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Techline - Answers to all your 4x4 tech questions

Posted in How To: Tech Qa on March 20, 2016
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Photographers: Four Wheeler Archives

Clutched
My dad has a ’90 Ford Ranger with a 4.0L and five-speed. The truck has a solid front axle swap and gets wheeled fairly hard. It also tows trailers regularly. It has gone through two OEM clutches. What would be your recommendation for a good replacement clutch that would perform well and last longer?
RJ Jackman
Via facebook.com/JohnCappa4x4

Factory OEM clutches usually do a good job of transferring power from the engine to the transmission in stock applications. When you add a lift and larger tires, especially when combined with the stock axle gears, you can begin to run into trouble. Compound this with trailer towing and you are likely reaching the limits of the OEM clutch. The factory clutch is only able to produce a specific amount of clamping force. The added stresses can exceed that clamping force, causing the clutch to slip. This creates heat buildup in the clutch and flywheel, which leads to the clutch slipping even more. It’s a vicious cycle. Increasing clutch life in an application such as this requires that the clamping force of the clutch be increased. This can have its own drawbacks, such as a heavier clutch pedal. However, companies like Centerforce (centerforce.com) specialize in performance clutches with increased clamping force that don’t significantly alter the pedal feel. The company uses centrifugal weights on the pressure plate diaphragm to increase clamping force as rpm is ramped up. Another technology the company applies is the use of a dual-friction disc in some applications. A dual-friction disc distributes pressure plate clamping force evenly over a 360-degree friction-facing on one side of the clutch disc, while the opposing side uses a segmented friction-facing or puck-style clutch to maximize clamping pressure and increase clamping capacity.

For your application, the Centerforce II clutch with the centrifugal weights will likely be more than enough. For higher horsepower or more abusive applications you might consider the Centerforce Dual Friction clutch. As with any clutch install, you’ll want to have the flywheel resurfaced and inspected for cracks and other damage prior to installation. Since you are already in there, replace the pilot bearing and throwout bearing. Trying to save a few bucks by using the old parts could result in you having to pull the transmission a second time. Also inspect for any oil leaks. A rear main seal or intake manifold oil leak can contaminate the clutch mating surfaces and friction material, leading to a short clutch life. Repair any oil leaks in the area before installing your new clutch.

TBI Fueling
I have a Toyota with a swapped-in GM engine and TBI fuel injection. I’m trying to figure out what the deal is with pump pressures and the TBI internal regulator. How much pressure can the internal regulator handle? My stock four-cylinder fuel pump has enough psi, but I guess it does not produce enough volume to feed the new engine.
Ken Basile
Via facebook.com/JohnCappa4x4

The GM TBI fuel injection generally requires a minimum of 15 psi. The factory fuel regulator on most of these engines is set at about 12 psi. The good news is that you can’t overpressure the regulator, it will simply send the excess pressure and volume back to the fuel tank. Now, one of the more common mistakes I see people make with these systems is that they get lazy and try to use the stock fuel lines. This doesn’t always work out so well. The GM TBI works best with a feed line of 3/8-inch and a return line of at least 5/16-inch. Trying to use too small of a return line will lead to the engine running very poorly and unpredictably. It causes an overly rich condition that can be exacerbated by the use of an aftermarket high-volume, high-pressure fuel pump. However, in your case, I suspect the factory four-cylinder in-tank fuel pump is not able to keep up with the requirements of your swapped-in engine. You have a couple options: you could remove the stock fuel pump and replace it with one that produces the required pressure and volume, or you can completely remove it and install an inline fuel pump on the framerail. There are advantages and disadvantages to both options. An in-tank pump will usually live longer. It’s quieter and runs cooler because it’s usually submerged in fuel. However, if it ever does go bad, you generally have to drain and drop the fuel tank to replace it. This can be a real challenge in the middle of a trail.

An inline frame-mounted electric fuel pump has the obvious advantage of being easily swapped out in the event of a failure. It’s also much easier to replace an inline filter than it is to clean or replace the filter sock on an in-tank pump. This can be a reoccurring problem if the fuel tank is rusty or if it has contaminants like sand sloshing around in the tank. The disadvantages of an inline fuel pump are that it’s usually noisier, and it can overheat and destroy itself. This usually happens if you run it dry too often or have it mounted incorrectly. An inline electric fuel pump should be mounted below the bottom of the fuel tank. These types of pumps are not very good a sucking fuel. They are designed to be pushers, so they should be mounted as close to the fuel tank as possible. This helps create a siphon on the feed line to the pump. Also, in order to keep the inline pump from running dry, try to use a tall narrow fuel tank rather than a wide and long short tank. This will ensure that when the fuel sloshes, the fuel pickup is always submerged, instead of sucking air, which will shorten the life of your electric inline fuel pump. Other options include the installation of a sump in your fuel tank, installing a Holley (holley.com) HydraMat in the bottom of your tank, or adding a fuel accumulator to the system. Any or all of these will help your 4x4 run at nearly all angles regardless of fuel level and fuel slosh.

Now, as for the fuel pump. An inexpensive inline electric fuel pump that works well for GM TBI engine swaps is the Airtex (airtexproducts.com) PN E2000. It or its equivalent can be found at pretty much any auto parts store. The E2000 rollervane pump produces 30-40 gallons per hour at 70-95 psi. If you are running a more powerful engine or an MPI fuel injection, check out Walboro (walbro.com) part number GSL392. This inline electric fuel pump supports up to 650 hp and produces 50 gallons per hour at 80 psi. It’s totally overkill for most trail trucks, but it won’t have to work as hard as a lesser pump. Walboro installation kit PN 400-939 allows the GSL392 to be plumbed inline with 3/8-inch barb fittings.

