Flyin' low...

[dwgates]

Well my new 540i (2001 540i) was given its 1st full load test this past weekend and the results were not ideal. I noticed some rubbing when the suspension loaded up after a bump and although my back seat passengers were not lightweights I expected a little less sagging. I measured the ground to fender distances on the new car (unloaded on a level driveway) and my other 2001 and noticed the average measurement of the new car for the front was lower by 3/4 of an inch at the front and the rear was ~1" lower than my old car.
I'm in the middle of pulling parts off the old car so it's a little lighter but don't think that's the source of the entire difference, car to car. I had enough rubbing on our trip that the shiny spots on the rear tires look to be between 2.5" and 3" from the fender lip so we must have looked like low riders to anyone we passed.
I got underneath the new car to see if there were any obvious sources for ride height differences and nothing stood out (no broken, rusted, or obviously aftermarket springs) with the exception of the front shocks. The passenger side measures 3.75" from the hub (clamp) to the sharp edge at the bottom of the strut. That side has a suspicious, less dirty spot, just below the hub clamp which makes me think someone before me thought they could lower the front end. The drivers side measures 3.5" and shows no witness line. Standing back it doesn't look as if the car sits out of level but that could be my bifocals (it's hell to get old). There is nothing other than the rear springs on those struts that could affect the ride height so either they aren't stock or they've drooped in the last 20+ years.
The car rides nice and handles well so I don't think the spring rates are way off but again with 4 passengers and a trunk full of picinic baskets we were flyin' low. I have a pair of rear struts from an e39 M5 on my old car and can pull them and swap with what's in place right now. I've looked thru my Bentley manual and can't find any set points for the front strut to hub clamps though. Does anyone have any information regarding setup at the front end? I'm assuming the position of the strut as well as rotation is an alignment setting and it would be good to hear from someone more knowledgeable than me to confirm this.
Also Bentley has two sets of settings for the front end based on sprt or non-sport. My new car window tag says "sport suspension calibration". Is that just struts and springs or is that what Bentley is calling out for the other group of settings?

[dwgates]

More info, I needed to replace both upper rear control arms due to torn boots at the ball joint end and I found 20 mm spacers behind all the wheels.
The car is still lower (the spacers won't change that) but at least I should have a little less chance of scraping on the inner fender when loaded to the gills.
I'm still thinking the car is sitting too low for its load rating though but at least I'm starting to get to the bottom of this.
Looking at the coil springs there doesn't seem to be any evidence of cut coils and the springs don't have any bright paint that the sets of Eibach and H&R seem to come in so I'm not sure if they're the issue but there's a measurable difference between the 2 cars in my driveway.
As an aside I pulled the M5 shocks and springs off my parts car and swapped in the old stock shocks and springs (one broken coil on the passenger side). The car measures the same height as with the M% shock and spring set.
The M5 springs are a bigger diameter wire and there are more coils so I'm guessing they may be a slightly heavier rate.
Again, if anyone has the stock set up and has measured how far the front shocks protrude thru the knuckle that would be helpful before I go in for an alignment.

[dwgates]

One more interesting observation, the wood block I use between the body and the swing arm to remove shocks is ~9.25" long.
The one I needed for the M5 struts was ~10.5".
Even with the longer block I had to lean on a 3' long crowbar (padded with wood at the fulcrum and body) to get enough space to remove the M5 shock.
The stock shock gave me no trouble at all.
Pretty big difference in stiffness...

[Monark John]

Yes, I was less than amused on my 540 when the manual said to watch for the hub dropping when the rear shock was removed.
I ended up with having my wife hang on a 4 foot tube to get it down far enough for shock clearance!