September 2005 4x4 Tech Questions - TechlinePosted in How To: Tech Qa on September 1, 2005
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Question: I have an NP205 transfer case from a '79 Ford F-150. Isn't this case supposed to be able to shift from 2-Hi into 4-Hi at speeds up to 50 mph? What would cause the transfer case not to? Would a rebuild be in order?
Answer: Well kind of, but not always. It depends on the condition of the 'case-they like 30 mph better. You kind of have to back off the throttle a bit until you find a neutral load condition and sort of "feel" the shifter into gear.
Question: I am 15 and own a '98 Jeep Wrangler. I have been reading your magazine for about two years now and think you guys do a great job. I am currently considering swapping in a TBI 383 small-block Chevy, a TH700R4, a Dana 300, and 35-spline Dana 44s front and rear. Do you think the transfer case can handle the power?
Answer: Shouldn't be a problem at all if you have an easy right foot and don't go super-big on tire size. The Dana 300 is a really nice compact transfer case that is quite strong. I ran one for a lot of years behind a very high-horsepower 383 and a 6:1 ratio four-speed trans without a problem. Do rebuild the case before the install, and in fact if you're worried, Novak Adapters (www.novak-adapt.com) has a shorter-than-stock rear bearing housing that uses a larger-diameter 32-spline output shaft and yoke. They also have a rebuilding kit for the case. An added advantage to the shorter and stronger output shaft is a longer rear driveshaft, which cuts down on driveshaft angularity.
Question: I have a '74 Chevy with a 350ci V-8, Turbo 350 trans, and NP203 transfer case. The trans is only a three-speed, and when I go down the highway, my foot is all the way down to the floor (it gets a couple mpg), and I would like something with more gears.
My buddies told me to go to a TH700R4 because that has an overdrive gear, and I have one sittin' in the back of the garage, but another mud bogger told me that a 700R4 would not hold up in my 3/4-ton off-pavement.
Will the 700R4 bolt onto the adapter plate that's between my 350 trans and 203 'case or should I stick with my "pedal-to-the-metal" trans?
I also have an NP208 'case. Should I just switch my 350 and 203 to the 700R4 and 208?
Answer: I would say you need more than an overdrive transmission. It sounds like you need a new engine. It shouldn't take full throttle to cruise down the highway. The first thing to do is to find out just why your motor is lacking power and getting poor fuel mileage. Maybe the engine isn't all that tired but just needs a major tune-up that includes a carburetor rebuild and some ignition reworking.
You also don't say what size tires you are running or the axle gearing. Could it be that you are running something like 39-inch tires and a 3.07:1 axle gear? Matching proper tire size to gear ratio is just as important as transmission choice and engine power.
Once you've solved the engine problems, do consider the transmission swap. The 700R4 is a great trans if properly built, as it has a much lower First gear ratio and an overdrive in Fourth. However, unless you know the history of the transmission, you should take it to a reputable trans shop for a complete rebuild, using all the good aftermarket components (see Jimmy Nylund's story, "Building a Better 700R4" in the May '05 issue for suggestions).
Most likely, it will cost you about $1,200 to $1,500 for a standard rebuild, and more to make it really stand up to hard use with a lot of horsepower and torque going through it. I am sure that you can find cheaper prices on a rebuild, but you just may get a "cheap" rebuild that won't hold up.
No, the adapter for the 350 to the 203 won't fit the 700R4 trans. Your choice is to buy a new adapter, or you will have to use the 208. OK, the 208 isn't as strong as a 205 or the NV241, but I think that it should hold up fine behind even a mildly built 350. You also get the advantage of a lower low-range gear. If you want to use the lockup torque converter, then you have to do some easy modifications to the trans, and this can be done during the rebuild. Summit Racing (www.summitracing.com) offers a kit to handle this modification.
Question: What's the best way to get sponsors? Should I first build up my Jeep a lot and then look for them, or should I start now? Is it hard to get sponsors, and is it worth it? How does sponsorship work? Would I have to go to certain shows or events?
South Wales, NY
Answer: The best way to get sponsors for a vehicle? Tough question. Most likely, it's best to have a rich uncle who really likes you!
OK, let's get realistic. First off, you have to put yourself in the shoes of the sponsor. What are they going to get out of it? For example, let's say you want to contact Company A for a winch. How many people are actually going to see that winch on your vehicle? Of those who see the winch, why are they going to be convinced to buy that particular brand? How many winches will Company A actually sell as a direct result of people seeing the winch on your vehicle? Where will the vehicle be displayed? What events will you attend? Will you be able to talk knowledgeably about the winch and compare it favorably to other winches on the market?
