Jeep YJ Wranglers Builder's Guide

131 9902 Jeep Yj Wrangler Builders Guide Line Up

Tah-dah! Here it is, ladies and gentlemen, the Jeep that started all those nasty round-headlight jokes. This Builder's Guide zeroes in on the '87-'95 Jeep YJ Wrangler, the one with the rectangular headlights and the, well, slightly less than totally glowing reputation. There's no use in pretending it ain't so.

Some of that put-down humor might apply to stock leaf-sprung Wranglers. But a whole passel of inventive aftermarketers has been hard at work for years developing tons of trick upgrades for the YJ, and they've created about a zillion ways to make the jokesters eat their words.

In fact, there are so many parts from so many sources that space forces us to concentrate on only some of the ones that enhance the YJ's off-road performance. We'll look at spring-under suspension lifts, spring-over conversions, and shackle reversals; engine and axle upgrades; and simple ways to improve stock suspension flex. We'll cover the related modifications you must do when you lift a YJ or run bigger tires.

To paraphrase Robert Kennedy's praise of John F., some Jeep fans think of the '87-'95 YJ Wrangler as it is and ask "Why?"
To paraphrase Robert Kennedy's praise of John F., some Jeep fans think of the '87-'95 YJ W
But others, like Chris Overacker of Mountain Off Road Enterprises (M.O.R.E.), dream of what the Wrangler might be and ask "Why not?" The major stock-YJ complaint is that the suspension just doesn't flex. Some CJ fans also dislike the NP231 aluminum transfer case and low ground clearance. As you'll see, the clearance problem can certainly be fixed. And with companies such as 4-to-1 Manufacturing offering extra-low NP231 transfer-case gears, the aluminum boxes are gaining in popularity.
But others, like Chris Overacker of Mountain Off Road Enterprises (M.O.R.E.), dream of wha
Rancho's 2- to 2 1/2-inch lift allows for mounting tires slightly larger than stock (30x9.50/15 versus the original P215 or 225/75R15), but it barely increases wheel travel as long as the anti-sway bar and track bar remain attached. The bars improve pavement handling at the expense of off-road flex. In ramp tests done by Joel Snider and Joe Shaff at Stage West 4 Wheel Drive Center, a bone-stock YJ scored a ramp-travel index (RTI) of 455. Merely disconnecting the front sway bar bumped the RTI to 621, and the YJ climbed to 749 when both track bar and sway bar were unbolted.
Rancho's 2- to 2 1/2-inch lift allows for mounting tires slightly larger than stock (30x9.

Considering the ramp-test data above, obviously the easiest suspension-flex improvement is adding quick-disconnects for the track bar and sway bar. J.K.S. offers the sway-bar disconnect shown here. Gaining off-road flex is as easy as pulling the pins, and safe on-road handling is restored simply by replacing the pins. For the front track bar, M.O.R.E. offers a SlipLoc track bar that replaces the original. The SlipLoc bar features a slip-joint that is locked for highway travel but allowed to slip for twisty-trail traction.
Considering the ramp-test data above, obviously the easiest suspension-flex improvement is
YJ Wranglers also have a rear track bar, but no rear sway bar. We know of no aftermarket disconnect system for the rear bar. Although no one can officially endorse or recommend the practice, many YJ builders simply toss the rear bar. As with the front bar, the rear rod improves highway handling and safety.
YJ Wranglers also have a rear track bar, but no rear sway bar. We know of no aftermarket d
The YJ Wrangler front suspension has the spring shackle at the front. When a tire hits an obstacle, the shackle must move in the opposite direction from the impact instead of moving with the impact to absorb it.
The YJ Wrangler front suspension has the spring shackle at the front. When a tire hits an

