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January 2007 4x4 Tech Questions - Techline

Posted in How To: Tech Qa on January 1, 2007
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Four Wheeler
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Los Angeles, CA 90048-5515.

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Question: I have a '96 Chevy Silverado pickup that I want to make the hood tilt forward like I have seen on show trucks. Does anyone make a kit for this type of a conversion, or does it have to be custom built?
Ray Patterson
Little Rock, AR

Answer: There's a company called Stylin' Concepts (800/434-4975, that offers a front tilt hood for '88-'98 GM fullsize trucks. The company also offers some other pretty weird stuff like suicide-door conversions, where the doors are hinged from the rear instead of from the front. (The "suicide" comes from what would happen if the door should open while traveling and you try to grab it and hold it closed; the wind movement will catch it and pull you out the door.)

Question: I recently converted my '98 Dodge 1/2-ton to '03 AAM 1-ton differentials, and all is good except the brakes. I can't get pressure when the vehicle is running. Do I need a conversion part or to fabricate something? Nobody seems to know. Can you help me?
P. Belanager

Answer: Do I understand right that the brakes work fine when the engine is not running, and will stop the truck when it is coasting downhill with the engine off? When you say you can't get pressure, does that mean that there is no line pressure to the calipers at all? Have you checked this with a pressure gauge at each wheel?

Did your '98 1/2-ton have disc brakes on the rear? My guess is that the master cylinder you're using does not produce enough volume and pressure to make the much larger disc brakes from the 1-ton axles work properly. The simple solution seems to be swap out the master cylinder from the donor truck that supplied the axles.

Question: I am not sure that the timing marks on my engine are correct due to the fact that it was assembled from various parts from different engines. There must be a way to check to see if the mark on the pulley is lined up correctly with the timing mark on the block when the engine is at top dead center. Can you help me out on this?
Phil Hanson
Boulder, CO

Answer: Here is how I find a true top dead center to make sure the crank pulley is lining up with timing mark.

First, I pull the plug and bring the motor up on the compression stroke and then screw in a positive stop for the piston to hit up against (you can make one from knocking out the center of a spark plug and brazing in a bolt that is a bit longer than the tip of the plug was), though the one I have is adjustable. Turn the engine over by hand until the piston hits the stop.

It's a lot easier if you pull out all the spark plugs to eliminate compression. Make a thin mark on the pulley in line with the timing tab. Turn the engine over the opposite way by hand and again mark the pulley. Now, the center distance between the two marks will be top dead center when you pull the stop out, and hopefully will line up with the factory mark and timing tab. There is always the chance of some piston rock, depending on how off center the stop hits the piston top with this method, so don't push the piston up too hard. While it's not as accurate as if you had the head off and a depth mike across the top of the block, it will be pretty close.

Question: What is with all of the hype about filling your tires with nitrogen? How can all of the bold claims that are advertised be true? Considering the fact that the air that we breathe (and we run through our compressors) is about 80 percent N2, where are all of the benefits coming from? The only difference that I can think of would be the possibility of getting very wet air from some sources.

Another similar question would be from the use of CO2, as from a popular trail accessory such as a Power Tank. This gas is much heavier than air or nitrogen. Could that cause any negative effects from its use?
Chris Lefevre

Answer: That is a great question, and while I have been using CO2 for some time now and have even written a "Willie's Workbench" on the subject (June '06), about the only thing that I know about N2 is that a lot of race cars use it. I gave Steve Sasaki of Power Tank (www.power a shout for help. He got back to me with some interesting information. It seems he was in the process of doing some testing on the very subject and was nice enough to share some of his information with me. He said that when he was finished with his testing, the completed information will be on his company's Web site. But for now, here is what he had done.

He took three equally sized bottles and filled them with N2, CO2, and air at 40 percent humidity and subjected each one to four different stages of temperature changes with interesting results. OK, his tests were more on the practical side than what a true scientific lab would use, but for our purposes, I would say they offered a reasonable amount of accuracy.

Pressure (psi)
Surface Temperature N2 CO2 Air *
-11 F (freezer) 40 40 40
86 F (office) 52 53 53
105 F (sun) 55 55 56
117 F (direct sun) 56 56 {{{57}}}
*Air at 40% humidity

Steve's conclusions so far are: "Low Pressure Expansion Test: So what kind of pressure differences would we see in passenger-car and light-truck tire pressures over a 128-degree temperature swing? The results show nearly identical thermal expansion rates for the three different bottles, showing that N2 as a tire-inflation gas is not appreciatively more stable than CO2 or air within the pressures relevant to automotive tires. We saw a 1 psi pressure change for every 8-degree temperature change."

You did bring up a good point as to moisture content of air. The CO2 and N2 contain no moisture. If you were constantly refilling your tires in an area of very high humidity with air, then in theory you could collect a considerable amount of water in the tire that could cause balance problems and rim corrosion.

