Just lowered my 06 GT, now rear end is creaking / chirping! Help!

[phils95cobra]

I lowered my 06GT (almost 150k on her) last week. I have noticed this very aggravating creaking / chirping noise coming from the right rear suspension. When going down an average road, it chirps like a bird, but with every little deviation in the pavement. On bigger bumps, not so much. Also, when I let off the clutch and first start to accelerate, I get a pronounced creak coming for that same right rear side.

This is very annoying. I have heard it somewhere that after you lower, in my case, 1.6" rear, that to maintain the correct suspension geometry, the factory panhard bar should be replaced. If it is not, it will push the suspension to one side further than the other. Could this be what is responsible? Also, while under the rear end, I noticed the bushings that are in the, what I call, 'dogbone' connected to the top of the differential are pretty dried out and looking bad. Can these be replaced? What is the name of this component?

Thanks all for your help!

 

[stkjock]

yes the bushings are replicable, that part is an upper control arm and yes, upgrade to an adjustable panhard bar. The bushing is the most likely the culprit IMHO

 

[08MustangDude]

Before you lowered it, did you loosen up the bolts to the both control arm
bushings on each arm; then re-tighten at ride height? You changed where
the suspension articulates on the bushings, and stressed them if you lowered
without loosening them first to reset their idle position, which is at ride height.
Same with the upper control arm (dog-bone as you mentioned). If it was not
making noise before you lowered it, then you needed to set ride height on all
the arms... All the sleeves in the bushings are now tweaked to a different
position in the bushings if you did not set ride height. That's also why you
never tighten bushing bolts on new parts with the suspension hanging, it all has
to, or should be done at ride height. Fronts too...

There is a post here on it:
https://www.s197forum.com/threads/lowering-that-s197-re-clock-your-bushings-please.122530/

Bushings are torqued when the suspension moves up and down, and are at ZERO
torque at ride height. When you lower the car, and do not loosen the bolts, you are
now putting a constant torque on the bushings. The sleeve may break loose and then
reset, but it will never be at ZERO torque at ride height if you did not loosen them all
before lowering, then tighten at ride height.

Lowering needs an adjustable track-bar so you can recenter the body over the
suspension. There is no factory bar that will correct that geometry, it's one
length.

You can replace bushings, but you need a tool to push them out, and press
them in. You can get a whole new arm, bracket, bolts and bushings on eBay
for $70.00 or so. Can also get an adjustable upper arm to reset your pinion
angle lowered.

Edit: A sellor countered my $60 offer with $65 for a brand new, dorman kit;
New UCA with new busing, Bracket (to body), bushing for differential housing,
and all new bolts and nuts.

https://www.ebay.com/itm/05-10-Ford-Mustang-Rear-Upper-Control-Arm-523-211/352687324334

 

[bl817]

did you cut the bump stops down? recommended to do that at least one nub. you can also install FRPP "jounce" bump stops.

 

[Gab]

Before you lowered it, did you loosen up the bolts to the both control arm
bushings on each arm; then re-tighten at ride height?

Nailed it.