December 2006 4x4 Tech Questions - Tech LinePosted in How To: Tech Qa on December 1, 2006
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Question: How stout is the six-speed manual trans in the new Dodge Power Wagon? I am seriously considering one. I'm just not happy with the performance on our '04 545RFE, even after the TSB reflash on the trans hunting problem. We tow a 27-foot Tailgator Toybox and have reached the limits of the limited-slip rear and open front diffs and we need more gears when going up the side of mountains on dirt and gravel roads.
Answer: Have you ever looked at one of these six-speeds? They are huge. If size alone has any bearing on strength (and it does), this trans looks like it belongs in a 10-yard dumptruck. In the real world, I have never heard anything bad about it. I am sure that the reason that Dodge decided to go with it was due to the fact so many people were pulling loads that were taxing the automatic to the limit, with failures common.
Question: I have a question regarding my '01 Ford Excursion with a 6.8L V-10 engine. It currently has the three-speed trans with overdrive. I'd like to know whether I can swap it for a five-speed Torq-Shift trans, and if I can, whether the transfer case will work-or will it need to be swapped too?
Farmington Hills, MI
Answer: While it would make for a great swap, I figured it was going to almost be impossible. Well, nothing is impossible with cubic money and cubic time to devote to it. I asked my Ford Guru, Mike Kelly, what he thought of the possibility and he had this to say:
"The Torq-Shift trans case is only made for the 6.0L diesel engine. It won't fit a 6.8L V-10 gas engine. If you could make an adapter to bolt it up, you would need a custom-programmed PCM to make it work electrically because it has a total different valve body and shifting strategy. The output shaft is also larger, so a different transfer case would be needed, or the existing transfer case would need the input gear swapped to the larger one."
OK, so it's not impossible, but a heck of a lot of work and expense. Is it worth it?
Question: I recently installed Gibson headers and even more recently installed a body lift. Now my steering shaft rubs the headers. Is there a header out there or another solution that fixes this problem?
Answer: You didn't say how much body lift or what the vehicle is. Guess it wouldn't make any difference, as no one makes headers specifically for a body lift. How bad do they rub? Rubbing to me means just touching. I would remove the steering shaft, and take a hammer to the headers. A small dimple in one tube will not make a whole lot of difference in the way the tube will flow.
Question: I have a '90 Wrangler with a 2.5L four-banger. What can I do to get more power out of it besides an engine swap? The foreign four-cylinder (for fast/furious types) seems to have all kinds of goodies to make it get on down the road. I'm new at the 4x4 scene and want to learn all much as I can.
Answer: You can add a set of headers from Clifford Performance (www.clifford performance.com) or Gale Banks Engineering (www.bankspower.com), along with a good performance exhaust system with a high-flow catalytic converter from Random Technology (www.randomtechnology.com). You could also install a throttle-body spacer, or maybe better yet, a throttle body from a 4.0L engine, which is about 6 mm larger. A higher-flow air intake and filter, of which there are numerous to chose from, will offer a great improvement.
When it all comes down to how much horsepower and torque you're going to gain for the amount of money spent, the gains are not all that much-perhaps about 14 more horsepower.
You might be better off spending the money on some gears in the 4.56:1 to 4.89:1 range and just screaming the engine down the highway. Remember the Jeeps called the CJ-2A, CJ-3A and the CJ-5? Well, they used a four-cylinder engine and 5.38:1 gears. Adding a locking differential will be a major traction helper. But then again, you're dealing with the Dana 35C rearend. That, even with the four-cylinder powerplant, doesn't really like tires that are much larger than stock.
Bottom line: If you're looking for better performance both on and off the highway, sell the Jeep and buy one with the 4.0L six and the Dana 44 rearend.
Question: I have been a reader and subscriber for 17 years. I own an '85 Chevy 1/2-ton shortbox stepside 4x4 with what I think is a 4.5-inch lift (3-inch suspension and 1.5-inch body; the body blocks were cut in half). I removed the 10-bolt axles and upgraded to 3/4-ton axles-a Dana 44 eight-lug in the front and a 14-bolt full floater in the rear-and 35x12.50/16.5 rims and tires.
The problem I am having is with the front axle. When I turn the steering wheel all the way to the left, the tire rubs the fender, and not when turning right. This started after I installed the Dana 44. I had no trouble with the old set of 35s when the 10-bolts were in it. The offset of the new 16.5x9.75-inch rims looks to be the same as the old rims and tires. Nothing is bent or misaligned.
