Most projects that change the way a vehicle steers start with a small complaint. The wheel has play, the truck wanders in crosswinds, parking takes muscle, the exhaust hit the rag joint, or the upgraded engine ate the old vacuum pump and power assist never felt the same. A steering box conversion kit can solve some or all of those frictions. It can also create new ones if you pick the wrong kit or skip the setup details that make the difference between tight and twitchy. I have installed, rebuilt, and tuned more boxes than I care to count on classic muscle, leaf-sprung 4x4s, desert rigs, and a few oddballs from British to Japanese. This review aims at what matters when you move from a stock system to a new box and supporting parts, especially when pairing a steering box conversion kit with an aftermarket steering shaft, a steering universal joint, or a full power steering conversion kit.
Why a conversion kit at all
Some factory boxes were compromised from day one, with slow ratios and overboosted valving that made highway corrections floaty. Others age out. Sectors wear, bushings oval, input seals leak, and by the time a car hits its third set of tires the center feel has faded. In trucks, larger tires magnify every shortcoming. Add a lift and you have new geometry that argues with old linkages. In some builds, swapping to a different steering box corrects geometry and clears headers or turbo plumbing that would roast a soft rag joint.
There are three scenarios I see most often. First, a manual to power steering conversion on vehicles where parking feels like a gym session. Second, moving from a tired OEM power box to a quicker ratio box, often with better on-center feel. Third, replacing an obsolete or unobtainable box with a modern unit that still bolts to the frame with brackets and a pitman arm that align with your drag link and idler or steering knuckle.
What a steering box conversion kit actually includes
Kits vary widely. At minimum they include a steering box, a frame bracket or adapter, a pitman arm matched for taper and drop, and fasteners with proper sleeve spacers. The better kits include a rag joint or a steering universal joint with the correct spline count, appropriate hardware, and clear spec sheets for torque, fluid, and box adjustments. Some go further and include pump brackets and a matched pump, hoses, and reservoirs for a full power steering conversion kit.
If your kit does not include an aftermarket steering shaft or joints, expect to source them. Universal joint steering components solved more headaches in my shop than any fancy damper ever did. A steering universal joint with the right spline and angle can save column alignment, especially when engines move or frame mounts change. Pay attention to shaft support. Any double U-joint arrangement needs a support bearing if the angle exceeds about 30 degrees total or if the span is long enough to introduce whip and column rattle.
Manual to power steering conversion without drama
Converting manual to power steering changes more than effort. It changes feedback, which is why some drivers end up disappointed with the feel after a quick Borgeson Universal Co but incomplete swap. The best conversions respect three variables. Steering geometry must still agree with suspension travel. Pump and box valving must match tire size and weight. And shaft angles must remain within the universal joint limits or you will feel bind, then wear.
On classic pickups, a common path is moving from a manual Saginaw to a 700 or 800-series power box on the outside of the frame. The kit supplies a plate that reinforces the frame and moves the input shaft to clear the column. With 33-inch tires, the stock pump often overboosts. A smaller flow valve and about 1,200 psi pressure landed closest to “OEM plus” feel in my experience, with more weight on-center and no parking squeal. With 35s and beadlocks, I target 1,400 to 1,500 psi and a cooler on the return line. A small stacked-plate cooler under the core support keeps fluid reasonable on summer trail days.
On vintage muscle, the concern is inside the rail. A quick ratio box can wake up a car if the rest of the front end is tight. I have seen more than one A-body Mopar transformed with a modern box and fresh idler, pitman, and tie rods. The hitch is header clearance. Many small block headers sweep into the space a large-body box wants. A compact box with the right clocking helps, but the downstream issue is often the rag joint too close to heat. This is where an aftermarket steering shaft with a needle-bearing U-joint buys you clearance and longevity. Use a heat sleeve on the joint if it sits near primary tubes. It is cheap insurance.
Choosing a kit by platform, not marketing claims
Kits are marketed with big promises, but the right choice usually comes down to three fit questions and two feel questions. Fit is non-negotiable. The box must bolt to your frame with enough reinforcement, the pitman arm must match your linkage geometry and taper, and the input must meet your column spline or be easily adapted. Feel is preference, but it can be predicted from ratio and valving.
Frame interface matters more than shiny powdercoat. Boxes load frames under repeated steering cycles, and older frames can crack around mounting holes. A kit with a full plate that spans the rail and, ideally, a captured sleeve through the rail to the inner plate, distributes the load well. Models that rely on long standoff spacers and single-shear bolts can oval holes over time, especially with big tires.
