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April 2008 4x4 Tech Questions - Techline

Send Us Your 4x4 Questions

Question: I've got a question about headers for an '06 Dodge Ram 1500 4x4. I am thinking about replacing the stock exhaust manifolds on my Ram with headers. The only thing slowing me down is my lack of knowledge of the difference between shorty, mid-tube, and long-tube headers. What would be the best for a truck that is daily-driven?

The Ram already features an AEM intake and a Flowmaster Super 40 exhaust. In my mind the long-tube headers sound like they will hang too low, and the shorty headers might need some extra add-on pipe to get to the existing Y-tube. Is the mid-tube the answer for a direct replacement? What are the advantages of each type?
Nate Richmond
Huber Heights, OH

Answer: As a general rule for street and off-pavement performance, you want to go with small-diameter tubing, and the tubes should be as long as possible without interfering with any of the driveline components, as well as going into a long collector. The small diameter of the tubes keep the flow speed up, and the long tubes prevent the gases from a reverse flow under negative pressure waves. My opinion is that there is not a lot to be gained with short-tube headers. On a previous Dodge project vehicle, we put some very nice, and expensive, short-tube headers on the 360ci motor and in reality I felt that it was a waste of time, effort, and money for the little we gained in performance.

Naturally, long-tube headers will cost more because of the fact that there is more material, and a lot more time in the design. Long-tube headers sometimes can be a real pain to install, and in some instances it is even necessary to take off a motor mount and slightly lift the engine in order to gain installation clearance. The shorter the overall length of the header, the easier it is to install.

The Flowmaster 40-series muffl ers are an excellent choice. They will give some great sound and are great for a truck that sees off-pavement use as they are quite solidly built.

Question: I currently own a '97 Chevy Z71 and I have a set of older Rally rims off of an '86 fullsize Blazer. I was wondering if I will need a lift to clear a set of 32-inch tires.

I was hoping to go no higher than maybe a 3-inch body lift, if any at all, because this truck gets used a lot hauling trailers and also a slide-in camper.
Craig McKenzie
Carthage, NY

Answer: I know that the Z71 package carried a lot of options that were grouped together, and one was a higher ride height of about 2 inches. This should allow plenty of room for the 32-inch tires, and in fact most likely the tires on the truck in a metric size are pretty close to 32-inchers.

The wheels off the Blazer have a backspacing that was designed for a solid front axle. The IFS wheels have a lot more backspacing. In other words, the Blazer wheels will stick out past the fender opening and put more load on the suspension and steering components. There also may be a clearance issue around the front brake calipers, but perhaps not because of the backspacing. I asked Dennis Franklin of Franklin Tire and Suspension in Yuma, Arizona, for his opinion on such a wheel swap, and this is what he had to say:

"The old-style Rally has 4 inches of backspacing, and the 16-inch Z71 has almost 6 inches of backspacing. One must also keep in mind that the Z71 wheel is 7 inches wide and the 15-inch Rally wheel is 8 inches wide. Combine these, and it means that the center of the tire will stick out 21/2 inches beyond what the factory intended. To make matters worse, the scrub angle goes to pot, causing the tires to slide around a turn. Not good for long or smooth tire wear.

"The factory tire was a 32x10.50R16. You can put on a 32x11.50R15; just make sure that you trim the fenders both front and rear because the tire will now swing in an arc, taking up more room in the fenderwell.

"Oh yes, and your friendly frontend man will love you too. Whenever you tweak up the torsion bars a little, and add high-offset wheels and tires, this then causes the idler arms and pitman arms to go south before winter, and the upper ball joints and control-arm bushing will also be very unhappy. Not a very good idea to swap wheels, in my opinion."

If you should decide that you want more tire clearance, I wouldn't recommend a body lift if you plan to use a slide-in camper. Using body spacers under the bed would perhaps put more of a leverage load on the mounts than they were designed for.

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