Power steering transforms the way an older vehicle feels on the road. The difference is more than just lighter steering at parking speeds. You gain control in tight maneuvers, more confident lane changes, and reduced driver fatigue on long drives. If you own a classic truck, muscle car, or any vehicle that left the factory with a manual box, a well-matched power steering conversion kit changes the character of the car in a good way. The job is not complicated for a careful DIYer, but it involves judgment, measurements, and a willingness to solve small fitment puzzles. That is where experience matters.
This guide walks through the process, from selecting parts to final bleeding and alignment. I will cover common pitfalls, how to choose the right steering universal joint setup, which hoses to run, and when an aftermarket steering shaft is the safer choice. I will assume you have access to a floor jack, sturdy stands, basic hand tools, a torque wrench, and patience. If you can safely replace a steering box or front suspension component, you can handle this.
Start with a plan that fits your car
Manual to power steering conversion sounds straightforward, but the details depend on your chassis. A 1968 C10 behaves differently from a Fox-body Mustang or a CJ Jeep with a frame-mounted box. The best approach is to begin by mapping what you have. Crawl under the nose and look at the layout. Is the steering box ahead of or behind the front axle centerline. Is the pitman arm splined or keyed. How does the column couple to the box, rag joint or solid shaft. Where can a pump mount on your engine, and do you already have the correct crank pulley alignment for a belt.
Most vehicle-specific power steering conversion kits include three anchors. A steering box conversion kit or integral power box that matches the frame pattern, a pump with brackets that fit your engine family, and a pitman arm that reproduces the correct geometry. Some universal kits provide an assist ram system, but most modern conversions swap to an integral power box or a rack and pinion. Each choice has trade-offs.
A new integral power box preserves the original steering geometry with the center link and idler arm. This avoids bump steer issues and usually bolts to the frame with minimal modification. Rack and pinion gives a more modern feel, but unless the kit is engineered for your chassis, you risk poor Ackermann, limited lock, or exhaust clearance headaches. When in doubt, stick with a steering box conversion kit that others have used successfully on your exact model.
It pays to spend time on the steering column side too. Many older cars used a collapsible column with a rag joint at the box. When you change box orientation or input shaft size, the original joint may not fit. This is where aftermarket steering components shine. A compact universal joint steering setup with a properly sized aftermarket steering shaft solves odd angles and tight clearances. Plan that now rather than when the car is half apart.
Choosing the right components without wasting money
The parts list looks simple on paper, but the wrong call in one place cascades into delays. Start by confirming the steering box spline size and input type. Many Saginaw 525 manual boxes use a 3/4 inch 30-spline input. Common power boxes use 3/4 inch 36-spline or 3/4 inch DD. The steering universal joint you buy needs to match both the box and the column or intermediate shaft, and it is worth paying for a double-D shaft and matching U-joints because they clamp securely and make indexing easier.
Pump choice matters more than people think. A GM Type II pump is compact and tunable with different flow control valves. A traditional Saginaw TC pump is robust and cheap to rebuild. Ford pumps tend to whine if starved or misaligned. If your engine already has brackets that accept one style, use that unless there is a compelling reason to switch. The real key is to match pump pressure and flow to the steering gear or rack. Many power steering conversion kits are designed around 1100 to 1400 psi. Racks often prefer lower pressure and less flow. If your steering feels twitchy or overboosted after the swap, a flow control change in the pump or an inline restrictor can calm it down.
Hoses and fittings deserve attention up front. Factory boxes often use SAE inverted flare. Many new boxes and racks use O-ring metric. Do not mash mismatched fittings together. Use the correct adapters or have hoses made with the right ends. If you are running headers, plan a return line route that keeps hoses away from heat. I have seen hoses baked to a crisp inches from a collector, all because the original return path was copied without considering the new pump location.
Lastly, make a decision on the shaft. If the angle between the column and the new box input exceeds about 30 degrees, a single U-joint binds or shortens its lifespan. A two-joint system with a support bearing gives a smooth sweep and steady feel. That means an aftermarket steering shaft with proper collapsibility is not just handy, it is often the difference between a safe conversion and a sketchy one.
Preparation that saves hours later
Good prep boils down to two things, accurate measurements and open access. Before tearing anything apart, measure toe at the tire or record tie-rod thread exposure. Scribe the relationship between the pitman arm and the box output. Center the steering wheel and count turns lock to lock, then mark center on the rim with tape. Take a dozen photos. You think you will remember every bracket and clip, but memory fades under a car.
