Power steering conversions are one of those projects that transform a vehicle from a chore to a pleasure. If you have a classic truck with pizza-cutter tires, a vintage muscle car with a big-block hanging over the front axle, or a Jeep that sees rocks and ruts, adding power assist reduces fatigue and sharpens control. The trick is approaching the job with a plan, the right parts, and realistic expectations. I have converted manual-steer vehicles across several decades and brands, and while every platform has its quirks, the core sequence, checks, and pitfalls stay consistent.
This guide walks through the real-world process, from choosing the system to final alignment. You will see trade-offs between a steering box conversion kit and a rack conversion. You will also see how to integrate an aftermarket steering shaft and a steering universal joint where clearances get tight, and how to keep safety at the center of every decision.
Start with the end in mind
Before turning a wrench, define what you want the vehicle to do. Are you building a weekend cruiser that needs lighter parking effort, or do you want more precise road feel for highway miles? A rock crawler with a hydro-assist plan is a different animal from a period-correct restoration. Your use case informs the parts choice, the fluid management, and even the alignment targets after the conversion.
Budget is not just parts cost. Add hoses, fittings, fluid, alignment, the sometimes inevitable second run to the parts store, and small items like clamps and heat shielding. On a typical 1960s to 1980s car or truck, plan a range of 800 to 2,200 dollars for a mechanical steering box approach, less if you score used components in good shape, more if you go with a new rack-and-pinion cradle, a new pump, and custom lines.
Choosing a path
Most DIYers land on one of two routes. The first is a power steering conversion kit that replaces or supplements the original steering gear with a hydraulic box. The second is a rack-and-pinion swap, either front-steer or rear-steer depending on the crossmember. Both can be excellent. The right choice depends on your chassis, header routing, oil pan, and ride height.
A steering box conversion kit tends to be simpler on trucks and body-on-frame classics. You keep the center link and idler arm, add the power box, and plumb a pump. This keeps geometry close to stock and preserves bump steer characteristics. It also tends to fit with fewer structural changes. The downside is slightly lazier on-center feel compared to a modern rack, though a tight box with good valving still drives well.
A rack-and-pinion conversion brings a more direct feel and often a quicker ratio. It can also free space around the engine bay if the original box and shaft fought your headers. The trade-off is geometry. The rack’s inner tie rod pivots must live on the same virtual line as the lower control arm pivots or you will fight bump steer. Good engineered kits solve this with brackets that establish correct height and fore-aft location, but custom mashups can create more handling problems than they solve.
No matter the route, read every installation PDF you can find for your specific vehicle and kit. A steering universal joint angle that looks fine on the bench might bind when the engine torques over and the shaft moves a few millimeters.
Parts that matter
A complete manual to power steering conversion needs a matched system. A pump with the right flow and pressure for the gear, a reservoir that will not aerate, and high-pressure hoses rated for heat and abrasion. The big items list usually includes a power steering conversion kit, brackets for the pump, crank and pump pulleys if your engine lacks them, new belts, the steering gear itself or the rack assembly, and a rag joint or steering universal joint as needed for the column interface.
Small parts matter. Return line routing that dips below the pump then climbs back up will trap air. A hose that touches a header tube will blister in a month, or sooner. If you are adding an aftermarket steering shaft, choose the correct splines at both ends: common sizes include 3/4 inch 36-spline, 3/4 inch 30-spline, 13/16 inch 36-spline GM, and DD profiles. Many steering universal joint offerings mix these without drama, but mis-matched splines will turn an afternoon job into a long weekend.
Tools and workspace
You will need line wrenches for hydraulic fittings, a torque wrench for critical fasteners, a puller for pitman arms, a pickle fork or ball joint separator to deal with tie rods and idlers, and a steering wheel lock or strap to keep the column from spinning while disconnected. A cutoff wheel and flap disc sometimes become necessary if the original rag joint or shaft coupling is seized.
Set up a clean bench with labeled bags for fasteners. Steering hardware looks similar at a glance but often varies in length and thread pitch.
Safety assumptions
Never work under a car supported only by a jack. Place jack stands under frame rails, not control arms, so the suspension droops and you have room to remove the linkage. Disconnect the battery if your hands will be near the starter cable while routing hoses, and keep fluid off belts and exhaust surfaces. After any steering work, the vehicle is not road-ready until you verify clearance lock to lock, bleed the system, and perform an alignment.
