Quote:
Originally Posted by Gangplank
I'm sure someone else will chime in on the differences the dampers and springs make, but my real issue with the soft suspension was a side-to-side and roll on corner exit. Its especially noticeable on off camber corners. The back end rolls and then moves laterally again. For me the RSFB inserts settled the rear end s-to-s and up-down axis.
I do have the M-sport suspension which comes with different bump stops than the stock 128 or 328 so not sure if that helps. After reading more in the above linked thread it sound like the Dinan RSMs do give some improvement. I don't think anyone is debating whether they make an improvement, but whether they do as much as the RSFB inserts or M3 RSFBs is the question.
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This is very difficult to quantify IMO because the upper shock mount and RSFB are in entirely different locations and serve different purposes. RSFB connect the subframe to the car while the shock mount is there to secure the shock. The stock ones both cause 2 separate problems, and you can't cure both by only upgrading one part. For a street car though I'd upgrade the shock mount before anything else. It's so much cheaper and sounds like the ROI is quite high. That being said, the ROI for the M3 RSFB is only entirely realized when the car is on a track. My car was a pogo-stick in hard turns even with my JRZ/Eibach setup. The entire cause was the stock RSFB; once I upgraded to the M3 RSFB, man you can throw that thing into any turn and the rear is just rock solid.
Quote:
Originally Posted by Gangplank
Of course one thing that I've seen repeated here and there is that members did the RSFB inserts and then eventually wanted more and did the full M3 RSFBs. I'm wondering if they inserts by themselves by being stiffer put more wear into the rear shock mounts so over time some of the looseness comes back. In that case it may be worth while to do both.
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Definitely; that energy has to go somewhere. Instead of being absorbed by the RSFB, it is now going to be absorbed by some other part.
