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August 2008 4x4 Truck Tech Questions - Nuts & Bolts

Posted in How To on August 1, 2008
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Confused? E-mail your questions about trucks, 4x4s, and off-roading tech using "Nuts, I'm confused" as the subject and include a picture (if it's applicable). Digital photos must measure no less than 1600 x 1200 pixels (or two megapixels) and be saved as a TIFF, an EPS, or a maximum-quality JPEG file. Also, I'll be checking the forums on our Web site (, and if I see a question that I think more of you might want to have answered, I'll print that as well. Otherwise drop it old-school style with the envelope addressed to the address below. Letters published in this magazine reflect the opinions of the writers, and we reserve the right to edit letters for clarity, brevity, or other purposes.

Nuts & Bolts
4-Wheel & Off-Road
6420 Wilshire Blvd.
Los Angeles, CA 90048-5515
fax 323.782.2704.

Nuts, I'm Confused
Fatherly advice for 4-wheelin'
Question: My son has a '79 Ford F-250 4x4 camper special, and my problem is a mixture of one teenager and one truck. He wants to enter truck pulls and go off-roading in mud bogs and do all the fun stuff, which I have no problem with. The problem is he's tearing out the rearend all the time, and we need rearend parts. Do you know any places that cater to older Ford parts?

Answer: I was talking to a father in a similar position as you. His son was beating the snot out of his truck and it was costing old dad a pretty penny. Some guys would say that a teenager shouldn't be given a vehicle if he can't keep from abusing it, while others would be willing to give their children whatever they can afford.

My dad thought it a better idea to give his boys a Volkswagen to drive than a truck so as to keep us out of trouble. Funny thing is, I remember bringing that VW home covered in mud more than a couple times. Eventually I realized I had to have a real 4x4, and since Dad wasn't going to let me take his farm truck out wheeling, I drug home a '73 CJ-5 with a V-8. I spent many nights under that old Jeep and learned a thing or two about how expensive it is to have, break, and fix my own ride.

I added a few notches in my tool belt as I learned how things worked, and I busted some rookie knuckles. I broke parts and learned to fix them, and I also learned how to wheel to keep them from breaking (not that I always heeded my own advice).

Playing and breaking stuff isn't a bad thing, but the cost of fixing stuff can become aggravating over time. Luckily your son's truck had a Dana 60 rear axle, which is very common and should be easy to get parts for (look in the back of this issue and almost any of the differential or gear supply houses will carry the parts you need).

However, before you go and sink more money in that rearend, let's stop and think for a second. Many smaller vehicles on the trails these days have Dana 60s in the rear, such as Jeeps and Toyota Land Cruisers. These rear 60s have been swapped in to replace the smaller weaker original equipment that broke after repeated abuse. So your son's 3/4-ton-truck rear axle is the upgrade for many 1/4-ton vehicles, which leads me to believe that maybe he needs to upgrade his rear axle with something larger, especially if truck pulls and tug-o-wars are in the forecast. Ford actually upgraded to a Dana 70 rear axle in the F-250 in the early '80s and then added the massive Sterling rear axles in the mid '80s. I would look to upgrade to one of these two rearends.

Swapping a rear axle complete isn't too hard if you can find one with the same gear ratio as your front axle. You may need to do some welding on the spring and shock perches to get them to the correct location, but the added size would be very helpful in keeping the truck together. No axle is completely indestructible, but hopefully they will survive until your son grows out his wild hair. If not, it might be time to upgrade again to something even larger like a set of Rockwell 21/2-ton military axles, but these will require a fair bit of custom fabrication to install.

Since I feel your story is useful both as a tech question and it gave me a chance to relive my glory days peeling out in that old Jeep, I'm going to award you this month's "Nuts, I'm confused" prize. Seeing as your question is axle-based, I called up the experts at Randy's Ring & Pinion (800.819.6024,, and they are willing to give you some parts for either the stock Dana 60 or a larger axle if you swap one in with a set of rear axleshafts made from 1541H alloy, providing up to a 25 percent increase in strength over stock. The axles have a five-year warranty against manufacturing defects.

Get On Track, Mr. Bumper
Question: I have an '03 Chevy Tracker with four doors. I am trying to find a front and rear bumper for it. Unfortunately, there isn't much of an aftermarket for this vehicle. I was thinking that there may be another vehicle that has similar frame dimensions that I would be able to fit on my Tracker. Any help would be greatly appreciated.

Answer: Your Tracker is the same as a Suzuki Grand Vitara. Calmini (800.345.3305, offers front and rear bumpers and a winch mount for it. Also check out Zuks Off Road (928.567.3061,, as they should have a bumper ready by the time this goes to press or shortly thereafter.

30 Something
Question: I have an '02 Jeep Wrangler with a Dana 44 in the rear and a Dana 35 in the front. I'm running 35-inch BFGoodrich M/Ts on it and I have an ARB Air Locker in my front Dana 35. Would I need to swap out my front Dana 35 for something bigger or is a Dana 35 strong enough to do any serious off-roading?
Joseph t.