This would be just one of the advantages of CO2 or N2 over natural air. It's also my understanding that the molecules that make up both CO2 and N2 are larger than O2 molecules. Tires will lose air over time, due to the fact that they are not a perfectly sealed envelope due to the porosity of the rubber. With CO2 or N2, the loss would be less over a given time period. How much less remains to be seen.

Question: I have an '85 4Runner, with the 22RE engine and automatic transmission. I just recently put a Wagoneer Dana 44 in the front, and I plan on running 37-inch tires. I ran 35s on the Toyota axle for more than a year, but I want lower gearing with the 37s. Do you know the name of the company that sells the adapter for the automatic to run the manual transfer case? I would like to go with dual cases with my automatic
James Nichols

Answer: It's not a real popular swap, plus it's a lot of work-but I guess if you're stuck with the auto shifter and don't want to swap over to a standard trans, you don't have much choice. There is a company called Inchworm Rock Walking Gear (925/766-6555, that does indeed have the adapter you're looking for. It took a bit of engineering to develop it so the price reflects that work. It allows the use of Inchworm double transfer-case adapters and geared cases behind your automatic utilizing the 23-spline input shaft, and allows stock rotation of up to 10 degrees for added ground clearance. This adapter does require a complete teardown of the factory automatic transfer case as well as some small parts-changing inside the transmission.

Question: I have a '66 F-250 4x4 that I am restoring. (Actually, it was my grandfather's truck that was passed on to me a couple of years ago.) I would like to restore it back to as original condition as possible, especially since it only has 67,000 original miles on it. Mechanically and bodywise, it's really sweet, but my problem is that it was in a wreck some years ago-OK, lots of years ago-which took out the grille, the radiator, and the fan shroud. The radiator was repaired by a local shop. But I can't seem to locate a grille or a fan shroud. I have this high phone bill I can show you from calling wrecking yards across the country trying to find these parts. I've been a longtime reader of your column and you come up with some great solutions to problems, so can you help me?
Mike Randal
Syracuse, NY

Answer: I almost gave up on finding those parts for your truck, as I figured Ford didn't build a lot of F-250 4x4s back in 1966. Then it came to me that the grille must be the same as the F-150 4x2, and maybe even the shroud. But then again, it would be quite difficult to find a 40-year-old grille and fan shroud in a wrecking yard, as you have obviously found out.

I started searching for new reproduction parts and came across National Parts Depot in North Carolina (800/874-7595). Seems that they have just about every part down to the correct nuts and bolts to build almost new Fords from '48 to '98, and they do have the F-150/F-350 '65-'66 grille, as well as a fan shroud. The grille is a bit pricey, due to the low volume sold, at around $480 includes shipping, but my guess is that it's your only choice. The radiator shroud is under $120.

Question: I have an '89 S-10 Blazer with 215,000 miles on it that runs fine. I would like to do about a 6-inch lift and run some 33-inch tires on it. Would this be a good project? I would like to keep it at around $1,500 or so, and my main objectives are trails and mud in the Uwharrie National Forest in North Carolina.
Michael Chalflinch
Julian, NC

Answer: Both Rough Country and Superlift offer only a 2-inch lift kit for the '83-'03 S-10 that is achieved with new torsion-bar adjuster arms and new upper control arms, but combine this with a 3-inch body lift, and you should be able to run 31-inch tires. This will keep you right in your budget range.

Trail Master does its kit a bit differently, with a differential drop bracket to maintain close to the original CV-joint angles, and it gives you 5 inches of lift to also be able to run 31-inch tires.

Perhaps, combined with a 2- to 3-inch body lift and some fender trimming, you could get 33-inch tires in the fenderwells, but it will be close. This kit is about $1,300, so that doesn't give you much left over for tires and wheels. You will also need to make a speedo correction for everything to work right. A Superlift True Speed speed sensor is about another $200.

Question: I wheel a modified '03 Jeep Wrangler Rubicon including the "Fool the Factory" locker safety bypass switch. My question is about the operation of the auto trans when in low-range. I have noticed I am still able to use the overdrive gear in these situations. That seems wrong to me, and I would think that Jeep would block that option to keep users from driving too fast in the drive gear range, as I can drive faster in OD than with it off. I try to remember to shut it off before driving in 4-Lo. Am I nuts? Please shed some light on this for your other readers and me.
Tom Curley

Answer: Driving in "overdrive" when in low-range? Well, I am not sure exactly what is the correct answer. For one thing, you would be spinning the transfer case pretty fast, depending on what the vehicle speed was, which could tend to be faster than if you were in direct drive (Third gear). For prolonged distances, there may be some lubrication problems, but I doubt that you would be traveling that fast for any extended time period to worry about it. I have found myself in overdrive low-range a time or two (with a TH700R4 and Atlas) but it's usually only for a short period of under a minute when the trail smoothed out for a short distance and I wanted to make up some time. I wouldn't make it a habit of driving in overdrive/low-range but I don't see that, like I said for short periods, it will hurt anything. Besides, it's not that much effort to shift into high-range. Readers, any comments on this subject?

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