Steering is the conversation between your hands and the road. If that conversation feels vague, heavy, or inconsistent, the steering box is often the culprit. Converting or upgrading the steering box can transform a vehicle, especially an older truck or classic car with worn or outdated gear. A steering box conversion kit brings the right parts together so you can move from tired manual steering to a precise power setup, or swap a problematic integral box for a better design without fabricating half the front end.
I have installed these kits on farm trucks that plow gravel roads and on restored coupes that see more show parking lots than fast corners. The same principles apply to both. You want predictable steering effort, clean on-center feel, and components that work together without interference or premature wear. That is exactly what a well-chosen steering box conversion kit should deliver.
What a steering box conversion kit really includes
The term kit gets misused. Some boxes ship with almost everything, others only include the gear. A proper steering box conversion kit usually contains the steering gear itself, a mounting solution to mate it to your frame, a pitman arm matched to the gear’s sector shaft and the vehicle’s center link geometry, and the hardware to bolt it on. If you are moving to power assist, expect a power steering conversion kit that adds a pump, brackets, crank pulley, hoses, and often a reservoir. The better kits go further and include an intermediate shaft, a steering universal joint that fits the column splines, and sometimes rag joint eliminators.
A note on the rag joint. Many older vehicles use a fabric-reinforced rubber disc that dampens vibration between the steering column and the gearbox. It works, until it cracks or compresses. Modern aftermarket steering components swap the rag joint for a Universal joint steering coupler, or for a pair of steering universal joints with a short Aftermarket steering shaft between them. This change tightens the feel at the wheel and removes slop. Just make sure the joints run straight enough to avoid binding.
Why convert in the first place
There are four common scenarios that justify a conversion.
The first is manual to power steering conversion. If you have ever parallel parked a 1960s half-ton with a snowplow, you know the shoulder workout. Power assist brings steering effort down to a manageable level and makes the truck far easier to live with. The second is the worn or obsolete original gear. Saginaw 605 boxes, for example, earned a reputation for vague on-center feel in certain applications. Replacing them with a Saginaw 700 series or a modern Delphi box can be a big upgrade. The third is engine or accessory changes that interfere with the steering box or its plumbing. LS swaps bring this up frequently. The fourth scenario is geometry correction. Lifted solid-axle rigs often suffer from poor steering angles and bump steer. A different box location or pitman arm length can improve geometry and road manners.
If your current power box leaks and has 3 inches of play at the rim, rebuild kits might buy you time, but most owners prefer to step up to a tighter ratio and a fresh casting. The difference you feel at the wheel can be measured as less steering input for the same lane change, cleaner return to center, and far fewer corrections on a windy day.
Steering ratios, effort, and feel
Gear ratio dictates how many turns of the steering wheel you need to swing the front wheels from lock to lock. Manual boxes often run slow ratios, sometimes 20 to 24 to 1, to keep effort manageable without a pump. Power boxes can be quicker, commonly 12.7 to 1 to 16 to 1. Quicker ratios mean less arm motion but higher effort. With assist, that extra effort is masked, but it still affects feedback and stability.
Variable ratio boxes add another wrinkle. They are slower around center for relaxed highway tracking, then quicken as you move off center into tighter corners. Drivers who came up on classic muscle cars often like the quick boxes, around 12.7 to 1. Drivers who tow heavy loads or drive on rutted roads sometimes prefer 14 to 1 or a variable ratio to take some twitch out of the steering. When choosing a steering box conversion kit, balance your use case. A slammed C10 that sees mostly smooth pavement can benefit from a quick box. A work truck with tall tires may feel better with a moderate ratio and a longer pitman arm for leverage.
Steering effort is also governed by pump output and valve tuning. Too much assist and the wheel goes numb, too little and you fight it at parking speeds. Manufacturers publish pump flow and pressure ratings, often in liters per minute and psi. For a typical light truck box, flows in the 2.5 to 3.0 L/min range with 1,200 to 1,400 psi relief pressure give a natural weight at the wheel. Mismatching a high-flow pump with a box valved for low flow can cause hiss, heat, and touchy response. This is where a matched power steering conversion kit earns its keep.
Matching input and output splines so everything connects
The intermediate shaft is the unsung hero in these conversions. Steering columns and boxes use different spline counts and diameters. A common setup is a 3/4 inch 36-spline input on the box and a double D or 3/4 inch 30-spline on the column. If you assume the joints fit, you might discover play or, worse, a joint that will not clamp correctly.
