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

Posted in How To: Tech Qa on March 6, 2019
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Brake Valve

I’m a longtime subscriber to Four Wheeler and I can’t wait for every new issue. I’m rebuilding a ’96 Toyota Tacoma. I replaced the frame and I’m putting a four-link under the rear with ORI struts. There’s a valve on the rear brakes, but I don’t know what it’s called. It changes the rear braking via a lever that moves with the weight on the truck. I want to eliminate this valve because of the longer travel and it’s kind of ugly. Could I use a proportioning valve from an older S-10 without ABS or install a manual adjustable valve on the rear brakes?
Larry Brownlee
Via facebook.com/fourwheelermag

The valve on the rear brakes of your Toyota Tacoma is often referred to as a proportioning valve or pressure reducing valve. Similar valves can be found on the rear of most Toyota trucks. The valve is plumbed into the rear brake line and mounted to the frame. A small control arm routes down from the valve to the rear axle. As a load is added to the bed of the truck, the suspension compresses and the axle moves closer to the valve. This causes the arm to open the valve, increasing available rear brake line pressure. The design of the valve is intended to make use of the increased tire traction afforded by a heavy load in the bed of the truck. When the bed is empty, less brake pressure is required before the rear tires will skid and slide.

Because you are building a four-link with air struts, you are likely not as interested in load carrying capacity as the OE manufacturer. The valve is very adaptable to most suspension designs, but if you choose to remove it, you can replace it. If you’ve switched to rear disc brakes from drum brakes, you’ll likely want to replace it anyway. The OE drum brake proportioning valve won’t be ideal with disc brakes.

There are many different aftermarket adjustable proportioning valves that can be plumbed into your rear brake line. Companies such as Baer Brakes (baer.com), SSBC (ssbrakes.com), Strange Engineering (strangeengineering.net), Summit Racing (summitracing.com), Tilton (tiltonracing.com), and Wilwood (wilwood.com) offer adjustable proportioning valves that can be tuned to meet the rear brake pressure needs of your Toyota. The adjustability will come in handy as you make other modifications and improvements including larger brakes, bigger tires, or an increase in overall weight. You’ll need to do some hard brake testing on different surfaces to find the adjustment that works best for you. There are also some off-road scenarios where you’ll want the rear brakes to lock up before the fronts, so you might want to draw indicator lines on the proportioning valve adjuster for each setting. If you like the idea of multiple settings, Tilton and other companies offer lever-style proportioning valves with up to seven preset adjustments and a maximum line pressure reduction of 50 percent.

FJ Jounce

I know Four Wheeler has tested the Bilstein 8100 series shocks. I’m thinking of going with the Bilstein Tacoma 8112 front coilover shocks and 5160 rear shocks on my ’14 FJ Cruiser. What’s your opinion on them? Anything I should I know about before I plunge in?
Tia Akif Altaf
Via facebook.com/fourwheelermag

You have a solid plan with one hiccup. The Bilstein (bilstein.com) 8112 and 5160 shocks will do a much better job of damping the suspension of your FJ Cruiser off-road than the stock shocks. They will also shed the associated heat much quicker and are less likely to fade than the factory shocks. However, even though the Tacoma and FJ Cruiser front suspensions are similar, their differences are great enough that you could run into some fitment issues on the Bilstein front coilover shocks. We reached out to Bilstein to get the full scoop. We were told the Toyota Tacoma shock is basically the same, but the main issue is the remote-reservoir placement. The Bilstein 8112 reservoir placement for the Tacoma won’t work on the FJ because of how the sway bar sweeps. Also, the Tacoma reservoir mount attaches to a Bilstein sway bar bracket drop spacer, and that spacer will not bolt onto an FJ. The FJ/4Runner 8112s also have a much different reservoir mount position and a different hose configuration to accommodate the vehicle.

There is some good news though. Bilstein just finished with the 8112 4Runner product development. Theoretically, this should carry into the FJ application, although Bilstein has not actually installed one yet at time of print. Our sources say they are 95 percent sure the 4Runner 8112 shocks will fit the FJ Cruiser too. The ETA on the 4Runner 8112 shock kit is around 6-8 months. The company will also be releasing a rear two-tube bypass shock at the same time, so it might be worth it for you to wait for the proper-fitting parts.

