Quote:
Originally Posted by Pio72porsche
Further, I’m assuming that Porsche sells it this way is that 964, 993 and the turbo 996 IMS gear is made of steel and not aluminum and probably not a good idea to mix gears. Sort of like a ring and pinion.
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Matching the steel gear sets is simply an attempt to minimize vibration to reduce gear noise. They set the gear up up in a test bench and spin them through the rpm range and measure the vibration. Their is a tolerance at which the noise level will be acceptable. I assume they mix and match gears until they meat the desired specification. Mixing the gears is probably not that risky because modern gears are pretty precise.
That said: Some of the new after market transmission gears are not tested to this extent and the result is sometimes a noticeable whine.