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Underdog Motorsports - 2015 STI Steering Rack Swap


Underdog

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Thanks yeah i havent touched mine yet, tho im only at 90k

Honestly im still happy w my steering

 

Whenever something breaks, my mantra is to replace it with something better in quality or performance or both whenever possible. You're likely still good at your mileage, though mine has been leaking for about 3-4 years which translates to about 45k. It just got to the point of no return and just in time since underdog was already chronicling the swap.

Updated parts list since original part-out here.

 

Original Full part-out of my LGT HERE!

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Adam - had the car aligned yet? If so, any issues with front toe?

 

 

Haven't had it aligned yet. A friend (wicknetzel) and I tried to get the toe as close as we could with a tape measure. It's close (within 1/16" )but pulls a bit. I've been facebooking with my subaru tech inside man to work out a date for alignment. I'll post up as soon as a do. I still have to run some figure-eights to work out all the air, but it's getting much better.

Edited by doobaruGT

Updated parts list since original part-out here.

 

Original Full part-out of my LGT HERE!

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Cool. Keep in mind that you might not have enough positive adjustment on the inner tie rod to compensate for column/rack indexing (if the u-joint is off a couple splines). So if the tech can't get zero toe on both sides you might just need to pop the u-joint and shift it a spline or two. Can't say for certain since I haven't put mine on the alignment rack yet either.
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Cool. Keep in mind that you might not have enough positive adjustment on the inner tie rod to compensate for column/rack indexing (if the u-joint is off a couple splines). So if the tech can't get zero toe on both sides you might just need to pop the u-joint and shift it a spline or two. Can't say for certain since I haven't put mine on the alignment rack yet either.

 

 

I actually do think I have enough room for positive adjustment. I should have taken some pics. When we installed, we did so at near max positive to get an idea and the wheels were noticeably positive. There should be plenty of meat on the bone!

 

 

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Updated parts list since original part-out here.

 

Original Full part-out of my LGT HERE!

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Yes it will swap in but it isn't cheap and I don't think the improvement will be worth the cost. Steering rack bushings are much less expensive and are known to make a noticeable, if subtle, improvement.

 

I know a few people who've installed the solid joint in place of the damped one and they all said it made no difference at all.

 

As to the VDC issue... The roll connectors for the '08~ GH/GE, GR/GV and SG are all the part number. They all have a 15:1 rack. I think the Legacy will have the same steering angle sensor encoding, even if the roll connector does not physically swap over. Since the STi model shows no ill-effect when fitted with the new 13:1 rack, I don't think you will have problems in the 4G Legacy either. Remember that the quick rack guys having problems were using racks in 12:1 or lower.

 

It was interesting that although GD Imprezas had a Group N steering angle sensor available for use with the GrpN (13:1) rack, the GH model did not. The rack was available (for several thousand $) but there was no sensor listed. We see now that this is because the VDC system is coded to accept the 13:1 ratio, probably because the WRX model was likely to be modified to GrpN rules. I can't tell if the Legacy VDC system will be this forgiving but there is reason to hope so, since the 4G Legacy and 3G Impreza have so much in common.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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So I'm aligned and driving on the new rack. I wanted to provide some basic observations. They will be completely subjective, unfortunately, until I figure some practical ways to take some measurable data. I'm open to suggestions.

 

In the meantime, attached is a pic of the tie rod end. You can see there are still threads left.

 

http://im1.shutterfly.com/media/47a5df38b3127ccee872204fc89500000030O00AauGzhs4cMWgPbz4U/cC/f%3D0/ls%3D00401886868520150119172345209.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

 

Cool. Keep in mind that you might not have enough positive adjustment on the inner tie rod to compensate for column/rack indexing (if the u-joint is off a couple splines). So if the tech can't get zero toe on both sides you might just need to pop the u-joint and shift it a spline or two. Can't say for certain since I haven't put mine on the alignment rack yet either.

 

Turned out that when I actually got it back on the road, my steering wheel was off about 10 degrees left. It drove me nuts and I was concerned about the indexing, but it seemed to work out just fine as she drives straight and the wheel sits at 12 once again!

 

Overall, the steering is noticeably tighter feeling than before. It's also very responsive. In my old rack, I had a small dead spot at 12 o'clock, I now get immediate response from the wheel when turned. I don't exactly trust my observations because I've already adjusted to the new rack; I can't really recall the complete feel of the old rack.

 

Having said that, if you can suggest some practical ways to compare, I'd be very willing to hear them and provide any data possible. Just say the word...:)

Edited by doobaruGT

Updated parts list since original part-out here.

 

Original Full part-out of my LGT HERE!

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  • 1 month later...

Has there been any new developments/updates on this conversion?

 

I have a 2005 JDM 2.0GT Auto which I despise the steering feel/ratio on. It's so light. It's horrible.

 

I was considering swapping the S402 one in, but wasn't sure if it'd be a direct swap. I am not 100% sure if my rack is 15:1 or not. Does anyone know for sure?

 

Of course, it's RHD too....

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Two confirmed swaps on the USDM BP/BL chassis that I know of. Can't speak for your RHD model or what your existing ratio might be, but I would be surprised if the crossmember or rack ratio were different than what we received. That kind of information would have been flushed out at some point in the last ~10 years I would assume. FYI there are unused mounting spots on the LHD crossmember that look like a mirror image of the rack mounting points, probably for the RHD rack. Edited by Underdog
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Adm pre MY07 rhd liberties and legacy (H6 and GT at least) are 15:1 aka a fast rack.

You can confirm next time the front is on stands by grabbing the part number on the sticker on the rack.

It's a direct swap for the JDM GR+ STi quick rack which are available eg from Japanparts or Subaru Japan for around $1400 inc delivery :)

Edited by bigBADbenny
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Unfortunately the price in the UK for the RHD rack is £650/$1000! Best I can get is 10% off that. Looks like I won't be rushing into this one, unless I find one being broken up for parts.

 

Anyone feel like getting a price quote for the rack in your region? Part number is 34110VA100..

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Does this change anything as far as turning circle? Or are the limits the same, you just get there quicker?

 

What about load on the power steering pump? I had a small leak in a ps hose that I had someone replace, and ever since, I sometimes get a small cut-out of the pump at idle when turning. Not long, and kicks back in in 1/2 a second, but it seems like the pump is starting to go. Wondering if this would put more load on the pump?

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No your turning circle stays the same it is just the wheel take less turns lock to lock.

Power steering pump is fine as long as it's in good working order. if not get that fixed first.

 

 

I highly recommend a PS fluid cooler if you're doing anything that puts more stress on the pump. Even increased caster can be enough to overheat the fluid.

Edited by fahr_side
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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