I have done a bunch of research on lift kits lately. Here are the high points of what I have found. I will provide more details if desired. I am not a suspension expert, just a customer who is looking for the absolute best solution.
As much as I love the smooth ride of our trucks independent front suspension (IFS), they have a lot of limitations. Now I do like how I usually can drive faster over rough roads than my brethren with straight axles, though they would beat me in really rough stuff. However, I did not get the truck for heavy off roading. I got it for smooth travel and hauling over rough roads, like when going hunting.
I am looking at the lift because our HDs are low slung and have tiny wheel wells. With 2"of torsion lift and 285s on 16x8 rims with 4.5" of backspacing, my clearance decreases to about 3/4" when turning the steering wheel 3/4 tavel. This is not enough to run chains, and I do get rubbing sometimes on a moderately heavy bounce when turning.
The general consensus seems to be 35x 12.5s are the max tire size that our IFS can handle without premature wearing of components, and if you off road hard with 35s you may get the early wear anyway. Realize most of the IFS experience is with the 88-98 trucks, and our HDs do have a sturdier suspension--or so I'm told. Folks that don't off road "hard" have had long life form 35s and even a bit bigger.
There are four ways to get lift with the HDs.
Cranking the Torsion bars
There are even aftermarket keyways (Hill 4WD) that will allow up to 3" of lift in the front. At 2" of lift and below, the ride is very good and the CV axles are not at too bad of an angle. Many guys have run 60-100,000 miles with their HDs lifted this way.
However, as you go over 3" with the torsion bars, the ride gets choppy. This is not because we are loading the torsion bars more. Raising them simply resets their "zero" point. Their spring rate does not change. What is happening is we are getting the shock absorber too far from the center of its travel and it doesn't dampen as well when we do that.
I currently have 2" of torsion bar lift and my ride is excellent. Part of this is because I have Bilsteins, but another reason is that I have a 1" spacer under the top shock mount which puts the shock closer to its center of travel.
While I did think of trying a 2" spacer and maybe getting 3" of torsion lift, I decided against that because I did not want to limit the travel of the shock anymore than I already have. Bottoming/topping out a shock is a bad thing.
Yes, if we could use a shock 3" longer than stock, we might be able to get 3" of torsion lift with a good ride. We probably wouldn't even hurt our CV axles, as this amount of change is well within their operating limits. However, no one makes such a shock. I also imagine that at 3" of torsion lift we'd want to flip our tie rods.
I rally don't like having my torsion bars cranked. While it doesn't hurt the CV axle itself, it does cause the folds of the CV boots to constantly rub against each other, which has to incease wear a bit. When the CV boot gets a hole in it, the dirt can get into the CV joints and then they will wear. The good news is CV axles are not that expensive. I was told $60-$70 each.
Body Lifts
Nobody yet makes a body lift for the diesel. However, some guys have installed them and made some simple mods. You will need to get some extended fender liners to cover the front wheel wells. Our trucks already show a lot of frame, and a body kift adds to that. If you run an aftermarket bumper like I do, there may be some additional brackets that need to be fabricated. The consensus of those I talked too on body lifts was they are not good for a work truck. Towing would be fine but it might be hard to get someone to install a 5th wheel hitch. You could do it yourself and fabricate spacers for the hitch to make sure it connects to the truck frame, but no one really knows how such a set up would hold up.
Suspension Lifts in General
There are two basic kinds--he kind that drops everything and the kind that has longer steering knuckles or spindles. Though two companies advertise 4" lift kits, there are all really 6" kits. I'll explain what I mean later. Most kits require cutting off the stock mounting ears of the front differential, so it would be hard to put the truck back stock with these kits.
Non-Spindle Drop Suspension Lifts
These kits lower the entire drive train except for the transmission. They make brackets that drop everything--front differential, steering components, etc, the proper amount. The truck can be aligned to stock specs. The two I have come across are Pro Comp and Superlift. The Pro Comp sells additional components to fix the problem of front drive train vibration when in 4WD at higher speeds. I think Superlift had solved that problem as well. These kits keep the same front track width as our trucks have when stock. Both of them have two piece sub frames. While a one-piece sub frame is sturdier, you probably don't need it unless you are doing some heavy off roading.
