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Transmission Noise - is the C4 just louder?(Noob Question)

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I just picked up a higher mileage (84K miles) 1999 C4. It seems that under load there is more significant noise from the transmission (than I am used to in my 951 which is silent for intents and purposes). This noise is a whine that exists mostly under load at higher speeds (55 to 75 mph). The car was PPIed by a dealer in Texas and my indie mechanic has changed the fluid. Neither have remarked anything untoward. I also drove another high mileage C4 today and it exhibited the same characteristics.

Is this normal behaviour for a C4 transmission?


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i don't know, but my car is loud at highway speeds for sure. I flushed the front differential and gear box and the noise remains. As an asside I can put it in neutral at speeds and the noise doesn't change, so i'm fairly sure it's not my tranny.

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  • 3 months later...

Problem resolved.

Had the transmission rebuilt.

The pinion bearing was failing and the spider gears were badly pitted. It also needed new synchro rings in 1st and 2nd. Main shaft bearing was fine.

There was no evidence of debris in the transmission and my mechanic indicated that the suspected a manufacturing defect in the gear not being hardened properly (he is a factory trained Cup car mechanic - so I believe him).

Cost was much less expensive than a rebuilt replacement transmission (due to my being in Canada and the associated cross border costs).

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