Aftermarket steering shafts take the guesswork out. They are sold with the right steering universal joint on each end to match your column and your new box. On lowered cars where the column angle is steep, a double U-joint setup with a support bearing keeps the angles within spec. Keep each universal joint under about 30 degrees. Over that, the joint binds and the steering stiffens at the ends of travel. Two joints with a straight intermediate section share the angle and give smooth motion.
If you need to reuse the stock column with a rag joint, be honest about its condition. The rubber disc can look intact yet be soft enough to compress under load, which feels like play at the rim. Many owners take a hybrid approach, a steering universal joint at the box and a compact vibration damper at the column, to retain some isolation without the squish of a full rag joint.
Pump brackets, pulleys, and the packaging dance
Mechanically, the box bolts to the frame. Hydraulically, it depends on a pump and hoses. The power steering conversion kit portion handles this. On small block Chevy engines, for example, there are at least four bracket families based on year, head bolt holes, and accessory layout. Mix a long water pump bracket with a short water pump pulley and you will chase belt alignment for hours.
Before you order, confirm which front accessory drive you have. Measure pulley offsets and note whether the crank pulley has one or two grooves. Power steering usually needs its own belt groove to avoid slippage at low speed. Many aftermarket kits include a Type II pump with a remote reservoir. Those are compact, easy to mount low, and tolerant of high rpm, but they need careful hose routing to prevent aeration.
Heat kills pumps and boxes. If you tow or drive mountain passes, a small power steering cooler mounted in front of the radiator keeps fluid temperatures in check. Add it if the kit offers one or budget it in. Most steering fluid likes to live under 200 degrees Fahrenheit. Overheating thins the fluid, which reduces lubrication and can cavitate the pump.
Pitman arms, center links, and geometry you can feel
The pitman arm translates the box’s sector shaft motion into linear movement in your center link or drag link. The arm’s length, drop, and indexing matter. A longer arm increases steering rate at the wheels for a given rotation at the box, but it raises steering effort. A shorter arm does the opposite. If you are moving from a manual box to a power box, resist the urge to go too long. It may feel great in a parking lot and twitchy at 70 mph.
Indexing is easy to get wrong. Most sector shafts are splined with a master serration or flat so the pitman arm only fits in a few positions. Still, if your steering wheel ends up two turns to the right when the wheels are straight, you either misindexed the pitman arm or the tie rod lengths need adjusting. Always center the box first, then fit the arm, then set toe. On some trucks, particularly 4x4s with lift kits, the pitman arm drop determines whether your drag link runs parallel to the track bar. They should be near parallel to minimize bump steer. A steering box conversion kit aimed at lifted trucks will often include a dropped pitman arm to preserve alignment.
Choosing the right kit for your platform
On classic GM A-body and F-body cars, the most common swap replaces a loose original or a Saginaw 605 with a 700 series quick-ratio box. The frames accept the newer box with an adapter plate that rotates the bolt pattern and corrects the sector shaft location. Expect a real-world reduction from roughly 3.5 or 4 turns lock to lock down to about 2.5 to 3 turns. Pair that with a matched aftermarket steering shaft and a steering universal joint, and the change in road feel is night and day.
For vintage Ford trucks, conversions often replace manual worm-and-sector gears with integral power boxes. The challenge is frame spacing and header clearance. Some kits relocate the box slightly forward to clear tube headers. On these, watch the intermediate shaft path around the exhaust. Heat sleeves on the shaft and hoses are cheap insurance.
Jeep CJ and early Wrangler owners run into the limitations of original Saginaw manual and power boxes. Heavy wheels and tires magnify play. A high-quality replacement box with a stronger sector shaft, coupled with a brace that ties the box to the opposite frame rail, tightens the system. Choose a kit that includes the brace if you wheel hard. It reduces frame flex and box deflection, which feels like steering wander.
LS-swapped trucks are their own category. The pump, lines, and reservoir need to match the LS accessory drive. If you try to feed an older box with a random LS pump, pressure and flow may not match the box valve. Good kits supply the correct pump, a pulley that aligns with your belt, and hose ends that marry GM metric O-ring fittings to your box’s flare ports or to a new box with modern ports. The fewer adapters you use, the fewer leak points.
