Pop Goes The Driveline
Question: I have a '76 Jeep Wagoneer and a '79 Jeep J-10. When I am under hard acceleration or my tires are spinning, like in mud, I get a popping sound. I have replaced the rear axle in the Wagoneer and I have checked the chains in the transfer case in both trucks, and they still do it.
Answer: Sometimes a "popping" noise can come from a bad U-joint or a missing tooth on a differential gear. But in your instance, it's a pretty good guess on my part that the noise is emanating from the transfer case. You didn't say which transfer case your Jeep has, which could have come with either the Dana 20 or the BorgWarner Quadra-Trac. With the Dana 20 being geardriven, and since you said you had checked the chains, that tells me your fullsize Jeeps are using the Quadra-Trac transfer case.
Let's start with the chain. Just how did you check it? The correct way is to remove the transfer case's chain inspection plug and insert what Jeep refers to as a "thread chain tension gauge" (PN J-25162). Actually, this is nothing more than a plunger that pushes against the chain and measures the amount of slack in it between the drive and driven gears. Good luck in finding one of these gauges.
Otherwise, I have no idea how to tell you how to figure what the proper tension is supposed to be. When there is not enough tension, due to wear in the chain's links, the chain will actually jump teeth on the drive gear with the resulting popping noise. If this is allowed to happen over an extended time period, then there is a good chance that the drive gear will have to be replaced.
There could also be another source of the noise related to the transfer case. Instead of a viscous coupling, like most full-time units now use, this transfer case uses a cone clutch assembly. When a preset amount of torque is applied to them, they slip, allowing the wheels of, say, the front axle to go faster or slower than the rear axle. These cones sometimes exhibit what's referred to as a "stick-slip" condition. The sudden release of the cones will cause a clunking noise. This usually doesn't happen in straight-line driving, but will be evident when turning, or, as in your instance, when in mud and a tire starts to spin.
Several things can cause this problem.
Uneven tire diameter: You have to be dead-on with equal tire diameter. All the tires have to be the same size, and in reality, the same manufacturer, the same tread design, equal amount of wear, and the tire pressure has to match the load carried by each tire. This may require higher pressure in, say, the rear tires if a heavy load is carried in the pickup bed. Some people I know have actually made themselves a height gauge to check this, but a level on top of the tire and a tape measure work fine.
The next problem deals with the use of the proper lubricants. You just can't use ATF, motor oil, or gear lube, as this transfer case takes a special Quadra-Trac fluid. If by chance you have not been using the proper fluid, then you need to drain and refill the transfer case with this special fluid. Then find a paved parking lot and drive the Jeep in both tight left- and right-hand circles for at least five minutes in each direction. This should hopefully solve that problem. Just as a note, this stick-slip condition sometimes will exist when the vehicle sits parked for an extended period of time, but after being driven for a few miles, it should go away.
If none of these measures helps, you might want to do what's referred to as a "torque bias test." Put the transmission in Neutral and be sure what Jeep refers to as the "emergency drive" is not engaged. Chock the front wheels and apply the emergency brake. Crawl under the vehicle and remove the rear driveshaft at the transfer case. You're going to need someone to apply the brake so the Jeep can't move. With the proper socket on a torque wrench, try turning the rear yoke retaining nut in a tightening direction. The release point at which the yoke turns should be between 80 and 170 lb-ft. If under 80, the clutch cones need replacement. If over 170, it's a pretty good sign the wrong gear lube has been used and it needs to be replaced.
There are some parts available for this case, but not a lot. A couple of sources are Novak Conversions (435/753-2513, www.novak-adapt.com) and Quadratec (800/745-2348, www.quadratec.com).
304 To 350 CJ Swap: What You Need
Question: I have recently purchased a '76 CJ-5 with a 304 under the hood. I want to put a mildly built 350 in it, but don't know what all will need to be done. Obviously, upgraded axles and probably the transmission, driveshafts, and so on. My main question is, what did the Jeep come with from the factory? Transmission, axles, transfer case, and gears are all unknown to me. Any and all help will be greatly appreciated.
A The year 1976 was good for Jeep as they redesigned the frame to make it considerably stronger, both in torsional and bending loads, and redesigned the floor and dash panel for more legroom.
Let's start with the engine. The 304 is an AMC-designed motor and is in the same family as the 360 and 401. A 401 is a direct bolt-in to replace your 304. Now don't sell these motors short, as they can be made to run quite well. While the 401 gains you almost 100 cubic inches, it also comes with a steel crank and steel rods-nice things to have when building any performance motor. OK, you can easily swap to a small-block motor and be like everyone else, or start looking for a 401-incher. If this is the way you plan to go, then take a look at Planet Houston AMX (www.planethoustonamx.com), which will give you the proper casting and cylinder head part numbers. In fact if you Google "401 AMC motors," you will find a huge amount of information on them. Just because they haven't been built for quite a few years doesn't mean that you can't find parts for them. Lots of stuff is still available, and Edelbrock (www.edelbrock.com) is even making performance aluminum heads for them.
Naturally you can easily install a small-block Chevy as it's a common swap. Both Advance Adapters (www.advanceadapters.com) and Novak Conversions have all the pieces that you would need.
Your transmission, most likely (according to my factory Jeep service manual), is a T-150, but lots of other references refer to a T-14 as the standard three-speed transmission. Either way, parts for them are getting scarce and either one is not the best, strengthwise or gearwise, with only a 3:1 First gear ratio. You may have gotten lucky and have the super-strong optional T-18 four-speed. This trans had a 4:1 First gear and can handle just about all the power you can put to it.
Jeep trucks had what was a "heavy-duty option," which was the same basic T-18 but with a much lower and viable First gear of 6:1. If you should run across one of these transmissions, be sure you get the matching bellhousing as there were quite a few different bellhousing/input shaft length combinations used over the years. Jeep offered a special version of the GM TH400 automatic but only in the longer-wheelbase CJ-7s. While you can swap to the auto-shifter, the CJ-5's short 84.5-inch wheelbase makes for an extremely short rear driveshaft along with a steep angle-unless, that is, you go with a custom high-pinion rear end.
The transfer case is a Dana 20 with a poor 2.03:1 low-range. However, there are kits to allow a 3.15:1 ratio to be swapped in.
In '76, Jeep swapped from the great Dana 44 to a less-desirable AMC model 20 rearend. The front is the Dana model 30. The standard axle ratio was 3.54:1, with an optional 4.09:1. You might get lucky and the gear ratio tag will still be attached to one of the cover bolts for an easy ratio check.
There is a lot more that I could cover about your Jeep, but half the fun of owning a Jeep is slowly discovering more about it and the modifications that can be made to improve its trailability.