Hydro-Boosted

What vehicles have the hydraulic (not vacuum) hydroboost power brakes from the factory?
@seedless61
Via Instagram @cappaworks

Swapped-in hydroboost power brake systems are increasingly more common, as engine compartments have become more cramped and diesel swaps, more-aggressive camshafts, and bigger tires have increased in popularity. The easiest place to find a hydroboost system is on some diesel vehicles, including the GM square-body 6.2L diesel trucks; however, hydroboost brake booster systems can also be found on some ’99-’04 Ford Mustangs, some ’03-’07 GM 1/2- and 3/4-ton vehicles, some ’97-’00 GM 1/2- and 3/4-ton vehicles, some ’90-’93 GM Safari and Astro vans, and some ’75-’76 Ford Thunderbirds and ’77-’79 Lincoln Mark IV and Vs, among many other applications. If you don’t want to search the wrecking yards and gamble with a used part or worry about modifying the part to fit, you can purchase new aftermarket bolt-in hydroboost brake booster kits from companies like Speed Manufacturing (powerbrakeservice.net) and Vanco (vancopbs.com). These kits can save you a lot of trouble when fitting hydroboost brakes to your 4x4 since the companies have already done the homework and necessary fabrication. You can also try Summit Racing (summitracing.com). The company offers complete hydroboost brake boosters mated to brake master cylinders.

HD Hummer H3 Steering

I need heavy-duty steering tie rods for my ’07 Hummer H3. I want them to be the same length as stock, but I need much stronger tie rods. All I want to change on the truck are the tie rods and nothing else.
Name withheld
Via email

As you and many others have found, the factory tie rods can be a weak link on the Hummer H3. They can be a problem even on otherwise-stock Hummer H3s when driven aggressively off-road. Problems usually arise when climbing hills or during general aggressive high-load, heavy-throttle attacks in four-wheel drive. The traction afforded by the large factory tires forces them to toe inwards, often resulting in tie-rod failure. There are many different companies that offer heavy-duty tie rods for GM applications, but the H3 does not enjoy the same abundance of aftermarket steering support. However, Outfitter Design (outfitterdesign.com) does offer heavy-duty bolt-on tie rods for your H3. They are designed to replace the factory 14mm or 16mm tie-rod assemblies. They are machined from 1-inch-thick 1144 hexagonal steel. Each tie-rod kit includes two inner tie-rod ends, two solid powdercoated adjuster sleeves, two outer rod ends, four jam nuts, two Disc-Lock nuts, and one tube of red thread-locking compound. The new tie rods are said to provide an OEM fit, allow for full suspension travel, and maintain factory steering geometry.

If you want something a little more custom, companies such as EMF (emfrodends.com) and JD Fabrication (jdfabrication.com) can custom-build heavy-duty GM and Hummer IFS tie-rod assemblies.

Expedition Explorer

I was in contact with you a while ago. I sent a pic of my old Ford Explorer with the rear modified like a mini RV. Since then I have done Easter Jeep Safari at Moab and found out what the old Ford can do against the Jeeps. On 3D there were 32 Jeeps and one Ford! I stayed with the Jeeps without problem. The problem I have is what to do with the IFS frontend if I don’t want to convert to a solid front axle. I have a Dana 35 IFS in my front end and I wonder what can be done to strengthen it. Will a Dana 44 IFS from a later-model F-150 work? I haven’t seen anyone tackle an IFS setup, only lots of solid front axle swaps. If I needed a solid front axle I would probably get an F-250 and go from there. The old Explorer has 225,000 miles on it and an Eaton Detroit Truetrac in the rear. It does OK, but I would be interested in seeing what I can do, if anything, to improve on the IFS frontend. Originally, I tried to get a locker for the front axle, but nobody seems to make one for the Dana 35 IFS. I wanted a selectable locker, as I know better than to try a drop-in lunchbox locker.

