2017 Legacy is very unstable at highway speeds

Hi, I have 2017 Legacy 2.5i got it brand new and since then I noticed that at highway it feels light and very unstable like cross winds are hitting it from all sides. Steering feels light and needs constant hand control. Anyone else noticed this?

No I have not. I have driven 80-85 and no problem at all with stability. Everything feels fine with the car.

What shape are your tires in? Are they properly inflated?

We have a windy bridge in my area and I’ve had no trouble. I fly through the mountain roads in WV and VA and have no issues. I rarely go above 90.

 

My rearsway bar is still stock.

This is a normal response to a new 2015 to 2018 Legacy owner. Subaru went with a very small rear sway bar in the rear. I believe its 16mm. If you upgrade to larger rear sway bars it corrects the issue and the car feels much more stable. You can swap out for a Cross Trek RSB which is 20mm and its a direct Subaru part.

 

https://subaruonlineparts.com/subaru-crosstrek-rear-sway-20mm-p-3920.html

The first year of the 5th gen had that problem. Increasing the tire pressure with 10 to 20% over what was recommended solved the problem.

 

But if the problem persists - check the wheel alignment first. No point in throwing parts on a car if it's badly adjusted.

Maybe the wind noise from the doors is creating a heuristic tactile illusion?

I’ve heard of a floaty feeling that was vastly negated by the RSB upgrade.

 

Wonder if it’s the feeling of electric vs hydraulic power steering. I had a similar experience when I drove my wife’s Honda with EPS until I got used to it.

 

But yes always start easy - check tire pressure, tire wear, etc.

Get the 20mm OEM rear swaybar upgrade and kartboy endlinks, the rear end will feel slightly more stable. People are saying the Perrin steering damper lockdown helps with the feel, and personally after reading in the Koni thread that the yellows work with our car, I ordered a set and I'm going to get RaceCompEngineering springs which lower the car around 20mm all around, not as low as some others so there's less worry of pot holes and speed bumps and steep driveways. I have my heard one bad thing about the koni yellows along with some sportier springs, even described as the car now rides like an upscale sport sedan. And you cant forget some lighter wheels with stickier tires. If that doesn't do it, trade for an RS3

I have a '16 and I just don't agree that there is a problem with the car at high speed. It does track and turn much better with the OEM tires changed, but even with the ones that came on the car it was fine. My personal feeling is that the car is, in general, "OK. It is certainly not the best driving car I have ever had and is far from the worst. Expecting it to be something other than what it is: a general family sedan is not realistic.

on the 3.6 what's the size of the front a rear sway? 20 and 16?

I just recently had my alignment done and I also installed the 20mm sway. I've got STI BBS wheels installed, with barely-worn DWS tires inflated to a few # over the door placard.

 

The Legacy's steering is very light on center. With lots of twists and turns, it's fine, but for straight highway driving over imperfect roads or with a decent amount of wind I feel as if I'm adding more input about center than I'd like. I've gotten used to it.

I just recently had my alignment done and I also installed the 20mm sway. I've got STI BBS wheels installed, with barely-worn DWS tires inflated to a few # over the door placard.

 

The Legacy's steering is very light on center. With lots of twists and turns, it's fine, but for straight highway driving over imperfect roads or with a decent amount of wind I feel as if I'm adding more input about center than I'd like. I've gotten used to it.[/QUOT

 

are you happy with 20mm sway now?

I’ve heard of a floaty feeling that was vastly negated by the RSB upgrade.

 

Wonder if it’s the feeling of electric vs hydraulic power steering. I had a similar experience when I drove my wife’s Honda with EPS until I got used to it.

 

But yes always start easy - check tire pressure, tire wear, etc.

 

that is what I am also thinking that it has something to do with electric steering torque sensor being too sensitive. My tires are OK. only 6K miles on the car

This is a normal response to a new 2015 to 2018 Legacy owner. Subaru went with a very small rear sway bar in the rear. I believe its 16mm. If you upgrade to larger rear sway bars it corrects the issue and the car feels much more stable. You can swap out for a Cross Trek RSB which is 20mm and its a direct Subaru part.

