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July 2009 Your Jeep - Tech Questions and Answers

Posted in How To on July 1, 2009
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Crown Jewels
I enjoyed very much your two-part article on the $500 YJ project ("Why-J," March '09)! I don't have a YJ, but I do have an '85 XJ I've owned since new and have been gradually restoring. Since it has the venerable 2.5L motor, a lot of your article applies to me, including the high-reading oil pressure gauge, which I never figured out until now!

I do have one question. When I logged on to Crown Automotive's web site at I come up with their catalog but no way to order online. How did you do that? They say their products are only available thru authorized dealers?Bob Packervia e-mail

Sorry for the confusion on the Crown Automotive stuff. You do have to go through one of Crown's authorized distributors. You can't order directly from Crown. What I always do is check Crown's web site and write down my part numbers, then call a few of the authorized dealers for prices and go with which one is giving the best deals. Prices may vary slightly from time-to-time, but my advice would be to pick whichever two or three are closest to you to save shipping charges and go from there.

I recently acquired an '83 Cherokee two-door that is very solid. I'd like to upgrade the drivetrain. It is equipped with a six-cylinder engine, a T-177 four-speed transmission, 3.73 gears in the Dana 44 front axle and AMC 20 rear with one-piece shafts, and an NP208 T-case.

I understand that the Buick, Pontiac, Olds and Cadillac bellhousing pattern is the same as the AMC. If this is the case, with a 4-inch lift and 33-to-35-inch tires, what are my best swap options and what would be needed? I'd consider a Dana 44 swap for the rear if it would not stand up to a V-8 with those tires. I'm in Arizona, so I have no limitations on engine swaps to meet smog requirements.AnonymousVia e-mail

You're wrong about the BOPC engine bellhousing pattern being the same as an AMC. It isn't. You can bolt an AMC V-8 to your bellhousing, though. You'll need the V-8 engine brackets and motor mounts. Otherwise you'll be able to bolt an AMC 304, 360, or 401 in place of your 258 six-cylinder.

An AMC 360 is a really common engine in junkyards that responds well to modifications. I'd find a good, complete running 360 and would swap out the factory Motorcraft ignition and electronic distributor. I'd also consider adding an Edelbrock Performer or Performance RPM intake manifold and a 600cfm four-barrel carburetor to get it going. Later, if you feel the need for more power, I'd add a Competition Cams Xtreme Energy camshaft and maybe a set of aluminum Edelbrock cylinder heads for an easy 400hp.

Back the 360 with a T-18 from another FSJ and think about keeping the NP208. It's a good T-case. The FSJ AMC 20 rear axle is quite a different animal than the ones that came in CJs. They have much better housings and good shafts. If you add a locker I'd think about maybe upgrading to some aftermarket alloy axleshafts and keep the stock shafts as spares, but I don't think there's any need to go swapping the rear axle for use with only 33s or 35s.

It's a Scout Thing
I have a '77 CJ-5 with a 304, three-speed, Dana 20 T-case, Dana 44s from an International Scout, Selectro hubs, and a set of 36x14.50-15 Buckshot Mudders. It has a Lincoln locker in the rear and a used Truetrac up front that I bought at the junkyard for $70. Problem is, when I put it in 4x4, only the front right tire spins when I'm in the mud. I jacked the front of the Jeep up and turned the tire by hand and it made a clicking sound from inside the locker and both wheels would turn so I had a friend hold the left tire while I spun the right side and only one turns instead of both. Is the locker I bought junk or do I have a bad hub or something?

Also, ever since I put the Dana 44s under my Jeep the steering sucks. I did the spring-over instead of the 9-inch shackles that were on it when I bought it. It handles so much better now, but the steering makes me sick. The Jeep cuts OK to the right, but when turning to the left it barely turns at all, making it not very fun to drive. It acts like there is no more turning left in the steering box. How can I correct the steering problem? Should I save my money and buy hydraulic steering or a different steering box? If so which one? Either way I will be in trouble with the wife for spending more money.Eric KiddWhitley City, Kentucky

First of all, a Truetrac is a limited slip, not a locker. Jack it up and try your test again, only this time, watch the axleshaft through the knuckle. If the axleshaft is spinning along with the tire, then the limited slip is bad. If the axleshaft isn't spinning, then your hub is probably just put together incorrectly. I had that problem with one of my Jeeps. Took off the hub dial and reassembled the hub and it was fine.