What will the vehicle be used for when done? What is the overall concept of what it will look like? What's your experience in building vehicles? Company A doesn't want its winch on some cobbled-together winch bumper with bubblegum welds. Generally speaking, sponsors of products want to know and see what you've done in the past. They want actual proof that you're capable of building a vehicle that will represent the image they want to present. They want to be sure that you will follow through and not stop the project before it's done. These are just some of the questions you need to be able to answer before you can even approach Company A. In other words, they want to get the best use of their advertising dollar. Once you've gained one sponsor of a product, even if it's no more than a set of lights, it's then easier to get the next.
What it all comes down to, unless you have a "silver tongue" and are a dynamic salesperson, is that you need to build a show-quality vehicle first and then go after the sponsorships on the next vehicle. And just as a starting clue, you don't send letters in pencil on notebook paper with spelling errors. You learn to write a professional letter on quality letterhead paper.
Question: I have a '78 Suburban and the shifter boot on my transfer case reads:
I've been told the NP203 is a full-time unit, so what's the "Loc" for?
Answer: You're right, your transfer case is a "full-time" system. However, instead of using special clutches or a viscous coupling within the transfer case, it uses a set of differential gears very similar to the ones found in a rearend. An easy way to understand its operation is to picture the transfer case as the rearend and the front and rear driveshafts as the axleshafts. With a rearend, as you go around a corner, one wheel has to go faster than the opposite one due to the arc of travel. The "differential gears" within the housing allow for this difference in wheelspeed. Well, the same thing happens with the transfer case. The front wheels travel in a different arc than the rear wheels when turning a corner. Actually, any steering input changes the front-to-rear wheelspeed as well as any slight differences in tire height due to size variation or wear. If you didn't have this differential action, the driveline would either bind up or the tires would have to slip.
However, all is not good. Just like a rearend, if you lifted one tire off the ground while in two-wheel drive (without some type of locking differential), that "free" tire will just spin as the power is directed to it. Now with your system, if you lift any one of the tires off the ground-that is, a front or a rear tire-the power is going to be transferred to that free tire and the vehicle will not move. On the highway and under light four-wheeling conditions, it works just fine.
When you get into low-traction situations, it obviously doesn't work very well. That's what the L-Loc and H-Loc positions are for. These positions lock out the differential gear action within the transfer case and couple the front and rear driveshafts directly together just like any part-time system. And like such a system, it then cannot be used in high-traction situations like a hard-packed dirt road or pavement.
Question: I purchased my first Jeep Wrangler about three months ago-a '00 TJ with six-cylinder and auto trans. I've been searching Web forums and looking through back issues for ideas to modify my Jeep. The more I read, the more disappointed I become about the Dana 30 and 35 axles. This will be a daily driver and will see hardtop about 95 percent of the time, but I also want capable off-pavement performance, no matter what the ride, gas mileage, and so on. The Jeep had 33x12.50s and a Superlift kit when I bought it. I'm not sure how much lift I have, though. I have about 6 inches from the bottom of the fender flare to the top of the tires. I plan on staying with the 33s and going with 4.10:1 gears (running 3.07:1s right now), maybe going to 35s plus a body lift sometime in the future.
What would you recommend for the D30 and D35-a Superior upgrade, or swap 'em out? I'm trying to decide between the Superior upgrade or a Ford 8.8 in place of the Dana 35. I honestly have no ideas for the front.
Answer: Yep, you're right about the stock Dana 30/35 axle combination really not being the way to go with 33-inch-tall tires. It's hard to believe that you can even drive it on the highway, let alone on trails with the 3.07:1 gearing. The 4.10:1 gearset would be just about right in the fact that you don't have an overdrive in your transmission and you see a lot of highway driving.
The Dana 30 has proven itself a pretty strong unit. The weak link is the axle U-joints. I definitely would, however, upgrade the axleshafts and U-joints to some stronger aftermarket units, and even consider going with some locking hubs. While the 30 is still not as strong as a 44, it will be a whole lot stronger and most likely capable.
For the rear, it's kind of a toss-up as to going with the Superior axle kit or the Ford 8.8 swap. The latter will be a lot more work, but will gain you a stronger ring-and-pinion combination as well as some stronger axletubes. You will lose some ground clearance under the differential, but not enough to worry about. Keeping the Dana 35 will be a lot less work, but the axletubes are not as strong, and you will still have the rather smallish ring and pinion. My choice would be the 8.8 conversion.
If you're positive you're going to put on some 35s in the future, maybe it's time to go for the 44s front and rear; 4.56:1 gearing may be a better choice for the taller tires if you plan on some serious four wheeling, but your highway speed will require a lot more engine rpm.
