I am trying to replace the rear coil springs on my 1968 Buick GS 350 California. the old springs have a free heighth of about 16.5, and all of the spring I look up for it have a free heighth of 12.5-12.9. I tried intsalling them, but they drop my rear end too much. I don't know if the rear end has been modified or not. It does not appear to have been. I'm not sure what to do. Please help! Any advice would be greatly appreciated.
Welcome to V8Buick !! try re-posting your question on the Bench section of the forum. More folks will see it there, and you'll get an answer Sorry, I don't know too much about those new Buicks. Good Luck
Free height doesn't mean that much. The spring rate has more to do with the ride height. Try here, http://www.springsnthings.com/ http://www.springsnthings.com/coil-spring.htm Try calling them and telling them what you are looking for.
Another good place is: Eaton Detroit Spring Inc. www.eatonsprings.com They have all the factory specs and make you the correct spring.
Here are two springs that should work fine on your car. These can be purchased at Auto Zone under a different brand name, but same part number, and very reasonable price. Moog 6321 about stock height, 14.29" free height. Moog 5379 slightly taller and firmer, 14.75" free height. (I currently use this one)