Cryogenic Freezing
I broke my Suzuki Samurai transfer case in half and wasted my gears. I’m building a new billet aluminum case, and I want to have the gears cryogenically treated. Have you ever had anything cryo’d?
Clay Clawson
Via facebook.com/JohnCappa4x4

Cryogenic treating gears, axleshafts, and other components made a big splash in the off-road world about a decade ago. Unfortunately, the advantages don’t really outweigh the cost in most cases. Cryogenic treating won’t significantly increase the kind of strength you are looking for, which is shock loading. Cryogenic treating is best used in other applications. The process will increase the wear life of gear teeth, splines, or bearing surfaces because it helps the part resist abrasion. Of course there is a small strength gain, but it’s negligible. Cryogenically treating a part essentially makes wear-prone parts last longer and run cooler. It's a good option for rare hard to find gears, bearings, shafts and other parts that you don’t want to wear out.

If money is no object and you want the stock gears to be as strong as possible, by all means, have them cryogenically treated. You can find many companies online that do this kind of work. To really increase the durability of the gears, you might consider putting them through several processes. Shot peening is said to increase strength by up to 30 percent. Micro polishing won’t really increase the strength, but it will reduce stress risers, help the gears shed oil better and allow them to run cooler. If nothing else, you’ll be able to rest at ease that you did all you could to keep the gears alive. If all else fails, throw more metal at it and swap to a larger transfer case.

Rust Away
What is the best way to protect the undercarriage from rust? We like the beach!
Ronnie Longoria
Via facebook.com/JohnCappa4x4

The best way to stop rust is to stay away from the beach. Unfortunately, there really is no way to completely stop rust from forming. The problem is that it is nearly impossible to get a coating or oil over every surface that salt water can wick its way into. Gotta love science and capillary attraction. But if avoiding the beach or salted winter roads is not an option, there are a few things you can do to slow (not stop) the rusting process of your 4x4. The first step is getting the salt off. Immediately after every beach or salted road run, you should thoroughly rinse off the entire vehicle with fresh water. Don’t be fooled by car washes that offer an undercarriage blast. Not only will this not clean your 4x4 well enough, in many cases these wash systems recycle water. That means that every other person washing their car is putting salt in the system. So you’re probably blasting salt water into places that there wasn’t any before. This is truer of automated car washes in winter-affected states, but it could certainly be an issue with car washes near the beach too. The next step is to make sure it stays dry. Park the 4x4 in a garage or at least a dry barn.

There are many different coatings and sprays available to inhibit rust. Any of them will do a decent job if you keep the undercarriage clean. Regularly spraying the underside with something as simple as WD-40 (wd40.com) will help keep rust at bay. The WD-40 Big Blast can will cover large undercarriages quickly. Mavcoat Steel Shield (mavcoatsteelshield.com) is another good option. It will last a lot longer than WD-40. Mavcoat is a polymer film that is sprayed on and dries. It leaves a clear coating with a slight dry tack that does not drip. It isn’t really a paint though. It’s said to withstand the extreme environments and harsh conditions found in applications such as, off-roading, landscape tools and equipment, irrigation, metal fabrication, and welding. It can offer up to six months of corrosion prevention. Obviously, you’ll want to avoid spraying the brake rotors. Any oil or other contaminants on your brakes is bad and will significantly harm braking performance.

Solid Axle Dakota Swap
I got a ’97 Dodge Dakota as my first 4x4. I want to do a solid axle swap. The truck has an 8.25-inch rearend with a six-lug pattern. I was thinking about getting a set of axles from a Jeep Cherokee of the same era. Would I be able to use the Dana 35 rear axle from the Cherokee? What other parts and modifications would I have to do to have a successful swap? I would like to use the coil springs from the Jeep if that would be possible.
Ian Allen
Via email

A solid axle swap can be done on a Dodge Dakota using several different axles. Keep in mind that this is not a bolt-in conversion. There will be a lot of cutting and fabrication required, so you should have great welding and fabrication skills before attempting to make a safe conversion.

The XJ axles are about the same width as the axles under your Dakota, so it’s a doable swap. However, the Dana 35 is a bit of a downgrade from the 8.25-inch rear axle in my opinion. Why not find an XJ 8.25-inch rear axle instead of the Dana 35? It will have the same matching 5-on-4 1/2 lug pattern as the XJ front axle, yet it will be more durable than a Dana 35. Another option is to locate the 6-on-5 1/2 lug front and rear axles from a ’80-’91 Wagoneer. These are even more heavy-duty than the XJ axles. The ’80-’91 Wagoneer came with an AMC 20 rearend with large robust axletubes. Up front is a stout traditional fixed-spindle Dana 44. These axles are easily 1/2-ton rated. I have also seen the Ford 9-inch rear axle and Dana 44 front axle from an early Bronco used in a Dakota swap like this, although these axles are uncommon and usually more expensive.

As for the ability to utilize the XJ coil springs, yes, it’s possible, but it adds a lot of complexity to your project. If you have not done a suspension conversion like this before, you will likely be better off sticking with leaf springs. I don’t know of any conversion kits to make this swap on your truck, but you may be able to adapt a solid-axle swap kit designed for a Chevy S-10 to work on your Dakota. Off Road Direct (solidaxleconversions.com) and Sky Manufacturing (sky-manufacturing.com) both offer do-it-yourself solid axle swap kits for the S-10 that may be adaptable to your application. The kits use leaf springs though, not coils.

Companies such as WFO Concepts (wfoconcepts.com) do custom fabrication work. The company has done a solid axle swap on a Dodge Dakota using links and coilovers. It certainly wouldn’t be an inexpensive endeavor to go that route, but you can certainly look at the company’s work on the website and borrow some ideas for your own conversion.

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