I mostly use the Explorer for overlanding and it does very well there. I’ve redone the rear quarters area. I have a son-in-law that is a finishing carpenter and I recruited him to do the rebuild. For long distance off-road I have a 12-gallon Titan auxiliary fuel tank. It gives me 29 gallons overall. I want to explore places like Alaska.
Name withheld
Via email

Unfortunately, there really isn’t a lot you can easily do to effectively upgrade and strengthen the Dana 35 IFS under the front end of your Ford Explorer. Adding a locker of some sort will most certainly help you find the weak link in the assembly, which would likely be the axlehousing, CV shafts, or the steering system. Trying to shoehorn a larger IFS axle assembly into your factory suspension system will open up a whole can of worms. Although, if you were into heavy suspension fabrication and interested in extending the width of your Explorer, you could try and dabble with the Dana 44 TTB from an ’80-’96 fullsize Ford F-150 or Bronco. It would require extensive frame, suspension, and steering modifications, but if done properly the result would be a significant increase in wheel travel and overall axle strength. You’d also be able to add an ARB (arbusa.com) Air Locker to the TTB Dana 44 frontend.

Now, if you simply want to improve the wheel travel and keep the basic suspension design you have, companies such as BTF Fabrication (btffabrication.com) and Dixon Brothers Racing (dixonbrosracing.com) offer long-travel A-arm suspension kits for your 4x4 Ford Explorer that will nearly double the wheel travel, offering a much smoother ride over rough terrain. Keep in mind that these long-travel suspension kits cost more than a used Ford Explorer, so it may not be a viable option if you are on a budget.

F-Series Non-Swap

I have a ’72 Ford F-250 with good 4x4 axles and a blown motor. I also have a ’80 Ford F-250 that has a good motor, but the front axle doesn’t have functioning four-wheel drive. Should I just swap the ’72 axles into the ’80 F-250? If not, what do you suggest I diagnose first on the ’80 front axle to get functioning four-wheel drive?
Thanks for any help you can give!
Eric McGrew
Via email

Unfortunately, the ’72 Ford F-250 front axle won’t be a good swap into anything, including your ’80 F-250. The axle is better left in the ’72 F-250 where it currently resides. It features undesirable closed steering knuckles and drum brakes. The closed-knuckle axles house smaller, weaker U-joints than the comparable open-knuckle axle counterpart. It’s just an antiquated design. This axle is also a low pinion, which will reduce the driveshaft ground clearance on your truck. The better option is to repair the front axle of the ’80 F-250.

If the truck has an unknown history, start by crawling underneath to make sure there is a front driveshaft and that it’s attached to the transfer case and front axle properly. If you can, safely raise all four corners of the truck on jackstands and shift the truck into four-wheel drive. The rear tires and the front driveshaft should spin with the engine running and transmission in gear. If not, you have a transfer case problem or you are not shifting the transfer case properly. Next, check the axles at the steering U-joints. If they are spinning but the wheels are not turning, there could be a broken stub axle or a broken locking hub. If the steering U-joints are not spinning, you may have a broken inner axleshaft, ring-and-pinion, or differential.

Broken auto- and manual-locking hubs are pretty common, so you might want to start here regardless. In a stock application, the 4x4 hubs are usually the first front axle component to fail under abusive conditions. You can check the locking hubs by removing them to see if they are operating properly. If the locking ring in the hub is broken or missing, you’ll need to replace the manual-locking hubs. Auto-locking hubs are typically much more problematic than manual-locking hubs. Companies such as Warn (warn.com) offer quality replacement aftermarket manual-locking hubs for most applications.

If the locking hubs look good, then you can disassemble the wheel bearings and remove the spindles to inspect the stub axles. Replace any broken parts or worn seals and bearings during reassembly.

If you have diagnosed the problem as something internal, remove the differential cover to drain the oil. If the oil is full of large metal flakes or metal chunks, you’ll need to dig deeper and check for broken teeth on the ring-and-pinion and differential gears. If the gears all look good, remove the front axleshafts and check them for breakage.

Replacing manual-locking hubs or a front inner or outer axleshaft is a fairly easy operation, but installing a new ring-and-pinion or differential will require some specialty tools and gear setup experience.

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