Quote:
Originally posted by arnebret
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And, i think i know why:
The gear linkage for a 944 is very long (tranny in the back) and this linkage is probably sensitive for some vibration in a certrain frequency range. Of course, the engineers designed the car in a way that the frequency of the engine, driveshaft and gear linkage would not go in sync.
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I wouldn't give the 1970's engineers credit for doing FEA on the 924/944. Didn't have the easy to use CADD and mechanical design software we have now. Any vibration dampening was done after the car was built and test drove if not a year or two into it's production runs.
As to 944 vibrations; if the engine will vibrate with the clutch in and in gear then look at the pulleys on the balance shafts. One (or both) is off by 170 degrees. The difference between the two keyways. You can notice this at idle by putting your hand on the engine. Has a high frequency vibration. Could also have the balance belt off a tooth or two.
As the drive shaft turns with the engine rpm by having the car in gear and the clutch pushed in you eliminate the drive shaft, clutch disk and trans as any potential source of vibration.