Techline: Your Top 4x4 And Off-Road Tech Questions Answered HerePosted in How To: Tech Qa on February 6, 2017
Ratio RightI own a ’01 Dodge Ram 1500 4x4 with a 5-inch lift. It has the factory center-axle disconnect Dana 44 front axle and a 9.25-inch rearend with a limited-slip differential. Both axles house 3.56:1 ratio gears. I want to regear the axles and run 35-inch tires. I’m torn between swapping in 1-ton axles or simply rebuilding the current axles with chromoly axleshafts and a truss kit. What gears will keep me at an optimal rpm range? When I do the math, it comes out to 4.09:1, but most charts say 4.56:1. Which gear ratio would be best? My truck isn’t a show truck. It’s my daily driver, pulls a boat to the lake, and goes off-roading to key hunting and fishing places. No terrain is off-limits.
Given how it sounds like you use your truck, I think you will be fine with the factory axle assemblies. This will save a lot of money that you can put elsewhere in the truck. A winch and heavy-duty bumpers could be useful.
If you decide to keep the factory open front differential and limited-slip rear differential, I think the factory front and rear axleshafts will survive just fine. There is no need to upgrade them. However, if you plan to install locking differentials front and rear (which I wouldn’t recommend for your planned use) and really beat on this truck hard off-road, you may want to consider some upgraded front axleshafts.
As for the axle gearing, what ratio you go with again depends on intended use. Because it sounds as though you regularly tow and hit the dirt more often than you hit the highway at 80 mph, I think you’ll want to stay on the lower (numerically higher) side. The 4.10:1 ratio gears would be a great option if you were trying to maximize fuel economy at highway speeds with an unloaded truck on mostly level roads. Because your truck has an Overdrive transmission gear, I think you’ll be happier with 4.88:1 ratio axle gears. They will provide much better all-around on- and off-road performance, as well as more torque for towing. The small decrease in fuel economy on long highway trips will be far outweighed by the improved performance and decreased long-term stress on the transmission, engine, and other drivetrain components.
Ram-Assist MountingFor a ram-assist, PSC states that the rod ends on the ram should be parallel to each other. Mine is mounted similar to the ram on the GI Gyp M1008 project truck. Do you think this is an issue?
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Installing a ram-assist system on any 4x4 can be an exercise in patience and creativity, especially on vehicles with tight engine bays, busy front suspensions, and narrow front axles. Mounting the ram properly is only part of the equation. All too often we see the ram-assist hoses mounted carelessly near bumpstops and other areas where they can be cut or smashed. When choosing a location for the ram you should always keep the hose routing in mind. As you mentioned, in an ideal world the ram will be mounted perfectly parallel with the tie rod that it’s attached to. This is not always possible. In fact, in most cases it’s not at all feasible, but you can usually get pretty close. This was the case with the PSC (pscmotorsports.com) ram-assist on the Dana 60 front axle on our M1008. We wanted to keep the ram and hoses out of harm’s way, so this was the best location for it. The heavy-duty RuffStuff Specialties (ruffstuffspecialties.com) differential cover provided a solid mounting point to weld the ram mounting tabs on the one side. On the other we used a clamp-on-style tie-rod mount. Although it never slipped on us, it’s probably best to either weld the clamp-on mount in place or use weld tabs for mounting to the tie rod.
Our PSC ram-assist system worked flawlessly. The truck was never trailered. We drove it to wheeling spots, despite the sluggish 6.2L diesel and dismal fuel economy. We had no problem turning our nightmarish 40-inch Boggers mounted on 15x12 wheels with 2 inches of backspacing from a dead stop, even with the tires aired down.
Dodge Steering And LiftI want to do crossover steering on my ’93 Dodge W250. Any recommendations on 4-inch lift springs that ride goodish?
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The push-pull steering system found on the first-gen Dodge 4x4s and solid axle GM trucks is far from ideal when the suspension is lifted or the truck is used off-road regularly. Fortunately, performing a crossover steering conversion on the first-gen Dodge trucks is very similar to performing a crossover steering conversion on the much more common solid-axle Chevy 4x4, which has a similar push-pull steering system. However, some of the clearance issues and parts used are a little different. Offroad Design (offroaddesign.com) offers a complete crossover steering kit for the GM trucks. As always, things are a little more difficult for the Dodge. Although, you can use some of the Offroad Design parts and ideas on your W250.
To do the conversion on your Dodge, you’ll need to move the factory steering box to the two-wheel-drive location on the frame. The factory power steering hoses should reach the new steering box location. If you have not already upgraded to a Borgeson (borgeson.com) steering shaft, now would be a good time. Your stock steering shaft will not work with the new steering box location. The pitman arm on the Dodge steering box is keyed every 90 degrees. You’ll need to remove it and rotate it counter-clockwise 90 degrees, so it faces the rear of the truck. Now, you may or may not be able to use the factory steering arm depending on lift and other variables. You may need a longer arm for the steering to cycle properly or you may need an arm with more drop built into it depending on where you need clearance.
