I ordered and attempted to install the following to a 1987 GTA:

Rear springs: ACDelco 45H3025
Rear shocks: Koni 30 1265 Sport

Both are advertised as suitable for stock ride height, and the shocks can be used with lowering springs to a max of 1.5".

The shocks are 1" shorter than the stock ones. The springs are a good 2" longer than stock. So they are absolutely incompatible. In fact, when I install these springs and jack up the axle with a half tank of gas, there is barely any compression at all. I would be riding with the shocks at their limits. In fact, you can see that the springs only compress 0.5" because the shocks are still 2.5" away from the bolt holes on the axle.

Can anyone suggest what gives here? Both manufacturers are lying about "stock ride height"?

Springs settled a lot when it was on the ground so I was able to install the shocks. The ride height even looks perfect. Crisis averted.

How is the ride?

Will post an update this weekend. I changed a few things along with this project, it's not quite road-worthy yet, but close!

Nice choice on the shocks and springs. I went with the on-car adjustable Koni’s and the Moog CC635 springs. Car rides so much better…hope yours does too.

Your struts probably need to be changed as well.

I bought mine from Sam Strano, best price I found anywhere and he knows his stuff.
http://www.stranoparts.com

I talked to him once and every question I asked threw him into a fit of frustration. It took a lot of effort on my part to steer the conversation, but stroking his ego seemed to help a lot with getting him to talk about what I wanted.

Said to a friend I called Strano and he gave me a weird look and asked, How did that go? LOL! We both had same experience.

Holy hell, what a difference! Car is no longer a bone shaker, sits level, and has a real crisp ride feel. Love it! Next up are front springs and shocks - currently sitting in a box.

Yup had the same experience, he ask what I did for a living, then proceeded to let me know I know nothing about my car. All good though, he did give me the best price, ordered the Koni on-car shocks and struts on a Friday just before 5pm and they were on my door step Saturday at 11am. I also ordered some Bilstein's for my H3 (did that through email so to avoid...)

Kwel, you may not need to change the springs, but if you have them and feel confident in changing them...go for it. I didn't want to mess with spring compressor, and wanted to just start with the strut to see what difference that made. Glad I did, because once I dialed in the dampers, that's all I needed. I had to rent a torque wrench to get 195 ft lbs, for the struts, mine only went to 150 ft lbs.

Passenger side: https://www.thirdgen.org/forums/nort...ml#post6426720
Drivers side: https://www.thirdgen.org/forums/nort...ml#post6427077

I was blown away what springs, shocks, and struts did to my car. It went from scary and floaty going over bumps at 60mph to zero body roll and much better ride. Eibach sportlines and kyb all the way around. I would definitely recommend installing the front springs, and a wonder bar. Basically anything is a leap and bound over stock.

Yep, front springs and shocks to install next (also ACDelco and Koni), and a wonder bar was the very first thing I did. After that, subframe connectors.