Soak fasteners with a good penetrant one or two days before you plan to wrench. Manual steering box bolts love to seize to frame nuts. Disconnect the battery, and if your car uses a column shift or neutral safety hardware, document how the linkage passes the column. It is easy to trap or bind those pieces later.
Support the vehicle securely on stands placed under the frame rails. You want the suspension hanging so the center link and idler arm are easy to move by hand. Set a clean bench for the new box and pump. Lay out adapters, pitman arm puller, torque wrench, and a fresh quart or two of the correct fluid. Most Saginaw pumps use Dexron ATF or specific power steering fluid, and many racks prefer dedicated fluid. Do not mix types, especially with new seals.
Removing the manual system without hurting anything
Start at the steering wheel and work outwards. Unbolt the rag joint or clamp at the base of the column. On older GM columns, two 9/16 inch bolts pinch the rag joint to the box input. Some cars have a solid shaft with a roll pin that needs to be drifted out. Leave the column in place. Moving the steering column is rarely necessary and introduces risk to collapsible elements.
Next, separate the pitman arm from the center link. Use a puller rather than a hammer. A hammer will mushroom the stud and damage the threads. If your kit includes a new pitman arm, you can remove the old one from the manual box on the bench where it is easier to control. With the center link free, support it so outer tie rods are not hanging by their boots.
Remove the box from the frame. Expect three or four bolts. Some frames use captured nuts that spin if they break loose inside the rail. If a nut spins, do not escalate with force. Cut a small access window in the inner frame face, hold the nut with a wrench, and plan to weld a new capture tab when you are done. That sounds dramatic, but it is safer than oversizing holes or leaving a compromised fastener inside the frame.
If the vehicle uses a manual drag link or idler arm that differs between manual and power systems, compare parts now. On many GM trucks from the 60s and 70s, the center link remains, but the pitman arm taper or drop changes. Mixing parts leads to bump steer or limited travel. Always match the pitman arm that belongs with your new box.
Mockup before final torque
Bench-prep the new box. Verify the input spline, lash adjuster plug torque, and that the box is centered. To center the box, turn it gently to full lock one direction, then count the turns to full lock the other way. Divide by two and bring it back to center. Many Saginaw-style boxes will show a slight high point on center that you can feel. Mark the input with paint.
Hold the new power steering box up to the frame and check bolt holes. Some kits include a spacer plate to correct the shaft angle. Do not omit it unless measurements show perfect alignment without it. If you see witness marks where the box contacts a raised weld seam or frame rivet, dress the area lightly. You want flat metal to metal contact. Install the box finger tight with grade 8 hardware and lock washers or prevailing torque nuts.
At the center link, position the new pitman arm. Check that the indexing splines match and that the arm points in the factory clocking when the box is centered. If the arm ends up one spline off, back up and verify the box is truly on center, not a half turn away. People get into trouble here. A box that is one turn off will steer more one direction than the other and the steering wheel will never center right.
Now mock the column connection. If you are using a steering universal joint directly, slip the joint over the box input and over the column shaft. If the angle is steep, move the box through its bolster slots within the limits of bolt holes to reduce the bend. Sometimes a quarter inch of shift changes everything. If you need a double U-joint setup, measure the distance for an intermediate aftermarket steering shaft and mark a location for a support bearing bracket on the frame. Avoid shoving the column forward or back to make up gaps. The column’s collapsible features are for crash safety and should remain in the design range.
This is the moment to confirm header clearance. With the box loosely mounted and the U-joint in place, turn the shafts by hand and watch for interference at full droop. Rub marks now are a warning that heat and flex will create a rattle later.
Pump mounting and belt alignment that stays quiet
Power steering pumps do not forgive sloppy alignment. If the pulleys are out by even two millimeters, you will fight belt squeal and premature bearing wear. Bolt the pump bracket to the engine and test fit the pump with the correct pulley installed. The pulley must be pressed onto the shaft to the correct depth, not hammered. A cheap installer tool pays for itself the first time you avoid ruining a pump.
Hold a straightedge across the crank pulley and compare to the pump pulley groove. Shim the bracket or choose an alternate bolt hole if the design offers it. Many small-block Chevy brackets, for example, have slight casting tolerances that require a thin washer behind one ear to square the pump. Spin the pump by hand and listen. Any scraping means the pulley is too deep and touching the housing. Press it out slightly.
Route the belt according to the bracket maker’s diagram and tension it correctly. A new belt should twist about a quarter turn with firm finger pressure at the longest span. Over-tightening masks misalignment temporarily, then tears up bearings.