Pitman arm geometry sets your turning circle and bump steer behavior. Matching the center-to-center length of the original pitman keeps your travel and Ackermann close to stock. Drop and clocking must match your drag link angle at ride height. If a kit includes an arm that shortens the effective length by half an inch, your quick ratio box just got quicker again, and you may walk into twitchy territory on the highway. I measure the original length and compare. If the kit supplies a different length, it needs a reason, like inner fender clearance or a conflicting idler arm on centerlink systems.
Input compatibility shapes your column plan. Older American columns often use 3/4-inch 36 spline or a 13/16 36, while many later Saginaw boxes use 3/4 30 or 3/4 DD intermediate shafts. Japanese trucks often use 17mm splines. Buy joints that match, or pick a steering box conversion kit that supplies the correct steering universal joint. Avoid stack-ups of adapters. Each added joint adds compliance and potential play.
Ratio and valving decide feel. A move from 4 turns lock-to-lock to 3 or 2.75 makes a vehicle feel modern. Going below 2.5 on a street car can make it wander with every crown if your caster is modest. On lifted solid axle trucks, a small bump in caster helps recenters automatically and pairs well with a quicker box. I target 4 to 5 degrees for stock tires, 5 to 7 degrees for 33s and bigger. Too much caster makes manual conversions heavy off center, which is another reason a power steering conversion kit can be the right call.
What changes when you upgrade the steering shaft
Many kits leave the column to you. The factory rag joint absorbs vibration and small misalignment, but it swells, cracks, and transmits fewer road cues than a quality joint. An aftermarket steering shaft with double D telescoping segments and a sealed bearing joint tightens the system instantly. The trade-off is noise and vibration, which rise a little, and maintenance, which shifts from none to periodic inspection and a light lube on splines.
There is a right and wrong way to clock U-joints. The forks should be in phase, meaning their yokes align when viewed along the shaft. Out-of-phase joints create a non-uniform rotational speed that you feel as pulsing resistance. At big angles, consider a double cardan joint at the column end. It smooths motion through high angles if you also add a support bearing halfway down. This keeps universal joint steering components within safe load limits and prevents steering bind at full droop on long-travel rigs.
A small story from the shop underscores this. A customer with a CJ on 37s complained of a catch near center after a box conversion. The kit was good, the box new. The cause was a single U-joint exceeding its happy angle by a few degrees after the motor mount swap. A double cardan joint with a mid-shaft bearing cleared the headers, reduced the angle, and the catch vanished. The box did not change at all. Shaft alignment fixed the feel.
Hydraulic supply is not an afterthought
Power boxes behave differently depending on pump flow and pressure. Kits often assume a generic pump. In reality, flow controls the speed of assist and pressure caps the force available for heavy loads. Quick ratio boxes with big tires can chatter at idle if the pump’s flow is too low. Turn the wheel into a curb at idle and listen. If the wheel fights you or sing-songs through the valve, you need more flow or a smaller pulley to spin the pump faster at idle. If the steering is feather-light and wanders at speed, the pressure and the torsion bar stiffness inside the valve may be mismatched for your use. Some specialists will revalve boxes. In less involved projects, a pump change and a slightly larger torsion bar in the valve brings back weight.
On road-race cars that see sustained high rpm, stock pumps aerate. A remote reservoir with a properly baffled return reduces foam, which keeps assist consistent. On trail rigs, heat is the enemy. Even a modest plate cooler buys a margin of safety on long days of slow, high-effort work.
Alignment and geometry after the swap
Any steering box change should end with a careful alignment. The box itself does not change toe, but your steering wheel position relative to the box center does. Center the box by counting turns lock-to-lock and halving it, install the pitman arm on the box center, adjust the drag link so the wheels point straight, then set toe to spec. Caster and camber depend on your control arms or axle geometry, but the interaction with a quicker box is real. More caster gives better return to center. Too little caster combined with a quick box feels busy and requires constant micro corrections.
Bump steer is another hidden gotcha. Change pitman length or drag link angle and you change how the steering reacts to suspension moves. On independent front suspension, the cure often lies in matching inner pivot heights and tie-rod end heights. On a solid axle, try to keep the track bar and drag link parallel and of similar length. Some kits with dropped pitman arms fix one side of that equation but push the other out of balance. Short test drives on known roads reveal the truth faster than any spec sheet.
