Well, I finally installed the add-a-leafs last week. I would have posted this information sooner, but my computer monitor died last weekend. Here's some information and tips for anyone interested in doing this. The add-a-leafs that I installed on my 1993 GMC Jimmy 4-door, 4WD are Explorer Pro Comp, part number 13124-1. I purchased them from offroadconnection.com. I was originally going to purchase the Trailmasters because they were cheaper ($43 + $8 S&H), but offroadconnection said that the Trailmasters were on back order and wouldn't be available for about 4-6 weeks but if I wanted, they would sell me the more expensive ($50 + $8 S&H) Explorer Pro Comps for the same price. I give offroadconnection a thumbs-up for that. If I remember correctly, my Summit catalog lists the same Explorer Pro Comps for $50.
As I previously mentioned, the Pro Comps are about 50" long. According to [email protected]
, the part number that offroadconnection sold me are the correct add-a-leafs for my application. The add-a-leafs are 2 ½" wide and 5/16" thick, which is the same as the stock leafs. They are advertised as adding 1-2" of lift. How much lift did I get? Keep reading. . .
Tip #1: If you have two different sizes of jack stands (as I do), use the shorter ones to support the truck and the longer ones to support the rear axle. I reversed it and had to start over, as the shorter stands weren't tall enough to support the rear axle.
Tip #2: Make sure before you start that you get new U-bolts, washers, and nuts. I (naively) thought that I could reuse my 8-year old stockers. Eight Michigan winters will put a nice coat of rust on them. I ended up breaking all four U-bolts, so I had to stop, take my wife's minivan, and order new parts at the dealer. Waiting for the parts to come in added a day to the project. New U-bolts, washers, and nuts will cost (are you ready for this) $84.56 from a dealer. The dealer I went to wouldn't give me their wholesale price, which really ticked me off, but I was in a bind, so I paid full price. Find a dealer who will give you their wholesale price, or better yet, order them from gmpartsdirect.com. The same parts cost $60.44 wholesale, and $48.32 from gmpartsdirect. The part numbers are: U-bolts (4) 15684331; nuts (8) 11507027; washers (pack of 10) 15650965.
Tip #3: Be prepared for the rear axle to rotate forwards when the last couple of U-bolts are removed. It will get your attention very fast. Put your second hydraulic jack under the pinion yoke to help support it.
Tip #4: This has to do with my original question about the spring clamps. The stock clamps are 1/8" thick steel, so there was no way that I could bend them. I cut off the bent-over ears with a cutoff wheel. I left the straight part of the clamp sticking up to help align the leafs (the stock clamp is riveted to the #2 leaf). I used the clamps that came with the add-a-leafs next to the stock clamps towards the axle. Use a C-clamp over the old clamp to compress the spring pack when installing the new clamps. So far, this setup seems to work well.
Tip #5: The hole for the centering bolt (the bolt that clamps the leafs together) is offset about 2" towards the front spring eye. Thus, each leaf has a front and a rear end. Don't mix the ends up!! The distance between the hole and the front end of each leaf is about 2" shorter than the distance between the hole and the rear end of the leaf. The hole in the add-a-leafs is in the center. However, the 50" add-a-leafs are too long (the front end runs into the front spring eye). I had to cut the same 2" off of one end of the add-a-leafs. I did this with a cutoff wheel and a 4 ½" angle grinder. Buy two wheels, cutting the leafs is hard on them.
Tip #6: Don't torque the nuts on the U-bolts until you have both sides done and have the heads of the centering bolts placed in the corresponding holes in the bottom of the spring perches. You'll need some play between the springs and axle to line everything up on both sides. Trust me.
I took Diver's advice and measured from the ground to the top of the wheel opening (actually the stock wheel opening flare) both before and after (with a half tank of gas). Again, my truck is a 1993 4-door with 160,000 miles that the previous owner used as a tow vehicle. The front dimensions didn't change (as expected) but for reference, the left front is 32" and the right front is 32 ½". Before the operation, the left rear was 31" and the right rear was 31 ½". So, the rear end had settled about an inch. You could easily see this when the truck was parked, and I've noticed that most of the older (pre-1995) Blazer/Jimmys that I see look like the back end is lower than the front. Now, after the operation, the left rear is 32 ½" and the right rear is 33". So, I gained 1 ½" on both sides. Also, the truck rides and handles great. Before, the back end bounced and swayed on the highway, and it really leaned in turns. Now, the ride has really settled out, and it hardly leans in turns. As my wife says, it now rides like a truck. So, I'd label this a big success. Better ride, better handling, 1 ½" of lift, and all for about $140. Oh, and about 10 hours of work. But, I could probably do it in about half the time if I had to do it over again.