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September 2008 4x4 Tech Questions - Nuts & Bolts

Posted in How To on September 1, 2008
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Q I have a '79 F-250 with a 400M engine and four-speed manual transmission. The truck is lifted and has 36-inch Iroks and lockers front and rear. My problem is I burned the stock clutch up, so I put in what I was told was a better clutch and wrecked that in a couple months. Am I burning up clutches because these tires are too much for it, or do I just need the best clutch I can find?


A Have you changed the axle gears to deal with the bigger tires? Or are you shifting gears a lot when the clutch is under water and mud? If it came apart that quickly I would say it was either severely abused or a bunk part to start with (or both). I would make sure you're running low gears like 4.56 to 5.13s to help the clutch. Try not to let a bunch of mud and slop get between the clutch and the flywheel by sealing up the bellhousing and only shifting when the bellhousing is above the mud line, and get yourself a good parts store replacement. I would go to the local parts store and get the stock replacement; dunking a high-dollar clutch in the mud isn't going to get a long life out of it, so you might as well run one that doesn't break the bank if you need to replace it every 12 to 24 months from severe mud use. And remember that even breaking in a new clutch with 200 to 300 miles of moderate use is difficult to do. It will still help the clutch live longer.

Q I have an '01 Dodge Dakota 4x4, and when I put on a brushguard on, it caused the front end to sag a little. I was wondering if cranking the torsion bars to bring it back up, or even going a little higher to level it out with the rear end, was a good idea?

Logan B.

A The Dakota came with a front rake from the factory, so be sure your brushguard is added to that before you adjust the torsion bars. Adjusting the torsion bars isn't a bad thing as long as you do it in moderation. You should be able to raise the front slightly to return it to the stock rake after installing the brushguard. Just make sure you don't overcrank the torsion bar until you are hitting the droop stops and topping out (overextending) your shocks. You want the suspension to ride so the A-arms are in between the bumpstops and droop stops and the shock is in the middle range of its travel at ride height.

Q You have lost me when it comes to unit bearings. I read the article comparing unit bearings and traditional hub/tapered bearings and I thought that it was great that you gave pros and cons ("Small Wonder," May '08). You never really took a side on which was better though. Then I read the article about the custom axle for the Danger Ranger, where the "last axle you will ever have to buy" included unit bearings. What I don't understand is, why are some aftermarket companies, such as Spidertrax and Currie, embracing the unit bearing while others, such as Dynatrac, are building kits to eliminate them?


A If you look at the benefits of a unit bearing, you'll see that they are fully enclosed, they bolt on easily to the knuckle, they are light weight, and they don't require any servicing. If you look at the downsides, they are expensive, they don't last forever, few allow the use of selectable front hubs, most older versions need the axle stub shaft to help hold them together, and you can't do any servicing to them to make them last longer the way you can with a rebuildable bearing style spindle and hub.

The major automakers undoubtedly went to the unit bearing for ease of assembly, ease of repair, and the fact that just about any person, robot, or monkey could install them on an axle whereas a rebuildable hub and spindle (RHS) requires an installer who can set proper bearing preloads and not damage seals. In fact the tolerances from the current factory OEM unit bearings are so high they can hardly be matched by someone servicing a spindle and hubs.

However, this does bring up the additional cost of a quality OEM unit bearing from a dealership versus a low-quality aftermarket part from some budget parts house, a fact that axle builders who use unit bearings will back up. One major advantage to an RHS is that the spread between the two bearings on the spindle should, hypothetically, deal with the leverage of big tires better. But when you look at the massive F-450/F-550 unit bearing used by Ford and the fact that it is designed for a 7,000-pound load, it starts to be a moot point. That said, the massive unit bearings in the Ford Super Dutys and the new unit bearings in the Jeep JK Wranglers are very different from those of older Jeeps, Chevys, Fords, and Dodges as over the years they have improved. There is also the argument that unit bearings will just fail one day and your wheel will fall off at highway speeds, but in reality there is going to be some noise when either a unit bearing or an RHS starts to fail, and simply jacking up the vehicle and checking for front-end slop, as you should do regularly with any modified vehicle, should let you know if either is in need of some work.

Also many people argue that unit bearings are more expensive and less common at parts stores than bearings and races. But should your bearing be ignored and eventually fail, then add in the cost of a new spindle and maybe a hub and the price difference starts to diminish. One big factor is that without selectable front hubs your unit bearing is going to diminish fuel economy because it will be requiring the front axleshafts to spin constantly.

