UPDATE on Front suspension

After driving on the add a leafs and zero rates for several years, in early 2009, the stock fronts had de-arched more than the add-a-leaves, so it was time for new springs.

I called ORD (offroaddesign) and they hooked me up with a set of Tuff Country 3" HD (not EZRide) front springs. I got them along with the HD front shackles, and the ride is night and day difference!

Part number TCI-18371 from ORD. Also replaced the steering arm while I was at it. The rear of the truck still has the zero rates and the add-a-leaves (and it is about an inch lower than the front) so I will eventually redo that as well.

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The initial lift

After putting 315/75 R 16 Pro Comp tires on the truck at stock height (they rubbed, even with some slight fender trimming), I decided I wanted a mild lift. I went with Add a Leafs from Rancho, as well as Some "Zero Rate Add a Leafs" from Off Road Design.

Here are the Add a Leafs I purchased (From Summit):

I think they were Rancho RS50012 for one set, and I forget the part number on the other set. They were supposed to raise the truck about 2.5 inches. I wanted a little more than that, so I also went with "zero rate" add a leafs from Off Road Design:

http://www.offroaddesign.com/catalog/Zero%20Rates.htm

Here is their description as well as a picture I copied:

Most Blazers and Suburbans sit low in the rear, and a lot of truck owners also want to relocate their axles forward or back a little for better fender clearance or for a bit more wheelbase and driveshaft length. This is the answer to both problems.

You're probably asking about the name. Well, we didn't want to call them blocks since they're really not a true block, they bolt to the spring pack just like another leaf. We didn't want to call them add a leaves since most people think add a leaves will stiffen the springs. So they're an add a leaf that won't stiffen the springs, they add "zero" to the rate.

These short leaves are CNC machined solid steel with offset holes to allow you to move the axle 1" or 1.5" forward or backward from the spring pin location. You can also leave the axle right on the spring center pin if you like and only use them to raise the truck 1". The top corners are radiused to prevent stress risers in the spring pack.

Since these are a true bolt in leaf, they are safe to use on the front or rear suspension for extra ride height or to relocate the axle. To use the offset, you bolt the leaf to your spring using one of the offset holes and cut the center pin off to bolt into the leaf in the center hole. This will move your axle forward or backward 1" or 1.5" depending on which hole you use and which way you mount the leaf.
To mount the leaf centered on the spring, you simply run the full length center pin through the center hole of the leaf and through the pin hole in the spring pack.

The kit includes the machined "leaves" along with new center pins and bolts to install them.
You will have to drill a hole in the ubolt plate for the new offset spring pin location. You will also need to make sure your ubolts are long enough, you need to have 1" or more of extra thread to use the Zero Rate™ kit. ORD has ubolt kits available to accomodate the extra length if yours won't.

On front applications with crossover steering be aware that you will be losing clearance between the draglink and your RH spring. The full 1" from the offset Zero Rates™ could cause you problems there, make sure to check it out.

I can report that they worked very well, thought I needed longer bolts (I had to get bolts from the store and grind the heads round). Not a big deal, and I like them a lot.

Here is a picture of them in the truck (the arrow is pointing to them):

Now, here is a couple pictures I took (crappy Camera Phone...) when I had done the rears but not the front springs to show the ride height increase (about 3 inches... maybe a little more):

 

And here is a picture of it as it sits now (another side shot):