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Hummer H3 Lift Kit - Cruising Altitude

Posted in How To: Suspension Brakes on July 1, 2006 Comment (0)
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Rancho Suspension's reaction to the new Hummer H3 was fast and furious. Within just a short time of the H3's release, Rancho unveiled the industry's first suspension system for said vehicle. Shortly thereafter, the accolades began rolling in--not the least of which was the '05 SEMA award for Best New Off-Road/4-Wheel Drive Product. Naturally, we were eager to install the kit and see what all the hoopla was about.

So we made arrangements to visit our friends at Attitude Performance in Arlington Heights, Illinois, while they installed the kit under a project vehicle belonging to Real Wheels Accessories. The install was eye opening--not to mention quicker than we expected. What follows is an overview of the major components and how they all fit like a glove.

PhotosView Slideshow
PhotosView Slideshow

It wasn't that long ago when most IFS kits took 16 or more hours to install and required gobs of cutting and welding. Those days seem to be fading. This H3 kit took the guys at Attitude Performance less than six hours to install (not including professional alignment), and as you've already learned it required only a minute amount of cutting and absolutely no welding. Naturally, that time would've been even less if we hadn't slowed the process by convening numerous photo sessions. After we completed the installation we ran the H3 through maneuvers at our Secret Illinois Test Facility. As advertised, the Rancho kit provided ample room for a set of 37x12.50R20LT BFGoodrich All-Terrain T/A tires (in our case, mounted on black 20x8.5 Zyoxx ZX2 wheels).


During testing, no tire-to-body contact occurred in off-highway travel even though we didn't modify the front air dam, fascia, or inner fender as recommended. Both on- and off-highway it was no surprise that the overall ride of the H3 was stiffer than stock, yet it wasn't uncomfortable. By the same token, we dropped the front end off of some 12- to 15-inch ledges and the front suspension absorbed the impact quite well, which allowed smooth absorption of the vehicle's weight without an overly jarring impact. During testing we experienced no driveline vibrations, and the rack-and-pinion steering retained its excellent response and good overall feel.

The kit provides an advertised 4 inches of lift, which improves the H3's already impressive approach and departure angles appreciably. Further, the Rancho/Realift torsion-bar relocation technology eliminates the low hanging torsion bars so often associated with IFS suspension lifts. Clearly, keeping the torsion bars tucked in close to the vehicle results in improved ramp-over as well as ground clearance.

RTI Stock

In stock form, the 111.9-inch-wheelbase H3 traveled 50 inches up a 20-degree RTI ramp, logging a score of 447 points. After the installation of the kit, the H3 traveled 47 inches up the ramp, logging a score of 420 points. Naturally, this loss of travel raised some eyebrows. Rancho says this: "The leaf-spring package that we originally released for the H3 was not exactly what we were after given the extremely soft rate of the original equipment springs. At the time, it was the best available.

RTI Modified

The reason for the difference in the RTI scores is primarily due to a higher-rate leaf-spring package along with excessive jounce bumper interference. We have since tweaked the rear spring design and included an updated jounce bumper bracket to correct for and maximize ramp travel (articulation)." They also noted that they would be happy to supply the updated components to any readers who are not completely satisfied with their Rancho H3 suspension system.

Wheel and Tire Specs for Rancho Suspensions H3 Kit (RS6588B)

Suggested tire diameter (in): 35
Maximum tire diameter (in): 37 (will require some trimming of the front air dam/fascia and inner fenderwell for clearance)
Maximum tire width (in): 12.5
Minimum wheel diameter (in): 16(this kit does not allow for reuse of the OEM wheels)
Maximum recommended wheel backspacing (in): 4.5 (16-, 17-, and 18-inch wheels); 5.0 (20 inches and above)


Rancho Suspension
Monroe, MI 48161
Attitude Performance
Arlington Heights, IL
Zyoxx Wheels


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