Is it normal to hear a whirring noise coming from the rear of the car at pretty much all speeds? I finally took my 86 (iron heads) L98 onto the highway (one mile) and the noise doesn't seem to be fading. I originally thought maybe some surface rust needed to wear off the rotors but by now that shouldn't be an issue. No grinding or squealing, just a whirring that obviously is coming from the differential or axles.Is this normal?

 

I just came home offthe highway in my '86 /w 4+3 and I hear the same thing. I hit around 80mph and it sounds the same as at 50mph. I recommend you at least check the oil level to make sure there is oil in it. If you want to check the axle bearings your going to need jack the car up and spin the wheels individually and see if there is slop.Most likely you have nothing wrong. good luck

 

Thanks Yankee...It's reassuring to know others are hearing the same sounds. I've only driven the thing about 5 miles and some noises seem to be strictly part of the Vette experience.

 

Does the noise increase or decrease with speed? Does it quit when you let off the gas?

 

The decible level remains constant at all speeds. The faster you go...the faster the pulsations of the sound. The sound continues until the car comes to a stop regardless of accelerator application.
After driving I've felt around both rear rotors for unusual heat but detected nothing alarming.
None of my C-3s sounded like this but I don't have anyexperience in C-4s to compare to.
I will say the ride seems a lot rougher in the C-4 as well as louder. I'm hoping it's just the difference in models.

 

Is it a roaring noise that gets higher pitched the faster you go? If so, more than likely you have a wheel bearing going out. If it is a bearing, can test sometimes by swerving car from side to side while driving (make sure no cops around ), if the noise quits while swerving to left, then it might be the left side because you are taking the load off, right side vise versa.

 

Roads finally dry enough around here to try the swerving experiment. The noise does go away for a split second when I veer to the right. Guess I'll be learning a little about C4 wheel bearings. Thanks Mech for the diagnosis.

 

Sorry if I seem a little dense...but after reading some older posts with a wheel bearing search I'm confused again.
Does the swerving test reveal a potential wheel bearing problem with the FRONT or REAR bearings? The noise sounds like the rear. Since it quits briefly when veering right..I was planning to service the right rear bearings.
This car has only 8400 miles on it. I'm a little surprised ANY bearings are bad. Apparently driving misfortunes can prematurely ruin bearings (this from another post) so I'm prepared to replace whatever I have to in order to silence the ride.
Am I looking at a sealed hub assembly with bearings or just bearing replacement on the rear? Any special tools required? Is it a bearing/brace arrangement or something more exotic?

 

More than likely it is the rear, but it is easy enough to pull both wheels, calipers and spin the rotor by hand on the lugs and listen and feel for a roughness in the bearing. I changed both of mine out last year and it is not the easiest of tasks. Good luck.