Do I need more lift? If so, how much, and how come the old tires did not rub? Am I missing something obvious?
Answer: There are only a couple of things that I can think of that would cause the problem. When you installed the new axle, you did not center the steering box. No, I don't mean centering it in the frame, but finding the exact center of the turning arc within the box when the wheels are pointed straight ahead. Usually it's when the flat indexing spot on the input shaft (the one that connects to the steering column) is at the top. If the box is not centered, then you will not have full turning capabilities in one direction while you can turn more in the opposite direction.
However, there is no adjustment on the stock steering drag link, and perhaps when you went to the new front axle, the attachment point on the axle was in a slightly different location than on the original axle. Generally speaking, when you go with a lift kit, it's advisable to also buy a longer drop-style drag link or an adjustable one. Just about every one of the major suspension manufacturers offers this in their kits or as an option.
Could it be that you don't have this new drag link? Why is this necessary? The steering box is attached to the frame, and the drag link runs from it to the front axle's steering knuckle. When adding a lift, the distance between these two points is increased, and the stock drag link is too short and pulls the steering box's pitman arm slightly forward off the center of rotation, which limits the turning radius in one direction and increases it in the opposite. Another problem that can develop is the extra load that is now placed on the steering box. Seems that now the steering knuckle can turn further than there is movement in the steering box. This load will, in time, crack the frame around the steering-box mounting holes.
You also mentioned that the wheel offset "seemed" to be the same. There is a big difference in "seemed" and actually measuring the backspacing. It doesn't take much in both tire diameter or width, or wheel offset, to make a clearance difference. Combine this with the steering box not being centered, and this could be your rubbing problem.
Question: I recently converted the suspension on my '98 Chevy K-1500 to a solid axle (Dana 60 front, 14-bolt rear, 4.88:1 gears). The truck has almost 200,000 miles on it, and the trans (4L60E) is slipping in overdrive-go figure.
Will a 4L80E swap electrically in place of the 4L60E? If not, what mods will be required? Will the transfer case (NP243C) mount up to the 4L80E without mods? Is this swap necessary, or will a 4L60E suffice? The motor is stock, and when required, it will be replaced with a Ram Jet 350. I have already dropped a lot of dollars into a 10-cent truck, and I need it to last and drive well. I don't go 'wheeling every day, but when I did in the past, I usually broke the IFS or gears in the locked 10-bolt. A point in the right direction would surely be appreciated.
Answer: By all means, keep your present transmission and have it rebuilt. Think for a minute-it's given you 200,000 miles of service. That is pretty darn good in my book. It's going to be a real pain to swap over to the 4L80E, as well as a lot of expense.
I would have a local shop do a quality rebuild. I don't mean one of the major chain-type transmission shops, but one that has been around for a while and which depends on word of mouth for its advertising. Tell them what you plan to do with the truck and your future engine plans. If you don't have a shop you feel comfortable with, you could always go with a performance trans from someone like TCI-which, by the way, I have heard does an excellent job building transmissions all the way up to handle over 600 hp.
Question: I've got a stock '97 4x4 Ford Expedition that I recently decided to take four wheeling. The SUV surprised me in how well it did, but throughout the trip I could hear those awful clunking and scraping sounds coming from the underbelly when it hit a rock-even with careful tire placement (I think). When I got back home, I searched for Expedition lift kits and found a cool 4-inch Rancho lift that allowed for 33-inch tires.
First, what would I need to do in terms of gears and other drivetrain components to keep everything running smoothly and without breakage? Second, I think my front axle is a Ford 8.8-inch, but I can't seem to figure out what my rear axle is, and I'd like to put an ARB Air Locker in it. I would think all the Expeditions had the same rear axle, but I could be wrong. Any help you could give would be great.
Answer: Depending on what tire size you choose, you should definitely regear, and think about adding a locker while you are in there.
I can't determine what makes the difference, but '97 Expeditions used either the 8.8- or 9.75-inch rear axle. What I have actually seen in them has been mostly the 9.75-inch ring-gear model. There is a big difference in size, so you should easily be able tell the difference between the two.
Question: I'm in possession of an '86 Jeep Cherokee Laredo with the 2.8L and three-speed auto. My questions are concerning a possible engine swap. Other than the 4.0L, knowing it will probably mean swapping out the entire front end, what other options might I have? Maybe an engine from another vehicle besides a Jeep, and which ones?