Dry fit before you commit
I start every conversion by dry-fitting the big components with no hoses or belts. Set the power box on the frame and snug the bolts. Hold the pump bracket on the engine and check for clashes with alternator brackets and the water pump outlet. If you are installing a rack, set the cradle in place and loosely install fasteners so you can check where the inner tie rod pivots sit relative to the lower control arm pivots. Place the pitman arm on the box, pointing straight back at the center link, and verify travel range.
This is when aftermarket steering components show their tolerance stack. A quarter inch here and there adds up. If the column shaft meets the box input at a bad angle, accept that you will need either a double-D shaft with a collapsible section or an intermediate shaft with a universal joint steering coupler to correct the angle. It is far better to decide this now than after hoses are cut and the pump is filled.
Removing the manual gear
Old hardware does not surrender easily. Soak pitman arm splines and the idler arm nut with penetrating oil the day before. Mark your steering wheel at top-dead-center and strap it so it cannot spin and damage the column internals. Unbolt the rag joint at the column end, then the gearbox from the frame. Use a proper puller on the pitman arm, not a hammer. A bent pitman arm is a silent hazard.
As the box comes out, compare input shaft length and major diameter to the new power box. If the new box uses a different spline, confirm that your steering universal joint matches. This is a common point where DIYers discover that the kit expected a later column or a different joint. Fix it now with the correct coupling.
Installing the new gear or rack
With the frame holes cleaned and any captive nuts chased with a tap, set the new box in place. On many GM and Ford frames, the top rear bolt fights the block and headers. I use a short hex-head bolt to get the box aligned, then substitute the correct length once the box is fully seated. Torque to the manufacturer’s spec. Most mid-size boxes want fasteners in the 60 to 90 foot-pound range, but follow the data for your kit.
If you are installing a rack-and-pinion, torque the cradle and rack mount bolts to spec, then set the rack at its mechanical center. You can find center by counting turns lock to lock and halving it. With the rack centered, place the steering wheel at its straight-ahead mark and do not move either until the intermediate shaft is connected.
Install the pitman arm on a steering box with the marks aligned. If the box ships uncentered, recenter it before the arm goes on. I prefer to tighten the pitman arm once the center link is connected, which helps the arm sit without twist. On a rack, thread the tie rod ends fully onto the inner tie rods at equal turns so your toe is in the ballpark for the trip to the alignment shop.
Pump and brackets
Power steering pumps like stable mounting and correct belt wrap. Bolt the bracket to the engine with all hardware loose enough to slip, then square the pump so the pulley aligns with the crank pulley groove. Eyeballing alignment invites belt squeal. A straightedge across pulleys is better. If the engine never had a pump, you may need a new crank pulley or a two-groove version. Many small-blocks share bolt patterns, but water pump length and accessory drives differ between short and long water pump configurations. If the belt rides one rib off, correct it now with spacers or the right pulley rather than hoping the belt finds its own path.
If your kit uses a remote reservoir, mount it higher than the pump inlet and keep the feed hose short with gentle bends. Reservoirs foam when return fluid drops too close to the outlet, so follow the orientation markings.
Hoses, fittings, and heat
Hydraulic hose routing is as much art as science. Avoid tight bends near fittings, keep away from exhaust heat, and ensure at least a finger width of clearance from the frame and moving parts through the full range of engine motion and steering travel. I often add a heat sleeve where a hose passes within two inches of a header primary. Use line clamps on the frame to prevent hoses from chafing. The pressure line will be a crimped assembly rated for 1,200 to 1,500 psi or higher. The return line can be quality power steering return hose, not fuel line.
Fittings deserve respect. Many pumps use an inverted flare or a metric O-ring style. Gearboxes may use SAE inverted flare or metric O-ring as well. Forcing a flare nut into an O-ring port will hold fluid until you load the steering, then you will see a mist of ATF or power steering fluid on the inner fender. If your steering box conversion kit ships with adapters, identify each by thread pitch before installation.
The steering shaft and joints
This is where the aftermarket steering shaft and steering universal joint earn their keep. The column angle and the new gear input rarely line up perfectly. A single U-joint can tolerate about 30 degrees of angle, but once you exceed 15 to 20 degrees, you will feel a speed variation through rotation. That is where a double U-joint and an intermediate support bearing create two smaller angles that cancel each other. Keep the U-joint yokes in phase, meaning the forks align along the shaft. Mis-phased joints cause binding and a notchy feel.