Answer: Actually your Jeep should have a Dana 30, as the Dana 35s were only used in rear axles of Wranglers and the front of the Ford Ranger. I would keep the Dana 30 up front with the 35-inch tires, at least until you break something. I think you're right on the edge of what that axle can handle, so I'd start saving for something bigger, but you might as well keep wheeling until you start busting parts. You'll probably be amazed at the abuse it can take. Just remember it's a 1/4-ton axle, and you need to be careful when rockcrawling, or in situations where the front tires get wedged in an obstacle and won't turn. Applying power to a front axle with the wheels turned all the way and the tires held firmly by a tight crack is when front U-joints or axles break.

Looks Could Kill
Question: I am looking at buying an '05 Dodge Ram Quad Cab 4x4 with a Hemi 4.7L. Will a 2-inch leveling kit let me clear 35-inch tires? Will the stock Dodge axles handle 35s or should I stick with 33s? This will be my first Dodge.
Loren B.

Answer: Both the front and rear axle could be fine with 35-inch tires, as most of the leveling kits for your truck claim to clear 35s. However, we found that our test Dodge of the same year would only clear 33-inch tires. Also you will see a loss of power and mileage with the 35s versus the 33s. I would probably go with 33s for the best performance since the lighter, smaller tires won't tax your engine and drivetrain as much as the 35s. But if looks are more important to you, then go with the bigger tire.

Help Her Out
Question: I really want to know how a lady goes about changing the perception that all big trucks (aka play toys) belong to men. I have a '97 Dodge 2500 that I really enjoy playing in, but it never fails, every time something requires professional repair, the mechanic asks what my husband wants done with it. I am single and while there are men in my life on occasion, this is my personal truck and play thing. Please, don't suggest painting it pink (surprise, I hate that particular color). I do have personalized plates (HER TOY) on the way, but there has to be more I can do.

Answer: Take your truck four-wheeling. When guys see you peeling out in the mud or bashing rockers on the trail, you won't have any problem convincing the guys that it's your truck. Plus the more you wheel the more you'll need to learn about your truck because there aren't always professional mechanics to help fix your ride on the trail. Yes many guys assume that a woman wouldn't own a truck or 4x4, but the fact is there are tons of women wheeling, racing, and driving big trucks every day and we know for a fact that number is growing. I definitely know a lot of guys who would love to see more women on the trail, just don't show us up too badly when you get there.

Ultimate Gross-Up
Question: I have an '84 Chevrolet K10 with a 6-inch lift, a custom flatbed, and 35-inch tires. I have a corporate 14-bolt in the rear and a big-hub Dana 44 in front. I recently boxed the framerails in fully with 3/16-inch-plate metal and went with stouter crossmembers. Can you tell me what this does to my GCVWR and my GVWR if anything?
Shelby M.

Answer: Your truck has a two weight ratings, but many different weights. The weight of the truck unloaded is known as the Curb Weight (CW), Gross Weight (GW), Unloaded Vehicle Weight (UVW), or Gross Vehicle Weight (GVW). The Gross Vehicle Weight Rating (GVWR) is the weight of the truck plus the cargo that can safely be moved by the vehicle. The cargo, payload, or Cargo Carrying Capacity (CCC) is the maximum weight that the truck can safely move and is determined by GVWR minus GVW. The Gross Combined Vehicle Weight Rating (GCVWR) is the combination of the (GVWR) and the maximum amount of trailer weight that can be towed behind the vehicle safely. Though you can change the GVW of your truck by adding weight such as when you boxed in the frame, only the manufacturer can legally determine the GVWR of your truck. And when the manufacturer determines GVWR, it is based on frame strength, suspension load capacity, axle load capacity, brakes, tires, engine power, engine cooling, and the ability to safely move and control that much weight. The manufacturers report that number to the Department of Transportation, which is a federal authority, so it is going to be difficult to get that number increased.

That being said, there might well be a loophole within your state department of motor vehicles that allows you to increase the "official" GVWR of your truck, but we have not found one yet. Also even though the "official" GVWR or GCVWR may be difficult to change, the actual ability of your truck only requires upgrading the frame strength, suspension load capacity, axle load capacity, brakes, tires, engine power, engine cooling, and the ability to safely carry a heavier load.

Of course, if you get pulled over by a representative of the highway patrol, DMV, DOT, or the National Highway Traffic Safety Administration, then you better not have a load exceeding the "official" GVWR or GCVWR of your truck even if you feel it is sufficiently modified to handle it, or you'll be getting a ticket and maybe walking home.

When More Is Less
Question: I run 32s on my '07 Wrangler Rubicon with 4:10 gears. According to the gear chart I looked at, it basically says I can run 35s and get as good or better fuel economy as my 32s. Is that even possible? If so, I'm bound to lose some power-right?
Tony O.

Answer: Going to a taller tire is equivalent to going to a higher gear in that the engine doesn't need to rev at as high an rpm to go at the equivalent speed.

RPM = MPH x GEAR x 336 Tire Size

At 70 mph, with 4.10 gears and 32-inch tires your engine will be turning 3,013 rpm, at the same speed with 35s it will be spinning 2,750. So at highway speeds you might be getting better fuel economy. However, in order to get the bigger, heavier tire with more rolling resistance to start moving, and then to keep it moving, will require more power out of your engine during acceleration. If the new tires and wheels are skinnier and lighter than the old tires, and you run them at high pressures to help them roll, and if you accelerate slowly but get to a high gear quickly, then you will probably not gain any mileage from going to bigger tires, and only if you are lucky will the mileage not drop.

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