Installation flow that avoids common traps
A conversion is not hard, but sequence matters. Remove the old box and pitman arm with a proper puller. Do not try to hammer the arm off the sector shaft, as mushrooming the splines ruins the shaft. With the box out, clean the frame rail and inspect for cracks around the original mounting holes. If the kit adds an adapter plate, test-fit it and set all bolts loose until the box is positioned. This gives you wiggle room to align the pitman arm with the center link without binding.
Center the new box by counting turns lock to lock, then back to center by dividing turns in half. With the box centered, position the wheels straight ahead and install the pitman arm. This ensures you have equal travel left and right. Connect the intermediate shaft and steering universal joint to the column, keeping the u-joint yokes in phase. If you use two joints with a support bearing, locate the bearing so that the intermediate shaft runs straight between the joints. Mark the joint clamp positions, then apply thread locker and torque them properly. Loose joints cause the dreaded clunk at the wheel.
For power steering conversion kit plumbing, route the pressure hose away from the exhaust and steering linkages. The return line can be rubber, but pressure lines need to be high-pressure rated with the right ends. Fill the reservoir, then bleed the system with the front tires off the ground. Turn the wheel slowly lock to lock without the engine running to move air through the system. Top off as bubbles purge. Then start the engine and repeat, watching for foaming. Foaming suggests a suction leak at the pump inlet or a return line submerged wrong in the reservoir.
When the car is back on the ground, set toe and center the steering wheel. Even if you marked tie rods during teardown, the new box and pitman arm rarely land in exactly the same position. A quick toe set with toe plates will make the first drive safe. Schedule a proper alignment soon after.
Real-world examples and outcomes
On a 1972 C10 street build, we installed a quick-ratio box, a matched pitman arm, and an aftermarket steering shaft with a single steering universal joint at the box. The truck ran a mild drop and 245-series front tires. The owner wanted modern steering without losing highway stability. We chose a 12.7 to 1 variable box, a Type II pump, and a small cooler. Steering went from about 3.75 turns to 2.75 lock to lock. Parking effort dropped, on-center feel sharpened, and the truck tracked straight with fewer corrections. The biggest surprise to the owner was the effect of replacing the soft rag joint. The lash he thought was in the box disappeared.
A different case, a lifted 1995 Ram used to tow a car hauler. The owner complained about wander and bump steer. The solution combined a stronger remanufactured box, a dropped pitman arm matched to the track bar drop, and a frame brace. We kept the ratio moderate to avoid twitchiness with 35-inch tires. The steering wheel’s dead band shrank to less than half an inch, and the truck stopped hunting grooves on the freeway. The lesson there is that geometry and chassis stiffness matter as much as the gear itself.
The role of universal joints in steering safety
People often treat steering universal joints like any other coupling. They are more critical than that. A worn joint adds play and can seize if the needles run dry. Cheap joints with soft yokes spread and lose clamp load. When using a Universal joint steering coupler in a high-angle setup, invest in needle-bearing joints from a reputable brand. Greasable joints are worth the small maintenance cost. On hot rods with tight headers, add a heat sleeve and inspect the joint at every oil change. If you can feel any notchiness when turning the joint by hand, replace it.
Alignment of the joints matters. When using two joints, phase them so the forks align. Out-of-phase joints can cause cyclic speed variation in the intermediate shaft, which you feel as a subtle pulse at the wheel. Keep the intermediate shaft length stable by bracketing it to the frame or the column, not to the engine. The engine moves on its mounts, the frame does not. If you tie the shaft to the engine, it will push and pull the joint with torque, which can bind or wear it out.
Fluids, filters, and why they matter more than you think
Power steering fluid is not universal. Some systems call for dedicated steering fluid, others run automatic transmission fluid. Mixing types is a common way to swell seals or foam the fluid. If the kit specifies a fluid, use it. If it does not, learn what the pump manufacturer recommends. Many modern pumps are happiest with a full-synthetic steering fluid that resist heat and aeration. Old Saginaw pumps often lived on Dexron ATF and still do, but if you combine an old pump with a modern box, test for noise and foaming before committing.