Collapsible sections are not optional. They provide crash energy management and make installation possible when tolerances are tight. Use a DD shaft or a splined slip section between joints. Lock the set screws with thread locker and the supplied jam nuts. On vehicles that see off-road use, safety-wire the set screws after torquing.
Fluid selection
Most modern pumps use dedicated power steering fluid, not ATF, though some older systems specify Dexron. Follow the gear manufacturer’s recommendation. Using ATF in a system designed for power steering fluid can create whine, especially when cold. If you have a hydroboost brake system, confirm compatibility because the brake assist shares pump output.
First fill and bleed
I favor a gravity prime before starting the engine. With the front wheels off the ground, fill the reservoir to the mark, crack the return line at the reservoir, and let fluid flow until it emerges air-free. Tighten the return line. Slowly turn the steering from lock to lock by hand, engine off, five or six times. Top up as the level drops. You will see microbubbles. Give the fluid a few minutes to let the bubbles rise.
Now start the engine and keep the reservoir cap off. Add fluid as the level drops and watch for foam. If the pump whines, shut down, wait a minute, and repeat the cycle. Do not hold the wheel hard against the stop while bleeding, and do not saw the wheel back and forth rapidly. A calm bleed prevents aeration and avoids cooking the pump on day one.
Centering the steering and setting toe
Once the system is bled and quiet at idle, set the steering wheel straight and recheck the relation to the gear or rack center. If the wheel is off by more than a few degrees, adjust it at the tie rods, not by pulling the wheel from the column. Make equal and opposite adjustments side to side to keep the rack or gear centered. Aim for slight toe-in if you must drive to the alignment shop, around 1/16 to 1/8 inch total on older vehicles. Excessive toe-out will make the car dart and feel unstable.
Clearance checks that prevent heartache
Turn lock to lock with the front suspension at ride height, then jack each side of the control arm to simulate bump. Watch the hoses, the shaft, and the joints. Make sure the steering universal joint clears header tubes through the entire arc. I have seen a hot header melt a boot in 20 minutes of runtime because the shaft was fine at static ride height but touched under engine torque. If clearance is marginal, use a dimple in the header tube or reroute the shaft with a second joint and support bearing.
While under the car, check pitman arm and center link geometry. The pitman arm should be roughly level at center. If it points uphill or downhill sharply, bump steer increases. Correct with the correct arm drop or box position per your kit’s instructions.
The first road test
Do not skip a controlled shake-down. Choose a route close to home with light traffic. Expect some initial stiffness as seals seat and air purges. Listen for belt squeal on parking maneuvers. Watch fluid level after the first drive. A pump that continues to whine after five to ten miles of mixed driving usually has aeration or a flow mismatch. Some gears prefer lower flow. You can install a small flow control orifice in the pump outlet on certain pumps to reduce assist and calm the system.
Pay attention to on-center feel. A too-fast ratio with big tires can feel darty. If you installed a quick box and now drive long highway stretches, reduce front tire pressure a touch or add a bit more caster during alignment for better self-centering. Many classic cars respond well to 4 to 5 degrees of positive caster with power assist, though stock specs might list 1 to 2 degrees. More caster increases steering effort slightly but stabilizes the car.
Real-world detours and fixes
Not every conversion goes to plan. I once fitted a steering box conversion kit to a big-block A-body that wore long-tube headers. The box physically fit, but the original rag joint sat within a finger of the header. The cure was a compact steering universal joint and a small shift in the column’s lower mount to create a fraction more angle. We added a collapsible DD intermediate shaft, phased the joints, and gained over half an inch of header clearance. Years later, the boots still look fresh.
Another common hiccup is pressure mismatch, especially when mixing a late-model pump with an older gear. Some Saginaw pumps output in the 1,300 to 1,450 psi range with 3 to 3.5 gpm flow, while an older box prefers closer to 1,100 psi and 2 to 2.5 gpm. Too much flow makes the steering twitchy and noise-prone. Many aftermarket vendors sell flow-control valves or different pump facts to bring numbers into harmony. If your steering feels overboosted, do not accept it as normal. The fix is usually a small brass valve and ten minutes of work.
When to replace the column and shaft
If your original column has worn bearings or a sloppy lower bushing, moving to power assist will not hide it. In fact, the added confidence reveals slop that you previously attributed to heavy steering. Rebuilding the column or installing a modern tilt unit with a new lower bearing often pairs well with an aftermarket steering shaft. You gain collapsibility, tight joints, and a fresh interface to the gear. For universal joint steering setups, aim for a maximum of two joints and one support bearing. More joints mean more places to introduce play, and the geometry becomes harder to keep in phase.
