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First of all, hello to all! This is my first post here as I just got a 2017 STI about a month ago. I’m really enjoying it, but have a few questions. I should preface this by saying I have very little experience driving AWD cars (all Haldex) and zero experience driving Subaru’s symmetrical AWD. I have a decent amount of experience tracking previous cars and have had this car to 1 track day and 3 autocrosses so far. I quickly realized that I needed a sway bar and some good brake pads/fluid to make it feel almost as small as my last track car, which has worked pretty well. One thing that is driving me nuts though, is that I’ve been trying to reap the benefits of throwing it into a corner, getting it to rotate, and stabbing the throttle without getting any wheel spin (unlike my last car, which had wheel spin all day), but I’m getting this weird sort of wheel hop from the front tires at low speed corner exit under full throttle, which makes me feel like I’m hurting/damaging something. I know the helical diff in the front has been described as “grabby” but I’d prefer to not replace any halfshafts or CV joints anytime soon. Is this normal? Also, I haven’t really messed with the center diff settings all that much. Would setting it on manual with a few “-“ clicks maybe phase this out. Any help would be appreciated.
 

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What settings are you running the center diff on? I'd keep it on auto. If you manually lock the center diff it really hurts turn in.

If you want to talk track suspension we have a line of custom sprung and valved Ohlins coilovers along with supporting mods.
 

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I'll be following this thread as I come from a similar background (BRZ track car). I just picked up my new STI last week and have felt surprising handling characteristics from the front end while turning under power. I assumed it was just a consequence of the AWD.
 

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Are you trail braking? What are your alignment specs? Also, what tires are you running? Stock, these cars are severely setup for understeer, even the newest chassis. Just a rear sway bar isn't going to fix that. If you're not on a DOT R tire already, the front tires are so overtaxed to begin with that a normal street tire >200tw is going to get greasy fast, where the rears will stay grippy.

Also, why do you want so much rotation and wheel spin? Isn't that the slow way around a corner? Sure it's fun, but the cost of 4 wheel drifting from a maintenance/repair standpoint on this car is not insignificant.

Lastly, the center diff isn't going to make or break the rotation imo. The variation in the settings is so small on the new cars. A F/R distribution range of 41/59 to 50/50 isn't going to decide whether you get serious rotation, without addressing much of the above.
 

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Discussion Starter #6
What settings are you running the center diff on? I'd keep it on auto. If you manually lock the center diff it really hurts turn in.

If you want to talk track suspension we have a line of custom sprung and valved Ohlins coilovers along with supporting mods.
So far I’ve been running it on “Auto –“ I’m thinking about trying it in manual, 2 clicks from completely back.

For the time being I want to keep it in street class, so I’m going to stick with the Bilsteins that came on it. Thanks for the offer though.

Could it be the torque vectoring? You might want to try shutting the traction control completely off if you don't already.
I hardly ever use traction control, even in the rain. My last car pretty much cut power to both wheels as soon as they broke loose with the traction control on, which was a really good way to break CV joints lol

Are you trail braking? What are your alignment specs? Also, what tires are you running? Stock, these cars are severely setup for understeer, even the newest chassis. Just a rear sway bar isn't going to fix that. If you're not on a DOT R tire already, the front tires are so overtaxed to begin with that a normal street tire >200tw is going to get greasy fast, where the rears will stay grippy.

Also, why do you want so much rotation and wheel spin? Isn't that the slow way around a corner? Sure it's fun, but the cost of 4 wheel drifting from a maintenance/repair standpoint on this car is not insignificant.

Lastly, the center diff isn't going to make or break the rotation imo. The variation in the settings is so small on the new cars. A F/R distribution range of 41/59 to 50/50 isn't going to decide whether you get serious rotation, without addressing much of the above.
Yeah, my last car was front wheel drive, so learning to trail brake properly was essential to turning halfway decent times lol. The sway bar did help quite a bit with the understeer actually, I ran it on the medium setting at the last event, and I don’t feel the need to make it firmer at all. I’ve been running the Hankook RS4’s for a couple of years now. I really like this tire. It may not be quite as sticky as the Bridgestone, but it’s pretty darn close when it warms up (takes a while to warm up), and lasts forever. I probably won’t have a chance to get a decent alignment until early next week.

As far as the rotation and wheelspin… I just need enough rotation to get it pointed the right way by mid corner, and I definitely don’t want wheelspin, but it’s almost like I’m getting wheel hop out of the front tires on corner exit, which I’m not used to. I was just wondering if it possibly had something to do with the auto setting on the center diff. I have read in a few places that people don’t like leaving it in auto because it can be unpredictable and upset the car during mid corner acceleration. I haven’t really had this problem yet. I also agree that the center diff will have little, if any, effect on turn in rotation. The only reason I can think of that would affect it would be the helical front diff. I haven’t really had a chance to research this front diff yet, and not all helical diffs are the same, but there are some (e.g. Wavetrac) that work sort of in reverse under deceleration. I have a hard time believing that it would make much difference in a car that also has a center and rear diff, but I’m not an expert.
 

