Quote:
Originally Posted by CSBM5
No question the E46 is from the old era before body-in-white torsional and bending rigidity took their big leap forward which occurred with the E9x generation (took place with the E39 generation in the 5 series). You can immediately feel the structure higher natural frequency when you back to back and E90 with an E46 or earlier. BMW published a nice paper for the E90 years ago showing how those improvements were made, how they employed very high and ultra high strength steel at various places particularly at the highest stress locations in the body, etc.
As to the rear subframe mounting points ripping out on an E46, one would assume the designers clearly underestimated the factor of safety needed for that area of the structure (since they obviously underestimated the amplitude of the cyclic stresses experienced). It's clearly not the best design by a wide margin, but it does come from earlier days still in CAD/FEM (i.e. early 1990s design work). I'm sure if they could do it over again, they'd easily fix that area plus the front strut top mounting area along with many other improvements. How cool would that be if BMW did a run of E46 body-in-white shells with greater than 100% improvements in torsional and bending rigidity along with fixing all the poor design locations plus using modern E9x era and forward ulta-high strength steels?
|
If you’re going to pick jump points on M3s, I’d say they’re e46 and f80. E46 M3 has a bunch of stiffening over the non M:
E36 m3: 10,500 nm/deg
E46 m3: 18,500 nm/deg
E90: 22,500 nm/deg
F80: 40,000 nm/deg
E39 was ahead of its time.
E39: 24,000 nm/deg