greetings all,

i have posted this in the c-5 forum ( i have a c-4) to grab an opinion from them. however, i wanted to run this by the c-4 guys for another opinion. i am asking this here for a friend whom drives a 2003. the car is stock with 17,500 miles on it. the symptoms are that when the driver makes left hand turns, there is a growling grinding noise from the rear end. the car is a daily driver and is babied incredibly.

the car was taken into the shop about a year ago with a differential leak and similar growling noise, with the shop replacing the rear end as i am told. just this week, the car was making the exact same noise and the shops solution was telling my friend that the muffler was replace because it was "loose" (sounds like a snow job to me!).

prior to her getting the car back today, they had said that they changed the differential oil (which was already running a synthetic and changed out about a year ago) and they contend that that was the problem. they had stated that the c-5's were notorious for differential problems.

like i said, it's a daily driver with no racing or anything like that. i am of the belief that the differential oil should last somewhere between 50k and 100k with normal use.

my belief is that since it the problem occurs with "left hand turns" only, i would suspect that it would be a rear wheel bearing "loading up" or a minimal belief of one of the u-joint taking a "dump". this is not tp preclude the differential being bad which the shop won't admit and may be trying to cover up with a heavier gear oil.

you c-4 guys, what do you think and do ya have any comments pertaining to what you may think it is or other suggestions relevant to the problem.............thanks!!

 

Why would a C4 owners opinion matter about a C5 problem? You don't guess at these problems and start replacing parts, you do some tests and measurements and inspections to find the problem. I doubt the problem is in the differential because the spider gears and the limited slip clutches are active on both right and left turns. The car needs to be put on a lift and the U joints inspected and the left rear wheel bearing looked at. While on the lift move each rear wheel back and forth and look at the axles and see if there is obnoxious slack between the wheel reversal and the axle moving. Thats how I found my bad left rear wheel bearing which only had symptoms of driveline slack.

 

well, as i see it, if anyone is a vette owner c-3, c-4, c-5, etc, what does it matter as we all are part of a special class. instead of you coming out with a comment bearing a sarcastic overtone such as you did, i would have figured that you or anyone responding would be "flattered" as a c-5 question was posted here for another opinion, as all of our cars have a posi rear end (unless you believe that the c-5 guys are more intellectual).

so, i think it does matter, especially since there may be more to the differential problem then meets the eye and that this problem can also exist in a c-4 car. if you re-read the question, nowhere have i stated that i or my friend was throwing parts in it. the car has a dealer warranty on it and while it is true that one could say "let the dea;er warranty handle the problem", she is afraid that they will mask the problem instead of fixing it until the warranty expires and she is stuck with the bill.

the replacing of a muffler, etc hardly seems to be a proper cure for what sound like a rotating mass problem on it's face. are there not "outboard" bearings in the differential carrier where the half-shaft yoke connects for the rear end? i don't mean to upset your apple cart here but ease up on the sarcasm please..........thank you for your response.

 

Read my first sentence again. It is a question, not sarcasm! The C4 and C5 rear ends are similar. Changing a muffler and diff oil sounds like changing parts without diagnosis to me, I am probably wrong though.
And yes, there is an outer bearing on the differential and I discount that because each bearing is under load when the engine is driving the car, so left turns IMO shouldn't be any different and it would likely make noise when driving straight. Maybe your friend should find a better shop to diagnose her left turn noise. If there is a local Corvette club, I would ask some members who in the area they would recommend. Hope she gets it resolved.

 

THANK YOU FOR YOUR RESPONSE.....