As for your steering, I'd do a couple things first before I ordered up new steering box or ram-neither of which will fix the problem.

First, point the front tires directly straight and then remove the drag link from the pitman arm so you can check where your steering is centered. Turn the wheel all the way to full left lock for starters with the drag link unhooked. Then count the turns it takes to turn the wheel all the way to right full lock. If it takes (just as an example) 4.5 turns to go from left to right, then turn the wheel back 2.25-turns from right lock and the steering should be centered. Put a piece of tape or something on the top of your steering wheel in case you bump the pitman arm.

Second, with the steering centered crawl back under to make sure your drag link will hook up to the pitman arm. If it's too long or too short, hopefully there's enough adjustment in your tie rod ends to hook the drag link to the pitman arm. If not, you'll need to build or buy a new shorter/longer drag link.

Third, if the drag link is the correct length, you may need a longer pitman arm. Measure your current pitman arm and then head to the junkyard to see which GM vehicles have the longest pitman arm in the shape that may work for you. Most GM cars came with Saginaw power steering boxes that have the same sector shaft splines as the power steering box that came on your '77. If you've got manual steering, then the sector shaft won't fit the GM car pitman arms. A longer pitman arm will allow more turning radius. A shorter pitman arm will allow less turning radius.

Fourth, a Scout drag link attaches to the knuckle. Generally speaking, shortening the steering arm will have a similar, yet opposite effect on turning radius as lengthening the pitman arm. In other words, a shorter steering arm will equal more turning radius and a longer steering arm will equal less turning radius. The factory Scout drag link mount on the knuckle is in front of the tie rod mounts, effectively mimicking a pretty long steering arm on the knuckle. It's possible you're losing some steering throw thanks to this, which can be offset by the longer pitman arm mentioned above.

Fifth, make sure the drag link isn't binding on the spring pack or frame rail or anything else. If it's making contact anywhere it'll limit your steering radius.

All Shook Up
I just bought an '06 Wrangler with a 4.0L and an automatic transmission. I want to put on a small lift and 31-inch tires. I saw a 2-inch spacer lift by Skyjacker which comes with the spacers, bumper stops, and shocks. I also saw that Skyjacker sells a transfer case lowering kit, which they recommend for a 2-inch lift. I saw another kit that was a 1.75-inch lift and this kit comes with a rear pinion angle cam kit.

Since I only plan to lift the Jeep 2 inches and put on 31s, do you think I need to put a transfer case lowering kit or a rear pinion angle cam kit on, or will the change not effect the driveline enough to make a difference?Stuart WoodsVia e-mail

If you had a manual transmission or a Wrangler Unlimited I'd say no on the T-case lowering kit. Since your Jeep is an automatic, which is longer than a manual tranny, you will need the lowering kit to correct the driveshaft angle. I think you'll need to install the drop brackets or you'll have bad vibration from the rear shaft when coasting or decelerating. And I'm sure the rear cam kit will prove useful in dialing out any vibrations the T-case lowering kit doesn't cure.

I need to replace my '80 CJ's gauge cover. How do I remove the current cover? Is it glued on? How do I remove the indicator lights?NoahAspen, Colorado

If you remove the gauge you'll see the indicator lights from the back of the speedo. The bulb sockets should come out with a half-twist. Then you can pull and replace the bulbs.

As for the speedo cover, the glass is held to the gauge via a steel bezel that's crimped on in about 4 places. You can carefully use a small, thin flathead screwdriver to bend the crimped areas up, allowing the bezel and glass to be removed. Be careful not to snap or bend the speedo needle. They're fragile.

