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Tech Line: Answers To All Your 4x4 Tech Questions

Posted in How To: Tech Qa on November 9, 2016 Comment (0)
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Vintage Windshield Replacement
Where can I get a windshield for a ’76 Jeep J10?
Noah Foley
Via Instagram @cappaworks

The early FSJ Cherokee, J-truck, and Wagoneer windshields are fairly common. Most windshield companies can get you one for about $120 plus installation. The later FSJ windshields are a little more expensive for some reason. I have seen them go for around $200 plus installation. Try Windshields to Go (windshieldstogo.com) when looking for hard to find 4x4 glass. Also, the Jeep FSJ windshield gaskets are notorious for rotting and leaking. If you need a replacement gasket, and you likely will, BJ’s Off-Road (bjsoffroad.com) has new ones available.

Bedliner Body Panels
Have you ever painted any of your wheeling rigs with Durabak bedliner paint? From what I read it seems to be the best on the market.
Andrew Insinga
Via facebook.com/JohnCappa4x4

When it comes to bedliner body panels, I may not be the best person to ask. I have not been a big fan of using bedliner on exterior panels. Of course, it’s a great option if you tend to drive off-road in areas with thick brush where traditional painted panels are often scratched and dinged in these conditions. However, if you ever have to weld on or repair the panels, it's a tough job and really messy. In most cases, you’ll have to remove the bedliner from the area that needs repairs and then reapply the coating. Also, some of the paint-on bedliner materials can fade or become chalky from extended sun exposure. Durabak (durabakcompany.com) is said to be UV resistant, so fading should not be an issue. The company offers a wide selection of colors to match nearly any color preference. Perhaps the best part is that the Durabak coating can even be applied with a roller, keeping application and touch-up costs low.

Ford Front
In your opinion, what's the best way to build a front Ford 9-inch axle? I don’t need anything super fancy. I was thinking about using Dana 44 ball joint outers. I want a 5-on-5.5 bolt pattern. I want to hit the junkyard for a parts donor axle for the outers. Any suggestions? I originally built Spidertrax axles for my project, but I want to save them for a buggy now. I feel they'd be way overkill for what the Jeep will actually see on the trail.
Richard A Morgan
Via facebook.com/JohnCappa4x4

Since you have the experience of having already built a pair of heavy-duty 9-inch axles, assembling the Dana 44 versions should be a no brainer. There are several applications where you can get the 1/2-ton 5-on-5.5 outer axle bits you are looking for. Some are better for your application and easier to find than others. I think you should skip over the International Harvester parts. They are not as common and the bolt-on locking hub design is inferior to the internal-spline locking hubs found on other 4x4s of the era. The Dodge knuckle parts can be used. However, you should avoid the early unit bearing outers. Look for the ’80-’93 Dodge 1/2-ton Dana 44 front axle with internal-spline locking hubs. The Ford 5-on-5.5 Dana 44 disc brake outer axle parts can be difficult to locate, but they were available on ’77-’79 F-150 4x4 trucks and on the ’78-’79 Bronco. These feature the desirable internal-spline locking hubs. Another option is to convert a 6-lug 1/2-ton ’75-’91 GM disc brake Dana 44 or 10-bolt front axle to the 5-on-5.5 pattern. This can be done with factory off-the-shelf bolt-on parts. This is also true of the ’74-’91 Jeep FSJ Dana 44 front axle assemblies. The earliest versions of the Dana 44 came with the small-bearing spindles you need. The later axles came with large bearing spindles and will need to have small-bearing spindles installed. To complete the conversion you will need the inner wheel bearings, wheel hubs, rotors, wheel studs, and wheel seals from a ’79 Ford F-150. Other years will work, but I always use ’79. The outer wheel bearings, brake calipers, caliper brackets, stub axles, and locking hubs will come from your junkyard six-lug GM or FSJ donor axle.

Will It Live?
Do you think I could get away with 37-inch sticky competition rockcrawling tires on a 3,800-pound CJ-5? It has a Dana 30 front axle with chromoly ’shafts, Dana 44 U-joints, and a cryogenically treated 4.10:1 ratio ring-and-pinion. It’s propelled by an AMC 360 with an 87:1 crawl ratio. Do you think this combo would be broken down often? Obviously, we've all seen any axle break. I have made stock axles survive pretty reliably on 35-inch tires under heavy ’wheeling. The only issue I had was spitting out the tiny stock Dana 30 U-joints. I just figured that with sticky 37s I could use my crawl ratio and less throttle more often. I was hoping this actually may be easier on parts in the long run.
Evan Knapp
Via facebook.com/JohnCappa4x4

Stepping up to 37-inch tires from 35s can be quite the gamble in some applications. There are many things to take into consideration. Ultimately, the survivability of your setup totally depends on your driving style and the kind of off-roading you do. Based on the crawl ratio you’ve noted, I'm guessing you have the AMC 360 backed up to a T-18 manual transmission. The direct drive of the manual tranny can be harsh on drivetrain components. An automatic transmission would help the parts live longer because the torque converter cushions the blows to the metal parts. However, your crawl ratio would be substantially diminished without the addition of a transfer case doubler or some other method of gearing multiplication.

