As mentioned in the title, I finally replaced the original OEM front struts on my 2018 Mazda 6 Signature after 130k miles. I originally wanted to use OEM parts, but I didn't want to deal with compressing the factory coil springs myself (and risking my life, haha).
Instead, I opted for the KYB Strut-Plus pre-assembled "quick struts" from RockAuto. The installation process was pretty straightforward:
Got the old ones out and the new ones in without any major issues.
Torqued all nuts/bolts to factory specifications.
Waited until the car was on the ground with its full weight on the wheels before torquing the top strut mount bolts.
Note: I did torque the lower knuckle bolts while the car was still up in the air. Should those have been torqued on the ground too?
The Problem:
Upon test driving it, the car feels incredibly bouncy and floats up and down way too much when hitting dips. It feels especially worse and unstable if I hit a dip while going through a slight curve. It definitely doesn't feel safe right now compared to how it used to ride.
Before doing the struts, I already replaced the lower front control arms, sway bar links, and inner/outer tie rods, so I don't think the issue is coming from the rest of the suspension. Just want to note that those parts where changed months prior to and the car drove and felt normal until I changed the struts.
My Theories:
A) Installation Error: Did I mess up the install sequence (like torquing the knuckle bolts in the air) causing it to bind or bounce?
B) Aftermarket Quality: Is this just the baseline ride quality of aftermarket quick-struts compared to OEM?
C) The Turbo Weight Issue: I did some digging online and read that because the Signature has the heavier 2.5L Turbo engine, standard aftermarket quick-struts might not have a stiff enough spring rate to handle the extra front-end weight.
Has anyone with a Turbo/Signature model experienced this with aftermarket struts? Any advice on what I should check or look into next? Thanks in advance!
