View Single Post
      08-24-2008, 04:24 PM   #46
Lieutenant General
swamp2's Avatar

Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

iTrader: (1)

Originally Posted by lucid View Post
Although I agree that it is unlikely for those dips to be real, I think it is too early to say what is and what is not real at this point. Who knows, maybe the issue I brought up with clutch slippage/engagement is plausible since things are happening so fast in the D3 shift, and maybe those oscillations that occur after the interval you have marked as "the shift" are artifacts of the engagement process as the clutch loses and regains traction. Unlikely but not impossible.
Some of the oscillations AFTER the shift may indeed be real. High frequency mechanical osciallations from a spike type input are the norm and possible here. As well the slipping you described may be actually measured. However, the deceleration (as visible just at the beginning of the D3 shift data trace - and to be 100% clear at the beginning of the displayed data, which is well before any sign of any clutching) cleary is not real. Since that represent a period in reality of relatively constant, smooth acceleration you can draw similar conclusions about similar noise levels in all of the rest of the data. The exception seems to be a lack of noise during high jerk (i.e. slope of acceleration). Particularly good for us but I have no idea why the data gets cleaner!

Last edited by swamp2; 08-25-2008 at 01:21 AM.