[Sixth Gear]

After a long search for a manual 3 series sport wagon, I found (and bought) a 2006 325xi (all wheel drive) with just about 100k miles after it cleared the pre-sale inspection a couple of months ago. I have since gone on a couple of road trips with the car but on several occasions, when driving over freeway joints (say, going over a bridge, etc.) at normal speed (~70MPH) the car "bottoms" and the body seemingly hits the rubber bumpers that limit the strut/shock travel. The car has a standard (not Sport) suspension and everything is stock (i.e. it is not lowered.) Other than this the car handles ok and the ride appears normal (even though a bit too soft to my taste.)

This has never happened on my Z3, or my previous E46, driving over similar or more severe bumps, so I am wondering:

- Is this an indication that the front struts or rear shocks are worn out and need to be replaced ? The "bounce" test does not seem to show anything since the car (spring) does not yield measurably no matter how hard you push down on the front of rear bumpers ?

- Do run-flat tires increase the chances of "bottoming" when going over sharp bumps ?

- If the struts on the car need to be replaced, any suggestion for what to replace them with for a slightly stiffer ride but without losing any ground clearance (I occasionally need to drive on rough roads to reach trailheads and need all the clearance that I can get !) Also, are the shocks/struts from the xi (all wheel drive) E90 interchangeable with those of the non-xi models as well as sport/non-sport suspensions ?

- Finally, someone is advertizing a full set of shocks+struts from an 2007 E92 (Coupe with sport suspension, removed from a car with ~60k miles) on the local CL. Would it be worth looking into them as replacement parts or 60K is considered high for OEM parts ?

And, on a side note, the car's headlight high (bright) beam seems to be pointing rather low (certainly compared to all my previous cars).
Is there a possible link between the two, or is it simply a matter of a headlight in need of a routine adjustment?

Would appreciate any insights or suggestions from those who have dealt with similar issues..

[HP Autosport]

Probably a good idea to make sure you are actually bottoming the suspension or just hearing the thud from the stiff side wall runflats.

[vwetish]

You definitely need new struts and shocks.
On average they go bad at around 75k
With that being said don't even consider replacing them with use set with 60k
If they come and are installed for free (you not doing the labor) yes, otherwise no. Is not worth it.
Replace the rears first, which is super easy, and kind of go from there.
Rear are interchangeable, fronts aren't.
If you have xenon light bad suspension can have adverse effect on the headlight beam.

[Sixth Gear]

Thanks much for the suggestions. I tried going over the same bump at different speeds and the sharp jolt (presumably from hitting the rubber chassis bumpers) starts abruptly around ~60 MPH so it does not appear to be a thump from the stiff side walls (which would probably be more gradual).

So it looks like it is time for new struts & shocks. As you suggest, replacing the rear shocks seems to be straightforward but since I don't have the tools/experience for dealing with the coil springs, I'll have the front done by the shop.

Where would be a reasonable place to order a full Bilstein B6 replacement kit (including the mounts ?) And are these common across the entire E90 series (E90, 91 and 92) or are body-specific ?

Thanks again !