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Yeah, my last car was front wheel drive, so learning to trail brake properly was essential to turning halfway decent times lol. The sway bar did help quite a bit with the understeer actually, I ran it on the medium setting at the last event, and I don’t feel the need to make it firmer at all. I’ve been running the Hankook RS4’s for a couple of years now. I really like this tire. It may not be quite as sticky as the Bridgestone, but it’s pretty darn close when it warms up (takes a while to warm up), and lasts forever. I probably won’t have a chance to get a decent alignment until early next week.

As far as the rotation and wheelspin… I just need enough rotation to get it pointed the right way by mid corner, and I definitely don’t want wheelspin, but it’s almost like I’m getting wheel hop out of the front tires on corner exit, which I’m not used to. I was just wondering if it possibly had something to do with the auto setting on the center diff. I have read in a few places that people don’t like leaving it in auto because it can be unpredictable and upset the car during mid corner acceleration. I haven’t really had this problem yet. I also agree that the center diff will have little, if any, effect on turn in rotation. The only reason I can think of that would affect it would be the helical front diff. I haven’t really had a chance to research this front diff yet, and not all helical diffs are the same, but there are some (e.g. Wavetrac) that work sort of in reverse under deceleration. I have a hard time believing that it would make much difference in a car that also has a center and rear diff, but I’m not an expert.
Not sure about the class restrictions that you're in, but if you're going to get an alignment performed, you might consider dialing back or keeping the same rear camber, and adding a bunch of front camber.

Any adjustment of rear camber necessitates aftermarket LCAs, and the front is adjustable by a full degree I believe with just the addition of aftermarket camber bolts in the lower bolt position. Also, check out your toe settings.

I don't have much practical experience with this, but I've read up on it and it seems that you've got just about everything else right to maximize rotation on corner entry, but the alignment might be the final step to get where you want to be, or to need to reconsider how much money you want to spend to get where you want to be :lol:
 

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Here's my 11 STI track car:


R888 street tires and Hoosier R6/7 track tires. I made a custom center diff controller for this but the stock controller in auto generally works best, especially on a tight course unless you have the power and desire to "dirt track" the car. Which is fun but not as fast in my experience.
 

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Discussion Starter #9
Here's my 11 STI track car:
Image Link


R888 street tires and Hoosier R6/7 track tires. I made a custom center diff controller for this but the stock controller in auto generally works best, especially on a tight course unless you have the power and desire to "dirt track" the car. Which is fun but not as fast in my experience.
That's a beautiful car. I'm trying to stay in the street class until I get absolutely bored and need to start modding. I've never really had any interest in "dirt tracking" or drifting or whatever. I feel like between the sway bar and getting a decent set of pads on the car, I'm able to trail brake more effectively, which solved my turn in pretty well. I still need to figure out my corner exit with this car though. Right now I've turned my best times by getting it into position by mid-corner, and then going immediately to full acceleration as soon as possible. It's not entirely slow, but I feel like there is probably a better way to do it. I'm going to mess with the manual diff settings a little bit at my next event just to see if it's more predictable. I've read both sides of the argument regarding auto vs. manual, but I realize everyone is different, and in some cases comes down to their previous experience and driving style.
 

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Discussion Starter #10
Not sure about the class restrictions that you're in, but if you're going to get an alignment performed, you might consider dialing back or keeping the same rear camber, and adding a bunch of front camber.

Any adjustment of rear camber necessitates aftermarket LCAs, and the front is adjustable by a full degree I believe with just the addition of aftermarket camber bolts in the lower bolt position. Also, check out your toe settings.

I don't have much practical experience with this, but I've read up on it and it seems that you've got just about everything else right to maximize rotation on corner entry, but the alignment might be the final step to get where you want to be, or to need to reconsider how much money you want to spend to get where you want to be :lol:
I was thinking the same about front/back camber. I lowered the pressures in the back and raised them a bit in the front which seemed to help a bit. I'm not sure how much camber you can get out of the stock front suspension, but if I could get near 2 degrees without a camber plate that would be great. Hoping to get an 1/8th or so toe out in the front. I'll probably just leave the back alone.
 

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Thanks!

Manually locking will hurt turn in and cause the car to push. You want the center diff open on corner entrance and gradually locking all the way from apex out as you fully apply the power.

Some supporting mods:












That's a beautiful car. I'm trying to stay in the street class until I get absolutely bored and need to start modding. I've never really had any interest in "dirt tracking" or drifting or whatever. I feel like between the sway bar and getting a decent set of pads on the car, I'm able to trail brake more effectively, which solved my turn in pretty well. I still need to figure out my corner exit with this car though. Right now I've turned my best times by getting it into position by mid-corner, and then going immediately to full acceleration as soon as possible. It's not entirely slow, but I feel like there is probably a better way to do it. I'm going to mess with the manual diff settings a little bit at my next event just to see if it's more predictable. I've read both sides of the argument regarding auto vs. manual, but I realize everyone is different, and in some cases comes down to their previous experience and driving style.
 

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Discussion Starter #12
I'll be following this thread as I come from a similar background (BRZ track car). I just picked up my new STI last week and have felt surprising handling characteristics from the front end while turning under power. I assumed it was just a consequence of the AWD.
The only thing that I really don't like about this car so far is the "panic break" feature. This car seems to need to be able to brake boost as much or more than a lot of cars that I've driven and I was really shocked when I tried to left foot brake the first time.
 
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