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August 2006 4x4 Tech Questions - Techline

Posted in How To: Tech Qa on August 1, 2006
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Question: I have an '80 CJ-7. A friend gave me a GM 14-bolt rear and a Dana 44 front axle out of a late-model Chevy. Plans for an AMC 360 and a TH350 are also in the works. I would like to use my springs, but I'm worried about axlewrap. Should I use springs out of a junkyard? If so, what kind? Would there be some kind of traction bar out there? The Jeep most likely won't see hard-core rockcrawling. I just want to hit the trails with other four-wheel enthusiasts.
Charlie Janek

Answer: That fella must be a great friend to just give you the axles. Yes, it is very doable and yes, you could just use your present springs. Poison Spyder Customs ( has a kit to do just this type of conversion. You would be money and time ahead to buy this kit, as all the engineering has been done for you already and I have always been impressed with the quality of the work. The kit includes, as stated on the company Web site, the front spring mount/reverse shackle bracket, rear shackle outboard brackets, winch-plate spacers, steering-box spacers, shackle mounting plates, as well as all the nuts and bolts needed. These plates bolt between the outboard brackets and the spring hanger to allow full shackle movement. The front spring bracket has a 1/4-inch gap between the frame to allow for winch-plate brackets. If you don't have a winch, then these brackets fill the gap. A CJ's steering-box support bolts to the original front spring hanger.

Question: I have an '87 Bronco II and I just got a Dana 44 and a Ford 9-inch from a '79 F-150 to put under it. Now that the U.S. government has blessed us with tax returns, I can finally rebuild them. I want to run 5.38:1 gears, which are actually 5.38:1s for the 44 and 5.42:1s for the 9-inch. I've been told that seeing as how it is pushing the border of .05, I should go with a different ratio.

Though the truck will never see the pavement, I do have the stock drivetrain (weak!). Second, I want to install a locker with a new stronger carrier in the Dana 44. The guy I am trying to order them from is telling me that the axle is too weak for a locker and I need to go with a Detroit Truetrac.

I really don't want to be doing any fancy brake work to get the front end to lock up. I would love to run 37-inch tires and I've been told that the axle can hold them, even with a locker, but I think that would be pushing it. But I have come to realize that I might have to run 35s which is OK too. Oh, please don't suggest an ARB-they're too pricey for me.
Clint Coombs

Answer: Don't worry about that slight of a difference in gear ratio. I have seen enough variation in tire height within the same brand of tires to amount to that much axle ratio variation. If your truck was a full-time four-wheel drive, that would be a worry, but not in this case. If you're really worried about the difference, you can lower the air pressure in the rear tires a bit more than the front to lower their overall height.

Your front axle should be strong enough for the 37s if you're easy on the gas, especially since the Bronco II is fairly light. In time, you could always go to some aftermarket axles. The weak links will be the axle U-joints. The real secret of keeping the U-joints alive is not to have the tire turned at a strong angle when you romp on the gas pedal.

By all means, go with the Detroit Locker up front if you want it. It's a bit harder on axles, and has some traits that make it not easily driveable on a snow-covered highway at speed in 4x4 mode. The Truetrac is an excellent unit and works great up front under all conditions. Sure, it's not as positive as a Detroit Locker, and it may take a bit of brake modulation to get it to totally lock up in some situations. In the rear, be sure you're using the larger 31-spline axle.

Question: I have a '98 Jeep Cherokee with the well-known 4.0L. It was plenty fast stock, but with a 3-inch lift and 31s, it has slowed down. I plan on building it up even more, probably to about 8 inches of lift, but that's a whole different story. My question is, has anyone ever swapped a 5.2L V-8 from a Grand Cherokee in to a Cherokee? It would seem to be a great way to get more power and low-end torque. Are the transmissions the same between the two models? Mine is an automatic.
Cory Phelps

Answer: I am sure that such a swap could be made and most likely has been. No, the Cherokee transmission will not bolt up to the 5.2, so a matching trans must be used, nor would it be strong enough to handle V-8 power. But before you go off the deep end and buy the motor and trans, I want you to locate a mid-'90s Grand Cherokee with a V-8 and take a look under the hood. You're going to notice that it's a pretty tight fit. Now keep in mind that your Cherokee doesn't have any more room under the hood than the Grand does-in fact it has less. Still ready to take on such a swap? You're braver than I am.

I think that one of the biggest headaches will be the wiring issue. No one to my knowledge makes any kind of a "stand-alone" wiring harness for the 5.2 engine, let alone a wiring conversion kit, so you're all on your own. Better get real friendly with the Chrysler factory service manuals and their wiring diagrams.

Question: I have a '72 Chevy K-5 with a 383ci V-8, Edelbrock Performer RPM heads and intake, Edelbrock 650-cfm AVS carb, Summit HEI, headers, TH350 trans, NP205 transfer case, and Dana 44 front and GM 12-bolt rear axles with 4.56:1 gears and 33-inch LTBs. I only put about 1,500 easy miles a year on this truck-weekend use, mainly. I don't run this truck in the rocks, just a little muddin'. I like to try to keep it rolling and not tear it up. Central Illinois is pretty flat, so muddy river bottom trails are mostly what we have around here. Plus it comes in handy in heavy snow.

My tranny has been goofing-you have to shift manually most of the time from Second to Drive, as well as other issues. This is the third TH350 I've fed to this critter, and I'm kinda tired of pulling them out and putting them back in. I've been reading up on manual trannies, thinking I'd like to put one in this truck. I have a fair idea of what it would take (clutch pedal install, clutch install, and so on), though I've never done this job before.

What tranny would be the easiest swap? An SM465? Any reason to think the First-gear granny low would be too hard on my 1/2-ton axles with gears and tires? Is the SM465 a good choice, or should I look for something else-maybe a five-speed?
Doug Crawford
Kincaid, IL

Answer: Before you give up on the automatic, I would really consider the source where you're getting the transmissions. Something is wrong here. A properly built 350 behind a mildly built motor should live to a ripe old age. Yes, you're most likely making some where around 400 lb-ft of torque with your motor, but it really shouldn't be a problem, especially since you don't use your truck as a tow vehicle. Before I would make a transmission swap, I would try to figure out just why the automatic is failing.

As to what transmission to use, a lot of that has to do with your budget on this project. The easiest and simplest solution would be to find a fairly complete donor truck with the pedal assembly, linkage, bellhousing, flywheel, pressure plate and clutch disc, transmission, transfer case, and driveshafts. That way, the swap will go pretty smoothly without numerous trips to the wrecking yard for the necessary parts and pieces. Even with all the parts at hand, it's kind of a pain to make the swap; not that it's all that hard, just a lot of work.

The SM465 will work just great. No one says you have to stand on the gas pedal when in First gear, and most likely if you're only playing in the mud, you won't be using that low First gear anyway.

A five-speed? Sure, it can be done. The NV4500 would be the choice over the not-as-strong 3500, but it's not going to be any stronger than the 465 and will be a lot more expensive. It will be longer, thus requiring a crossmember change and a new transfer-case adapter, plus longer font and shorter rear driveshafts. Because your primary use of the truck is as a play toy, and also due to the limited highway miles you put on, there wouldn't be any real benefit in the Fifth gear overdrive for you.

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