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Cure Bumpsteer: Steering You Straight

Posted in How To: Suspension Brakes on December 13, 2016 Comment (0)
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Push-pull steering isn’t commonly found on modern vehicles, but it was standard issue on 1979-1985 Toyota pickups, 1967-1987 square-body Chevy and Dodge trucks, and 1960-1989 Toyota Land Cruisers. If you own a Jeep or Ford though, don’t stop reading. Plenty of the steering tips we cover in this story can be applied to your vehicle as well. Whether your rig came from the factory with crossover steering or you are adding it, the goal is to have a drag link as long as possible and nearly flat (perpendicular to the ground) at ride height. This minimizes bumpsteer; that is, when suspension movement feeds back through the steering system and turns the wheels.

Seems simple, right? It isn’t as easy as it sounds. Oftentimes steering parts want to share the same space as suspension components and oil pans. What fits at ride height might come crashing into the oil pan at full compression, so compromises must be made. The situation gets even more complicated when you add a suspension lift, created additional distance between the frame and the front axle.

Our 1981 Toyota pickup had plenty of compromises in the steering system. The factory push-pull steering was marginal due to the short drag link that connects to a J-arm on the driver-side knuckle. Once we added an Old Man Emu suspension lift, which provided additional articulation, we quickly found the limits of the steering. The drag link angle would change dramatically as the truck articulated, resulting in bumpsteer through the steering wheel. Additionally, the drag link end was binding when the driver side was at full droop, which could lead to breakage at the worst possible time.

The solution came in the form of a Hy-Steer kit from All-Pro Off Road. All-Pro addresses all of our issues by converting the steering from push-pull to crossover, with a drag link that connects to the knuckle on the passenger side instead of the driver side. As a result, the drag link is considerably longer and the angle change is minimized as the suspension cycles.

After a long day in the garage, we had a steering system that was not only stronger than stock but also minimized bumpsteer and made our 34-inch Super Swampers easier to turn on the street and the trail. All-Pro uses the type of high-quality components you want to look for when shopping for steering components, regardless of what you drive. These include key items such as 4340 chromoly steering arms, large body tie-rod ends, and a tie rod and drag link constructed from thick-walled DOM tubing.

The factory steering places the puny tie rod in front of the axlehousing below the leaf springs. This makes the tie rod vulnerable in the rocks, and the thin-wall construction doesn’t hold up well to abuse. The new All-Pro tie rod is made from 0.250-wall DOM tubing and tapped for the tie-rod ends, rather than using weld-in bungs.
The factory suspension uses a torque rod that connects the top of the axlehousing to the frame. The idea is to keep pinion dive and axle travel in line with the horizontal drag link, which minimizes bumpsteer. Converting to crossover steering allows the torque rod to be removed, freeing up additional articulation when the appropriate shocks and brake lines are used.
The factory push-pull steering box has to be replaced with an IFS steering box from a 1986-1995 Toyota pickup or 4Runner that swings left-to-right rather than fore-and-aft. The new steering box mated directly to our original steering shaft. If you are adding crossover steering while performing a solid-axle swap to your formerly IFS Toyota all that needs to be changed is the pitman arm.
The torque rod was unbolted and we used our Miller Spectrum 375 plasma cutter to take the brackets off the axle and frame. This made quick work of the brackets, and all we had to do was hit them with a flap disc on a grinder and some black paint afterward.
All-Pro Off Road offers optional frame plates to add the IFS steering box to the front of the frame. We pushed the box as far forward as possible, butting it up against the front cab mount and burned the plates on with our Millermatic 190 MIG welder. Moving the box forward provides additional clearance between the tie rod and drag link at full compression.
Our 1981 truck had manual steering, so we had to add a power steering pump and lines to the 22R engine. All-Pro does not include these components but they were easily sourced from our local junkyard.
The difference in length between the factory drag link and new All-Pro drag link is obvious. The longer the drag link, the less the angle changes as the suspension cycles. Less angle change equals less bumpsteer. This is true for all mechanical steering systems, not just the crossover steering we installed here.
All-Pro Off Road uses 23mm shank tie-rod ends originally designed for the 80 Series Land Cruiser. We prefer tie-rod ends to spherical rod ends for steering for several reasons. Tie-rod ends are sealed, making them last longer in dirty environments, and replacement parts are easy to source at the local parts store.
Steering is no place to use cheap parts of questionable strength. All-Pro Off Road’s steering arms are formed from a single piece of 4340 chromoly steel and machined to exact tolerances. Given the strength of the arms, it is critical to set the steering stops properly, otherwise sheered steering studs or even broken knuckles could result.
Toyota front axles use a closed knuckle with trunnion bearings rather than ball joints, similar to a Dana 60 kingpin design. These make it easy to add the new steering arms, which are secured by cone washers. It is a good idea to check the hardware on the steering arms after each hard wheeling trip to ensure that they remain tight.
It is possible to machine the knuckles on some Dana 44 applications to add steering arms. These arms typically use three studs and cone washers to hold them in place. The added leverage of high steer can accelerate the wear of the knuckle ball joints though, particularly when combined with hydraulic-assist steering and wheels with shallow backspacing.
Pitman arms with different drops are available for a variety of applications, including Toyotas. More drop results in a decreased drag link angle and less bumpsteer, but too much pitman arm drop places added leverage on the sector shaft of the steering box, so sometimes compromises must be made. The factory pitman arm has a tie rod integrated into it, while All-Pro’s pitman arm accepts the 80 Series tie-rod ends.
The new steering system places the tie rod above the leaf springs where it is protected from damage. Note how flat the drag link is at ride height. This allows full range of motion of the tie-rod ends and also limits angle change as the suspension cycles.
Linked suspensions require the use of a Panhard bar (also called a track bar) in order to control side-to-side movement of the axle, regardless of whether they use coils or coilover shocks. The Panhard bar should be as close to level at ride height as possible in order to lower the roll center of the vehicle and provide the best possible handling. The Panhard bar and drag link must be similar in length and at the same angle, otherwise bumpsteer will result when these two bars react differently as the suspension cycles.

Sources

Miller Electric
Appleton, WI 54912
920-734-9821
www.millerwelds.com
All-Pro Off-Road
Hemet, CA 92543
406-961-0126
www.allprooffroad.com

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