My local used parts suppliers all offer the 4.0 but with an extensive list of items that I would have to gather from various other vehicles. No engine would be complete. And the used sales lots want about as much as it would take me to transform my machine.
My intentions for this machine are a daily driver and some light 'wheeling in the foothills around Las Vegas, with an occasional trip to Moab or the like to explore some of the beginner trails. I'm looking at a 3.5- to 4.5-inch lift with slip-yoke eliminator, shafts, and 31- or 32-inch tires.
Answer: Let me tell you right off the start that selling the Jeep and buying one with a 4.0 in it will place you money ahead. My guess is that you didn't factor in the time involved. Also, don't forget you're going to have to swap out the wiring harness as well as the computer. I also would never consider buying a motor that was not complete. It's a crap shoot as to just how well the motor ran before the accident that placed it in the salvage yard. It would be very frustrating to make the swap and then find that the motor had a terrible knock or smoked badly. By trading up, at least you know what you're getting because you can drive the vehicle and actually check the motor out.
As far as an engine from another vehicle, I have seen some Chevy 4.3L V-6s installed that came out quite nicely. These incorporated the trans as well as the transfer case from the donor vehicle. Again, remember you're going to need the wiring harness and computer to match the new engine.
Question: I own a '00 Ford F-250 Super Duty 4x4 with a 7.3 Power Stroke. Its main job is to pull a 25-foot travel trailer on trips, or an '01 Jeep Wrangler to destinations like Colorado. The owner's manual said, "Never tow in overdrive."
The Jeep weighs 3,500 pounds and the trailer (loaded) weighs a total of 6,000 pounds. That's half or less what it's rated to tow. Towing out of overdrive doesn't seem to load the engine at all, and the turbo can be heard unloading. When in mountains, I would never use overdrive, but on long, straight, flat stretches of interstate, would I hurt anything towing in overdrive? My goal is to use less fuel and have the truck outlast me.
Answer: I would suggest that you go ahead and tow in overdrive. The transmission, if an automatic, will shift down when needed. Keep it in Drive when in the mountains, or whenever it wants to hunt between Drive and overdrive. I would suggest that you invest in a transmission temperature gauge and try to keep the temperature between 180 and 200 degrees. Never let it exceed 220, and if you do, change the transmission fluid at the first opportunity.
If it's a manual six-speed, I also suggest towing in overdrive. I have a similar ZF transmission in my own truck, and I tow in overdrive all the time. While in overdrive, my diesel can pull most small grades, even with a total load of 20,000 pounds, because it makes a considerable amount of horsepower due to aftermarket accessories and modifications. However, under a heavy pull up a grade, I often slow down and shift to Fifth gear (direct) to lessen the load on the clutch and rather smallish overdrive gear. Like you, I want the maximum in fuel mileage and life out of my truck.
Question: Is there any advantage to running a slightly smaller-diameter tire in the front of a fullsize rig? Seems that most of the weight of that kind of rig is at the front, so would it benefit from having the front tires turning slightly faster? Seems rear tire traction would be somewhat slower, which would provide a more balanced application of power.
Off in space with too much time on my hands.
Daniel G. Johnson
Answer: Yep, you are off in space with this one. But I like people who think. New ideas get tried-some work, some don't.
Unless it is a full-time system with some sort of viscous coupling or a differential within the transfer case, the front and rear axle are locked together and must turn at the same speed. What is going to happen if there is good traction and the tires can't slip? Something is bound to break, be it the U-joints, driveshaft, or gears.
Now if the front tires can slip, that means rubber is going to be worn off a lot faster than if the tires didn't slip. This wear will even take place on dirt.
A tire only generates a given amount of traction, be it forward or sideways motion. If the tire is slipping while going forward-let's say 30 percent-then there will only be 70 percent of the traction left for steering input. Now with that said, some mud racers do exactly that; let the front tires turn faster than the rears, but keep in mind that they are in a very low-traction situation, and some think that there is some stability to be gained. Just as a note: Some full-time 4x4 systems actually split the power unequally front to rear for better handling on the street.
