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Techline: Your Top 4x4 and Off-Road Tech Questions Answered Here

Posted in How To: Tech Qa on August 10, 2017
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9-Inch Info

Are the 31-spline Ford 9-inch axleshafts from pickups pretty consistent in length? Summit Racing seems to only have axleshafts that are about 32 inches long, actually 31.895 inches.

Verne Simons
Via Email

The Ford 9-inch rear axle is one of our favorite junkyard axle swaps. Of course, there were many different variations of the Ford 9-inch used over the years on cars, 1/2-ton trucks, and SUVs. One of the most durable, common, and versatile versions of the Ford 9-inch can be found in the ’74-’86 F-150 pickup and ’78-’86 Bronco. These 9-inch axles feature right and left axleshafts that are of equal length at 31 27/32 inches. This is a convenient characteristic if you carry spare axleshafts. You’ll only need to carry one. All of these particular F-150 and Bronco 9-inch axles run the large Ford axle bearing, although there are a couple different axleshaft bearing retainer bolt sizes that were used through the years. Keep in mind, not all of the Ford 9-inch pickup axles came with 31-spline axleshafts. Some of the ’70s two-wheel-drive 9-inch rear axle assemblies came with less-desirable 28-spline axleshafts. The really coveted version came from the Camper Special pickup. This 9-inch came with 31-spline axleshafts and a factory nodular iron third member, which is slightly stronger than the traditional cast third member found in most 9-inch rear axles.

The ’74-’86 pickup and ’78-’86 Bronco Ford 9-inch measures in at 65 inches from wheel mounting surface to wheel mounting surface. All of them came with a 5-on-5.5 wheel lug bolt pattern and drum brakes. A disc brake conversion is an easy bolt-on upgrade and complete kits are available from companies like TSM (tsmmfg.com).

Another advantage of these Ford 9-inch axle assemblies is that they can be easily upgraded to 35- and even 40-spline axleshafts with completely bolt-on parts. The axleshafts, third member, and carrier assembly are all that need to be upgraded.

In most cases, you can find a complete F-150 truck/Bronco Ford 9-inch rear axles for less than $200 or so. However, because OE versions of the Ford 9-inch haven’t been manufactured in more than 30 years, they are starting to get to be a little more difficult to find in wrecking yards. Fortunately, because the Ford 9-inch is so incredibly popular both on- and off-road, you can build one using aftermarket parts. Companies like Currie Enterprises (currieenterprises.com) and RuffStuff Specialties (ruffstuffspecialties.com) specialize in building aftermarket front and rear Ford 9-inch housings in nearly any width and differential offset. These companies, along with many others, offer complete, assembled third members as well, so you can custom-build your 9-inch however you like to fit whatever application you are working with.

Winch Repair

I just bought a used Warn X8000i winch for $96. It wasn’t working and the owner thought that the motor was smoked. I took it apart and found that only the wires on the remote plug were fried. When I bypassed the plug and solenoids, I could get the winch to spool in and out just fine. What’s the best way to fix this winch and put it back to work?

Ted Olmstead
Crest, CA

Most Warn winches are of high quality and they typically don’t die very easily. It’s fairly difficult to completely kill a quality electric winch motor. As you have found, it’s actually pretty easy to diagnose a non-working winch, even if you only have a very basic understanding of automotive electronics. Warn (warn.com) offers replacement parts for all of its winches, including most of the discontinued winches, such as your X8000i. Pay special attention to serial number cutoffs when ordering parts. Changes were made to some winches mid-production. In your case, it sounds as though all you need is the plug and wiring pigtail assembly that attaches to the winch body and connects to the solenoids. This is a simple repair that you should be able to make using Warn part number 16296.

Weak Axle ID

What axle is under the front of a ’63 Chevy K10? It looks like an 8-lug closed-knuckle Dana 44, but I am not sure. Do you have any info or specs about it?

