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Answers To All Your Jeep Questions

Posted in How To: Tech Qa on August 8, 2018
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Ousted AMC V-8

I have an ’81 CJ-7 with a carbureted AMC 360 in it. It has a Ford T-18 manual transmission, Dana 300 transfer case, and Dynatrac axles front and rear. It rolls on 37-inch Boggers and is beat on regularly. The AMC 360 is finally tired. I looked into rebuilding it for 400 hp, but the cost is kind of ridiculous for this Jeep. The AMC motor always had plenty of torque, but it was gutless. Also, pretty much all of the accessories on the front of the engine are worn out. At this point, I’m kind of done with the AMC engine and I’m not a Jeep purist. A friend is practically giving away a complete Chevy 350 V-8 with all of the accessories. How viable is this swap, and what parts would you use?
Dustin Ewing
Via email

The AMC V-8s are well known for having an incredible amount of off-idle torque, making them great off-road engines, especially at slow speeds. AMC V-8s are also well known for being significantly more expensive to rebuild and hop up than the more common GM V-8. Having said all that, an engine rebuild is almost always less expensive than an engine swap, but it’s not always more practical, especially in the long haul over several decades. In your case, you can purchase a stock rebuilt AMC 360 long-block from companies such as ATK (atkvege.com) for around $2,700. A comparable GM 350 long-block is about $1,000 less. Given that it sounds like you have your hands on a complete, inexpensive GM engine in good shape and that you already have your mind made up, you should sell the complete and still-running AMC 360 to recoup some of the costs of your GM V-8 swap. There are likely plenty of Jeep purists around looking for a good AMC 360 core to rebuild. Good cores are not plentiful, and new engines have not been manufactured in more than 25 years.

It’s fortunate that you have the Ford T-18. This is probably one of the most adaptable manual transmissions available. It can be easily married to most popular engines and transfer cases. However, the Jeep version of the T-18 was available with many different length input shafts, several of which are completely unusable when doing an engine swap in a short-wheelbase Jeep. Advance Adapters (advanceadapters.com) offers a 360-degree bellhousing kit that will mate the GM 350 to your Ford T-18 (part number 712549). The kit includes a bellhousing, dust cover plate, GM release lever, GM throwout lever spring clip, ball pivot, pilot bushing, and the necessary hardware. This aluminum bellhousing is also drilled for the ’77-’79 Jeep T-18 transmissions that have a 2-inch-long pilot tip. A high-profile GM 11-inch diaphragm-type clutch assembly is recommended for this bellhousing. Centerforce (centerforce.com) part number CF165552 works well. The included ball pivot and clutch release arm are designed for a location that is limited to only the high-diaphragm–type clutch. This larger 11-inch clutch assembly will require the use of the 168-tooth GM flywheel. Ford T-18 input shafts are normally 1 1/16-inch diameter with 10 splines, which will require the use of a Centerforce clutch disc (part number 281226) or equivalent. A Centerforce throwout bearing (part number N1714) finishes out the clutch assembly. Your stock CJ-7 slave cylinder and bracket can be retained and adapted to the new bellhousing and GM clutch release arm.

Advance Adapters offers both weld-in (part number 713007) and bolt-in (part number 713089) adjustable motor mounts for your CJ-7. The weld-in mounts are generally a better choice for a Jeep that is used hard off-road. Both mount styles feature massive 5/8-inch through bolts with isolators that will pretty much put an end to rubber motor mount failures.

Novak Conversions (novak-adapt.com) takes a different approach when adapting the Ford T-18 to a GM V-8. The company retains the GM bellhousing and mates it to the Ford transmission with a few simple and cost-saving modifications. This gives you the ability to use most GM bellhousings, including full-circle or open-bottom types. Novak Conversions also offers adjustable weld-in motor mounts to secure your GM engine to the Jeep CJ frame.

As for cooling, you’ll need a new radiator with the proper inlet and outlet locations. Fortunately, the popularity of the CJ-7 has led to the availability of numerous aftermarket radiators with GM V-8 inlets and outlets. Bolt-in GM V-8 conversion radiators are available from companies such as Advance Adapters, Champion Cooling (championcooling.com), Summit Racing (summitracing.com), Radiator Express (radiatorexpress.com), and many others.

You may be able to keep the transmission and transfer case where they are currently located, which will simplify your engine swap and reduce costs by not requiring driveshaft modifications. The key areas to make sure you have enough clearance will be between the rear-mounted GM distributor and the firewall, as well as around the engine, exhaust, and accessory group clearance near the factory CJ-7 steering shaft. If space is limited or there is contact between the components, you’ll have to evaluate the options of modifying these areas or simply move the transmission and transfer case to accommodate them.