Question: I'm about to buy an '89 Ford F-150 4x4 with the I-6 and five-speed transmission, but I don't know about the transfer case. The truck has got a 3-inch body lift and 33-inch Buckshots. The owner says it has 4.11:1 gears and I'd like to know what size of tire best suits the 4.11:1 for highway use and still have some power to turn off-pavement?
I also want to know about some performance modifications for it. I've got some 37-inch Wrangler MTs. Will they fit the 4.11:1 gears better than the 33s? What are the best upgrades for fuel mileage?
Answer: The 4.11 gears and 33-inch tire combination are just about the right compromise of good fuel mileage and overall performance, especially with your five-speed transmission. When you put on those 37s, your truck is going to lose both fuel mileage and performance. Swapping gears into the 4.56:1 to 4.89:1 range will surely help the performance, but my guess is that fuel mileage is still going to-well, to put it bluntly-suck. While the 37-inch tires may fit with just the body lift, with any twisting of the suspension there is going to be some body contact. You're going to need about another 3 inches of suspension lift to make sure everything clears like it should.
One of the problems with lifted trucks is they sit high up off the ground, letting lots of air travel under the truck instead of over and around the body. The body is smooth and slippery, while the underside has all sorts of things that disturb the airflow-like axlehousings, shock mounts, driveshafts, transmission, and transfer case. Plus, the taller tires are also wider and heavier, so it takes more power (and fuel) to move them.
Your six-cylinder engine will respond to modifications just like a V-8 will. Bolt-ons such as headers and a good free-flowing exhaust system will help somewhat.
Question: Recently I have bought a new (to me) truck, a '00 Dodge 3500 dualie 4x4. I need the big truck to haul my boat at just over 10,000 pounds. It has the Cummins power and works just great. But I would like to add a lift that doesn't hurt towing capability. I have not been able to find any info for lifts for this truck.
What is the tallest tire that I can put under this truck at the stock height? I'm running 235/85R/16s now, and want to add a taller tire until I can get the lift and new tires and wheels. Where can I find wheels and big tires with the proper load rating?
Newman Lake, WA
Answer: Yep, you've got a couple of problems when it comes to bigger and taller tires for your 1-ton. You most likely won't find a tall, narrow tire with the load capacity that is up to your truck. You can't go too wide, or the dual rear wheels will rub against each other. Interco (www.intercotire.com) may have a tire that will work for you. Take a look at the Narrow Super Swamper series. The taller tire will raise the overall gear ratio and may affect the ability to pull with the transmission in Overdrive.
Any lift will have to be custom-built. The same goes for the wheels if you wanted to go with a wider wheel, or a wheel with more offset so that the spacing would be correct with a wider tire. In this case, the tire will be way outside the fender and just may make the truck too wide to be legal. One source for custom wider wheels is Stockton Wheel (209/464-7771, www.stocktonwheel.com).
Question: I have a '91 F-150 with a 4-inch lift, but other than that, it's fairly stock. I am considering ladder bars as my next mod to save on U-joint expenses. I know I can just add more leaves to stiffen the rear, but I don't want to compromise ride or flex. What is the best way to build my own? Complexity is no problem. I'm just not sure where to start. What are my cheapest options (i.e., college student working on pocket change)?
Answer: I have to assume that you must be experiencing wheelhop or axlewrap since you're taking out U-joints. The simple way would be to back off the throttle when the rear axle starts to hop around. The next best would be to get rid of the lift blocks (that I'm assuming you have as part of the lift).
A quality set of rear springs with the correct amount of arch can gain you the necessary lift and won't have the leverage factor. Places like Alcan Spring (888/321-0870, www.alcanspring.com) or Deaver Spring Company (714/542-3703) can build anything you would need. Or, there's always the chance that you have a spring builder locally who can do the work.
Ladder bars would be my last choice as they generally do limit suspension articulation. If I was going to build some, they would be the same length or a bit longer than the front half of the rear spring and use something like a flexible joint at each end like those sold by Currie Enterprises or Rubicon Express. I would use a pivoting shackle arrangement for the front mount. If the front mounting point will be a solid mount, you're going to have to determine that point by cycling the rear suspension through its travel numerous times. The easiest way I have found to do this is to take the springs apart and use only the main leaf. Then, with the rear of the truck on jackstands, you can lift the rear axle up and down with a floor jack and note the proper angle and location that allow for the most movement without binding. There will be some compromise. For material, I probably would use some 1 1/4-inch-diameter, 0.25-inch-wall DOM tubing.
I think that if your heart is really set on traction bars, you may be better off buying a set from a shop that specializes in suspension control. Sure, they may cost considerably more than what it would cost you to build them, but you know that the engineering would be right and they would allow the maximum amount of articulation. A couple of companies that offer such bars that come to mind are Off Road Unlimited (818/563-1208, www.offroadunlimited.com) and Superlift (www.superlift.com).