Between the few hundred pounds of stuff I carry and a truck cap, the factory springs were always riding the overload leaf; so, I wanted to make an improvement to spring capacity when I lifted the truck. I contacted a number of lift manufacturers about putting an AAL on top of the block they supply with their kit and basically all of them recommended against it due to drive shaft angles. So, I looked into various options and selected a setup that works, though I'm not real happy with the results. The problem I'm having is getting the right height and load carrying combination as I describe below.
My current setup: I have a 6" BDS lift (Fox rear shocks) with a ProComp AAL and a 3" tapered ReadyLIFT block. ProComp stated up to 2.5" of lift from the AAL, but this varies with truck configuration and loading. I got about 1.5" out of it in a CCSB when loaded as described, giving me a total rear lift height over the axle of about 4.5"--roughly 3.5" more than stock. I say it's roughly 3.5" more than stock, but since the spring rate on the new setup is different it's probably not a good comparison. The truck looks barely level loaded and if I throw any additional weight at it, well it doesn't look good. A taller block could help here, but when I'm not loaded up I may run into driveshaft issues.
The problem I have is not just looks. The Fox rear shocks have little room for travel and at rest there's probably less than 3" of the piston rod showing. Any major axle movement and I'll bottom out the shock. Not only that, but due to taller springs and increased bump stop distance, my tires (35s) can nearly contact the bed frame with sufficient bed weight and enough axle movement. Going back to factory springs should set the shock travel and bump stop distance back to where they should be, but then I still have to increase load capacity.
Things I considered: I carry a lot of weight and use the truck off road. The easiest possible solution for me would be keep the AAL and find a slightly higher block, though I'm open to other solutions. Most blocks I found were 3" (like the ones I'm using), 5" (like the ones that came with my kit), or 5.5" (like the ones provided by some others kits). I think a 4" to 4.5" would be ok and not put too much strain on the u-joints or pull on the driveshaft too much. The only 4" double-pin block with bumpstop I found was a ProComp, which I ordered along with their 3" block kit. I returned both and went with the ReadyLift I mentioned above. The ProComp 4" block was generic and used bolts with nuts in place of molded pins... scary. The ProComp 3" block was of poor quality and had inconsistent wall thickness. Supposedly the Rancho kit uses a 4.5" block, though I could never get confirmation. Everyone else seems to just build on a generic block (note: I have not called Autospring Corp. yet). Any suggestions on finding a 4" or 4.5" double pinned block with factory bump stop is greatly appreciated.
I also looked into sticking with the BDS 5" block and going with a number of helper setups including RAS, Hellwig, SuperSprings, SumoSprings, Air Bags, etc. However, the helper springs each had their issues for offroading (mostly interference or the possibility of coming undone) and the bump stop style helpers would limit suspension travel too much. I even considered a custom set of springs, though the investment would be too much and I'd be greatly disappointed for the money if they didn't work out. I also looked at blocking up the springs available with the Skyjacker kit, though they are supposedly not setup for carrying much weight.
Long story short, my questions are:
Are there any other factory style 4" or 4.5" blocks available?
Can anyone confirm the height (please measure front and back to account for possible tapering) of the block included with Rancho 4" lift kit?
Do I require a tapered block? The BDS kit's 5" block is not tapered. Does a taller block have more, less, or no effect on whether tapering is recommended?
If I go with a taller block with the AAL, what problems could I run into? Is it manly stress on the u-joints? Do I run the risk of binding and messing up the transmission and rear? Is there anything I can do to accommodate more height (for example, a driveshaft spacer?).
Finally, are there any spring helper setups I missed that would be good off-road?
Deaver leaf springs. Custom made rear leaf springs. This would be the better option. If you are riding on the overload spring, blocks are not the answer. While they will give you lift, they won't relief the stress on the springs. Deaver can make you a custom leaf spring assembly that gives you lift and in a higher spring rate to keep you off the overload springs.
I feel more like I do right now, than I have all day.
If your rig is lifted that much and being used as a work truck you might want to consider going to a full leaf spring or at least a mini pack leaf add on.
Deaver is making both I do not see them on their web site though.
any time you increase the rear block height, then you are essentially pulling the drive shaft away from the transmission. An angled block, or a block shim will help offset some of that affect.
i installed a set of airbags on my previous truck, and they win my vote any day! they give you the adjust-ability of setting your height for different weight in the bed. If you also go with an on-board air compressor, you can do it fro the driver seat in a few seconds.
the only flaw to a set of airbags, IMO, is that when working on the truck, you can only lift the truck by using the rear axle. If you lift with the frame, then you will stretch and can tear the bags.
Some people will say that they offer a stiff ride, etc.... but these are trucks after all!
2011 XLT SCREW 5.0, 4X4 offroad.
With: TT mirror upgrade, locking tailgate mod, homelink visor mod, Weathertech floor liners, Husky mud flaps, FORD remote starter, Door Detent 3.0 check arms (A huge thank you to Northlight labs!)
I tried two other rear setups before settling: 1) using the 2-to-1 pin offset 5" blocks provided with the BDS kit plus the ProComp AAL, and 2) these same blocks with Firestone air bags, which is my current setup. The former was too much lift and tension unloaded, plus the ProComp AAL are poorly designed and put point loads on the factory springs. The latter is working, but I have to always keep about 20 pounds in the bags to ensure they're not getting crushed due to a combination of the offset springs (less height between the top of the spring pack and air bag frame mount), my payload (topper, tools, etc.), and the height of the air bag cradle (about 5/8", see below). To my dissatisfaction, this means I'm always riding on the bags, though it seems like this is often the case with bags that sit over leaf springs.
One nice thing is that I put in the Daystar air bag cradles, so I don't have to worry about disconnecting the bags when I'm raising the truck or when I go offroad, though suspension travel is still limited by the bags. The cradles work well, but they were a pain to center and tend to collect small gravel, which get pulverized and pushed into the cradle's grooves that are likely there for this purpose. This has not caused any problems, but I clean them out periodically to ensure there's room for more dirt collection. Note that these cradles may not work so well if your setup has a rubber bottom (Firestone's is metal) since debris may be rubbing or smacking against the bottom of the bag.
I have about 10k miles on the bags and cradles and am generally happy with them. The bags hold air well and the only ongoing hassle is adjusting the pressures as necessary. I could get the compressor as suggested, but pumping the bags at the Schrader valves is not inconvenient enough to motivate me to purchase the onboard compressor and perform the install.
To the comment on the SuperDuty, I debated for a while whether to stick with a diesel, but for the most part I am happy with this truck.
Regarding the custom springs, I contacted Deaver, National, and a few local shops, but due to the modified aspects of my truck, only the local outfits were willing to build me a pack. Due to load variations, towing, etc., I think in the end I would have supplemented it with air bags anyway.
Thanks everyone for your feedback, and hopefully my experience helps someone in the future.