Beadlocks or Bust

I really enjoyed “DIY Beadlock Mounting Tech” (Aug. ’18). I’ve been thinking about installing a set of beadlock wheels and wanted an opinion from someone other than my friends. I have a ’12 JK Unlimited Rubicon. I have the stock Dana 44 axles and axleshafts, but I’ve trussed the front axle with an Artec truss, which included beefing up the end forgings. I currently run 37-inch tires with 20-inch wheels. I really haven’t had any problems (knock on wood) running all the trails in Northern California. I’ve only ever peeled a tire bead once, but it seated back up quickly when I moved off the spot I was on. With my current setup, are the beadlocks and new 37-inch tires too heavy for my stock axles? I tend to drive pretty gingerly on the trail and don’t rock hop it or drive it like I stole it. I like to make it out in once piece. I was thinking about the Raceline Monster wheels. Any advice you can provide would really be appreciated.
Chris Scott
Reno, NV

The decision to run beadlock wheels isn’t always as simple as personal preference. In some areas, traditional beadlocks with bolt-on locking rings are frowned on by the local police and vehicle inspectors. Technically speaking, traditional beadlocks with a removable outer ring are not Department of Transportation (DOT) compliant. That’s not to say they are unsafe at highway speeds. On the contrary, traditional beadlock wheels can be found on desert race trucks that regularly hit more than 100 mph, and even on top fuel dragsters that reach speeds of more than five times the legal limit on most U.S. highways. The problem is that they simply don’t meet the required tire bead surface dimensions dictated by the DOT. Having said that, there are some legal non-traditional beadlock alternatives available to keep your tires from popping a bead. Companies such as Rock Monster Wheels (rockmonsterwheels.com) and Coyote Enterprises (coyoteents.com) offer tire beadlock solutions that are 100 percent street legal in every state.

Moving past the legality issues of traditional beadlocks, I think you should consider altering the wheel size. The 20-inch wheels are heavy, which is hard on steering and axle parts. They also don’t offer enough tire sidewall to properly envelop trail obstacles. The result is decreased traction and a rougher ride off-road. If you do any kind of off-roading at all, you should stick with 17-inch wheels. The commonly accepted rule of thumb is that your wheels should be no bigger than half the diameter of your tires. In your case, your 37-inch tires should be matched with 17-inch wheels for best on- and off-road handling, traction, and overall performance. Going with 17-inch wheels will also open up both your tire and wheel options.

Most beadlock wheels are not all that much heavier than a comparable non-beadlock wheel. However, just as some wheels are lighter than others, some beadlocks are too. For light-duty, low-speed off-roading and street use, lighter wheels and tires are generally the best choice. A lighter tire and wheel package not only helps preserve your axles and other drivetrain parts, it will offer improved acceleration, braking, ride comfort, and handling over a heavier tire and wheel package.

Your Dana 44 axles are at about their operational limit in strength and durability with 35-inch tires. The 37s are beyond what JK Dana 44 axles are designed for, even for mild off-road use. That’s not to say you can’t keep the axles alive. If you drive sanely, you should be able to keep the JK Dana 44s in one piece, but you should expect things like ball joints and unit bearings to wear out prematurely thanks to the additional weight and leverage of the 37-inch tires. Of course, if you drive aggressively off-road, you’ll be rewarded with a bent or broken axlehousing, shattered axleshafts and steering U-joints, and maybe a busted Rubicon locker.

Bound T-Case

I have a ’53 M38A1 and have a problem with it. When I shift it into four-wheel drive, it will not shift back to two-wheel drive unless I raise the Jeep up off of its wheels. On the lift you can run through all the gears and in and out of four-wheel drive and the transfer case high and low range. If the Jeep is on the ground, I can use all gears and high and low in two-wheel drive, but when I engage the front axle, I can go through all of the gears in high or low, but it will not let me disengage the front axle unless I pick up the wheels off the ground. The tires are the same size and the gear ratio is the same in the front and rear axles. Do you have any ideas what could cause this?
Richard Gundal
Via email

As you have noted, it’s important to make sure that all of the tires are the same diameter and that the front and rear axles have the same gear ratio. Any significant variance could cause the driveline binding you are describing.

It’s not at all uncommon for a Jeep transfer case to become bound up. Even some late-model modern transfer cases can become bound up when put into the wrong scenario. The Spicer 18 in your M38A1 is not at all a complex transfer case. There really isn’t anything inside of it that could be causing the problem you are having, as long as the transfer case gear oil is clean and not glittered with metal shavings. Keep in mind that the M38A1 four-wheel-drive system is designed to operate on a dirt surface. There is no differential inside the transfer case, so the system requires that the tires slip at least a little when cornering. If you are engaging the four-wheel drive and operating the Jeep on a hard paved surface, you could be causing the driveline bind.

