Remember this Jeep? If you're a long-time reader we're betting you will. It's the '99 Cherokee we purchased from Collins Bros Jeep back in '02 and introduced to you in the Nov. '03 issue of Jp magazine. Since it came from Dallas and had a "Ewing" dealership badge on the tailgate, we named it JR after one of the main characters of that cheesy '80s TV show. During the subsequent buildup the little "badass from Dallas" was transformed into a pretty slick high-speed off-road toy with a worked 4.6L stroker huffing nitrous oxide, a Currie Ford 9-inch with 4.88s and an Eaton Truetrac out back, a trussed Dana 30 front, and a long-arm suspension. In all, it was a great little daily-driver for over 60,000 miles until mechanical troubles and corporate apathy shelved it for a couple years. However, now that the ink is dry on the bill of sale and this little Jeep is finally owned by the staffer who built it, Project JR is coming out of mothballs.
Naturally, during its hibernation some of the trick components were laid to the wayside, put to use on other projects, or just plain disappeared. But no matter, because time marches on and so does technology. In many instances there's much better stuff out there and we intend to redo all the niggling problems that plagued us from the first buildup. And to that end, we're kicking JR's rebirth off with a brand new suspension.
Back in '03 when we first built JR, long-arm suspension systems were new and exciting. However, nowadays off-roaders demand a bit more out of their suspension and we weren't content to keep the clunky control arms and less-than-ideal geometry our old four-link offered. Additionally, we were looking to clean up and simplify things underneath while, at the same time improve the potential for flex. We decided to search for a clean, well-designed three-link suspension as an upgrade to Project JR. Poly Performance brings XJ owners several high-quality long-arm suspension options based off its bolt-on four-link bracket set.
All arrangements use the same superb track bar setup and heavy-duty lower links with Poly Performance's double adjuster sleeve, but the bolt-on four-link brackets give the option of running either the factory upper control arms axle mounts (as a four-link) or utilizing a new weld-on upper control arm axle mount (as a three-link). Why a three-link? In addition to providing more clearance on the driver-side, a three-link has less potential for binding and more potential for flex than a standard four-link suspension. Sometimes less can be more.
We brought our '99 to Poly Performance's San Louis Obispo facility so designer Drew Burroughs and his crew could professionally install the new front suspension. In this first installment we'll familiarize you with some of new suspension's features and show some install highlights. Next time around we'll be dropping the front ride height with some progressive-rate coils from Deaver Spring, debating the benefits of adding air bumps, and bolstering the rear with a set of Poly Performance's absolutely bombproof rear spring hanger brackets.
Poly Performance XJ Three-Link
Here's our new Poly Performance three-link suspension in all its CAD-designed, laser-cut, computer-bent glory. The components really are exceptionally nice. The lower links are 2-inch, 0.250-wall DOM with a slight bend for tire clearance at full lock and OE-style rubber bushings at the axle end. The frame ends feature large Johnny Joints with Poly's double adjuster sleeve that eliminates the need for right/left hand threaded ends and allows easy shortening/lengthening with the links mounted on the vehicle.
The upper is 1 3/4-inch, 0.120-wall DOM with Johnny Joints at both ends and weld-in bungs. Of course, you can also opt for pre-built four-link upper control arms that tie into the factory upper axle mounts, but we chose the new three-link upper control arm and axle mount featuring additional gussets. The new track bar bracket and brace tie into preexisting holes in the Unitbody and the track bar is solid 1.25-inch chromoly steel with a polyurethane bushing at the frame, Poly's double adjuster sleeve and a rod end at the axle mount. Also, note the bolt-on four-link brackets. If you're building a competitor or just hate drilling holes, the brackets can be ordered bare and then welded-on instead. But we chose to bolt them on since the majority of at-home installers will probably do it this way. We'll show you the rear spring brackets going on next time.
After removing our old suspension...
After removing our old suspension and cutting off the factory control arm mounts from the Unitbody, the crew at Poly Performance began the installation by bolting up the laser-cut control arm brackets. The brackets sandwich the Unitbody and require a few holes to be drilled. It all locates off the factory T-case crossmember mounting holes which eliminates the need for measurements. Standard nuts and bolts are utilized wherever possible, but a few channeled areas of the Unitbody require the use of self-tapping bolts.
You may or may not need to...
You may or may not need to make modifications to the exhaust downtube for clearance depending on the model year and engine type. The downtube on our '99 4.0L had been modified in the past to clear our old long arm brackets so we dodged that bullet this time around, but you should be aware exhaust mods may be a requirement. With the brackets mounted to the frame, the lower control arms can be installed.
Poly Performance's four-link...
Poly Performance's four-link system features upper control arms that attach at the factory upper control arm mounts on the axle. However, the three-link requires the passenger-side upper control arm mount to be cut off, since the three-link upper control arm is straight and features a flexier Johnny Joint control arm end.
With the upper control arm...
With the upper control arm mount cut off, the Poly Performance track bar bracket and reinforcement is bolted to the Unitbody using existing holes. With the bracket in place, the 1.25-inch solid chromoly track bar is bolted in place at the frame end first.
Next, the existing 10mm track...
Next, the existing 10mm track bar mount at the axle must be drilled out to 9/16-inch. Poly Performance offers a weld-on reinforcement plate to bolster the factory mount. Note the Poly Performance's slick double adjuster sleeve that allows shortening/lengthening without removing the link end mounting bolt.
With the track bar in place,...
With the track bar in place, it's time to install the new three-link upper control arm mount. Burroughs says he positions the axle roughly at ride height and sets the caster, then welds the bracket on at zero-degrees as shown. Don't forget, the upper and lower control arm mounts are adjustable, so any fine-tuning of the caster or pinion angle is possible once the vehicle is sitting on the ground under its own weight.
Note our upper control arm...
Note our upper control arm mount is just tacked on for now. That's because our old, bent Dana 30 is getting the heave-ho in the near future. Regardless, with the new axle bracket in place, the upper arm can be bolted in place.
On the frame end, this nutsert...
On the frame end, this nutsert plate is slid inside the Unitbody channel for the 9/16-inch upper control arm mounting bolt. The Johnny Joints on the upper control arm and the rubber bushings at the axle on the lower control arms should hopefully provide a nice quiet ride without limiting flex.
Here's where we'll leave off...
Here's where we'll leave off for now. Check back next time when we'll drop down to some shorter-but-better coil springs and figure out the correct bumpstop height. You'll also get a sneak peek at the new front axle and can gawk at Poly Performance's heavy-duty XJ rear spring hanger brackets.