 

https://subaruonlineparts.com/subaru-crosstrek-rear-sway-20mm-p-3920.html

 

interesting I will look into it and see how to do it myself.

The first year of the 5th gen had that problem. Increasing the tire pressure with 10 to 20% over what was recommended solved the problem.

 

But if the problem persists - check the wheel alignment first. No point in throwing parts on a car if it's badly adjusted.

 

I did experiment with different tire pressures with no change. Steering is not pulling or anything. I think it has to do with electric steering and maybe needs .5 to 1 degree of negative camber. Will check alignment definitely to see how far is from factory specs.

I just recently had my alignment done and I also installed the 20mm sway. I've got STI BBS wheels installed, with barely-worn DWS tires inflated to a few # over the door placard.

 

The Legacy's steering is very light on center. With lots of twists and turns, it's fine, but for straight highway driving over imperfect roads or with a decent amount of wind I feel as if I'm adding more input about center than I'd like. I've gotten used to it.

 

are you happy with 20mm sway now?

 

I’m very happy with it.

 

It does nothing for the feel about center, but stability on the highway is improved and cornering is slightly better-feeling. I don’t drive super aggressively, though. If you do, you’ll notice it even more.

What shape are your tires in? Are they properly inflated?

We have a windy bridge in my area and I’ve had no trouble. I fly through the mountain roads in WV and VA and have no issues. I rarely go above 90.

 

My rearsway bar is still stock.

 

only 6k on the clock, tires are good

I have not noticed an issue at highway speeds with my '16. The car is simply a reliable sedan. Nothing spectacular about the handling (good or bad) at any speed. Stability was improved on mine by junking the OEM tires, but even with the originals it was fine. To expect anything other than the handling of a non-premium sedan is unrealistic. The Legacy will never be a 3 series BMW! Then again, it was a hell of a lot cheaper.

Lol. My two previous cars were both 3 series before the Legacy. Yes. The Legacy will not behave like the BMW.

 

aki334, try setting your tire pressures to 37/38 all around. I normally run my car at 38 all around. But then again, I usually have 30+ lbs of rifle armor and ammo in my trunk. Not sure if the extra weight does anything.

I have not noticed an issue at highway speeds with my '16. The car is simply a reliable sedan. Nothing spectacular about the handling (good or bad) at any speed. Stability was improved on mine by junking the OEM tires, but even with the originals it was fine. To expect anything other than the handling of a non-premium sedan is unrealistic. The Legacy will never be a 3 series BMW! Then again, it was a hell of a lot cheaper.

 

Nicely said. To clarify, I like how the Legacy handles. I remember how badly the 2010 MY handled (like a smaller land-yacht).

 

HOWEVER comma the one steering characteristic I truly dislike is the loose on-center feel. Road feel is great and the ratio is good for the segment. It’s not as connected as my previous STI, or my LGT, but it’s perfectly fine and not unenjoyable to drive at all.

 

Coming from an STI, I don’t feel like I’m in a grandpa-mobile. I don’t feel the (strong) need to trade it in on an STI any time soon........

 

Just know, as soon as the STI gets a 350HP 2.4DIT, you’ll probably never see me log on to this site again

I’m very happy with it.

 

It does nothing for the feel about center, but stability on the highway is improved and cornering is slightly better-feeling. I don’t drive super aggressively, though. If you do, you’ll notice it even more.

 

Does this mod require an alignment? Or is this something I can do in my driveway?

You can do it in your driveway

Install was very quick and easy. I sprayed all fasteners with penetrant a week prior, while bleeding the brakes.

 

This does not affect alignment at all.

Does this mod require an alignment? Or is this something I can do in my driveway?

Since a sway bar don't change the ride height or any other geometry like new springs do you don't need to re-do any alignment already done.

I actually think my 3.6r 2018 legacy is really stable at high cruising speeds.