Philippe Gauthier
Via facebook.com/JohnCappa4x4

There were two types of closed-knuckle Dana 44 axle assemblies used under the front of the ’60-’69 GM 4x4 pickups. The standard-duty Dana 44 axles with eight-bolt knuckle ball seals were used on the 1/2- and light 3/4-ton models. The heavy-duty Dana 44 front axles used on ’62-’69 high-GVW 3/4-ton trucks came with 12-bolt knuckle ball seals. Unfortunately, the closed-knuckle Dana 44 axles are not all that desirable. They have drum brakes and many of the components are weaker and more difficult to find than what can be found on the ’73-’80 open-knuckle Dana 44 and ’81-’91 10-bolt front axles. If you’re leaving the truck stock, want to restore it, and keep it period correct, Torque King 4x4 (quad4x4.com) offers hard-to-find closed-knuckle Dana 44 replacement parts. If you plan to add larger tires and use the truck off-road, you’ll be better off swapping to a later model open-knuckle Dana 44. The open-knuckle Dana 44 axle assembly will turn sharper, will have stronger outer axleshafts, bigger steering U-joints, better locking hubs, and most of them came with disc brakes.

HD Coilover Conversion

Who makes a heavy-duty coilover for the Ford F-250 through F-550?

Daniel Little
Via facebook.com/JohnCappa4x4

As you have likely already found out, the diesel and gas versions of the heavy-duty F-series trucks typically require different lift systems. The diesel versions need heavier coils to support the additional weight of the engine and increased GVWR to maintain the proper lift. Fabtech (fabtechmotorsports.com) offers several different complete lift kits for Ford Super Duty trucks up to the F-550. You can get either radius-arm or four-link front suspension lift systems. Both kits are available with massive 4.0-inch-diameter Dirt Logic coilover shocks loaded with heavy-duty coil springs, which have been designed to support the weight of the big F-series.

You could also go with a custom-made suspension. Any number of fabrication shops should be able to build what you are looking for or use a combination of off-the-shelf and custom parts.

If you decide to go with smaller diameter shocks, you may need to double up on the coilovers. Smaller-diameter coilover shocks may not have heavy enough coils available to support the weight of your project. If you decide to go the custom route, do the calculations ahead of time to make sure you can get the coil rates you need for the shocks you plan to use to support the truck and maintain the ride height you desire.

Weight Wrong

Why do some suspension lift companies use spring rates that are way off? It seems to me that it costs the same to make springs that ride good as it does to make springs that ride too stiff. This is something I have wondered for years.

Jim Mac McMillan
Via facebook.com/JohnCappa4x4

Providing the correct spring rate to get a smooth ride on a given 4x4 may not seem like rocket science, but it kind of is. The problem stems from the fact that most everyone builds and outfits their 4x4 differently than the next guy. A 4x4 could be loaded down with body armor, heavy-duty bumpers, a winch, and a bunch of camp gear, or it could be a svelte daily driver that never sees the dirt. Most lift kit companies try to cover the full gamut of possibilities with one spring rate for each lift height application. Diesel vehicles usually require their own heavy-duty springs. In most cases, the lift companies will err on the heavier side because let’s face it; most off-road enthusiasts usually don’t stop with just a lift kit. Some lift companies provide a light and a heavy spring rate option, giving you the ability to pick which is right for your application and ride preference. Providing two different spring rates does cause a bit of a stocking problem for the manufacturer, distributors, and retailers. It requires two part numbers instead of just one, so it’s understandable why most lift suspension manufacturers choose not to go this route.

There are certain spring design characteristics to keep an eye out for when looking for a soft-riding lift for your 4x4. For example, coil springs can be manufactured with what is known as a progressive-rate, a dual-rate, or a variable-rate coil wind. These coils are more complex and expensive to manufacture than a traditional constant-rate coil spring, but they usually offer a much smoother ride. Companies like Skyjacker (skyjacker.com) offer both soft-ride lift kits and traditional lift kits. If you want a softer ride, look for the lower spring rate options or lifts that are marketed as soft-riding.

