mwill00

I have a 2012 Mustang GT and just had it lowered with eibach pro kit with dampers. I have noticed a weird squealing noise from the rear end (i think) that only does it early in the morning (around 5am) and it does it even if I am on a normal road (not over speed bumps). I have opened the back seats and set my phone in the back seat to pick up the sound of it the best I can. I will put it in a youtube video to show the sound and since youtube would not just allow me to upload an audio clip, I had to create a non relevant video clip as well. I will post the link below. I did take it to the shop that installed the kit and of course they could not reproduce the noise and said it might just be moisture in the LCA or lower ball joint seals. I also thought it was the strut mounts but now I am almost certain it is coming from the rear. Please let me know what you think.

Derf00

I can't hear the video (work computer) but it could be the rear LCA bushings binding.

Pro kit is pretty low so you would also need to reset the pinion angle on the driveshaft. LCA bushing bind would require you to loosen and retighten the Lower control arm mounting bolts so that the bushings aren't twisted. This would need to be done with the suspension loaded, otherwise you would end up with the same problem.

mwill00

So under load would be to jack it up and put stands on the differential then loosen the bolts and re-tighten.

Derf00

I'd put jack stands on either side of the axle tubes instead of just the diff pumpkin but yes.

You'd jack the vehicle up. Place the stands under the axle tubes (preferably towards the ends, then lower the car until the jack stands under the axle tubes are holding the weight of the rear of the car.

For pinion angle you would also either need a pinion angle gauge or a plumb-bob and protractor