My 2000 300m has 185k km on it (114k miles) and here's what I've had to deal with regarding suspension issues:
- About 2 years ago in January, before I put the snow tires on, I was coming down a slight hill that had a curve and I spun out, with the rear passenger-side wheel hitting the curb hard. Put a 3-inch long crack in the 17" Razorstar rim, but not deep enough to leak air. The impact bent the axle so the tire rolled on an angle - but the wheel still rolled true and straight. Drove it like that for months. Finally bought a new axle-knuckle, monroe quick strut, and bearing. Turns out the old bearing race had been broken in 3 places, but it still held together (and really didn't make any noise). Got a used rim from a local junkyard.
- Last December (Dec. 24 to be exact) in the morning I was at the bottom of a hill with a dip or pothole and felt a hard bang - like the suspension had bottomed out with metal-to-metal contact. Car was still drivable but something didn't seem right, but I was only a mile from home. Turns out the lower plate that supports the suspension spring had rusted and had separated from the strut, and the spring forced the plate to drop about 1/2 inch and rest against the steering arm (on one side) and the tie-rod link arm (on the other side). The plate was now in slight contact with the tire. This was on the driver side. Went to a local auto parts store and bought a monroe quick strut, and a few hours later everything was back to normal. A few months later when I was taking off my snow tires, I had a close look at the passenger side and the lower spring support plate on that side was half rusted through, so I replaced that with another monroe quick strut.
After replacing the first strut, the steering wheel points to 8-2 o'clock (instead of 9-3) when the car is driving straight, but otherwise on a flat, level highway the wheels drive straight (no pulling to one side or the other) so I figured no alignment was needed.
More recently I've been messing with the lower control arms, tension strut bushings, sway bar bushing and sway bar links, trying to eliminate a knocking sound coming somewhere from the front.
I replaced the sway bar bushings last year, but what I notice is that even new bushings have a loose fit - I think because of some erosion of the sway bar. I've re-worked the bushings (wrapped some steel wire around the sway bar) to make it a tighter fit.
What really surprised me is how badly the tension strut had rusted/eroded under the bushings. The strut is dealer-only part. The new strut is 3/4" in diameter where it rides inside the bushings. The old strut had lost a minimum of 1/16" and in some places 1/4" due to rusting.
Replacing the tension strut didn't really eliminate the knocking. That leaves the tie-rod end and wheel bearing as the next candidates. I really don't want to start messing with the steering rack and it's various joints and bushings. Would a worn tie-rod be felt through the steering up to the steering wheel? Because I don't feel anything in the steering wheel.
According to a 300m web-forum (the one you have to pay $10 - $15 a year to post to), there is a thread where someone claims that you need to replace aftermarket strut-bearings and mounts with OEM versions when buying aftermarket quick struts. I didn't see an explanation as to why that is, or what happens if you don't. And I don't know what the "strut bearing" is - I don't see that part in exploded views of the front suspension.
In other threads on that same web-forum, I've read where there were issues with these monroe quick-struts - something about them not being able to fully tighten down against the top strut mounting plate so that they were a bit loose. Was that the issue? I don't think mine are loose. Mine are black - not the blue "economatic" version, which I think are exactly the same as the black except for color and warranty. Around here, parts stores only stock the black ones - the blue ones are special order.