I personally think the tide is changing from when rebuilding your hubs was king to the time of the unit bearing where you don't need to get as greasy. And even though there are kits to replace unit bearings with spindles and hubs, there are not yet kits to replace spindles and hubs with unit bearings. I run hubs and spindles on most of my vehicles, but I just built an axle in last month's issue and used the big Ford unit bearing because I've started to see some benefits. I often think "which part I would want if I was crossing the Amazon Jungle or the Sahara Desert and my life depended on it." The rebuildable hub would have been my first choice, but if I have a spare factory unit bearing with me, I know I can change it quicker, it doesn't take up any more space in my truck than a set of bearings, seals, and grease, and I can change it without getting sand or mud in the hub or needing a special spindle nut socket. I think it comes down to personal preference. I prefer the rebuildable style currently, but I'm learning to enjoy the easy unit-bearing lifestyle.

Q I just got a little promotion at work, which is great, but I had to transfer to another plant that is a 45-minute drive one way. I needed something good on gas so I sold my '92 Chevy K1500 (my daily driver and off-roader) and bought an '03 Ford Escape. Don't laugh at me yet, it still has four-wheel drive! I want to make it a little more capable off-road, maybe even get a little more power out of the 3.nothing V-6 (without sacrificing gas mileage). I've looked online but can't seem to find anything other than rice-burner stuff and this $20 mod chip that promises 50-plus horsepower, 50-plus lb-ft of torque, 20 mpg, and rocket boosters or something.

Josh B.

A You have done what so many people are doing these days, selling their trucks or SUVs to buy newer fuel-efficient vehicles so they don't have to pay as much at the pump. The problem I see is that you now have a less-competent vehicle. It has all-wheel drive, without a low-range transfer case. I don't consider it a true four-wheel-drive, and I'm sure you are paying more on it than you owed on your '92 Chevy. Plus very few performance-enhancing upgrades will actually increase fuel mileage, especially if you want it to increase off-road performance as well. And many engine upgrades also require running premium fuel, adding more cost. I'm not saying get rid of the Escape now, but I am passing on your plight as an example to others. Don't sell your 4x4; rather, buy an old Honda Civic, Ford Pinto, or VW bug that gets good mileage and can be purchased for a lower buy-in cost, drive it back and forth to work every day, and then take your truck wheeling on weekends. You'll save money and you'll save wear and tear on your off-road truck (those big expensive tires will last longer).

Q I just bought an '06 Ford F-150 FX4. I'm new to the off-road scene. Plus I've been deployed to Iraq, and while I'm away I thought you guys could help me out with the best brands for a 4-inch lift kit, tires, and rims.


A I can't usually give out recommendations on a product because I haven't had a chance to test every manufacturer's offering. However, back in 2004 (Race 150 buildup, Jan. through Apr. issues) we had a chance to work with a small fabrication shop known as JD Fabrication (760.740.0442, While we were there they designed and began producing a long-travel front suspension for the '04-and-newer F-150s. This isn't so much a lift kit as it is a suspension system that will offer greater wheel travel, a wider track, and stronger front axleshafts. Also, when outfitted with fiberglass fenders, it has clearance for 37-inch tires. I will admit that this kit is a lot more expensive and involved than the normal off-the-shelf lift kit, but if you're looking for better off-road performance, this is the direction to go. As for tires and wheels, that is a personal choice everyone must make themselves, but I am fond of a mud tire on a 17-inch rim.

Q I would like to know what it would take to put a 4L80E behind the 6.2L diesel in my '83 GMC Jimmy. I plan on the 203 and 205 doubler from Off Road Design and I need a relatively cheap overdrive transmission that won't break. The truck rides on 38s.

Kevin B.

A The 4L80E will bolt in right behind the diesel; it will give you a .75:1 overdrive and it is similar in strength to a TH400. If you find an early ('92-'99) one, then you can reuse the TH400 flexplate. It would be a good time to do the 203/205 doubler as the 4L80E is longer than your current trans, which is most likely a TH350 or a TH400 automatic and will require driveshaft and crossmember changes. You may need to look into a torque converter with a stall speed specific for a diesel however, or you could find a 4L80E from behind a 6.5L diesel. Also some sort of aftermarket transmission controller will be needed to make the electronic transmission shift properly.

Q My truck is a 3/4-ton '94 Dodge 4x4 with a Cummins. Once again my steering is wandering. The last time it was because of a recall steering shaft. It is worn out again, so I thought maybe somebody makes a tough conversion to replace this? It is like the track bar-replaced every six years.

Tom K.