This results in a stiff, jouncy ride. Most YJ owners prefer to swap in a shackle-reversal kit such as this M.O.R.E. system. The completely bolt-on kit also adds an inch of lift and moves the front axle forward an inch to lessen tire contact with the fenderwell during flex. Along with the shackle reversal, you'll need a longer-travel slip-yoke for the front driveshaft.
This results in a stiff, jouncy ride. Most YJ owners prefer to swap in a shackle-reversal
M.O.R.E. offers a shackle-reversal system and optional Buggy Spring shackle mounts. During extreme flex, the Buggy Spring allows the shackle to pull away from the frame, adding up to 2 inches of axle flex.
M.O.R.E. offers a shackle-reversal system and optional Buggy Spring shackle mounts. During
Due to the YJ's extremely short rear driveshaft, driveline angle becomes a problem with even very low suspension lifts. Owners report vibration with lifts as low as 2 inches. One solution is to lift the body instead of the suspension. In fact, many builders combine both body and suspension lifts.
Due to the YJ's extremely short rear driveshaft, driveline angle becomes a problem with ev

Even the 2- to 2 1/2-inch Rancho suspension lift requires driveline-angle correction. The Rancho solution is to lower the tranny and transfer-case crossmember an inch. This, of course, gives up some of the ground clearance you gained. Practically all major suspension companies offers suspension lifts for the YJ in heights ranging from 1 1/2 to 4 inches and body lifts from 1 to 3 inches.
Even the 2- to 2 1/2-inch Rancho suspension lift requires driveline-angle correction. The
The preferred (but more expensive) method of correcting rear driveline angle is to convert the transfer case's slip-yoke to a fixed yoke setup with a CV joint. Commonly called short-shaft kits, the conversions add driveshaft length, allow greater operating angles, and eliminate transfer-case fluid loss if the rear shaft breaks and must be removed on the trail. JB Conversions, Currie, MIT, Tomken Machine, and Rubicon Express offer tail-shaft kits.
The preferred (but more expensive) method of correcting rear driveline angle is to convert
As tire size increases, so does the need for beefs and mods to the YJ steering system. Snider recommends adding a steering-box brace if you're running 33-inch or taller meats. The stock box's mounts just can't handle the strain when a big tire is jammed and steering is cranked during tough 'wheeling. Brace kits are available from sources such as Tomken Machine, Currie, Stage West, and M.O.R.E.
As tire size increases, so does the need for beefs and mods to the YJ steering system. Sni

Snider recommends replacing the stock drag link (arrow) with a J.K.S. chrome-moly link if you do any hard 'wheeling, even in a stock-height YJ. The thin stock tube is prone to bending, and a suspension lift that increases the drag-link angle also adds strain to the drag link itself. Thus, adding a dropped pitman arm, a stronger drag link, or both becomes a necessity in lifts of about 3 inches or more.
Snider recommends replacing the stock drag link (arrow) with a J.K.S. chrome-moly link if
A spring-over axle conversion nets 5 1/2 to 6 inches of suspension lift, even if you retain the stock springs. It also requires extensive steering mods. M.O.R.E.'s Spring-Over steering conversion kit relocates the tie rod from beneath the steering knuckles to the top and moves the drag link above the leaf springs to connect with a M.O.R.E. pitman arm. The kit includes a custom track-bar bracket that can be used with either the stock bar or M.O.R.E.'s SlipLoc track bar.
A spring-over axle conversion nets 5 1/2 to 6 inches of suspension lift, even if you retai
A custom track bar was needed in Ron Esch's 5-inch-lifted YJ, built by Stage West. Even though Snider and Shaff had to curve the bar for clearance, they assured proper steering geometry by keeping the track bar's mounting points parallel with the drag link's mounts. They chose to leave the springs under the Currie Ford 9-inch front and rear high-pinion Dana 60 to keep axlewrap to a minimum with the rig's 300-horse Chevy 350.
A custom track bar was needed in Ron Esch's 5-inch-lifted YJ, built by Stage West. Even th

