Yeah, 4.5 inches sounds like a lot of fender clearance.
When the wife gets home I can check mine.
But, a 0.25 increase in shim ht on the spring can make a much bigger difference in the ride ht of the car, due to the leverage effect of the
control arm. I went up one size on the rear of my car, and I swear it raised the rear over an inch.
I looked up the std spring shims for the 126 that are used, depending on engine, equipment, weight, etc.
8mm = .32"
13mm = .52"
18mm = .72
23mm = .92
Yours probably came with the 13 or the 18 (being in between the lighter 300SE and the heavier 500S).

But, all things being proper, a change in ride ht should not create a rumbling noise.

DG