Updating the Alcan Leaf Pack

January 3, 2018

When I got my Alcan leaf pack, I knew it was top quality. I really liked how the guys at Alcan asked what I wanted from the pack, as far as "every day" weight in the back, as well as "loaded" weight for adventures.

So far, I've been really happy with how it has held the weight in the bed, provided a better ride than my OEM leafs (which were perpetually riding on the overloads and bump stops), and have given the truck back it's aggressive stance, even when loaded.

Once I got bigger tires however, I got concerned that my wheels weren't centered in the wheel wells - they were further back than center. That didn't matter with stock tire sizes, but with 255/85R16's, I could tell that if the tire ever really stuffed, that I'd have some issues.

So, over the last few months I've been flexing the back in various situations and then checking for clearance. I've never been able to get contact, but it's been close. I've also read up and talked to others who ran into the same situation - solving it via a center pin relocation plate or by getting the center pin moved forward ½-¾" on a custom leaf pack.

And, it seems that there's no rhyme or reason to running into the issue - some trucks do, some don’t, even with the same leaf pack.

I didn't really want to use a center pin relocation plate (the back end of my truck is already tall enough, and I don't love the drive shaft angle), so I talked with Alcan and they manufactured a new top+torque leaf for my pack that would shift the center pin forward ¾" - so the distance from the center of the front eye was 23 3/8" instead of the 'stock/normal'* 24 1/8".

* 'stock/normal' is according to Alcan. I should note that when I measured the distance from the middle of the front eye to the center pin of my OEM leaf springs, it was almost exactly 23 3/8", not the 24 1/8" that Alcan claimed. Perhaps we measure differently?

Those showed up in mid-November, but of course, I had no time to install them, what with the holidays and whatnot. I'm a busy dude.

With the holidays behind us however, I decided to make the swap today. It was a brisk 38°F out when I started, but sunny - not much more I could ask for! Before I got started, I snapped one last pic of the tire in the wheel well - definitely shifted back.

Then, it was off with the wheel, and up onto the jack stands so I could remove the u-bolts and then ultimately the passenger leaf spring itself. My plan was to do the passenger side completely, then the driver side - that way, if I ran into trouble, I could always roll it into the garage for the night.

The passenger leaf came out easily (probably just like the last time, but I knew what I was doing this time, so it seemed easier). When it did, I noticed that the perch for the leaf pack already had two holes in it! I wondered if I should just drill a third hole, ¾" forward of the center hole and use the existing leaf pack - but I decided against that, unsure if I'd be able to drill out the perch, or if the hole would be too close/encroach on the existing hole.

I do still wonder what that rearward hole in the perch is for…it's too small for a center pin.

So I proceeded to disassemble the leaf pack - an easy job with a couple of clamps - and then reassemble the pack with the new top and torque springs. While the curvature of the new leafs wasn’t exactly the same as the rest of the pack, I think that's just a matter of time - the weight on the truck will "mush" everything together.

Then, it was back to the truck where I reinstalled the passenger leaf pack and ran into trouble. There was no way that I could pull the axle forward ¾" to align it with the center pin on the leaf pack - the u-bolts on the driver side kept the axle from moving that much. I could also tell that if I were able to rotate the axle, that the center pin wouldn't line up anyway - the radius created by pivoting the axle on the driver side would pull the perch too far toward the center of the truck.

So I figured the only thing to do was to take off the driver side leaf pack as well. This presented me with a couple of "issues." First - I only had two jack stands, and they were supporting the frame of the truck. I was using the floor jack to support the rear diff and axle - fine when one side is fixed, but a bit "iffy" when both sides are free - 'cause that axle wants to tilt forward when it's not secured. Second, I wasn't sure how I'd move the axle forward if I wasn't pivoting it off of the other side - perhaps by pushing the floor jack a bit…but that too seemed iffy.

Undeterred, I rigged up some ratchet straps, ropes, and a support block to keep the axle "in place" (or at least from rotating forward and falling to the ground) when I removed the driver side, and got out the high-lift to enable raising/lowing of the truck independent of the real axle.

It all looked just a little bit sketchy to me, but - I figured - no sketchier than some of the trail repairs I've seen performed!

Swapping the leaf's in the driver pack went just as smoothly as the passenger side and I got it mounted back up on the frame in short order. Then, it was time to attempt axle repositioning.

To my surprise, I was able to simply push the floor jack forward the requisite amount and boom! Everything was aligned. Clearly, I've used all of my 2018 luck on day three of the year.

With the center pins on both sides aligned, I was able to raise the floor jack to get the leaf packs fully seated on the perches, and then a bit higher to position the u-bolt plates correctly to install some u-bolts (and of course re-install the bump stops).

With that, I torqued everything to spec (u-bolts: 97 ft-lbs; leaf pack front mount: 116 ft-lbs; leaf pack shackle mount: 67 ft-lbs) and reconnected the emergency brake before reinstalling the wheels.

And then, I was done. And the tire is definitely more centered in the wheel well. Whether that makes a difference in the long run, I have no idea, but it makes me feel good. And I'm keeping the original top+torque leafs just in case.

 

 

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