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August 2006 4x4 Tech Questions - Techline

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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
via fourwheeler.com

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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