Question: I am 16 years old finally and school has just ended. I have a job and have some money, and I'm interested in a summer project. I was looking into an M38-A1 that a guy near me has. I was just wondering if it would make a good summer road-legal machine with some trail prowess. The seller says it runs, and he has the windshield and everything. It is kinda rusty, but it's OK for Wisconsin. I have been doing a bit of research into the M38-A1s, but it is kinda empty in the realm of the aftermarket. Are the Spicer axles it has the same as Dana? The front is a 25 the rear is a 44. I want it to wheel OK but still take me to school.
Answer: The M38-A1 was the forerunner of the CJ-5. It has a bit better frame than its civilian counterpart and a lot heavier springs, and a bunch of little things like the grille and fender mounting are different. The dash is lower and what a lot of people call a "knee-buster." Unless it has been converted, it runs on 24 volts, which is kind of a pain to deal with. It can be changed over to 12 volts by using the civilian counterparts such as the starter, generator, distributor, as well as changing out the gauges and bulbs.
Keep in mind that it is about 50 (or more) years old, so lots of things can be worn out. It has 5.38:1 gearing, and this makes it pretty darn slow on the highway with a limit of about 55 mph for continuous driving. The brakes flat suck with their little 9-inch drums.
Yes, the front and rear axles are a Dana 25 and a Dana 44, respectively. The rear uses 19-spline axles instead of 30-spline and uses a tapered axle and hub assembly. It's important to keep the nut on the end of the axle torqued properly.
If you were my son, I would tell you to convert to some 11x2-inch brakes from a pre-'72 Jeep Wagoneer and make sure they were always adjusted up; the stock master cylinder is a bit small in volume so will require more pedal travel (cylinder stroke) for stopping. I would have you also buy a used Warn or a new Saturn overdrive from Advance Adapters. This way, you would have not only an overdrive for the highway, but a way to "split the gears" with your three-speed T-90 transmission for better performance both on and off the highway.
Now, after going to this much work, if you plan to keep it for a while, I would suggest some much better seats, and swapping the tapered rear axleshafts out for some flanged axles.
With it being your first Jeep, you might want to buy a copy of my book, The Jeep Bible by King/Worthy. Any bookstore can get it for you. It's not a service manual, but has some pretty darn good information in it, and it's done on a humorous note. You might also want to buy a reprint of a factory service manual. These are available from places like Portrayal Press (P.O. Box 1913 G, Bloomfield, NJ 07003, 201/743-1851, www.portrayalpress.com).
Question: I am getting ready to build up a 4.0L engine for my '98 Cherokee. Is there any particular engine that I should look for? I want to build a separate engine and have it all ready for the swap instead of having my Jeep down for the buildup time.
Answer: It seems that there have been at least five different cylinder blocks and heads since its inception back in 1987, when the engine was rated at 177 hp and 224 lb-ft of torque. In 1991, there was a new design of the block and head, and the horsepower increased by 13 and the torque by 8 lb-ft. The casting number on these blocks is 53008405, and the head, I believe, is 7120. In 1996 a new engine block came out that is easily identified by the "NVH" on the side, which stands for "noise, vibration, and harshness." (This means that they did some strengthening of the block.) It also got a new cylinder head and a different piston design. In 1998, the oil-filter mounting location got changed so that the oil filter is mounted 90 degrees to the pan rail instead of pointing downward. A big change came in the '99-to-present blocks and cylinder heads, making them even stronger. Keep in mind that they also changed the way the accessory drives are mounted, and so they're not interchangeable with the earlier blocks. Also, the heads may not flow as well due to modifications made to improve emissions. These carry the casting numbers 53010327AB and 53010328AB. There were some changes also in the connecting-rod design, but overall, the center-to-center length, pin diameter, and weight all stayed the same.
There have been some major changes to the electrical system as well as the FI systems. The pre-'91 engines used a French designed Renix fuel-injection system that was, well, French, and it would be better to stay away from it if possible. There were also some major exhaust manifold cracking issues up to about 2001, but I would strongly suggest a set of aftermarket headers with whatever year engine you go with as it's a great performance gain.
When it comes down to it, I would suggest finding one built between 1996 and 1998 if possible. However, some states with emission testing require that the engine be the same year or newer than the vehicle that it's going in.
Now if you want to go all out, perhaps you should consider one of the stroker engines or engine kits from HESCO (205/251-1472, www.hesco.com) or Golen Engine Service (800/591-9171, www.golenengineservice.com). Rusty's Off Road (www.rustysoffroad.com) offers an aluminum cylinder head that not only flows better but is about 30 pounds lighter.