The roar is usually the fan clutch going into full lock-up. If it does not stop after a few minutes then the clutch has failed and must be replaced. If it roars continually you should get a check engine light with the corresponding code.
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Wheel bearing
I think it's called an engine
Sounds like it could be a bad wheel bearing
A roaring sound is usually caused by a worn out wheel bearing.
Front Rear End? Does that make sense? Front differential? maybe? Low fluid, wheel bearing, choppy worn tires?
That will be the engine. A necessary component in a motor vehicle.
From my research on the Internet , the wheel bearing assembly needs to be replaced. Most likely both of them while you are doing one.
Bearings misassembled, tire nosie, brake noise, noise in axle, noise in transmission, etc.
There are many reasons as to what may cause a roaring noise in a rear end 1997 Infinity. However, this could be the brake system or needing a new catalytic converter.
Your front pads are most likely gone on at least one side-check them.
More then likey it is either the left are right front wheel bearing that is bad.
Brakes