Cabin Noise Level

[BradP]

I have a '66 Wildcat 2-dr that seems to have a fairly high level of ambient noise in the cabin (not wind noise.) At first I thought it was due to the tires (5,000 mile Michelin Radials.) However, I'm suspicious that it may be the rear-end (or some other bearing) causing this. Can anyone give me a sense of how loud these cars were inside? The noise seems to cycle with the tires but I can't believe this is a normal. Should I go searching for worn bearings? Advise. [color:\\"black\\"]

[heidigirl]

two piece driveshaft? it could be the intermediate bearing carrier.

it could also be the rear wheel bearings.

check the oil level in the rear end.

[Bhigdog]

If you suspect Drive line noise one way to check is to raise the rear wheels off the ground and run the car at the speed/gearing most noise is heard at. Noise can be isolated with a piece of 3/8 tubing used as a stethoscope. DISCLAIMER.......

THIS IS POTENTIALY DANGEROUS. Use a lift NOT a jack or jack stands. DO NOT get near moving parts. DO NOT rapidly apply brakes to stop drive line/wheels. DO keep your wits about you and excercise EXTREME caution. IF you have ANY doubts of your ability to do this safely have an experianced technition perform this test......Bob.

[NTX5467]

In many cases, bearing noise can be isolated by "load" and "no load". In the case of a wheel bearing, gently swaying the car side to side as you drive down a deserted roadway will load and unload the rear wheel bearings. Noise when loaded, less when unloaded. Pinion bearing and some gear noises are related to "power" or "coast". The center carrier bearing can have its own noises, but will be mostly all of the time and probably proportional to vehicle speed.

Perhaps you need to get a Buick Chassis Service Manual and follow their noise isolation/diagnosis criteria. Those older factory service manuals were more like a training manual than just how to change parts--which is highly worth having if you are planning on keeping the vehicle.

ANY time you need to see about operating "noice" with the vehicle's driveshaft turning, it NEEDS to be on a chassis lift--period--AND these things are a two-person job--PERIOD--unless such diagnosis is taking place while all four wheels are on the ground/roadway surface.

In trying to use a stethoscope for chasing these noises, you'll need to have a "quiet" reference vehicle for comparison as all rotation assemblies have a certain amount of mechanical noise in them. The listening device will tend to magnify what's there, which is why you need a good reference to compare things to. Using the listening devices, even some normally-operating and correctly assembled rotating components can sound like they are getting ready to self-destruct.

In general, all of the GM large cars of that era were pretty quiet, being body-on-frame construction (except on gravel/rocky roads where things striking the underbody would make noise). Some of the cars had undercoat in the wheel wells and others didn't. Much of the road noise that your Chrysler might have had on equivalent surfaces should be more absent in the Buick (other than the flying rocks/gravel previously mentioned as many of the Chryslers had factory-applied undercoat on their floorpan and other underbody areas).

Many times, tire noise can sound like bearing noise. If it is tire noise, it should be the same if the offending tire is swapped with the other tire on the same side of the vehicle. Depending upon at what speeds the noise is, it can even be due to the radial tire characteristics in the earlier chassis. The radials, being stiffer in the tread area, can also have greater impact harshness (which can also generate noise) than the bias ply tires the car was designed for. This impact harshness can increase with tire inflation pressure, too. The tire tread can look "normal", but can also have some wear patterns that can generate noise when the vehicle is being driven.

If the sound has a harmonic that comes and goes with speed, I somewhat doubt it's a bearing. A bad bearing might have a characteristic "whomp-whomp" sound (generally louder under load and quieter not under load) whose volume and frequency is proportional to vehicle speed--typically. Try the easiest and least expensive things first!

Hope this helps,

NTX5467