Plumbing with the right hose and fittings
On the high-pressure side, use a rated hose and crimped or field-serviceable fittings with proper support. Banjo fittings on the pump require copper or aluminum crush washers. Inverted flare unions need clean seats and the right flare shape. If you are mixing SAE and metric, use purpose-made adapters. Do not stack adapters upon adapters to make a connection. Each joint is a potential leak and pressure drop.
The return hose operates at low pressure but still deserves quality hose. Route both lines away from heat sources and moving parts. A simple heat sleeve near headers extends hose life. Use insulated P-clamps to keep lines from buzzing against the frame. Plan a gentle downhill path back to the reservoir. Loops or high spots can trap air.
If your pump includes a remote reservoir, mount it higher than the pump inlet with a direct, short feed. Remote reservoirs help prevent aeration, especially with racks, but only if the return dumps below the fluid level and the inlet never starves.
Steering shaft and universal joint details that matter
A steering universal joint is not just a coupler, it is part of the safety system. Choose joints with double set screws and include dimpled flats on the shaft where the screws land. Use threadlocker on the screws and safety wire if the joint provides holes for it. If your conversion uses two U-joints, a support bearing for the intermediate shaft is mandatory. Without it, the shaft will whip under vibration and load.
Phasing the joints is often overlooked. When two U-joints are used, their yokes should be aligned so that input rotation translates to output rotation evenly. Misphased joints create a speed fluctuation that you will feel as a rhythmic tug. Look straight down the shaft, align the yokes, then tighten the set screws and lock nuts to the joint manufacturer’s spec.
Choose an aftermarket steering shaft that is collapsible. A double-D telescoping design allows fine length adjustments and preserves energy absorption in a crash. Do not weld solid sections together to fix length unless you also incorporate a collapsible element elsewhere. If your local regulations require it, keep records of the shaft and joints used. Some inspections ask for proof that the system remains collapsible.
Filling, bleeding, and the first start
Before you fire the engine, prefill the pump reservoir. Jack the front of the car so the tires are clear of the floor. With the engine off, turn the steering wheel slowly from stop to stop ten to fifteen times. This moves fluid through the box and expels air without aerating it. Watch the reservoir and add fluid as the level drops. Bubbles will rise and pop. Give it a minute between sweeps if the fluid froths.
Once the level stabilizes, start the engine and let it idle. Do not rev during the first minute. Watch the reservoir for foaming and the pump for noise. A soft whine at first is common and should fade. Continue to turn the wheel gently lock to lock, pausing near the ends. If the pump screams or the fluid churns into a milkshake, shut down and let it sit. That usually means an air leak on the suction side or a return line dumping above the fluid level.
As the system settles, check for leaks at every fitting. Touch with a clean paper towel rather than fingers. Tighten only enough to stop a weep. Over-torque ruins seats and guarantees a leak later.
Road test expectations and alignment
With the tires back on the ground, confirm the steering wheel is straight and the car tracks reasonably on a short neighborhood loop. A fresh conversion often reveals slight toe change or wheel off-center. That is normal. Set the steering box to center using the input marks you made, remove the wheel and reindex it if needed, then schedule a proper alignment. Ask the shop to set caster at the high end of the factory spec or a half degree above if the hardware allows it. Added caster improves return to center and straight-line feel with power assist.
If the steering feels overboosted at highway speeds, consider a smaller flow valve in the pump or an inline flow reducer. If parking effort is still higher than expected, confirm the pump pulley size matches the kit recommendation and that the belt does not slip. Larger pump pulleys slow the pump at idle, which can make a well-bled system feel lazy in tight maneuvers.
Common mistakes I see and how to avoid them
- Miscentering the box and then adjusting tie rods to make the wheel straight, which shifts the high point off center and leaves you with uneven steering feel. Always center the box first, then align tie rods. Using a single U-joint at a steep angle that binds near full travel. Measure your angle and move to a two-joint setup with a support bearing if needed. Ignoring pump alignment and relying on belt tension to hide a problem. Belts become tensioned bandaids that fail at the worst time. Reusing a hard, flattened rag joint disc with a new box input. It feels ok in the garage, then shows play on the freeway. Fresh joints or a modern U-joint setup tighten the system. Bleeding impatience. Fluid that looks clear in the reservoir can hold small bubbles. Give it time and keep the tires off the ground until the assist feels smooth.
When a rack and pinion swap makes sense
Some cars benefit more from a rack than a power box. Light unibody cars with long steering links often gain precision and reduced compliance with a rack. However, installing a rack that was not designed for your geometry takes engineering. The inner tie rod pivot points must match the original virtual swing points to avoid bump steer. If a rack kit includes fixed brackets and specific tie-rod lengths for your chassis, great. If it expects you to improvise, think twice. In many classic trucks and A-body cars, a quality steering box conversion kit delivers 90 percent of the feel improvement with far less risk and fabrication.
