Speed wobbles and abs on light turning

[frstplace]

Long story short, I bought this Scion FR-S about 4 months ago, I love the car but their is an issue. The issue started around the time I purchased the car, on very light turns like barely any turning the abs kicks in and I can feel the breaks pumping every second which kind of jolts the car and makes me slow down on the turn. So I then proceeded to get brand new tires all around, and eventually the issue went away, alignment felt fine, and I could be going like 50 mph on pretty sharp turns without any abs or breaking happening. But the other day I rotated my tires, front tires to back and back tires to front, and it seems like the same issue has returned. At around 90 mph + the car does not feel safe at all, it kinda of swerves slightly left and right back and forth like a wobble. And in very little turning scenarios the abs kicks in hard. So I’m wondering if it could be the way I put on the wheels? Could I have possibly not tightened the wheels enough before lowering, causing it to be angled off? I retorqued all the wheel bolts and they were all tight.

[norcalpb]

Significant uneven tire wear between front and rear tires can cause tramlining which will destabilize the car at speeds.

Even with my semi slick tires TC will come on over bumps, I just turn it off completely when I’m on a windy road.

When you feel the car “brake” from TC it’s actually potentially hurting your rear differential as the diff is locked, as the brakes are slowing down one wheel which causes the diff to slip (metal shavings).

[strat61caster]

Alignment 'feels fine' does not mean it is, if anything the high speed instability is indicative of an alignment issue or some part of the suspension being worn, a good alignment shop can spot worn items when doing an alignment. The car should feel very stable at high speeds, it shouldn't move on you unless there are high winds which even those should be predictable.

As above sounds like traction control is doing it's thing, it's very conservative and will activate well before you think it should in default mode. Also worn and possibly unevenly worn tires can cause issues.

imho: alignment check at a good shop (new tires/part if recommended by shop) -> see if problems exist -> sport mode to see if TC is more lenient


Any mods?

[frstplace]

Originally Posted by strat61caster

Alignment 'feels fine' does not mean it is, if anything the high speed instability is indicative of an alignment issue or some part of the suspension being worn, a good alignment shop can spot worn items when doing an alignment. The car should feel very stable at high speeds, it shouldn't move on you unless there are high winds which even those should be predictable.

As above sounds like traction control is doing it's thing, it's very conservative and will activate well before you think it should in default mode. Also worn and possibly unevenly worn tires can cause issues.

imho: alignment check at a good shop (new tires/part if recommended by shop) -> see if problems exist -> sport mode to see if TC is more lenient



Any mods?

Could I really have uneven tires? I bought them all at the same time about 2 months ago brand new.
No mods

[strat61caster]

Originally Posted by frstplace

Could I really have uneven tires? I bought them all at the same time about 2 months ago brand new.
No mods

Depends on how bad the alignment is and how many miles you've been on the tires.

But given that info I'd suspect it's unlikely that the tires are showing uneven wear unless you have a pretty intense commute.

[humfrz]

Yep, like mentioned, I'd suggest you take it to a good alignment shop and have them check it out and fix it.


humfrz

[x808drifter]

Did you do a car history report before buying?

[wparsons]

I'd have the car checked out to make sure there isn't significant play in any of the balljoints or other suspension components or if anything is loose.


You've checked the tire pressures, right?

[Decep]

id suspect wheel balance over alignment, seems like alignment issues would show up before 90mph

[Stang70Fastback]

To be perfectly blunt, this discussion is pointless until you have an alignment performed. That would be the first step in solving this problem regardless. If you haven't had one, you should get one done.

[churchx]

1) were tires balanced when mounted? I don't think much people just mount them to save a bit, but still, possible
2) have you checked tire pressures? Just as you know answer to (1.), it's easy to check this, just drive in any fuel station with air compressor & check them, if they are even and pump up or let out some for that. Again this "check" is free & simple.
3) alignment. Worth doing even for new/stock car, due wide allowed to pass stock alignment ranges, which at margins of passing range extremes may make car behave very differently. Also prior alignment shop/rig visit i'd take opportunity & buy set of front camberbolts (relatively cheap thing), & ask install them at a time & ask for a bit more camber front, for less understeer bias. If one will spend time/money on alignment anyway, why not make it better?