Underdog Motorsports - 2015 STI Steering Rack Swap

From this thread - http://forums.nasioc.com/forums/showpost.php?p=44366274&postcount=532

This is actually the post I meant to link (that one just confirms his car)

http://forums.nasioc.com/forums/showpost.php?p=44377887&postcount=538

This user has the same issue I do with the rack and he has a 2012 WRX. According to cars 101, the 2012 WRX has a 15:1 rack. He found the only fix was to turn off traction control (what I am currently doing)

All the legacy guys are slow with this mod

No point in the thinner jam nuts unless you also remove 2-3 threads from the ITR; otherwise the OTR will bottom out on the unmodified ITR. M14x1.5 is the universal Subaru tie rod thread size among all '05+ turbo models that I checked.

LGT and Spec.B are the same 15:1 however the Spec.B actually has less total range (internal stops) to prevent the larger Spec.B tires from rubbing at full lock.

 

LGT and Spec.B are the same 15:1 however the Spec.B actually has less total range (internal stops) to prevent the larger Spec.B tires from rubbing at full lock.

Given the larger tires on the Outback it would seem that the SpecB rack would be the optimal rack versus an LGT one since you don't rub and don't have VDC issues.

So last weekend I took the car back to my home town which is deep in the Appalachian mountain, so there are a lot of really curvy roads. I did some spirited driving around my hometown and the VDC was kicking in quite a bit even with the traction control turned off. It was hitting the brakes right in the middle of turns.

I called the dealer and told them the car is worse now than when I brought it in asking for the VDC to be re-calibrated.

I'm going to call the dealer back on Monday and talk to the Tech to see what they say.

At this point I'm thinking about doing this. I'm thinking about unplugging the steering angle sensor which should disable the VDC but also throw a check engine code. I then plan to use my Cobb AccessPort to delete the codes that get thrown by unplugging the sensor.

Anyone have opinions on this approach?

That might put you into a limp mode where full throttle is not available.

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That might put you into a limp mode where full throttle is not available.

 

 

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Ok so I went and unplugged the steering angle sensor. Its a plug right at the back right side of the bottom of the steering column cover. After I unplugged the sensor, the traction control off light came on but everything else seems normal. No codes, sport / sport # seems normal. So I'll drive around like this for a bit and see what happens.

Ok so I went and unplugged the steering angle sensor. Its a plug right at the back right side of the bottom of the steering column cover. After I unplugged the sensor, the traction control off light came on but everything else seems normal. No codes, sport / sport # seems normal. So I'll drive around like this for a bit and see what happens.

Any updates regarding potential issues?

Thanks

Any updates regarding potential issues?

Thanks

No issues so far, but I haven't gotten a chance to drive the car hard enough for traction control or VDC to kick in.

No issues so far, but I haven't gotten a chance to drive the car hard enough for traction control or VDC to kick in.

Please keep us posted, since this would be the only way for me to make the swap.

Please keep us posted, since this would be the only way for me to make the swap.

Keep in mind that the difference between your stock rack and the STi rack is much smaller than the OBXT and the STi rack so even if he does have issues, you may not.

Keep in mind that the difference between your stock rack and the STi rack is much smaller than the OBXT and the STi rack so even if he does have issues, you may not.

That's a valid point. I just want to make sure that should resetting the sensors not work, I can unplug it and avoid any VDC unwanted interventions.

Ok so I am happy to report after a full day at Dominion Raceway today that for sure unplugging the steering angle sensor completely disabled traction control and VDC. The only side affect is the traction control off light is on.

Also for anyone wanting to know how good the STI rack is. Here is a raw video of one lap at Dominion Raceway today. This is a very tight track and having the STI rack here was awesome.

That's a valid point. I just want to make sure that should resetting the sensors not work, I can unplug it and avoid any VDC unwanted interventions.

I want to report also that I drove on a dirt road where I was able to "drift" aka have some wheel slippage occur and some slight amount of sideways and I didn't feel the VDC kick in when I turned it off (just pressed it off)

I also drove quickly over mountain passes with no steering issues (just fun). I had my dog in the back so I was focused on smooth though.

Basically, I think anyone should do this. The VDC issues seem minor and defeatable.

I want to report also that I drove on a dirt road where I was able to "drift" aka have some wheel slippage occur and some slight amount of sideways and I didn't feel the VDC kick in when I turned it off (just pressed it off)

 

I also drove quickly over mountain passes with no steering issues (just fun). I had my dog in the back so I was focused on smooth though.

 

Basically, I think anyone should do this. The VDC issues seem minor and defeatable.

Ok so I am happy to report after a full day at Dominion Raceway today that for sure unplugging the steering angle sensor completely disabled traction control and VDC. The only side affect is the traction control off light is on.

 

 

Also for anyone wanting to know how good the STI rack is. Here is a raw video of one lap at Dominion Raceway today. This is a very tight track and having the STI rack here was awesome.

 

Great news. Thanks for the feedback.

so what's the final list of parts needed to make this work? No need to mix/match inner and outer tierods?

I got an old 05 sti rack just sitting in my garage

The 05 STI rack is not an upgrade.

That STi rack came in the Saabaru from the factory (as well as the 06-07 WRX), and is noticeably quicker than my LGT's steering. Might not be as tight as the '15+ STI unit, but it's definitely tighter than the Legacy. I drive them back to back almost daily.

edit: did some digging and most sources say both racks are 15:1... however, they don't feel the same to me

LW - really not a fair comparison due to differences in the chassis. All else equal the car with the shorter wheelbase will feel snappier on turn-in due to the moment of inertia. Think of trying to spin a ball versus a dumbell.

There are several other factors that could play into what you are experiencing. Wheel/tire specs would be a major consideration.

LW - really not a fair comparison due to differences in the chassis. All else equal the car with the shorter wheelbase will feel snappier on turn-in due to the moment of inertia. Think of trying to spin a ball versus a dumbell.

 

There are several other factors that could play into what you are experiencing. Wheel/tire specs would be a major consideration.

That makes sense! Was comparing on equal 225/45/17, but wheelbase didn't even register for me

so what's the final list of parts needed to make this work? No need to mix/match inner and outer tierods?

 

I got an old 05 sti rack just sitting in my garage

What is the track width of an 05? If its the same as 2008+ Nothing is needed, just bolt it up. For the 2015, nothing is really needed. I used thinner jam nuts and cut the tie rod ends to make sure there was plenty of adjust ability, none of that was really needed though.

The 05 STI rack is not an upgrade. The only part needed is the 15+ STI rack, everything else is optional.

It is however an upgrade to an Outback (but not a Legacy).