If you do choose a rack, the same rules apply for the column connection. Aftermarket steering components give you the flexibility to route around headers and crossmembers, and the steering universal joint count and phasing become even more important. With a rack, pressure and flow tuning matters too. Overboosted racks feel twitchy and darty. A flow control change at the pump often solves it.
Real-world example from the shop
A customer brought in a 1972 Chevy C10 with manual steering that felt like rowing a boat at low speeds. He wanted a manual to power steering conversion without changing the truck’s character. We chose a well-proven integral power box that bolted to Borgeson the factory frame holes with a small spacer, a Saginaw TC pump on a bracket set that matched his small-block Chevy, and a new pitman arm matched to the box sector.
Mockup revealed the column to box angle was acceptable with a single 3/4 inch DD to 3/4 inch 36-spline steering universal joint, but the plug wire loom on cylinder one touched the joint at full bump. A small relocation of the loom solved it. We pressed the pump pulley to align within about one millimeter to the crank pulley, used a crimped high-pressure line with an O-ring pump end and inverted flare box end via a steel adapter, and routed the return line behind the crossmember in a heat sleeve.
Bleeding took two rounds. The first revealed a faint whine that faded after five minutes at idle with the wheels free in the air. On the test drive, initial steering felt overboosted, so we swapped the pump’s flow control from 3.5 gpm to roughly 2.5 gpm. The truck settled into a confident, light but not nervous feel. Alignment with 3 degrees of caster and a hair of toe-in made it track straight on the freeway. That truck became a pleasant daily driver without losing its vintage personality.
Safety checks before calling it done
Look over every fastener you touched. Torque the steering box to frame bolts to the kit specification, often in the 65 to 85 ft-lb range for 7/16 or 1/2 inch hardware, but confirm for your case. Check the pitman arm nut torque. Many require 170 to 200 ft-lb and a cotter pin or staked nut. Verify set screws on the steering universal joint are tight and that you used threadlocker. Make sure the intermediate shaft still has visible collapse travel, not bottomed out in the sleeve.
Turn the wheel from stop to stop while a helper watches the box and frame. Any visible flex or movement means the frame holes are ovaled or the spacer is crushing. On older frames, reinforcing plates are inexpensive insurance. Finally, with the engine idling, hold the wheel lightly at full lock for no more than a second. The pump should not howl. Extended holds at full lock overheat fluid and shorten pump life, so avoid that habit.
Maintenance and long-term reliability
Power steering systems reward clean fluid. After the first few hundred miles, siphon the reservoir and refill. The initial break-in washes small particles from new hoses and seals into the fluid. A cheap in-line return filter rated for power steering use keeps the system clean without restricting flow. Inspect hoses annually. Any sweating at crimps or soft spots near heat sources deserve attention before they become leaks.
If you ever feel new play at the wheel, check the column joints first, then the box lash adjuster. A quarter turn is a lot in that context. Adjust lash gently on center with the wheels straight and the system at operating temperature. Over-tightening creates a bind and ruins the box.
When to call in help
Most hobbyists can complete a power steering conversion kit installation over a weekend. Seek help if your frame hardware spins or tears, if your steering angles require more than two U-joints and a support bearing, or if you cannot achieve pulley alignment within a millimeter or two without modifying brackets. A good alignment shop that understands older cars is not a luxury, it is part of the project. The final five percent of effort on alignment and flow tuning makes the steering feel natural, not just lighter.
A short step-by-step to keep you on track
- Document the existing setup, center the box, measure angles, and photograph everything. Remove the manual box and pitman arm, then loosely install the power box and spacer if provided. Mock the steering shaft with the correct steering universal joint or joints, add a support bearing if angles require it, verify phasing. Mount the pump and brackets, press on the pulley to proper depth, align belts, and route high-pressure and return hoses away from heat. Fill, bleed with wheels in the air, check for leaks, road test gently, then align and fine-tune pump flow if needed.
A power steering conversion is one of those upgrades that changes how often you reach for the keys. With the right steering box conversion kit, thoughtful use of aftermarket steering components, and careful setup of the shaft and joints, you get a car that steers with confidence at any speed. Take your time, measure twice, and treat the little details like they matter. They do.
Borgeson Universal Co. Inc.
9 Krieger Dr, Travelers Rest, SC 29690
860-482-8283