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March 2008 4x4 Tech Questions - Techline

Posted March 1, 2008

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Question: I have a '75 Ford F-250 four-wheel-drive with power-assist steering. I've heard that a GM gearbox is an easy conversion to power steering. Could you tell me what year or type of gearbox to use? My guess is a box from a '67-'72 truck, but I'm not sure.
Tim Koller
Stillwater, MN

Answer: Every year or so, I get a question similar to yours on how to solve the power-steering problems associated with the ram assembly on the early Fords.

One of the nicest kits I have ever seen comes from Benchworks Steering Systems (480/946-3992, www.benchwork steering.com). While on the pricey side, it has everything you will need so you don't have to go out searching for parts and pieces that may or may not be right. This complete kit includes a rebuilt 16:1 ratio Ford power-steering gearbox (14:1 is also available). Everything is included from the column to the steering arm on the axle-which means the intermediate shaft, gearbox, pitman arm, drag link, a bolt-on bracket to mount the gearbox to the frame, all the hardware, and factory-style hoses.

Question: I have a '92 Chevy K-2500 with the 350 V-8 and 4L80-E tranny. I just put a front differential in it. When it's on jackstands in two-wheel drive, the back tires move. When in four-wheel drive, all tires move. When in 4-Lo and 4-Hi, the tires are moving. When I shut the truck off, grab the front tire and spin, the front driveshaft also spins. However, driving down the road in two-wheel drive, the front shaft now spins.
Jason Speck
New Kensington, PA

Answer: If you look on the passenger side of the vehicle coming off the differential case, you will see that there is a difference from the driver side. That is because there is a thermal-operated inner axle disconnect mounted here. When you shift into four-wheel drive, a switch on the transfer case directs 12-volt power to a heating element that in turn causes a gas to expand and pushes a shift fork that locks the axle to the differential. For whatever reason, your shift fork is constantly engaged. It could be for some reason that the switch that sends 12 volts to the thermal actuator is constantly on, but I kind of doubt it. More than likely someone didn't put things back together properly when the differential was replaced.

Question: I have an '88 Jeep Cherokee with the 4.0L Six. I want to put a Chrysler 440 V-8 and a TorqueFlite tranny in it. Is this realistic? Does anyone make motor or transmission mounts for this? Since I only use rear-wheel drive, what do I do with the front axle? Any other problems that you can see?
Art
via fourwheeler.com

Answer: Well, anything is possible if you have enough time, money, and expertise. Before you even think anymore about this project, find a local used-car lot that has a '90s ZJ Grand Cherokee with a V-8 in it and take a good hard look. The engine compartment was designed for the V-8, and as you can see, it's a darn tight fit.

The Cherokee XJ's engine compartment is a lot smaller than the ZJ's, even though the front suspension is almost identical. You will find that the 440 engine is 3 inches taller, 4.5 inches wider, and a bit longer than the 318 that was used in the Grand, and it weighs in at 670 pounds versus the 318's 550 pounds. All of the components to do this conversion, such as motor mounts and radiator mounts, will have to be custom-fabricated, so it's not going to be an easy task. I have seen some small-block Chevys in XJs, and they are a pretty tight fit.

As to what to do about the front axle, well, I think that would be the least of your worries. Jeep actually offered the XJ in a two-wheel-drive version. The front axle was nothing more than a large piece of straight tubing with the steering knuckles and components from a 4x4 version. All the mounts and control-arm brackets are the same. If you can't find one of these axles, I would think that someone who is capable of installing a 440 engine in an XJ would also be capable of building an axle using the 4x4 components minus the axleshafts and differential housing.

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