The first time you maneuver a mid sixties pickup into a tight parking space with manual steering, you understand why the factory steering wheel is the size of a ship’s helm. Manual boxes transmit every pound of tire scrub straight to your forearms. On open roads that can feel connected and honest. In town, especially with modern sticky rubber, it’s work. Converting a classic from manual to power steering changes more than steering effort. Done right, it reshapes how the car fits your life, from weekend coffee runs to long highway trips. The key is choosing components that respect the original geometry and installing them with a mechanic’s discipline.
This guide walks through what improves, what can go wrong, and the parts and practices that separate a satisfying upgrade from a wandering, leaky disappointment.
What changes when you add assist
The obvious difference is effort, particularly at low speeds and during parking. A good power steering conversion takes the steering from two handed heaves to one finger adjustments at a Borgeson steering stop, while still reading the road once you are rolling. Less obvious, but just as important, is stability over broken pavement and mid corner corrections. A well matched pump and box will damp kickback, so that potholes and expansion joints do not jar the wheel. That reduces fatigue over an hour or two behind the wheel, and it makes a car with a quicker ratio feel calmer.
Ratios deserve a closer look. Many manual boxes live around 20 to 24 to 1, with four or more turns lock to lock. Power boxes often land near 12 to 16 to 1, three turns or less. The difference on a two lane road is real. You spend less time hand over hand and more time placing the car accurately. If you autocross or just enjoy a good mountain pass, you will appreciate the change.
The other improvement sits under the car where you rarely look. Fresh tie rod ends, idler arms, rag joints, and hoses often come along with a power steering upgrade. The sum is less play, less compliance, and tighter transient response. Many owners attribute that crisp feeling to the assist itself, when it is just as much about renewing the linkage and correcting geometry issues that accumulated over decades.
Respecting geometry and feel
Assist alone does not guarantee better handling. Steering feel depends on caster, camber, toe, friction in the linkage, and how the box or rack is centered relative to the steering arms. Old cars often left the factory with minimal positive caster. They ran bias ply tires and chased low effort. Switch to radial tires and add power assist, and the car may feel light on center unless you increase caster into the 3 to 5 degree range, sometimes more. Shimming control arms on GM A bodies or adjusting strut rods on old Fords is part of the job, not an afterthought.
Similarly, bump steer becomes more obvious when you quicken the ratio. If you are converting to a rack on a car that originally had a recirculating ball box, take measurements. The inner tie rod pivot points must line up with the control arm pivots in plan view and height. If they do not, the car will toe in and out as the suspension moves. A well engineered steering box conversion kit stays with the original architecture for this reason. When you do choose a rack, pick a package with brackets, center link geometry, and a track record on your exact chassis.
Steering feel also lives in the joints. A rag joint in good condition filters vibration and a little kickback. Worn rag joints cause slop and vague response on center. Many builders prefer a steering universal joint and double D shafting for positive engagement. If you go this route, choose quality universal joint steering components and support the shaft with a firewall or frame bearing where needed. A single long unsupported shaft can oscillate and feed vibration into the wheel. An aftermarket steering shaft with proper support, clearances, and correct joint phasing keeps everything smooth and precise.
Component choices that pay off
The core decision is whether to use a power steering conversion kit tailored to your chassis or to assemble the parts yourself. A well designed kit saves time and usually includes a matched pump, a steering box or rack, brackets, pulleys or spacers, and the fasteners and hoses you need. A steering box conversion kit that retains factory pitman arm geometry and accepts your original or replacement linkage will preserve turning circle and Ackermann. For many domestic classics built between the 1960s and 1980s, this path provides the best mix of simplicity and factory like driving character.
If you source your own pieces, match pump flow and box requirements. Classic Saginaw pumps typically deliver 2 to 3 gallons per minute at around 1,200 to 1,400 psi. Many modern racks prefer lower flow and pressure. Excess flow makes the wheel too light and twitchy, and it can aerate fluid at high rpm. Pressure shims and flow restrictors help dial in feel, but it is easier to select a pump and valving appropriate for the steering gear from the start.
Brackets deserve almost as much attention as the pump itself. Misaligned pulleys squeal, eat belts, and prematurely wear pump bearings. On small blocks with multiple accessory configurations over the years, the correct bracket stack matters. If your engine uses aftermarket heads or an intake with different bolt bosses, verify bracket fit before you are deep into the install. The better power steering conversion kits include brackets designed for common engine families and clear instructions. If you build your own, mock up with a straightedge across the crank and water pump pulleys and adjust with spacers until perfect.
