Fact #1 - My car sits low in the back due to audio equipment
Fact #2 - Had 3.73 gears installed and they whined a lot.
Fact #3 - Had them reinstalled, this guy supposed to really know his stuff and swears they are in perfect - still whine

Talking to various mechanics, pinion angle gets mentioned due to how they are whining.
Pinion angle perhaps? How do you measure?????

Anyone seen edlebocks new upper? I Have BMR lower non adjustables.

 

can you give more details...what kind of audio equip weights enough to lower the car down...got pics?

or am I missing something here?

 

Go over to the Suspension & Handling forum. There are many threads about pinion angle.

 

Large amp and 12 in sub both mounted in the back far corner of the trunk.
My car sat lower when I bought it so I am not sure how much the equipment is affecting things.
My back wheel gap is equal to my front without aftermarket springs.

 

I doubt you have enough weight in the back to seriously affect the pinion angle, unless your box/amp weigh 200+ lbs.

Did you buy your car used? Does it have aftermarket springs in the rear?

 

Bought the car brand new with 8 miles on it.
You are right - audio equipment does not weight that much at all but it is OBVIOUS my car sits lower than a stock mustang. I it side by side the other night with a new one and the difference was OBVIOUS.
Looks like it is dropped Looks great but this whine is driving me nuts and mechanic says everything is fine and has the experience and the blown 03 Cobra to prove it

 

As for the pinion angle, there's a bunch of threads discussing how to measure it over in the Handling section. If your pinion angle is off, you need either an adjustable upper control arm or adjustable lower control arms to correct it. I suggest the lowers. Again, more info over in handling.

If it's not the pinion angle, it may be the gears. Gears that have defects or that are set up incorrectly whine. It may be that you got a whiny set from the factory. If that's the case, then Ford should replace them under warranty

 

did you mechanic take the ring and flatten the back of it on a sanding table per the motorsports instruction sheet? I havent found one yet who does that. Sanding the back of the ring makes sure it is flat (the heat treatment of the ring can make it uneven on the backside) and has no run out issues when bolted to the carrier.