A Yep, call Borgeson (860.482.8283, They offer a steering shaft that replaced the original shaft and rag joint with one that uses two needle-bearing U-joints.

Scratch Scrambler
Q I've been in love with the Jeep Scrambler (CJ-8) ever since I was about 12 years old. I think that this is the decisive Jeep and they never should've discontinued it. The larger 103-inch wheelbase conquers the CJ-7 with the extra cargo space for gear, but is still the solid Jeep CJ that history has grown to love. I've been helping my buddy over the years with the buildup of his '81 Scrambler that includes a Vortec swap, a lift kit, power brakes, and a complete body and engine wiring job. This project has been fun and is still ongoing after three to four years of work. Instead of following suit and doing a classic Scrambler buildup, I've been considering the option of building an AJ (aftermarket Jeep) out of the readily available and plentiful aftermarket Jeep parts out there.

Needless to say, there is enough support out there to build a Scrambler from scratch and have it be exactly as I would want it, done right, the first time. Is this an economically feasible option? With rusted-out Scramblers going on eBay for more than $5,000, I like the AJ option more and more. Do these thoughts betray my allegiance to the CJ legacy? Or would my AJ Scrambler help raise awareness about the strong CJ legacy as an epic tribute vehicle?

Kelly R.

A I am writing this column in the midst of a wrench fest to get my Fun Buggy project finished for a major off-road trip. As such, I am trying to wrap it up after three years in the making and we're getting to "the point of a thousand little things." You may be wondering what all this has to do with your dream Scrambler project. Well, I thought it would be cool to build a vehicle from scratch. Now three years later, I know it is cool, but it is not easy and it is not cheap.

What you have to decide first is what exactly you want. If you want a Scrambler with mostly Scrambler drivetrain, then those rusted-out $5,000 Scramblers on eBay will have a bunch of good parts that you can start with, even if they need to be rebuilt. Either way your Jeep from scratch will require you to purchase every single nut, bolt, and wire, and those things add up quickly. I'm not saying don't do it. I am saying be ready for it to take a long time and cost more money than originally planned. In fact if you look at the rusted-out Scrambler and you realize that the frame may need to be replaced as well as the body and you would rather have an aftermarket drivetrain like an Atlas transfer case or a B&M automatic transmission, then starting from scratch is the way to go.

Not everyone can afford brand-new parts, and my advice on a budget-minded project is to get a vehicle that is running and build it up. When your project doesn't move under its own power for more than six months, it quickly burns up all your motivation. If you can drive it and slowly upgrade parts at the same time, you'll be amazed at how much more fun it is. Plus it's easier to spend money on a vehicle that you can actually drive-the paybacks are right there.

I know you love the Scrambler, but consider the long-wheelbase Jeep TJ Unlimited. This has all the benefits of the Scrambler-wheelbase is the same within an inch, they were only made for a few years so they might go up in value, and they are currently being ignored in the market. Plus these Jeeps are fuel-injected, were available with the locker-equipped Rubicon package, and have the classic Jeep round headlights and seven-slot grille, and the frame is way stronger than the old CJs.

However, if you set cost aside and look at value, I think building the vehicle from scratch is the way to go, simply because you will know the vehicle inside and out, and you'll have something you won't ever want to part with. It will take time and money, but you'll never forget the experience of building a vehicle from the ground up.

The guys from Superlift Suspensions (888.299.4692, would like to help you get started on your project with a set of their Superide Ten-stage velocity-sensitive shocks that continually adjust depending on terrain and vehicle speed. To keep vital axle parts protected, they are throwing in an eXtreme Ring Differential Cover Protector. Built from laser-cut 1/4-inch plate and designed to fit over the factory diff cover for additional protection, these zinc-coated protectors are available to fit most popular American trucks: Chevy, Ford, Dodge, and Jeep-including the complete Dana axle line.

Confused? E-mail your questions about trucks, 4x4s, and off-roading tech using "Nuts, I'm confused" as the subject and include a picture (if it's applicable). Digital photos must measure no less than 1600 x 1200 pixels (or two megapixels) and be saved as a TIFF, an EPS, or a maximum-quality JPEG file. Also, I'll be checking the forums on our Web site (, and if I see a question that I think more of you might want to have answered, I'll print that as well. Otherwise drop it old-school style with the envelope addressed to the address below. Letters published in this magazine reflect the opinions of the writers, and we reserve the right to edit letters for clarity, brevity, or other purposes. Write to: Nuts & Bolts, 4-Wheel & Off-Road, 6420 Wilshire Blvd., Los Angeles, CA 90048-5515, fax 323.782.2704. E-mail to:

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