Keep in mind that shocks can be tuned for a light or heavy vehicle. Also, more aggressive driving will generally require firmer shock valving. Shocks with exterior valving adjustment knobs or bypass tubes can be utilized to provide a smoother ride. High-end shock companies such as Fox (ridefox.com) and King (kingshocks.com) offer bolt-on shocks for popular 4x4 applications with this kind of adjustability.

Manual Habit

I have a question that has been bugging me for a while. I have a Jeep Wrangler with a five-speed manual transmission. When coasting to a stop and not engine braking, should I row through the gears or just wait until I'm at a complete stop before shifting into First? I have a habit of shifting into Second at normal Second gear speeds and then into First, but never letting the clutch out until I'm ready to go after stopping.

Josh Jamieson
Via facebook.com/JohnCappa4x4

Unfortunately, this manual transmission shifting habit is probably causing some unnecessary wear on transmission internals like the synchros, but probably not a significant amount of wear worth worrying about. There really is no need to row through the gears with the clutch depressed when coming to a stop. And while we are on the topic of shifting a manual transmission, downshifting and using the engine and transmission for compression braking under normal driving conditions also causes unnecessary wear on the clutch, transmission, and engine. In most cases, the brakes are best used for this purpose. Brakes are cheap—engines, transmissions, and clutch replacement are not. Of course, if you are hauling a heavy load and don’t want to overheat the brakes, it makes perfect sense to use engine compression braking to help safely slow down the vehicle. The key is to learn to know when it’s necessary to use compression braking and when it’s not.

Dana 35 Dilemma

I have an Eaton Detroit Locker (part number 162C-66A) in the rear Dana 35 axle of my Jeep. It has the 30-spline G2 Super 35 axleshafts. It broke by shearing off all the teeth inside the locker on the passenger side. Now I have a three-wheel-drive Jeep.

The Jeep is set up for mild rockcrawling, but I never push it because it is too expensive to repair. It’s probably more capable than I give it credit for. It rolls on 35-inch tires, but it broke when I was driving on wet pavement around a corner. It skidded, the right tire caught a dry patch, and then pop, it was gone.

I can’t find a new side gear. Do I have to buy a whole new locker?

Alec Schortzmann
Via facebook.com/JohnCappa4x4

The Dana 35 rear axle has never been known to be a venerable axle assembly. It simply isn’t a great axle, especially with a locker, and more so with tires that are larger than 31 to 32 inches tall. The 35-inch tires are a recipe for disaster, even for a street-only Jeep. Are there people who can make this combo live? Of course, but it’s still a ticking time bomb. Part of the problem is related to Dana 35 axlehousing flex. Over time, the smallish Dana 35 axletubes have a tendency to wobble around in the cast centersection. This movement causes oil leaks around the axletube and casting junction. It also causes the axleshafts to pull the differential (locker) side gears out of alignment with the rest of the carrier. Larger-than-stock tires have even more leverage to flex the housing, exacerbating the issue. Some lockers will not even properly engage in well-worn Dana 35 axle assemblies because of the housing flex. Eventually, poor locker tooth engagement will lead to tooth failure in a situation like you described. Simply replacing the broken side gear would not solve this problem, and it would likely fail again. Unfortunately, replacement locker side gears are not available. The best solution is to upgrade to a stronger and more rigid axle assembly, such as a Dana 44 or other equivalent aftermarket axle. However, if you insist on sticking with the Dana 35, you can purchase and install a new locker or try and find a used locker side gear, and then add a rigid axle truss. Properly trussing the Dana 35 can help keep the internals alive longer if the housing is straightened and aligned prior to truss installation. With the axlehousing straight and not flexing, the locker side gear teeth will maintain proper engagement and be much less likely to fail again.

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