Having said all that, I think it's possible to make this combo survive. They key to this will be in how well you can avoid undercuts and ravines that pinch and grab a tire while in your lowest gears. Even at idle, the torquey AMC 360 will have enough oomph to shatter a Dana 30 axleshaft, U-joint, or gearset when backed up with an 87:1 crawl ratio and 37-inch tires. You’ll also have to keep from throttle-bouncing the Jeep on climbs. Careful, elegant driving will go a long way in making the components you have survive with 37-inch tires.

Full-Hydro Legal
I live in Colorado, and I’m currently in the process of building a Chevy Tahoe with a solid axle swap. The guy building it really wants to run full hydraulic steering as opposed to crossover steering with a hydraulic assist. I am worried about running full hydro for a number of reasons. Is it safe for driving on the highway? Is it street legal or not? What are the pros and cons? I can't really get a straight answer from anyone. Hopefully you can give me some insight on the laws of lifted trucks in Colorado. Even the police can't give me a solid yes or no answer. Thanks for your time. Hope to hear from you soon.
Adam Carr
Via facebook.com/fourwheelermag

Full hydraulic steering isn’t a new concept. It’s been used on heavy equipment, small tractors, and even larger rider mowers for decades. With full hydraulic steering there is no mechanical connection between the steering wheel and the front tires. It is a hydraulic connection. The traditional automotive steering column, rack-and-pinion, or steering box and drag link are replaced with what is called an orbital steering valve, high-pressure hoses, and a steering ram of some sort, which is attached to the axle and tie rod.

When assembled with the correct components, a full hydraulic steering system provides unsurpassed steering power in slow-speed off-road situations. However, it does have some drawbacks. Some drivers feel that full hydraulic steering can be a little too twitchy at speed, especially on the highway. Overpowered or poorly matched systems will offer very little steering feel and no return-to-center capability. The proper load-sensing orbital valve can help make a full hydraulic steering system more roadworthy and less twitchy.

Another drawback of full hydraulic steering occurs if the engine dies. The power steering pump will no longer be spinning and providing pressure to the system, so you will lose all steering control. However, many orbital valves have what is known as a Gerotor pump built in. This allows for some steering control without the engine running, but it’s very slow and difficult. Obviously, if a hose fails or the steering fluid leaks out or is contaminated, you lose all steering control.

Many off-road–vehicle builders prefer full hydraulic steering because it is much easier and less time consuming to install than properly mounting a steering box with correct suspension and drag link geometry. A poorly designed suspension, steering box, and drag link installation will cause poor handling and bumpsteer.

Another thing to keep in mind with a full hydraulic steering system is that the steering wheel will never return to exactly the same place with the wheels facing straight ahead. Sometimes it might be upside down, turned 90 degrees one way, 45 degrees the other way, or perfectly centered. This bothers some drivers, especially if the factory steering wheel is retained.

Now, is full hydraulic steering safe for the highway? That’s a less simple question to answer. If the system is properly designed, well put together, and you are used to the caveats of full hydraulic steering, it can be just as safe as a traditional steering box with mechanical linkages. However, I personally would not freely toss the keys to my mom or dad for them to try and drive it down the road. It will not drive or steer the same as a vehicle with a steering box.

Street legality is another cloudy area. As you have found, even well-informed law enforcement officers may not have an answer for you. In most states, there are no regulations regarding the specifics of steering system construction. This includes Colorado. However, it’s safe to say that if your steering system looks sketchy and causes the vehicle to wander unsafely down the road, you’ll likely get stopped by law enforcement.

If you plan to operate this 4x4 on the highway regularly, I highly recommend utilizing a steering box with a ram assist, rather than go with the full hydraulic steering system. If done properly, your 4x4 will handle more predictably on- and off-road, especially at speed.

Snow Tire Selection
I live on the Western Slope in Colorado. I have to drive to work early in the mornings and sometimes the roads are covered in snow because the plows haven’t cleared that section yet. I also like to take advantage of the nearby OHV trails. These can have dry, smooth rock in the summer, slick smooth rock in the winter/spring, thick sandy areas, and fine hard-pack dirt in the summer.

After doing some research online, I found that most tires are rated for “snow,” based on the idea (so it seems) that you will be doing full on snow wheeling. That’s not my goal with these tires. My goal is to do mild wheeling (exploring OHV roads and getting to mountain bike trailheads) and drive my 4Runner safely even when it’s snowing on the highway. So, what would be a good tire for these conditions when driving a midsized SUV like my ’01 Toyota 4Runner?
Eric McGrew
Via email

There are generally a few compromises that you have to make when selecting a tire to be used for on-road snow and general all-season off-roading. Many of us will typically steer toward the more aggressive mud tires. However, this is not a great idea if you plan to encounter regular snow and ice. Even though mud tires are often rated for mud and snow, there are better alternatives available. In most cases, an all-terrain tire will be your best choice. Given that snow and ice is a certainty, I’d recommend an all-terrain tire with the three-peak mountain snowflake rating, such as the BFGoodrich (bfgoodrichtires.com) All-Terrain T/A KO2. Very few tires receive the three peak mountain snowflake rating so search carefully.

If you plan on seeing some sloppy and slick mud conditions, you may want to consider a slightly more aggressive tire, such as the Goodyear (goodyear.com) Wrangler DuraTrac. It also has the three-peak mountain snowflake rating.

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