On the axle end, you will need to add a high-steer arm to the passenger-side steering knuckle. On the Dana 60 front axle of that era, it is simply a bolt-on procedure. Dana 44 axles will require the installation of a flat-top knuckle that has been machined and drilled to accept a steering arm. Again, the length and design of this arm will be dependent on steering swing, the clearance you need, and how the suspension is allowed to cycle.
You’ll need to fabricate a drag link that clears the front crossmember. An Offroad Design crossover drag link designed for a GM truck has been used by some people, but again, what works for you will be dependent on many factors.
In most cases, you will need 4 inches of lift, and you will need to remove the factory front sway bar to make room for crossover steering. However, some creative individuals have fit crossover steering with less or no lift using different combinations of parts and limiting the suspension travel.
As for the lift springs, the first-gen Dodge W250 doesn’t enjoy the same aftermarket suspension support it once had many years ago. The good news is that Skyjacker (skyjacker.com) still offers 1- to 8-inch lift kits for your truck in both gas and diesel versions. Not all lift heights are available for both engines.
The key to making your truck ride smooth will be in shock selection and proper tire pressure. Unless you plan to haul heavy loads or run down dirt roads at speed, you’ll likely want some lightly valved shocks. A standard twin-tube off-road shock may be all you need. However, some type of adjustable shock like a Rancho (gorancho.com) 9000XL will give you more versatility and offer a smoother ride.
GM Solid Axle SwapI’m probably beating a long dead horse, but is there anyone that has ever published or released a start to finish leaf-sprung solid axle swap on a ’96 GMC Yukon? I’d like to see it done by a reputable source, not the misleading BS from the millions of forums.
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The IFS suspension, differential, CV axles, and steering parts found under the ’88-’98 GM 4x4 platform are delicate and can be extremely problematic when combined with lift kits, large tires, and aggressive driving off-road. If you're tired of constantly replacing frontend components or you simply want improved trail performance, it’s hard to beat a solid-axle swap. Fortunately, the ’88-’98 GM 4x4 chassis is probably the most common to receive a solid axle swap. Offroad Design (offroaddesign.com) specializes in solid-axle conversions for this chassis. The company offers a very simple kit that can be used to complete the conversion in your own garage or driveway. It’s really not all that complex, and once you see the components you’ll get a much better idea of what’s involved.
Perhaps the most difficult part of the swap is removing the original front end components and cutting off the welded-on A-arm suspension and axle brackets. You’ll likely want an oxyacetylene torch or a plasma cutter for this project, but it may be possible with an angle grinder, a lot of time, and determination. The kit is completely bolt-on and uses many of the existing holes in the frame. However, there is some drilling involved. Each kit includes a pair of brackets for the front of the springs, a pair of brackets for the shackles at the rear of the springs, a pair of shackles with greasable bushings and bolts, instructions, and all the necessary hardware. The conversion provides an additional 3 inches of lift over the lift springs you select. It works on 4WD and 2WD trucks, although 3/4- and 1-ton 2WD trucks require significant frame modifications.
Kits are available for use with several popular leaf spring and front axle options. Your stock steering box is retained in the factory location, but a crossover steering system is required. It’s not a big deal since it consists of all bolt-on parts that Offroad Design offers, regardless of the front axle you choose. All of the spring and axle options are noted on the Offroad Design website.
Suspension FabricationI’m building a custom suspension under my ’97 Jeep TJ with a ball-joint Dana 60 front axle from a Ford F-350. There was no easy way to make the track bar the same length as the drag link. I settled on making the track bar about 8 inches shorter than the drag link. The angles are roughly the same and aren't too extreme. Do you think I will have problems with death wobble? Any other solutions you can suggest? The spring placement prevents me from making the track bar longer. Would a ram-assist steering help in any way to prevent bumpsteer?
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Building a custom suspension that works properly requires a bit of thought, planning, vision, and knowledge of basic suspension geometry. What might seem like even the most insignificant of changes can make a 4x4 quite a handful on- and off-road.
To maintain proper geometry and good handling as the suspension cycles, the track bar and steering drag link should be equal lengths, parallel, and as level to the ground as possible. The mounting points of both components should also mirror each other. If they are not equal lengths, not parallel, or the mounting points are not mirrored, your 4x4 will experience bumpsteer as the suspension cycles. How bad the bumpsteer is will depend on how off your suspension and steering geometry is.
As you have experienced, it’s not always possible to make the drag link and track bar mirror each other exactly. Some small variances are acceptable and will be unnoticeable in most cases. An 8-inch length difference is pretty significant and not advisable. The bumpsteer created by this setup may be maddening if you drive the Jeep at any kind of road speeds. You may not be able to add length to the axle side of the track bar to match drag link length, but you could add the length to the frame side. It’s not ideal, but the full-width front axle will afford you more room on the outside of the framerail. Custom suspensions are almost always full of compromises.
A ram-assist will not correct bumpsteer. Ram-assist systems are designed to help steer larger, heavier, and wider aired-down tires in rough terrain. Installation of a ram-assist on the tie rod of a 4x4 with significant bumpsteer will cause a binding situation in the steering linkage as the suspension cycles. This could lead to prematurely worn tie-rod ends, broken steering arm bolts, and other steering-related failures.