After you replace the glass, install the trim ring and carefully crimp the cover back on using a pair of needle nose pliers or a small flathead screwdriver and a hammer to strike the crimps back down. Associate Editor Trasborg recommends a dab or RTV to keep the seal in place during reassembly.

Bad Vibrations
I was wondering about a problem I have with the rear of my XJ. There is a crazy vibration that feels like the rear driveshaft or maybe the yoke into the T-case. The tires are all freshly balanced. Is there a fix for this without a big cost of replacing too much? I was thinking possibly the U-joints were bad, but it only does it at 50 kph and than it starts again at 80 kph-130kkph. At the higher speed range its pretty crazy. Maybe the lift is the cause? I've got about 4.5 inches of lift, but any suggestions on the fix would be awesome.Anthony FietzeVancouver Island,British Columbia, Canada

Did the vibration present itself once you did the lift? Here's the thing; 4.5 inches is a lot of lift for an XJ even though the rear driveshaft is a lot longer than a Wrangler.

I'd first check the rear driveshaft U-joints. Place the vehicle in Neutral with the parking brake engaged and the wheels chocked so it can't roll over your skull. Then crawl under and check for rotational and lateral play in the rear driveshaft U-joints (just grab the shaft and try to spin it, then pull it up and down in relation to the U-joints). You'll see any play in the joints pretty clearly. If they're hammered, replace them.

Second, you're going to have to do something to correct the driveshaft angle on the rear. Most companies offer a T-case drop kit to lower the rear output shaft and help point it back towards the rear pinion. This, in conjunction with shims in the rear springs can help get the rear driveshaft angle back in line. Rusty's Off Road,, offers a nice T-case drop kit for the XJ for only $20 under PN RC-TCD1-XJ. Try the drop brackets first and then worry about the rear axle shims on the spring packs if you still have a bad vibration.

If you're not running a CV rear driveshaft with a slip-yoke eliminator (which is the correct thing to do when funds permit) you want the angle at the T-case output to be equal to the angle of the pinion. Check the "Tech Info" section of Tom Wood's Custom Drive Shafts web site for a clear illustration of this at

I just purchased an '03 Rubicon. I've been searching through my back issues of Jp trying to find the article about how to keep the air lockers working in High Range. Could you help me out with an issue date?William GossettMohler, Washington

I believe it was the July '03 issue. The TJ wiring colors changed either in '04 or '05 Take off the connector to the rear locker switch and look at it from the female side (side the terminals go in). On the far left you'll see numbers 1 (black wire) and just below that 4 (red w/ white stripe).

What you want to do is splice in a toggle switch to the black and red/white wires so you can fool the computer into thinking it's in 4-Low (it basically grounds to the red/white wire when Low is selected). You can use a Scotch Lock or splice into these wires carefully, but leave them hooked up to the factory switch. Throwing the toggle will ground the red/white wire and allow High Range operation of the rear locker.

Many Mods
How much power will I gain on my '04 LJ by installing the Edge Trail Jammer kit, a header, an after-cat exhaust, and a high-flow catalytic converter?

On a different subject, my Jeep has the Trac-Lok 4WD system in it. How does it work exactly, and will it mess the system up if I put a Trutrac in the rear?Farris ParkConway, Arkansas

Installing the complete Edge Trail Jammer package (cold air intake, bored throttle body, and electronic module) should get you almost 20hp at the rear tires. Honestly, I don't think you'd need the high-flow catalytic converter unless your factory unit is plugged up or rattling because the catalyst brick inside has come apart. And since it's an '04, I doubt either of these things has happened. You'll see a bigger boost in performance in going to an after-cat exhaust and ridding yourself of the restrictive factory 13/4-inch tailpipe. Gibson makes a nice unit that isn't obnoxiously loud, although you will hear the difference. Figure you can add another 5-10hp into the mix with the after-cat exhaust for a total of 25-30hp at the rear tires.

As for the "Trac-Lok" 4WD system, you're a little off on your vocabulary. For starters, your Jeep uses a "Command-Trac" 4WD system, which is just Jeep's fancy term for its NVG231 T-case. You've got 2WD High, 4WD High, Neutral, and 4WD Low. The 4WD system refers to the engine power distribution to the front or rear axles.

