Dana 44: Enough Axle for Ford With 40s?
Q I have a '91 Chevy shortbed single-cab with IFS. I've also got a high-pinion Dana 44 frontend out of another Ford, which I plan to swap into my truck. Now I want my truck to flex great with leaf springs. Any ideas on leaf springs?
Can I put a Ford NP205 transfer case behind my stock five-speed transmission? If so, what year of Ford should I look for?
I plan on using a kit from Sky-manufacturing.com to install the solid Dana 44 under my truck, and also plan on putting 38- to 40-inch tires under my rig. What size lift would I need to fit 40-inchers-plus with a good flexy suspension? Sky-manufacturing says with their kit it will give you six inches of lift over stock.
A First, you need to rethink your plans, especially if you really want to go to 40 inch tires. That Dana 44 is not going to live very long with 40s. In fact, it probably will not like anything larger than, say, a 37-inch tire, even with some quality aftermarket axleshafts. Yes, there are Jeeps running around with a 44 up front and big tires, but they also have a major weight advantage.
Okay, let's say you really have your heart set on some of those 38- to 40-inchers. To fit them, you're going to have to trim the fenders, move the axle slightly forward, and raise the truck at least four inches higher than the conversion kit will gain you. Even then, I suppose you will have to somewhat limit compression travel. The front-end lift is not a problem-you just order some 4-inch-lift springs of the proper length for their kit and capacity. However, to get the necessary lift out of the rear, you have to either use some tall lift blocks, some quite stout springs with lots of arch, a rear shackle flip, or a combination of all three.
Then true trail capability start to fail. The truck now sits very high, which translates to "tippy" on side hills, with overall lack of stability. You will have to figure out some way to control rear axle hop, and those so-called "traction bars" generally will limit suspension articulation. A lot of axle life depends on just how hard you plan to use the truck. If you're a "spare no prisoners, pedal to the metal" type of guy, then sell the 44 and start saving for the Dana 60 that you really need. If your driving style is a bit more even-tempered, then most likely a set of 35s or so may just be the right combination. Okay, I know lots of people reading this are going to say something like: "Oh, I run 40s and don't have a problem." Well, all I can say is, that's great, but either you're really nice to your truck, or you're lucky for now and that your axleshafts are going to eventually break when you're in a really nasty spot.
Now as to the transmission and transfer case: you didn't say which transmission you had. If it is the NVG3500, or the Muncie 5LM60, which was used in 1/2-ton pickups, don't even consider using it. If you have the NVG4500 five-speed, then you're good to go. As to what adapter you're going to need, as well as which transfer case, I suggest you contact Off-Road Design (970-945-7777, www.offroadesign.com). They are really nice guys, and I'm sure they can help you out.