I got to see two lifted HDs side-by-side. Both had the Pro Comp 6" kit. One had 305/70R 16s and the other 315/75R16s. The truck with the 315s was lifted more--the torsion bars were cranked a bit. The 305/70s--same diameter as 385/75s but 3/4" wider--looked great on the truck. The truck with the 315s was a couple inches higher in the nose and almost an inch higher in the tail. The difference in tire size accounts for some of that. The 305/70/16s are 32.8" tall and the 315s are 34.6" tall. This equates to a .9" difference in ride height. However, the truck with the 315s looked much bigger.
Spindle Drop Suspension Lifts
This seems to be the newer technology. The steering knuckles or spindles are longer than stock. These systems keep steering components--like the center link, tie rods, and pittman arm, in the same location relative to the frame of the truck as when stock. This method seems to reduce wear on these components, and these components have been weak points in the IFS in the past. These kits also allow alignment to stock specs.
I am told all the spindles are made by one or two companies. Also, they say all the spindles have the same amount of drop, whether they are for the Trailmaster 4" kit, the Rancho 4" or 5" kit (It's amount lift depends on which catalog you read), or the Tuff Country 6" lift. In fact, Trailmaster's 4" and 6" kit use the exact same spindles. With the 6" kit the CV axles are horizontal--like stock, and you get a true 6" lift. With the 4" kit the CV axles are drooped (inner CV joint is lower than the outer CV joint) and they give you a 2" lift block for the rear springs vs the 4" lift block you get with the 6" kit.
I personally don't like a lowered front diff. The reason I got my torsion bar keys and lifted the nose of my truck in the first place was because when hunting on a rough, rutted road, I filled the skid plates with mud and grass because the front diff in the stock location is kind of low to the ground. When I raised it, that problem went away. Most of these spindle kits drop the front diff about 1.5" less than the spindles, so it helps keep the diff up out of the way even without cranking on the torsion bars.
Last year, the Rancho kit was advertised as a 4" lift, this year it's a 5" lift but nothing has changed. I am told Rancho is always conservative with it's set up, and that they use the same length spindles as everyone else does on their 6" kits. Rancho uses a 2.5" rear lift block. I am not sure how they get down to 4" or 5" of lift with their long spindles, but they do manage to keep the CV axles horizontal and the trucks are level.
One thing to keep in mind is all the spindle drops increase our front track width. Stock, out trucks are already about 2.5" wider in the front track than the rear. With the Rancho, Trailmaster, and Fab Tech kits, the front track is increased another 1.5" per side, not even accounting for wider tires and wheels. My 285's on 16x8s already stick out past the front fenders 1.5" per side. If I installed one of the three kits I just mentioned, they'd stick out 2.5" per side. Wider tires would be worse. Now the guys with these kits tell me they look fine--and they do. However, they say it is hard to keep mud, water, and debris from hitting the sides of the truck.
The Tuff Country, RCD, and Skyjacker kits only increase front track width about 1/2" each side. Tuff Country offers a one-piece sub frame. Skyjacker does not require cutting the mounting ears off the front diff, so it is easily reversible. RCD comes with Bilstein shocks.
I am going to get the Tuff Country kit, mainly because I can order it from a local shop and get it delivered to my door for about $200 less than the mail order places charge. I also like it's minimal increase I track width and it's one-piece sub frame. I'd prefer the Bilstein shocks, but I can do that later if I need to. I'd really rather have a true 4" lift, but nobody is making such a kit. I'll run my 285s for while with this kit. they will look a tad small. Later I will get larger tires--either 305/70s or 315/75s.
I plan to use the Tuff Country kit and keep my current 285s on 16x8 rims. I will keep the lift on the lower side of the range.
I have left a lot of stuff out, but I hope I can point folks in the right direction. All the company reps were very helpful, and I think any one of these kits would be a good choice, depending on what you prefer.
Blaine
Why not delete the IFS!!
. I'm sure nobody here would want a truck this extreme but look at the endless lift choices.