On the column side, decide whether to keep the factory column or convert to a tilt column with an integrated hazard switch and turn signal wiring. If you keep the original, measure the firewall to box dimension. An aftermarket steering shaft lets you fine tune length, joint angles, and collapsibility. Collapsible sections add safety in a frontal impact and simplify fitment when headers crowd the original shaft path. Use high quality steering universal joints with proper spline counts that match your box or rack. Loose tolerances here turn into play at the wheel.
Cooling and fluid can be surprisingly important. If you run headers next to the pump and hoses or you live where summer heat and low speed cruising are common, add a small fluid cooler. Power steering fluid is not just hydraulic oil. It has anti foaming and anti wear additives tailored to vane pumps. Some systems can use ATF, some cannot. Check the box manufacturer’s recommendations and stick to one fluid to prevent seal issues.
The tactile payoff
I have had owners step out of a freshly converted car and ask why they waited so long. The transformation is easy to feel when you roll into a parallel parking spot on a busy street. Where the manual box telegraphs tread blocks grinding across asphalt, the power system lets the tires glide. With a properly sized box, the wheel-light feel at a stop firms up as speed builds, and you still get road texture through your hands. With a little more caster and radial tires, the car wants to track straight. You check your mirrors more often because the car holds its lane without constant nudges.
On a two lane road, a good system makes quick left-right transitions clean and tidy. You sweep into a gentle bend, add a quarter turn, and the nose follows without delay. There is less sawing at the wheel in mid corner bumps. When the chassis does move, the assist filters the sharpness without dulling the message. That last sentence depends on component choice. Overboosted systems feel video-game light. Underboosted systems make you work. Aim for middle ground, and do not be afraid to fine tune pump pressure or flow.
Originality, value, and reversibility
Purists often worry about resale value or authenticity. On high-dollar historically significant cars, originality often trumps convenience. For the other 95 percent of classics that see road miles and grocery runs, a reversible manual to power steering conversion can increase enjoyment and value. The trick is to avoid cutting the frame or column in ways that cannot be put back. Choose a kit that bolts to existing holes or uses brackets that respect factory geometry. Keep the factory manual box on a shelf with the pitman arm and hardware tagged. If a future owner wants manual steering again, the path is open.
From a buyer’s standpoint, a clean, leak-free installation with tidy brackets, properly routed hoses, and a straight steering wheel reads as care and investment. A hacked together system with mismatched joints, loud pumps, or seepage reads the opposite. Rarity matters. On some models, power steering was a common factory option and a conversion simply mirrors what the factory sold. On others, particularly European cars with unique racks or boxes, conversions can look out of place. Research the community norm for your model before committing.
Safety and ergonomics as hidden benefits
Steering effort ties directly to safety in emergency maneuvers. Panic avoidance, quick lane changes, and correcting after a rear tire bites a paint stripe all go better if you can turn the wheel fast without muscling it. For drivers with shoulder or wrist issues, power assist keeps them in the hobby. I have worked with owners rehabbing from injuries who could not drive their manual-steer cars more than twenty minutes without pain. With assist and a slightly smaller wheel, they drive for hours.
Ergonomics includes steering wheel size and reach. Manual cars used 15 to 17 inch wheels to multiply effort. After converting, a 14 inch wheel often feels right. Before you swap, measure leg clearance and sight lines to the gauges. A smaller wheel can help tall drivers fit under the rim with better thigh clearance. It can also obscure warning lights on some clusters. Try a mock-up with a similar diameter wheel before committing.
Doing it right the first time
Conversions look simple on paper. In the real world, a header tube often claims the same space as a universal joint, the sway bar wants to live where a pump reservoir sits, and the belt wants to run through a radiator hose. That is why dry fits and test cycles before final assembly matter. Set the car on ramps or jack stands under the control arms so the suspension sits at ride height. Turn the wheel lock to lock and watch the aftermarket steering components for clearance. Run the suspension through a couple inches of bump and droop while turning. Check hose sweep. If a hose sweeps a header primary, you need heat sleeves or rerouting.
Torque values matter more on steering than almost any other assembly outside of brakes. Pitman arms belong on clean, undamaged splines torqued to spec with a new lock washer or nut. Drag links should not bind when the box is centered. If you use a steering universal joint, ensure you have at least 3/4 of spline engagement and that set screws land on flats or dimples. Double jam nuts and thread locker are your friends here. On double D shafts, align the flats so the joints run in the same plane, which reduces binding at high angles.