The Trac-Lok is a limited slip differential made by Dana Spicer that was an option in the rear axle. A standard open differential will send engine power to whichever axleshaft (and tire) has the least traction. This can cause loss of forward motion if a tire is lifted off the ground, is stuck in mud, and so on.

The limited slip differential sends engine power to both axleshafts (and thereby to both tires) at the same rate until a predetermined torque bias is reached, at which time the axleshafts may spin at different speeds. The tighter the differential, the greater the torque bias must be to overcome the differential action and allow one axleshaft to spin faster or slower than the other. The Trac-Lok is a relatively low-torque bias differential. It doesn't take much force to overcome the differential and allow one tire to spin at a different rate than the other. That's why they offer lackluster performance off-road compared with a differential with a higher torque bias, such as the Eaton Truetrac.

So, in my roundabout way, to answer your question, yes, you will realize better off-road performance by swapping out your factory Trac-Lok rear differential for a Truetrac. The Truetrac offers exceptional off-road performance for a limited slip with very civilized street manners.

Why Not Swap
I have a 130,000-mile '84 CJ-7 with a 4.2L, a four-speed, and Dana 300 T-case. I bought it two years ago with 129,480 on the odometer. It was completely stock with a shot suspension and little stock tires. The tires said something like P225/75R15 on them. I have put a lot of work into the Jeep, including a 4-inch Rough Country lift, 31x11.50-15 Super Swamper LTBs, 15x10 black steel wheels, reclining buckets out of a '91 S-10 Blazer, Herculined the inside, and changed the paint from a postal white to red. It looks really nice and everyone around loves this Jeep. I just so happen to have a '96 Dodge Ram 1500 pickup lying around with a good 318 in it. Which engine would you rather have; the 4.2L six-cylinder or the 5.2L V-8? I know it's a lot of work to swap, but I have everything but the adapter to connect the engine to the tranny. I would like to keep the four-speed and the Dana 300. The six-cylinder runs great, but with 130,000 on it, I know something is going to happen eventually. If I could just get your opinion, it would be greatly appreciated.Chris PoulinYork, Maine

Keep in mind that the Chrysler 318 is one of my all-time favorite engines. But with only 130K on the clock, I think you've still got a lot of life left in your 258. They're hard to kill. And if you're happy with the performance, maybe the engine swap can wait.

For starters, with only 31-inch tires you won't be stressing the drivetrain too much. However, if you do pull the trigger on the swap, you've got to consider a few things. Your '84 could have two possible manual four-speed transmissions : the T-18A (granny low 6.32:1 First) or the T-176 (3.82:1 First). If you've got the T-18A there's no need to worry, but the T-176 could have trouble with a V-8 and big tires. Technically, it should be fine since Jeep used them behind the factory 304 V-8, but it's not as burly as a T-18.

Second, the wiring harness will really need to be pared down on the Dodge's 318 and I'm not certain if the ECU will allow a manual transmission to be used if it was originally an auto. Most Mopar ECUs are linked to the tranny and unless they sense the signal from the lockup converter they'll throw a check engine light. Performance-wise it's nothing to really worry about, but it's an annoyance if you've got to have smog done in your area and would need to hook up a check engine light to get past a referee.

Don't forget about the electric fuel pump, high pressure lines, and return line to the tank for the MPI injection, hooking up the power steering, exhaust, and so on. All not too complicated, but folks tend to forget about the little stuff

I'd say you'd be really happy with a 318-powered CJ-7, but the time and effort you'd put into it could really turn the 4.2L six into a well-running machine. If your stock 258 has good compression and isn't leaking like a sieve, maybe consider a Howell injection system and electronic ignition for a small boost in power, mileage, and drivability. Chances are excellent that your 4.2L will last until at least 250K miles before needing any serious attention.

Got a tech question you're just itching to get answered? Send it on in to Jp magazine, Your Jeep, 6420 Wilshire Blvd., Los Angeles, CA 90048, or e-mail

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