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November 2008 4x4 Truck Tech Questions - Tech Line

Willie Worthy | Writer
Posted November 1, 2008

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Techline Four Wheeler
6420 Wilshire Blvd.
Los Angeles, CA 90048.

All letters become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department also can be reached through the Web site at www.four Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

Lift Or Leveling For HD Ram?
Question: I have an '00 Dodge Ram 2500 diesel and I am planning some upgrades on the suspension system. I do not intend to lift the truck more than necessary for proper wheel travel. When I read Four Wheeler's article about the Baja Bomber, I thought that was it. Here is the perfect system for me. But after contacting KORE Racing and getting the price, I decided to rethink the project: $6,000 U.S. is a bit on the high side, especially considering that the price almost doubles for the import to Iceland.

Therefore I am wondering if you could guide me in the right direction by doing it a bit cheaper. What I am mainly thinking of is to improve the suspension in the prerunner direction. I am not going to race the truck, but I would like to be able to keep a good speed on the rough tracks. Furthermore, I also travel with a slide-in camper now and then, and am thinking about using airbags to compensate for the extra weight. I am used to doing all the work on my trucks, and I am able to build most things myself.
Stefan Gunnarsson
Hafnarfjordur, Iceland

Answer: Having a slide-in camper changes the whole picture of things when it comes to a suspension lift for your truck. I assume that it is a large camper if you are considering using airbags to handle the extra weight. My suggestion is that you go to one of the "leveling kits" that most aftermarket suspension companies offer. This is nothing more than a large thick spacer that fits between the top of the coil spring and the spring tower. I think that these come in about a 2-inch (or so) lift. Now your truck will sit level when empty and not have that tail-high attitude. However, when you put the camper on, the headlights will be looking for owls and the tail end will be down.

The airbags would be a great solution to both level out the truck and to gain a bit of lift. I would suggest a quality set of shock absorbers to handle the higher center of gravity when the camper is on. We used this combination back in '96 and '97 on our Dodge Project Rammit and it worked out quite well, and yes it carried a cabover camper.

Causes Of Tahoe Driveline Noise
Question: My '03 4x4 Tahoe has a whoomp-whoomp sound in the front drivetrain. It sounds like a helicopter rotor when stopping at low speed to accelerating from a low speed. It's either the four-wheel-drive hub on one side or the 4x4 transfer case in the middle.
Oak Harbor, WA

Answer: Noises like this are hard to diagnose through the mail, but I am pretty sure I have an answer to this one. This noise may be caused by a low clearance condition within the differential in the front axle assembly. In 2WD mode, the front differential has a large amount of relative motion between the differential pinion and side gears. In the 4WD or Auto 4WD modes, the transfer case turns the front propeller shaft, and the relative motion between the differential gears is reduced or eliminated, so the noise is eliminated. The solution is to have your dealer replace the front differential case with PN 26018131. In case the service manager questions you on this, have him look at Technical Service Bulletin Number 03-04-19-004B, dated December 12, 2005, that covers this problem.

Newer GM Engine Into Older GM Truck
Question: I am rebuilding an '84 GMC 1/2-ton fullsize 4x4 pickup with a standard transmission that had caught on fire at one point with a prior owner. I have a donor pickup: a 2WD '91 GMC Sierra C-1500 automatic that has fuel injection. Is it at all possible for this engine to swap over to my '84 GMC? And what are some of the same parts that I can take off the '91 that will fit the '84?
Clint Kartchner
Mule Creek, NM

Answer: Sure, it's possible to make the engine swap, but you had better be an expert at wiring, as that is where the work is. You can use the standard transmission along with a new computer designed for a standard trans or the automatic trans with an adapter from, say, Advance Adapters. I suggest that you contact Painless Wiring for a new replacement wiring harness.

What else you can use off the truck? That depends on what you are swapping. Some stuff may take just some simple adapting, while others may not be worth the effort.

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