At the tail end of a rear subframe refresh: full removal, teardown, rust proofing, all new parts except springs/shock assembly (as that was brand new <100 miles before I bought it), including bushings, control arms (top and bottom), sway bar, end links, etc.

On assembly, i had everything loose, put the wheels one, lower the rear end onto ramps, and... ride height is about 3-4" higher than it should be. I am looking for stock 25 1/2" ground to wheel well and L/R is ~28.5/29 . Trouble shooting I've done so far:

1. ​​​On @WayMotorWorks suggestion, removed lower shock bolt, lowered car to desired ride height (was able to) and torqued control arms and trailing arm bush to spec
   1. installed shock bolt... same ride height.
2. Begin to panic, then troubleshoot more
   1. Remove sway bar endlinks to ensure they are not causing binding. no change.
   2. Remove spring assembly to ensure the previous owner put the right spring top mount on it. L for passenger. so good there.
   3. Try adding weight to the car and, cringe, a little bounce to make sure nothing isnt seated or something weird.
   4. Finally loosen trailing arm bushing to body bolts (the only things that have been tightening this whole time) and loose any chance of my alignment staying put. no change.

WTF am i missing? All conspiracy theories welcome. All i can come up with is the new control arms are minutely misaligned rotationally, even though i set the length to the original arms using the 'inset old bolt method.'

 

Thread search rabbit hole showing that Bilstein shocks sometimes not compressing for some people. Perhaps this is part of it??? Anyone else ever experienced this?

 

Did you release the brakes?

 

Had removed calipers and rotors along with the suspension. Not hooked back up at this time.

 

Well, so much for the easy theory.

 

Have you driven the car since after the refresh?
Like you and many here; I had preformed the same/similar rear-end refresh and parts with the exception of trailing arm bushings (i.e: new lower adjustable control arms, 22mm adjustable swaybar, drop links, new Bilstein B4's w/stock springs, powerflex top shock mount bushings...)....
While after finalizing the installation and lowering the car back on the ground, I did notice a slight 1"-1.25" increase in rear ride height. (Although not nearly as extreme as your 2.5" - 3" increase); It did take a few laps around the metro to finally settle to what seemed to me to be back to "normal"/stock ride height.
My apologies - I'm not sure if I have the answer as to what the issue or fix might be in your situation.

Notwithstanding:
The one thing I will note in my aforementioned experience is; afterwards I heard a clunking noise from the rear while driving slow over rough roads and speed bumps.
After numerous times raising the car inspecting and re-torquing nuts and bolts and test driving, I realized I had not preloaded the trailing arms (lowering the car/rear trailing arms down on a set of jack stands), before installing/tightening down the upper rear shock mount bolts.
Only after doing so - the clunk went away.
I had discovered that that procedure is also an important step while installing the rear shocks. But I don't think it would have any influence on ride height.
Sorry.

 

Thanks, in your case did you get an alignment done while it was still riding high, after it settled, or both?

 

No. I did not.
I figured since I didn't mess with the trailing arms, the components I replaced weren't that old, the rear camber was even and the car drove straight.
In my opinion/my case - no need.

 

If you only just replaced the subframe and all suspension, and haven't actually driven the car yet, there will be some resistance between the tires and ground that will prevent the suspension from dropping all the way. I would wait to get excited until you have an opportunity to drive the car around a little bit.

Also, definitely wait until the suspension settles before getting an alignment.

 

So the car is right hand drive? Because otherwise...

If not is it possible springs / mounts are not lined up or got swapped side to side somehow? Was thinking of doing a similar refresh, going polyurethane throughout. Will watch this thread; looking forward to your resolving the issue.

 

good catch, that's just my typo in an exhausted, panicked haze.

 

Wanted to provide an update on this issue. Essentially much to worry about nothing. I was assuming that I did not need to take the front end off the jack stands, because I wasn't finished with the brake job, and that the back end would have enough weight given that the car is evenly distributed. So that's wrong. Decided to install and torque everything, finished the brakes, and once she was all put together and back on the ground, like magic, all four wheels at perfect ride height. So I think this is a version of the make sure the parking brake is off suggestion and not enough weight could be put on the rear end so not enough movement to settle the suspension.