... (Dealing with over the shelf inner and outer tie rods)

Solution. Grab a die (or buy one) and cut in new threads onto the INNER tie rod. M14x1.5 is the size you'll need, but I suggest bringing a tie rod with you and checking with each die to make sure you have the right thread. I made mine work with a 1/2 20nf die.

I added between 1/4" of threads to the driver side and about 1/2" of threads to the passenger side. Now, the oem jam nut is massive, so I suggest ordering the McMaster Carr jam nut that is provided in the link above that Underdogg posted. This nut is much more thinner than the oem jam nut and will give you an additional 3-4 threads of adjustments.

Now...last thing to note.

If all else fails, there is still available space on the OUTER tie rod that you can cut off without affecting the adjustment cutout area. It's about 1/2 of available space (depending on the tie rod, seeing as the Whiteline bump steer outer tie rod is longer) and cut that off.

That said...these are my experiences. Any damages done to your vehicle, I am not liable to. I took the risks of modifying suspension parts and I'm solely responsible for my own actions.

I'll get an alignment again tomorrow and see if I need more threads to achieve 0 toe, but as a look from above the fender, I seem pretty good with the current results.

Anybody know anything about the rack in the STI Type RA? The part number for its rack is 34110VA140 which is different from that of the original 2015+ STI (34110VA120).

In Japan, the S207 and S208 special edition STIs have an 11:1 ratio. Could it be that this rack finally made it into a USDM car (the Type RA)?

What I also can't figure out is why there are more different part numbers for the non-Type RA 2018 STI rack:

34110VA130

34110VA131

You can see the supported car variants for those two parts here:

https://parts.citysidesubaru.com/a/Subaru_2018_STI-STI-Limited-25L-TURBO-6MT/_54100_6464454/POWER-STEERING-GEAR-BOX-FITTING-EXCEPS/V10-347-03.html

Anybody know anything about the rack in the STI Type RA? The part number for its rack is 34110VA140 which is different from that of the original 2015+ STI (34110VA120).

 

In Japan, the S207 and S208 special edition STIs have an 11:1 ratio. Could it be that this rack finally made it into a USDM car (the Type RA)?

 

What I also can't figure out is why there are more different part numbers for the non-Type RA 2018 STI rack:

34110VA130

34110VA131

 

You can see the supported car variants for those two parts here:

https://parts.citysidesubaru.com/a/Subaru_2018_STI-STI-Limited-25L-TURBO-6MT/_54100_6464454/POWER-STEERING-GEAR-BOX-FITTING-EXCEPS/V10-347-03.html

I will try and verify or get more info because I need to stop and get some parts, but this is what my research found: https://forums.nasioc.com/forums/showthread.php?p=45521736

Post #1322: The document from Subaru doesn't list any difference with the rack itself; just the rod ends and stiffener. My guess is that the new part number is because they sell it as a complete unit with the updated parts.

Anybody know anything about the rack in the STI Type RA? The part number for its rack is 34110VA140 which is different from that of the original 2015+ STI (34110VA120).

 

In Japan, the S207 and S208 special edition STIs have an 11:1 ratio. Could it be that this rack finally made it into a USDM car (the Type RA)?

 

What I also can't figure out is why there are more different part numbers for the non-Type RA 2018 STI rack:

34110VA130

34110VA131

 

You can see the supported car variants for those two parts here:

https://parts.citysidesubaru.com/a/Subaru_2018_STI-STI-Limited-25L-TURBO-6MT/_54100_6464454/POWER-STEERING-GEAR-BOX-FITTING-EXCEPS/V10-347-03.html

My dumb ass didn't realize that the 11:1 rack for only the JDM S207 and S208 would be right-hand drive, which isn't super compatible with left-hand drive cars.

I got in touch with Subaru of America and they confirmed that the Type RA has a 13:1 rack:

"Thank you for contacting Subaru of America, Inc.

We appreciate you taking time out of your day to contact us.

The 2018 STI RA features a 13:1 steering ratio.

Thanks for the opportunity to be of assistance."

Quick follow-up on this statement: "PLEASE NOTE: The OBXT uses subframe spacers requiring a longer u-joint. OBXT owners can use the Perrin Steering Lockdown Kit (PSP-SUS-565), cut and weld in a length of steel rod, or remove the body lift (a project in itself)."

Will the existing OBXT oem u-joint mate up with this, or MUST I swap in the modified Perrin version to make this work? Thanks...

Quick follow-up on this statement: "PLEASE NOTE: The OBXT uses subframe spacers requiring a longer u-joint. OBXT owners can use the Perrin Steering Lockdown Kit (PSP-SUS-565), cut and weld in a length of steel rod, or remove the body lift (a project in itself)."

Will the existing OBXT oem u-joint mate up with this, or MUST I swap in the modified Perrin version to make this work? Thanks...

The Perrin damper lockdown is not a U-joint. It is a modification to a U-joint from an Outback, Legacy, or WRX. The Perrin part does not change the form factor / length of the U-joint. It's only to increase the rotational stiffness.

If you are swapping this rack into an otherwise-unmodified Outback, I'm pretty sure you need to use the Outback U-joint, as that's the only one that's long enough. I believe Legacy, WRX, and STI U-joints are all the same length, which is shorter than the Outback's.

I can confirm that the OBXT u joint works unmodified with the STI rack.

The Perrin lock down is really nice though.

The Perrin damper lockdown is not a U-joint. It is a modification to a U-joint from an Outback, Legacy, or WRX. The Perrin part does not change the form factor / length of the U-joint. It's only to increase the rotational stiffness.

 

If you are swapping this rack into an otherwise-unmodified Outback, I'm pretty sure you need to use the Outback U-joint, as that's the only one that's long enough. I believe Legacy, WRX, and STI U-joints are all the same length, which is shorter than the Outback's.

Thanks - that solves the issue. Talking to my mechanic about this rack swap for existing leaky OEM rack while the engine is out getting rebuilt...seems like the right thing to do, and given its a non-VDC car I don't expect any issues...