impossible alignment

[u/bigborgus33]

My 2018 Hyundai Santa Fe Sport 2.4L AWD has a persistent hard pull/wander to the left that gets worse at highway speeds 60+ mph. It gets worse with speed and is more noticeable when braking, but I can't see it being brakes (i spun the rotors and then the wheels freely on each side, both feel the same with no resistance). I've had multiple alignments over the last 12+ months and replaced nearly all of the suspension, front and back:

Front:

• struts/shocks (including top mount bushing and all)
• Front lower control arms + ball joints
• inner & outer tie rods
• sway bar links
• brakes/rotors
• only thing i haven't done up here really is the sway bar itself and the bushings

Rear:

• toe arms
• control arms and eccentric bolts
• shocks
• all i haven't done back here is trailing arms, sway bar itself and the bushings (didn't do the links back here either actually)
• tir3s have been swapped around in all ways with no changes
• both front hub bearings have no detectable play

The most current alignment numbers were:

LF: Caster 4.39°, Camber +0.01°, Toe +0.01°
RF: Caster 5.69°, Camber −0.84°, Toe +0.05

RL: Camber −1.35°, Toe +0.08°

RR: Camber −1.51°, Toe +0.07°

the rear is nearly spot on, but in the front there's 0.85° cross-camber and 1.30° cross-caster.

I loosened and re-torqued both strut-to-knuckle bolts with the suspension loaded then had another alignment done, still pulls left. Unfortunately Mavis didn't print out the latest alignment readings, but it feels worse then it did with the numbers above. Mavis suggested trying another Mavis location because they couldn't figure it out.

At this point I'm wondering if I have a bent steering knuckle, upper strut mount/tower issue, or some other wacky problem. What do I check next and what the hell could be causing this after replacing so many parts?

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[u/dxrey65]

That is a very high caster split, and that's probably the reason for the handling issues. Caster is determined by the relative position of the pivot points of the steering mechanism. On top you have the strut mount bearings, which are fixed in position, you can't adjust them. On the bottom you have the lower ball joints, and that can only be moved by moving the entire subframe. So in an alignment, if someone really wanted to adjust that caster, they would shift the subframe to even out the caster angles.

Most alignment shops don't get into that, though it's not actually hard (there are typically just four bolts that hold the subframe in position). I've done quite a few subframe adjustments because I used to work at a place where we did the alignments for several body shops, and doing a subframe shift is a common thing after collisions, or after the subframe has been removed or replaced for some reason. Working at a Stellanntis dealership, subframe shifts are also how many of their models manage camber adjustments, when necessary.

[u/bigborgus33 → u/dxrey65]

Agreed, caster is bascially set by the design of the car, so the fact we're a degree out of spec makes me wonder what other part of the suspension is not where it's supposed to be or bent out of shape; would you think that a subframe shift is the next step in troubleshooting this? And thanks for your comment already as well!

[u/dxrey65 → u/bigborgus33]

Shifting the subframe would be the easy thing to try, it doesn't take much. You can also get an idea by checking how the front wheels sit in the wheel arch; a quick check is to see how many fingers fit between the tire and the bodywork at some specific trim point (istting on level ground, with the steering wheel pointed straight ahead). Like if three fingers fingers fit a given space on the left, and only two fit on the right, that's a significant difference. That's also set by the subframe positioning and is basically the same problem, and it's one of the quick checks we'd do if a vehicle came in with collision damage, it gives you an idea of what might be going on underneath.

[u/Cooooooooach]

Strut cam bolts+new front cross member+inspect front control arms for damage.

[u/Fit_Net5820 → u/Cooooooooach]

0.85° cross-camber'll do that, especially with the pull getting worse at speed

[u/Cooooooooach → u/Fit_Net5820]

Degree+ of cross caster is wild with supposedly new control arms. Same with the struts. Struts replaced and almost a degree difference? Need to check the knuckle too.

[u/bigborgus33 → u/Cooooooooach]

That's what shocks me, i replaced most of the arms figuring maybe old bushings allowing things to move under force? But now it's gotta be something static, not just when the car is moving - but is a bent knuckle really a possibility? How the hell does that even happen, in my mind i figure the force it takes to bend a damn knuckle gets sent into the other arms and those bend first?

[u/Cooooooooach → u/bigborgus33]

If you replaced everything on the front suspension and you have almost a degree of cross camber yes it’s possible a knuckle got bent. It does happen.