Inline power steering filters are cheap. Install one on the return line when you first fire the system and replace it after a few hundred miles. It will catch debris from hoses and assembly. If your old pump shed metal, the filter might save the new box. Persistent pump whine often traces to aeration on the suction side. Keep the reservoir above the pump when possible and minimize sharp bends in the suction line. Remote reservoirs with internal return diffusers reduce foaming.
Common pitfalls and how to avoid them
Conversion kits solve a lot of problems, but they invite new ones if you rush.
- Misaligned pulleys cause belt squeal and pump speed issues. Use a straightedge across the crank and pump pulleys, shim brackets as needed, and confirm belt tracking under load. Over-tightened belts ruin pump bearings. You want enough tension to stop slippage, not a twanged guitar string. Steering stops forgotten during swaps allow tires to rub control arms or frame rails at full lock. Adjust the stops to protect tires and fenders. Angle mismanagement on the intermediate shaft causes stiffness or snap-back near lock. Keep joint angles modest and aligned. Incorrect pitman arm clocking leads to uneven steering travel and a crooked wheel. Center the box first, then fit the arm.
That list could run longer, but those five account for most of the headaches I have seen in the bay.
Cost, value, and what to expect over the long term
Steering box conversion kit pricing varies widely. For common muscle car platforms, a well-matched kit with a new or premium remanufactured quick box, adapter plate, pitman arm, and hardware often lands in the 700 to 1,200 dollar range. Add a power steering conversion kit with pump, brackets, hoses, and reservoir, and the total can reach 1,200 to 1,800 dollars depending on brand and finish quality. Trucks with heavy-duty components or specialty applications can exceed that. Labor runs from four to eight hours for most installs, more if you are fabricating brackets or dealing with rusted hardware.
On the road, expect a meaningful change right away. The steering wheel will likely sit at a different clocking after the first drive as the suspension settles and any air clears from the system. Recheck fluid level and look for seeping fittings. After a few hundred miles, retorque the steering universal joint clamps and pitman arm nut. New parts bed in and relax, and a quick check keeps them safe.
Over the long term, power steering systems ask for little. Change fluid every few years, or sooner if it darkens or smells burnt. Inspect the pump belt and hoses annually. If the wheel develops play, check the intermediate shaft joints first, then the box lash adjustment. Many boxes have a top adjuster for sector shaft lash. A quarter turn can tighten a lazy on-center feel, but over-tightening causes binding off center and accelerates wear. If you do not know the spec, leave it alone or have a steering specialist set it.
When aftermarket steering components make the difference
Factory parts do a lot right, but they were designed for factory tires and ride heights. If you run wide modern radials, aggressive alignment settings, or lift and lower beyond stock, aftermarket steering components bridge the gap. That might be a beefy pitman arm with a proper taper for your center link, a collapsible Aftermarket steering shaft that clears headers, or a steering universal joint solution that keeps the column angle sane.
Quality shows in the small details. Look for zinc-plated hardware, machined adapters with clean threads, hoses with crimped ends instead of hose clamps on pressure lines, and clear instructions with torque specs. Steer clear of kits that expect you to reuse worn-out tie rod ends or that bundle unknown pumps with no flow rating. The steering system is not the place to gamble.
Final guidance grounded in shop-floor reality
If you are deciding between rebuilding your existing box and buying a modern quick-ratio replacement, consider how you use the vehicle. If it hauls and tows, prioritize stability and moderate effort. If it corners hard and you value response, lean toward a Borgeson quick or variable ratio. For a manual to power steering conversion, buy a kit that includes the pump and bracketry proven for your engine. That saves time and avoids a mix of pulleys that will never line up.
Measure twice before ordering. Confirm the column spline, the distance to the box input, and the path around headers. Plan for heat management with sleeves and a cooler if needed. Do not overlook the alignment step, both for the wheels and for the steering wheel. If the installation feels beyond your tools or time, a shop that specializes in classic or 4x4 steering will do the job in a day, and you will get a centered, bled, aligned vehicle back.
Most of all, expect your vehicle to feel different in the best way. The wheel will load up predictably in a corner. The truck will stop chasing ruts. Parking will become easy. A steering box conversion kit, done right, does not just fix play. It brings back the confidence that the front end will do exactly what you ask, no more and no less. That confidence is why we drive these machines, and why the right parts matter.
Borgeson Universal Co. Inc.
9 Krieger Dr, Travelers Rest, SC 29690
860-482-8283