You don't have to lift a YJ very much before you outstretch the stock shocks and mounts. Of course, exactly at what height you need which shocks and mounts depends upon how much flex you want. Esch gets an RTI of 826 with his YJ on 35x12.50/15s with Rancho RS 9000 12-inch-travel shocks in Stage West custom dual loops.
You don't have to lift a YJ very much before you outstretch the stock shocks and mounts. O
Super suspension flex can cause stock spring shackles to invert, that is to move past vertical and fold back against the frame. This locks the spring in its over-arched position and freezes the suspension-a bad deal. To prevent the problem, anti-inversion shackles, such as the one shown here, are available from many YJ-buildup parts suppliers.
Super suspension flex can cause stock spring shackles to invert, that is to move past vert
Mounting larger-than-stock tires on stock YJ 15x7 wheels causes tire contact with the springs and sway bar. Stock backspacing is 4 1/2 inches. Many aftermarket wheels use 31 3/16 inches backspacing. That means at least 1 1/16 inch more clearance for larger tires. And the real clearance gains are often greater because sidewalls don't bulge as much on 8- or 10-inch-wide wheels.
Mounting larger-than-stock tires on stock YJ 15x7 wheels causes tire contact with the spri

M.O.R.E.'s Overacker increases tire clearance by trimming about 3 inches from the rear of the YJ's front fenderwells to follow the shape of TJ flares. Then he installs the TJ flares (shown). Rear fenderwells are extended about an inch in front and 3 inches in the rear to accept TJ flares back there as well.
M.O.R.E.'s Overacker increases tire clearance by trimming about 3 inches from the rear of
The YJ stock rear axle is a C-clip-style Dana 35. Dana 44s weren't options for Wranglers until '97 TJs. Many YJ builders want to scrap the 35, but Stage West's Joe Shaff points out that the 35 is lighter than the 44 and offers an inch more ground clearance. He eliminates what he considers the 35's two weak points by swapping in Summers Brothers alloy axleshafts and C-clip eliminators. Warn offers a full-floater conversion that not only adds an extra wheel bearing per side, but alloy axleshafts too.
The YJ stock rear axle is a C-clip-style Dana 35. Dana 44s weren't options for Wranglers u
Rear Dana 44 fans can catch a clue from John Winters' '90 YJ. This 44 is found in '87-'89 XJ Cherokees with tow packages. It's the right width and bolt pattern for the YJ, but the spring pads and shock mounts must be relocated. According to Shaff, the relocation provides a good opportunity to set the pinion angle correctly according to lift height.
Rear Dana 44 fans can catch a clue from John Winters' '90 YJ. This 44 is found in '87-'89

M.O.R.E.'s Overacker opted for super-beef in his YJ rear by installing Currie's 8.8-inch Ford rear axle from a '95-or-newer Explorer. This is the same size axle found in Ford 1/2-ton pickups, but the Explorer version is within 1/2 inch of the correct YJ width and has disc brakes and the correct bolt pattern. The trick diff cover from Currie reinforces the 8.8 ring gear's main bearing caps.
M.O.R.E.'s Overacker opted for super-beef in his YJ rear by installing Currie's 8.8-inch F
The YJ's high-pinion, reverse-cut Dana 30 front axle is generally considered to be stronger than the earlier CJ version. Some people don't like the vacuum-operated axle engagement and the lack of locking hubs. However, Warn makes a locking-hub kit that eliminates the vacuum function. And for brawn, you can upgrade to larger U-jointed axleshafts from Stage West. Also, ABS-equipped Wranglers have larger U-joints than non-ABS rigs. Finally, building up a 30 is far less expensive than swapping in a 44 or 9-inch, and you get more ground clearance.
The YJ's high-pinion, reverse-cut Dana 30 front axle is generally considered to be stronge
The '87-'90 YJs came with either a fuel-injected 2.5L inline-four or a carbed 258ci (4.2L) inline-six. Jeep's much-admired fuel-injected 4.0L six came online in the '91. Owners of carbed 258s can add complete EFI systems from companies such as Mopar Performance and Howell Engine Developments. The Mopar system shown here on Matt Winters' '90 258 is reportedly an easy bolt-on, including the intake manifold with injectors, a computer, sensors, an electric fuel pump, and a new distributor. And the gas tank does not have to be modified.
The '87-'90 YJs came with either a fuel-injected 2.5L inline-four or a carbed 258ci (4.2L)