Bleeding the system is not just starting the engine and cranking the wheel. Fill the reservoir with the recommended fluid, raise the front wheels, and turn the wheel slowly from stop to stop with the engine off to purge air from the box or rack. Top off, then start the engine and repeat slowly, avoiding hard holds at the stops for more than a second or two. Aerated fluid looks milky and will foam if you rush. Let it sit, then repeat until the fluid runs clear and quiet.
Common pitfalls and how to avoid them
The most common complaint after a conversion is a car that wanders on center. Usually, the culprit is not the power steering system but old alignment settings carried over from manual days. Reset caster, camber, and toe for radial tires and modern speeds. Add caster until the steering returns to center with authority but does not bind at the stops. Toe should be set slightly in for most rear wheel drive classics, often in the 1/16 to 1/8 inch range total, but verify by model.
Noise under the hood ranks second. A high-pitched whine can be air in the system, a cavitating pump, or a belt alignment issue. If bleeding does not cure it, look at the pump inlet hose. Kinked or undersized inlet hoses starve pumps. Replace with the correct diameter and avoid tight bends. Misaligned pulleys can whistle. Sight across all pulleys with a straightedge and correct as needed.
Leaks trace back to old flare seats, mismatched hose ends, or over-tightened fittings. If you adapt a factory box to AN lines, use proper inverted flare to AN adapters designed for steering pressures, not generic fuel fittings. Tighten to spec and stop. Over-tightening deforms flares and leads to drips that will haunt you.
The third issue is steering bind. A joint that feels fine on jack stands can bind once the weight of the car compresses the suspension and the header heats up. Check with full weight on the wheels, after a road test, and inspect for witness marks on shafts and joints. If you need a second joint to clear obstacles, add a support bearing between them. Keep joint angles within manufacturer limits, typically below 35 degrees for most steering universal joints.
The economics of the upgrade
Costs vary widely. A basic steering box conversion kit for a common domestic chassis often falls between 900 and 1,800 dollars, pump and hoses included. Add brackets, belts, a cooler, and an alignment, and the total lands around 1,500 to 2,500 dollars if you do the work yourself. Labor at a shop adds 8 to 16 hours depending on complications, so budget another 1,000 to 2,000 dollars. A true rack conversion with custom brackets and an aftermarket steering shaft can push the parts bill higher. If you refresh the entire front end while you are in there, it makes sense financially. Labor overlaps, and the improved feel will reflect the whole system, not just the assist.
On the savings side, you gain miles driven. It is hard to quantify, but I see owners doubling their seat time after a manual to power steering conversion. Cars that used to come out once a month show up at weekend meets and midweek dinners. That return matters more than a spreadsheet.
Choosing between box and rack
Keeping a recirculating ball box has virtues. It honors original geometry, usually clears oil pans and headers, and feels right in larger cars and trucks. A good box with modern valving provides a firm on-center feel and progressive assist. Turn-in may be a hair slower than a fast rack, but the steering is robust and tolerant of imperfect alignment.
A rack and pinion shines in smaller cars where engine bay width allows ideal tie rod geometry. The rack’s direct gear mesh eliminates the tiny hysteresis present in a ball nut design. If the kit places the inner tie rods at the correct height and spacing, bump steer can be lower than stock. The key is that geometry conditional. Universal kits that bracket a rack below the crossmember or ahead of the center link without matching pivot points often create more problems than they solve. For most domestic muscle and full-size cars, a well sorted steering box conversion kit offers fewer compromises.
The role of aftermarket steering components
The aftermarket is broader than just the pump and gear. Tie rod ends with better seals, idler arms with improved bushings, and center links with tight tolerances all contribute to steering accuracy. So do quality joints in the column. A steering universal joint with needle bearings and precision splines rotates smoothly across the angle without notchiness. Cheap joints bind and wear fast. An aftermarket steering shaft that includes collapsible sections and correct firewall seals improves safety and reduces fumes and heat in the cabin.
When headers, turbo plumbing, or tight engine compartments force creative routing, universal joint steering components allow joint stacking and angle changes that a rag joint cannot handle. The trade-off is maintenance. Set screws must be safety wired or double locked, and the joints should be inspected at service intervals. That is a small price for packaging flexibility and precision.
