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Underdog Motorsports - 2015 STI Steering Rack Swap


Underdog

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Thanks guys.

 

What's the ratio on the OBXT? I've found the lock to lock is higher (3.2 vs 2.6? or thereabouts) vs the LGT but I can't find the ratio listed.

 

Having the 05 STI steering rack already is the primary reason I'm looking into the upgrade.

 

Though when I ran it in my 03 Legacy (mind you, the wheel base are somewhat similar to the OB) the steering feel was substantially tighter and felt more "dialed-in" - although the latter could also be because I was running more negative camber and other STI front suspension bits like the control arms.

 

Rhitter, did you also upgrade the U joint? I think I read somewhere the OB U joint being longer than the LGT, so I'm not 100% sure about the '15 STI U joint being 100% interchangeable.

 

And yes AFAIK the track and suspension geometry on the OB did not change throughout the BP chassis years.

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  • 5 weeks later...

I am getting ready to pull the trigger on this for my '05 OBXT. Current rack has a lot of slop and still making some noise after new inner/outer tie rods.

 

I've got some LGT rear LCA mounts and plan to remove the subframe spacers. I'm assuming that I will be able to just swap to a solid STi steering joint and I'll be GTG. Is that correct?

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This thread almost makes me wish my steering rack was crappy.

 

Can't justify replacing a nice tight 85k mile LGT rack, although I can absolutely appreciate the difference a faster rack makes.

 

My accord handles better than my LGT, but since the LGT has a much faster rack it feels a lot more willing and responsive chucking it around.

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I'm finally getting my car aligned... It only took me 9ish months to complete the install and get it to an alignment shop.

 

Just been so busy, lazy, forgetful... This should have only been a weekend job.

 

Sent from my SM-G935T using Tapatalk

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Just got back home. The steering feels wonderful. Smooth and solid. The turning ratio takes a bit to get used to. I did a few things along with the steering rack so your mileage may vary.

 

- '15 STi Steering rack (purchased a used rack off eBay for $299)

- STi steering joint

- Whiteline Steering bushing kit

- Whiteline roll center kit

 

I do have the VDC light on. Not sure what is causing it to light up. I did pull off my steering wheel to help center the rack, and I also applied a new etune. I'll have to check with the tuner to see if there is a setting that is causing it to light up.

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It it's non-functional right now LED remains lit upon start-up. This wouldn't be anything the steering rack did since the steering rack is all mechanical. I must have tripped something up during the install, fuse, etune setting, or something in the steering wheel/clock spring.

 

Disconnecting the 12v battery did nothing to clear the error.

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Did you turn the wheel without it being connected to the rack? This would break the roll connector and give you that warning light. I have since learned my lesson. :lol:

 

I did, but didn't rotate it more than 1/2 way remember reading about folks breaking this before. I'm thinking that I may have broken something there regardless though.

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  • 2 weeks later...
I am about to make the swap on my 08 spec.b. Bummed to find out that I have to disable VDC. More so because I just wanted the car to still have a OEM feel, so no lights or quirks. Driving with it off isnt a big deal. Maybe ill have to look into the arduino hack.
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If the harness connectors are the same installing the '15 sti abs unit should fix the vdc issues. Roll connector is just a input for the abs/vdc control module. Another option that might work is to have a dealer set the parameters in the abs/vdc control module to sti spec. If your stock control module accepts the parameters it would think it is in an sti and should not freak out with the different steering angle values. Just some ideas.
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  • 1 month later...
Just picked up one of these 2015 racks on ebay for a pretty good price. So next question, sti u-joint vs torque solutions lockdown damper? I think because I have an outback I have I have to use my stock u-joint correct?
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I just put the Perrin damper lockdown in my car, since the install took 10 minutes and I'm too lazy to swap the u-joint. I'm really happy with it and it's also much cheaper than the Sti part.

 

If they are essentially the same result in steering I'll do the lockdown. I did find a used sti joint for $80 though. I think Torque Solutions makes an identical one to perrin and I found one for $50.

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Found this, and now I'm wondering about it. I saw Underdog cutting the inner tie rods, but was it necessary? If so, 6-8mm seems fine.

 

Next question, OEM, Reman, or? If I could source a wrecked STI, that would be my best bet.

 

Next question...what are the major challenges in the swap? I've been reading up, but haven't found anything of the sort.

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