Posted: 1/29/2008 4:00:17 PM EDT
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I installed 2" lift shackles on my 2000 blazer ZR2. The rear springs are sagging to the point that it took 2" of lift to bring it back to near the stock height. I now have a vibration when I take off from a stop. It goes away almost immediately, just the initial take off to about 10-15mph it shakes. After I get my new rear driveshaft (long story) I had planned to either pay 4wheelparts to check and adjust it, or do it myself. How hard is it? I know I hafta get shims and ajust the pinion downward because the shackles moved it upward. Is there a quick and idiot proof way to get the correct shims? |
I dunno. I lowered the rear of my F150 with 2" shackles and had to add 2 degree shims to get rid of a vibration on acceleration. |
| They made the leaf springs too weak, and the blazer has a lot more wieght on the back end than the pickup does. They ALL sag. New spings are like $600 to get some custom built that should hold up longer. Sucks. Everyone who did stock replacements ended up with a saggy rear again after 2-3 years. |
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I can't imagine that 2" would affect it that much, especially in a longer wheelbase vehicle like a blazer. I had 4" in my CJ7 and the pinion angle didn't cause any problems at all. The jeep drove fine, no vibration or anything. eta- I didn't see where you had replaced just the shackles. My lift was a full spring lift, where the geometry changed relative across the spring. Changing the shims shouldn't be hard at all. When I replaced my axle, the shims were simply located in place on the center locating pin that came off the axle perch and into the leaf spring. Unbolt the Ubolts, lower the axle down a hair, and the shim plates should tap off easily. Installation would obviously be reverse, of course use new Ubolts. |
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The whole problem lies with the fact that the vehicle is so short, I'm told. The driveshaft is pretty short. Its a 2 door blazer with 4wd. So t-case to diff isn't that far. I'm wondering if I should just shitcan the whole idea and either try 2 add a leaves or just buy a whole new leaf spring set up. Alcan springs would cost near $600 so thats a lot more than I want to spend. |
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www.zr2usa.com/home.php Here's an all ZR2 forum, they may have more specific fixes tailored to your model. |
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Why would you get a vibration if you brought the vehicle BACK to stock ride height? Are you sure you have the problem identified correctly? With the weak springs I'm guessing you are getting some serious spring wrap which would give you vibes under acceleration. You need, new, heavier duty springs. |
| Here is what you are looking for. I would get steel shims instead of aluminum shims. I had aluminum on my cj7, the shim broke, axle jumped sideways and I almost flipped it. I found the steel ones on the net somewhere, can't remember where. This should give you a good idea. I would start with the 4* shims due to the springs sagging and the lift you installed. |
I'm a member there. Its where I got my custom shackles and started this ordeal.  Plan B is now in full effect. I found a local heavy duty truck place that can re-arch my springs and add a leaf to them. This will restore my height, and prevent future sag. Its really cheap too. Obtaining replacement springs is a huge iffy proposition. Nobody can tell me exactly what I need... so having the originals reworked is ideal. Pinion angle is definately fubar. I can look at it and see how its rotated up. The shackles do not lift the vehicle evenly, they rotate the rear axle as they lift. I also *still* have saggy springs and reduced suspension travel as a result. I've been quoted as much as $600 for new springs with no guarantees about ride height and so forth. So I'm happy to spend a hundred bucks or so and get mine fixed. As I've been going over things in my mind, I realize I made a mistake, and I will fix it by reinstalling the original shackles and repairing the springs instead of using band aid repairs that will do nothing but give less than stellar results. Shackles work in certain situations, but this is an exception. They do work, but I need to repair the root cause and not the symptom. |
| The problem with that truck is the axle sits on top of the springs so you can't use lift blocks which are angled to comp for the pinion angle. Different springs or rearched springs is the only way to do it. Be shure to check the shocks after you get the springs back to see if they are long enough. You may need longer shocks depending on the lift. |