A short planning checklist
- Confirm kit compatibility with your exact chassis, engine, and exhaust setup, including pump bracket fitment and pulley alignment. Decide on steering ratio and feel, then match pump flow and pressure to the chosen box or rack. Plan the column path using an aftermarket steering shaft and steering universal joint if headers or accessories crowd the original route. Refresh wear items and align to modern specs with added caster, then bleed the system properly and verify clearance lock to lock at ride height. Road test, fine tune fluid choice and pump valving if needed, and recheck fasteners and joints after the first 100 miles.
Anecdotes from the shop floor
A 1972 Chevelle came in with a complaint familiar to many owners. The manual steering felt fine above 40 mph, but was a chore in parking lots, and his wife refused to drive it. We installed a power steering conversion kit using a quick ratio box, paired with a Saginaw pump on factory style brackets. Headers pinched the lower column path, so we added a steering universal joint and a collapsible aftermarket steering shaft with a support bearing on the frame. We bumped caster to 4.5 degrees and set toe to 1/16 inch in. The car came off the rack and felt half its size. We ended up adding a small fluid cooler because summer traffic and a big block kept under-hood temps high. Two years later, the owner still sends photos from road trips.
On a 1965 F100, space drove the decision. The original column shaft ran close to a long tube header. A steering universal joint solved the angle, but it introduced new vibration through the column. We added a firewall bearing and a second joint to flatten the angles, then balanced the assembly with a small shim at the box coupling. The truck, now with power assist and fresh kingpins, drives better than most modern half-tons in town. The owner also replaced the 18 inch wheel with a 15 inch version, which finally gave his knees room under the rim.
A BMW 2002 taught a different lesson. The owner wanted power assist with a rack conversion. The kit used a rack mounted ahead of the crossmember with different inner tie rod spacing. The car gained assist, but also a hint of bump steer on rough city streets. We measured toe change through the travel, then corrected tie rod height with spacers and moved the rack slightly to improve pivot alignment. It never felt exactly like a factory solution, but the car became predictable enough to keep the assist without losing the nimble character that defines the model.
Living with power steering in a classic
Once the conversion is sorted, maintenance is simple. Check fluid level and color every oil change. Replace hoses every ten years or sooner if they show cracking or seeping at crimps. Inspect the belt for glazing or fraying. Watch the rag joint if you kept it, and inspect universal joint steering components for play. Listen for changes in pump noise. If it gets louder, address it before it wears seals or contaminates the system with debris.
There is one behavioral change to remember. With quicker ratios, a small input at the wheel moves the car more than before. That precision feels great on the open road and during lane changes, but it can surprise drivers used to slower manual steering. A few days of commuting resets muscle memory. Most people adapt within the first hundred miles and then wonder why they lived with the old setup so long.
When manual still makes sense
Not every classic benefits from assist. Lightweight sports cars with narrow tires and balanced weight distribution often steer easily at low speeds and communicate brilliantly without help. Aluminum heads, small wheels, and careful alignment can bring effort down to an acceptable level. If you own a car that spends most of its time on winding roads and rarely sees city traffic, keep manual steering and invest in renewing the linkage and bushings. You will save weight over the nose and keep the mechanical intimacy that defines those cars.
Trucks and big sedans with wide front tires live on the other end of the spectrum. They benefit from assist, and the driving experience improves across all scenarios. In between are muscle cars and mid-size coupes. For them, a manual to power steering conversion is often the difference between a car you fight and a car you reach for on a Tuesday evening.
Final thoughts from the bench
Power assist does not cure every ill, and a sloppy front end will still be sloppy with a pump pushing fluid through it. Approach the upgrade as part of a system. Start with tight joints and bushings, choose a steering box conversion kit or rack package with proven geometry, and use an aftermarket steering shaft and steering universal joint where they make sense. Align for modern tires. Take the time to route hoses wisely and bleed with patience. The payoff is not just lighter parking. It is a classic that feels eager, accurate, and comfortable for real miles.
The parts catalog offers plenty of options. The best combination for your car keeps steering geometry honest, matches hydraulic assist to your preferred effort, and packages neatly alongside whatever exhaust and accessories you run. If you are on the fence, find a friend’s converted car and drive it. The first tight U turn without a grimace usually settles the debate.
Borgeson Universal Co. Inc.
9 Krieger Dr, Travelers Rest, SC 29690
860-482-8283