According to Snider, the big problem with a V-8 swap into a YJ is that the stock five-speed transmissions tend to explode under torque. The '87-'90 manuals are especially prone to fail, so it's best to swap engines and trannies at the same time. GM V-8s with TH350s or TH700-R4s (or 4L60Es) are particularly popular. Companies such as Advance Adapters offer the needed swap parts. The AMC V-8 engine family, which is a bolt-in replacement for the 258 in CJs or YJs, isn't so easily adaptable to the 4.0L YJ and swap parts are not readily available. Shown here is Ron Esch's 300-horse injected Chevy 350 with a 4L-60 tranny and NP242 transfer case installed by Stage West.
According to Snider, the big problem with a V-8 swap into a YJ is that the stock five-spee
The bottom line about YJs is that improving them isn't a choice between black and white. There are lots of good ways to go. Shaff went spring-over with stock springs in his black '95's front but kept the rear spring-under and used Old Man Emu springs with an added leaf.
The bottom line about YJs is that improving them isn't a choice between black and white. T
Greg Jesuroga kept his white '92 all spring-under. He added a Dick Cepek 3 1/2-inch lift with Cepek shocks to clear his 33x12.50s. As with most buildups, it'll help your planning if you find someone who has built a rig on the kind of budget you have and who 'wheels the way you want to.
Greg Jesuroga kept his white '92 all spring-under. He added a Dick Cepek 3 1/2-inch lift w

SOURCES
Rancho Suspension 1 International Drive Monroe MI 48161 734-384-7804 www.gorancho.com	Howell Engine Developments 6201 Industrial Way Marine City MI 48039 810-765-5100 www.howellefi.com
Currie Enterprises 1480 North Tustin Avenue Anaheim CA 92807 714-528-6957 www.currieenterprises.com	Warn Industries 12900 S.E. Capps Road Clackamas OR 97015 800-543-9276 www.warn.com
Mountain Off-Road Enterprises P.O. Box 690 Delta CO 81416 877-533-7229 http://www.mountainoffroad.com/	JB Conversions P.O. Box 2683 Sulphur LA 70664 337-625-2379 www.jbconversions.com
JKS Manufacturing P.O. Box 98 Alliance NE 69301 308-762-6949 www.jksmfg.com	Tomken Machine P.O. Box 4939 Buena Vista CO 81211 719-395-2526 www.tomken.com
Old Man Emu 15304 Pheasant Lane Austin TX 78734 888-907-4625 http://www.arbusa.com/	Mopar Performance & Accessories P.O. BOX 21-8004 Auburn Hills MI 48321 800-992-1997 www.mopar.com/performance
Rubicon Express 3290 Monier Circle Rancho Cordova CA 95742 877-367-7824 www.rubiconexpress.com	4-To-1 Mfr P.O. Box 1365 Sandy UT 84091 801-641-1421
Advance Adapters 4320 Aerotech Center Way Paso Robles CA 93446 800-771-6171 www.advanceadapters.com	MIT Drivetrain Specialists 1112 Pioneer Way El Cajon CA 92020 619-579-7727 www.mit4x4.com
Dick Cepek Tires & Wheels 4600 Prosper Drive Stow OH 44224 330-928-9092 www.dickcepek.com	Summers Brothers 4747 Brooks St. Unit D Montclair CA 91763 909-399-5121 www.summersbrothersracing.com

Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!

Upgrade Tips for Yuppie Jeeps

More from 4WheelOffroad: