Living Better Through Hydraulic AssistFirst, let me commend you on a job well done in your tech articles. I'm going to build a fullsize truck with the airbag lift I saw in your Sept. '04 issue. In this same issue, I saw a truck that got a 6-inch lift in the rear with a 4-inch lift in the front. What got my attention was the hydraulic-assist steering that was added for safety. I'm concerned that once I add this airbag lift to my truck, I'll gain some turning radius when I inflate the airbags to their full 10-inch lift height. I've read in other off-road magazines that the addition of hydraulic steering solves the problem of bumpsteer and increased turning radius. I intend to add hydraulic steering to stay away from the steering loss. What I need to know is if hydraulic steering is slower in turning than a normal drop crossbar conversion. If there are any advantages, what are they, and where can I find such systems? Thanks for your time.David ColesonTallulah, Louisiana
Thanks for reading, David. What you've seen are two distinctively different steering systems that both involve hydraulic rams. While seemingly similar, a closer look into hydraulic-assisted steering systems and their fully hydraulic counterparts reveals big differences in terms of system layout and driving safety. We're big fans of hydraulically assisted steering systems, such as those available from AGR, Lee, Howe, All-Pro Off-Road, and West Texas Off-Road. These systems keep the stock steering setup in place and add a hydraulic ram between the axlehousing and tie rod. Instead of the tie rod transferring 100 percent of the steering forces into the tires, the stock steering system is now assisted by a hydraulic ram that pushes and pulls on the tie rod in the same direction. On other trucks, such as those with IFS systems, the steering ram may push and pull on another part of the steering system, such as the centerlink or the steering rack in a rack-and-pinion system.
We like hydraulic assist for two reasons. First, it makes steering a low-effort endeavor, even when tires of 35 inches or larger are used. Secondly, hydraulic assist takes the steering strain that's normally concentrated on one component, such as the steering box, pitman arm, or frame, and spreads the load out to other structures. After you add hydraulic assist, you'll be able to turn just as fast as before, but with much less effort. Having multiple structures handling the forces of steering means less component breakage. With hydraulic assist, there is still a physical link between the steering wheel and the front wheels. If the hydraulic assist should fail, you will still be able to steer your truck. Not so with fully hydraulic steering.
With fully hydraulic steering, the only connection between the steering wheel and the front wheels is a pair of hydraulic hoses and a hydraulic ram. You'll have almost no road feedback at the steering wheel, and return to center will be virtually nonexistent. If the ram blows a seal, or if the hydraulic hoses rupture or become clogged, you can kiss your steering good-bye. You'll frantically flail at the steering wheel in the last seconds before you crash. If you're lucky, you'll be able to stop in time and avoid personal injury and damage to your truck. If you're unlucky, you'll hurt yourself, your truck, and other innocent people.
It's true that a fully hydraulic system won't have bumpsteer, because the steering system does not have to be in synch with the suspension's travel path. That makes hydraulic steering an attractive way to go for rigs that are driven at slow speeds off public roads. Off-road-only slow-speed trail rigs and competition rock buggies are good candidates for full-hydraulic steering, but for everything else we'd go for a hydraulic-assist setup instead.
If you do go with a full-hydro setup, let us know what roads you drive on so we can stay away.
LETTER OF THE MONTHFlexy Chassis BluesI've been building up an '89 XJ and so far I've rebuilt the 4.0L inline-six and the tranny, and put a slip-yoke eliminator kit on the transfer case. I've put a Dana 44 up front and plan to put a Dana 60 in the rear. I've got an 8-inch Skyjacker lift, and I'm rolling on 36x13.5x15 IROKs. I also have 4.88 gears, and the front Dana 44 has a Detroit Locker. I was wondering what I can do to stiffen up the unibody so I don't tweak it four-wheelin' or trail riding. Chris Dearinger, Bethany, Oklahoma
Sounds like you've got a good rig in the making, Chris. You've already got a great drivetrain in place, and when you get the '60 swapped into the rear, you'll have a nearly bulletproof ride. To stiffen up the chassis, check out T&J Performance's XJ chassis stiffeners. These slick items connect the rear spring hanger to the front suspension pivot points and do so without consuming any ground clearance. Since your Skyjacker kit leaves the frontend's mounting points accessible, the T&J stiffeners will bolt right up. You can reinforce your chassis further by welding small plates between the T&J chassis stiffeners and the unibody's main rails. Check out www.tandjperformance.com for more information, including photos of the installed product. If you've got an archive of OFF-ROAD back issues, take a look at the Aug. '03 issue for a comprehensive look at the JeepSpeed racing series and the products that help XJs survive the harsh courses of SCORE, MDR, and Best in the Desert. We think you'll find that many of the same products, tips, and tricks that let XJs make it through a racing series will also help your '89 survive mile after mile on the toughest trails.
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