Manual to power steering conversion checklist
- Verify parts compatibility by spline count, pulley alignment, and fitting types before disassembly. Center the steering gear or rack and secure the steering wheel before connecting the shaft. Route hoses away from heat and movement, clamp them securely, and use the correct fluid. Bleed the system with wheels off the ground, then at idle, and recheck after a short drive. Schedule a professional alignment and request additional caster to suit modern driving.
Aftermarket steering components worth the money
Spending wisely on key parts saves time and prevents noise. A quality pump with the right pressure curve changes the character of the steering more than people expect. Good hoses with proper crimps resist weeping that ruins belts and alternators below. An aftermarket steering shaft with a true collapsible section and properly machined yokes provides smooth, predictable response. A well-designed steering universal joint with the right angles makes the difference between silky and notchy. Cheap joints can brinell after a season and start clicking under load.
The steering box conversion kit you select should include a pitman arm matched to your center link geometry. Using a random arm with the Borgeson steering shaft wrong drop or clocking will change effective ratio and bump steer. If you have a tie rod-over conversion or a dropped spindle setup, tell the kit supplier. They can often supply a different arm or advise on center link position that keeps geometry correct.
Alignment targets and tire considerations
Alignment deserves its own thought because the vehicle’s steering effort and stability depend on it. With power assist in play, you can run more positive caster without making parking miserable. On many classics, asking your alignment tech for 4 to 5 degrees positive caster, close to zero camber for even tire wear, and a touch of toe-in at roughly 1/16 inch will produce a calm, straight-line car that still turns in well. Big tires increase scrub radius and leverage. If you run 275-section fronts on a muscle car, expect a bit more kickback over potholes. Dial in an extra half degree of caster to help the wheel return to center.
Tire pressure affects feel. A front tire at 30 to 34 psi on a stout sidewall will sharpen response. Too low and the tire squirm feels like steering slop. Too high and the car chatters over expansion joints. Take notes and adjust two psi at a time.
Rack conversions, geometry cautions
If your heart is set on a rack, spring for a kit that puts the inner tie rod pivots in the right place. A generic crossmember mount with a universal rack might look tidy but can worsen bump steer to the point where the wheel wriggles over every bump. The correct solution usually involves a rack whose centerline and pivot spacing match your lower control arms. Ride height changes after the conversion also alter bump steer. If you lower the front by more than an inch, recheck tie rod angle. Some kits offer spacers at the tie rod end to bring the angle back.
Exhaust routing often improves with a rack conversion because you lose the bulky box at the frame. On the other hand, oil pan clearance becomes a new constraint. Many rear-sump pans clash with rear-steer racks. An aftermarket pan with a different sump shape solves it, but that is another purchase and possible pickup tube change. Budget and plan accordingly.
Maintenance and follow-up
Power steering systems like clean fluid. The first fluid change after a conversion comes early. At 500 to 1,000 miles, draw out the reservoir and refill. If the fluid looks glittery or brown, find the source. Gray shimmer suggests pump wear, brown hints at overheated fluid. A faint whine that grows with steering input but fades on the highway typically points to low fluid level or aeration. A constant whine that tracks engine speed points toward an unhappy pump bearing or a belt issue. Keep a spare belt in the trunk for the first month, especially if you are mixing pulleys and belts from different vendors.
Periodically check the set screws on your steering universal joint and the support bearing locknuts. Mark them with paint after torquing. A quick glance during oil changes tells you if anything has walked.
When the job is done right
The final test is not just fingertip parking. It is a relaxed drive on a rough two-lane where the car tracks straight without white-knuckle corrections. It is a steady highway run where a gentle input yields a predictable lane change. It is a trail climb where you can steer at a crawl without wrestling the wheel. A properly executed manual to power steering conversion delivers all of this without leaks, squeals, or mysterious clunks.
The aftermarket has given us a deep bench of parts to make it happen. A well-matched power steering conversion kit, an aftermarket steering shaft that clears tight spaces, and a properly phased steering universal joint turn a decent plan into a clean, safe installation. Take your time with geometry, treat the plumbing like you would brakes, and verify every clearance twice. The payoff is miles of driving that feel modern without losing the character that drew you to the vehicle in the first place.
Borgeson Universal Co. Inc.
9 Krieger Dr, Travelers Rest, SC 29690
860-482-8283