If you end up with a bound up transfer case, never force the transfer case shifter. It can cause damage to the shift linkage, the shift fork inside the transfer case, along with other components. To unbind a transfer case, pull the Jeep forward and back in a straight line once or twice on a loose surface and stop prior to attempting to shift the transfer case out of four-wheel drive. If it’s still bound up, drive a short distance forward in a straight line, stop, and try again. Repeat the process until the transfer case can be shifted without forcing the shifter to the point that the shift lever is flexing. Shifting in and out of low range generally requires the Jeep to be stopped, but you should be able to shift the transfer case in and out of four-wheel drive high range with the Jeep moving at a slow speed. The only way you should be able to shift the Spicer 18 in and out of two-wheel-drive low range and four-wheel-drive low range is if the interlock pill inside the transfer case is removed. Two-wheel-drive low range is not a shifting option if the interlock pill is retained. Partial disassembly of the transfer case is required to remove the interlock pill.

Locked Up Locker

I own a ’71 CJ-5 with a 4.3L V-6, SM465 manual transmission, Spicer 18 transfer case, and Dana 44 axles with 4.56 gears and Lock-Right lockers. The rear axle has a Warn full-floating kit and the Jeep has disc brakes all around. It sits on a spring-over suspension with Wrangler leaf packs and rides on QR78-15 Buckshot Mudders. After sitting for a while, the Lock-Right in the rearend won’t ratchet like it used to. What is a possible cause for it to stick and make the rearend act like it has a full spool? I have taken the diff cover off and I was expecting to find water in the differential, which would explain the locker not clicking or ratcheting when turning, but I found no water or rusted components.
JC R.
Via email

Drop-in lockers like the Powertrax (powertrax.com) Lock-Right are a great low cost and easy-to-install full locker alternative. It’s perfect for those that want to dip their toes into the aggressive traction-adder world without breaking the bank or committing to a gear set up. By design, these drop-in lockers are typically not as durable as their full carrier replacement locker counterparts. This is mainly because the drop-in locker simply replaces the differential gears and is fitted into the factory open differential carrier. In most cases, only one cross pin is used to retain the drop-in locker in the cast open carrier, where a full locker will typically have four pins that attach the locker to a much more durable machined steel differential carrier.

Over time, drop-in locker performance and reliability can diminish. How long this takes depends on several factors including horsepower, gearing, vehicle weight, tire diameter, driving style, and gear oil cleanliness. There are several things at work here. The added stress can cause the cross pin to wallow out the cross pin bores in the factory carrier, which will lead to wonky locker operation and possibly catastrophic failure of the differential carrier. Inspect the cross pin bores. The pin should fit in them well; if there is excessive play or cracking around the bores, you’ll need to replace the carrier.

The small springs and pins used in the drop-in locker can fail too. It’s a good idea to check them periodically. Any broken locker springs or pins should be replaced. Broken springs and pins can cause the locker gear teeth to disengage unevenly or not disengage at all. It’s not a bad idea to carry spare springs and pins. They are inexpensive, small, and can easily fit in a tool bag or glovebox.

Contaminated oil could also cause faulty operation of a drop-in locker. The remaining oil oozing out of the differential in the photo you provided looks pretty dirty. Zooming in even reveals larger bits of sediment. There are also traces of water visible. You should thoroughly flush and wipe out your differential housing, extend your breather hose, and maybe even put a small filter on the end of the hose. This will help keep water and other contaminants out. Refill the differential with the proper fluid and check it regularly if you frequent deep water crossings and heavy mud.

Flattie 4.3L Exhaust

Regarding the Garage Project GPW, did you run stock exhaust manifolds on the 4.3L V-6? I was looking for a short header, mostly because I need to buy a passenger-side manifold anyway. However, I don’t want to add any trouble by installing headers.
jwilson_55
Via Instagram @cappaworks

I considered several options when choosing the exhaust on my flatfender. The only thing I knew for sure is that I wanted the exhaust system to run inside the framerails for protection. Anyone who has ever worked on a flatfender engine swap can vouch for it being quite the task. Due to frame clearance, I originally started with some Sanderson (sandersonheaders.com) headers (part number CV95). The driver side appeared to be a clean fit in my application, but the passenger side dumped out right where my front driveshaft wanted to be. So I reverted back to the stock cast-iron manifolds that came with my ’02 4.3L van engine. The van manifolds are slightly different than what came on the pickups and some other applications. The 4.3L van manifold outlets kick rearward rather than straight down. This provided more exhaust clearance around the frame. Which manifolds or headers will work best for you depends on many different factors including engine location, frame modifications, suspension design, and more. The best way to see what fits is to get in there and mock it up with what you have. If what you have doesn’t fit, try something else.

The easiest way to fit the exhaust system on a flattie with a GM 4.3L V-6 swapped in is to run the Advance Adapters (advanceadapters.com) fenderwell headers (part number 717019). These headers require modification of the inner fenderwells and exit the exhaust on the outside of the framerails. Going this path has two major advantages. It routes the exhaust away from all of the cramped problematic areas inside the framerails, and it evacuates a lot of heat away from the passengers and drivetrain. The only real downside, which I already mentioned, is the exhaust vulnerability to rocks and such. You’ll have to decide how you plan to use the Jeep. If you don’t plan to drag the sides of the Jeep over boulders like I do, then the Advance Adapters fenderwell headers can save you from a lot of engine-swap headaches.

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