Material, build quality, and rebuildability
On-paper specs do not reveal bearing quality or machining tolerance. Boxes built with modern seals and high-grade sector shaft bearings last longer under side loads. Look at the sector shaft diameter. Larger shafts resist flex with big tires. Peeking under a dust cap tells you little, but user communities and shops that see failures will tell you which brands hold up. I prize rebuildable designs with available seals and gears. A good steering box conversion kit that uses a common Saginaw pattern makes parts sourcing easy years down the road. Obscure one-off boxes tied to a single kit manufacturer can strand you if they vanish.
Shaft components matter as much. Cheap universal joints often use sloppy cross pins and soft setscrews. Quality joints have needle bearings, proper yoke machining, and real setscrew seats with dimpled shafts. Add a through-bolt on at least one end if your design allows it. A pinch-bolt yoke with a relief slot clamps more evenly than a straight bore with twin setscrews. If you step up to an aftermarket steering components bundle, try to buy once, cry once. Steering is not the place to save the last hundred dollars.
Real-world impressions across common platforms
Classic GM A and F bodies respond well to faster boxes around 12.7:1, about 2.75 to 3 turns lock to lock. Pair with modern tires and a bit more caster than stock. A firm-valved box keeps the car from feeling nervous at highway speed. Kits that use the 600-series compact box clear most headers and weigh less than the older 800-series. Use a collapsible intermediate shaft if you still have the original solid piece. Safety matters here, and many conversions present the chance to modernize that element.
Jeep CJs and YJs benefit from stout sector shafts and frame reinforcement. The steering box can act as a pry bar when a front tire wedges on rock. Good kits include a plate that boxes the frame rail and sleeves for the bolts. Universal joint steering at the column saves knuckle clearance and keeps things from binding when the suspension droops. Pressure around 1,400 psi with adequate flow felt best on 35s with lockers. Add a cooler if you also run a hydraulic assist down the line.
Toyota mini trucks and older Land Cruisers have their own dance. Power conversions wake them up on pavement, and trail manners improve with the right valving. Retaining the steering feel that makes a Land Cruiser pleasant demands a pump matched to box volume. Some kits pair domestic pumps and boxes to Japanese frames. This can work beautifully, but measure five times. The pitman arm taper and drag link end require careful selection.
Old Ford F-series trucks are a playground for conversions. Column shifts, long intermediate shafts, and engine swaps create unique angles. Here an aftermarket steering shaft with two joints and a support bearing lets you place the box where the pitman arm lines up with the axle and not where the column dictates. Keep the phases aligned. Get the support bearing mounted on a solid section of frame or crossmember. Test with the front end on jack stands first, turning to both locks through full suspension travel if possible.
Installation details that separate success from regret
Prep the frame. Clean and inspect for cracks before test fitting. Dry-fit the box and pitman arm without hoses attached, center the box, and verify you can reach both locks without interference. Install any sleeves through the frame and torque bolts in stages, then re-torque after a few heat cycles. Use thread locker rated for the temperature environment near the exhaust.
Bleed the hydraulic system correctly. Fill the reservoir, turn the wheel slowly lock to lock with the front end in the air and the engine off to purge air from the box without foaming. Top off, then start the engine and repeat. If the fluid looks milky, let it sit, then repeat. Aerated fluid causes noise and erratic assist.
If you install a new steering universal joint, mark the original wheel position, then reset and center after the box is centered. Never adjust the worm gear preload blind. Conversion boxes often ship pre-set, but re-adjusting the sector shaft lash a quarter turn at a time with a beam torque wrench on the input gives repeatable results. Too tight and the box binds at center and heats the fluid. Too loose and you get the same old play wearing a new coat.
Road test in stages. Start with a simple loop at neighborhood speeds. Feel for self-centering, check that the steering wheel returns predictably, and listen for hose rub. Then a highway run. The first trip tells you where caster and toe land with the new feel. Adjust if the car darts in ruts or needs constant correction. If a vehicle pulls under throttle and relaxes off it, look for a mismatched pitman length or a binding joint before blaming the box.
Comparing kit types by use case
- Daily-driven classic with mild upgrades: Choose a steering box conversion kit with a 12.7:1 to 14:1 ratio, firm valving, and a compact body for header clearance. Keep the pitman length stock and add an aftermarket steering shaft with a single high-quality joint to remove rag play. Weekend trail truck on 35s: Pick a stout box with a large sector shaft, include a frame reinforcement plate, target 1,400 to 1,500 psi pump pressure with a cooler, and use double U-joints with a support bearing. Consider future hydraulic assist when choosing the pump and reservoir. Restomod muscle with autocross duty: A quick box around 2.5 to 2.75 turns, higher torsion bar rate for weight, matched pump flow, and a collapsible intermediate shaft. Dial in 5 to 6 degrees of caster and tight compliance in idler and tie rods. Manual to power steering conversion on a work truck: Choose a power steering conversion kit that includes pump brackets and hoses, keep the ratio moderate around 3 to 3.25 turns, and prioritize reliability over ultimate quickness. Use a steering universal joint if exhaust or column angles changed. Engine-swapped project with tight clearances: Build around universal joint steering components and a telescoping aftermarket steering shaft to route around headers and accessories, choose a compact box with the right clocking, and confirm pitman clearance at full lock.
Cost, value, and what not to cheap out on
A complete steering box conversion kit ranges from modest to eye-watering, depending on platform rarity. The middle ground, where you get a quality new or professionally remanufactured box, correct brackets, and a pitman arm, gives the best value. Saving money by reusing tired tie rods, an old idler, or a questionable rag joint undermines the upgrade. Steering feel is a chain, and the weakest link wins. Budget for an alignment and, if you changed to a much quicker ratio, a set of tires with stiffer sidewalls can sharpen response more than you expect.
Do not cheap out on the steering shaft hardware. The setscrews must bite into relieved dimples. Torque them and then safety them if the manufacturer specifies. If you plan to wheel hard or track the car, inspect joints and column support once or twice a year. A little play telegraphs through the wheel long before something fails, and early correction costs very little.
Edge cases and lessons learned the hard way
A few pitfalls show up enough to mention. A box that seems to wander even after alignment sometimes sits off center mechanically. The control valve is most neutral at center. If you install the pitman a spline or two off and correct the wheel with the drag link, the box spends most of its life on the slope of the valve, not on the flat. Recenter the box mechanically and it will calm down.
Heat kills rack boots and seals, but it also hardens steering box input seals. If your steering shaft sits near a header primary, wrap the shaft and joint area with a woven sleeve and add a small heat shield off the frame. Ten minutes of tin snips and rivets save a season of weeping seals.
Quick ratios magnify toe change. A tiny toe-out setting that felt lively with a slow box can feel darty with a fast one. For street setups where stability trumps razor turn-in, a hint of toe-in, perhaps 1/32 to 1/16 total, keeps the car planted. If you run modern performance alignment numbers, add just enough caster to make the quick ratio feel centered and serene.
Where universal joints shine and where they do not
Universal joints give you freedom to route around obstacles and correct angles. They also transmit everything. On cars with stiff mounts and no rag joint, a little gear whine or tire scrub comes through. I lean toward a hybrid approach on street cars: a quality needle-bearing steering universal joint at the box, a short collapsible section in the shaft, and, if needed, a small vibration reducer at the column. On trucks with big tires and lockers, I accept the extra noise. Precision beats isolation in off-road contexts where accurate wheel placement matters more than quiet.
There is a limit to how many joints you should stack. Two joints at moderate angles with a support bearing are fine. Three joints feel busy and add too much compliance unless you have no choice. If you must run three, keep angles equal and in phase, and place the support bearing such that no unsupported span exceeds about 12 to 14 inches depending on shaft diameter.
Final takeaways for choosing and living with a conversion
If a steering box conversion kit promises a night-and-day change, it might be telling the truth, but only if the surrounding pieces support it. Pick a box and ratio that fit your use, reinforce the frame, keep pitman geometry honest, and feed the box with the right pump. Match an aftermarket steering shaft and a steering universal joint to the angles at hand, phase them correctly, and support the span if it is long. Expect to re-align and fine tune caster and toe to match the quicker response if you chose that path.
The reward is a vehicle that does what you ask with calm precision. The best compliment I hear after a conversion is not about speed, it is about confidence. The truck tracks straight with one finger on the wheel. The car turns in without drama and returns to center naturally. Parking feels easy but not numb. Those are the markers of a conversion done right, where the parts, from the box to the universal joints to the pump, work together instead of fighting for attention.
Borgeson Universal Co. Inc.
9 Krieger Dr, Travelers Rest, SC 29690
860-482-8283