Power steering is something that just about everybody takes for granted. If you think about it, every time you put effort into the steering wheel this represents your most direct contact with the car. Perhaps even more than what you feel through the cushioned seat of your pants. We spent a couple of days with Allan Padelford, owner of Lee Power Steering and came away filled with a reservoir full of slick tricks, ideas, and ways to make the power steering system in your street car far more responsive and or efficient.
Most of the material presented here is aimed at street-driven cars that can benefit from directly applying these ideas to your car. Some are free, others are affordable, and one or two are somewhat pricey. All are aimed at improving the connection between you and the road.
One of the first things we learned from Padelford is the high-pressure hydraulic system that reduces steering effort is very sensitive to dirt and debris. It’s not uncommon to find vehicles with 200,000 miles which are likely still operating with the original hydraulic fluid still in the reservoir. So if a new power steering box is in the plan, Padelford recommends that you also change the hoses and pump at the same time. He doesn’t recommend this because he wants to sell more parts. Instead the recommendation is based on his years of experience where boxes quit working due to varnish or debris knocked loose from inside the old hoses or pump.
A common complaint with ‘60s muscle cars is the lack of “feel” in the steering wheel compared to newer cars. Many assume this comes from increased line pressure. The reality is a little more complex.
Inside the steering box, splined directly to the steering column, is a small torsion bar. When the steering wheel is initially moved, this input twists the torsion bar. Original ‘60s steering boxes used very small diameter torsion bars to minimize the effort, creating that “one finger” feel.
Later model steering boxes began using larger torsion bars to improve the response and feel. Padelford can upgrade a typical ‘60s GM steering box and improve the feel just by adding a larger torsion bar. However, the hot ticket is to go a step further and quicken the original 24:1 ratio with a more responsive 12.5:1 ratio along with the larger torsion bar.
In a recent test on an early Chevelle, just by changing from a light to a heavier torsion bar, the higher-effort box immediately felt superior even though the ratio did not change. If you were to upgrade from a 24:1 to a 12.5:1 box, the difference would be amazing. Not to mention the lock-to-lock distance would also change from nearly four turns to just over three.
The company prefers to identify the torsion bars by the amount of effort required to deflect the bar. The early stock, lightweight Saginaw boxes require only 20 to 25 pounds of effort. The typical street-performance box which Lee builds requires between a 30- to 40-pound effort. The effort tends to increase with the ratio in the box, so that’s something to keep in mind.
We’ve listed the common GM ratios in a separate chart, but most ‘60s Saginaw steering boxes came with a 24:1 ratio. Later model cars quickened that ratio to 12.6:1 beginning in the early-‘70s with the Z28 Camaro and WS Trans Am cars. Another move in ratio occurred with variable ratio where the on-center ratio is 16:1 but then quickens to a faster ratio as the wheel approaches full lock.
Because power steering is all about the hydraulic circuit, anytime a component is changed, it’s important all the air is bled out of the hydraulic circuit. While that sounds difficult, the process is really very simple. Let’s say you’ve completed the install of a new steering box along with new hoses and an external power steering reservoir. If you bought your steering box from Lee, it is already filled with fluid, which helps, but the procedure is still the same.
Fill the reservoir with fluid and then jack the car up so the front tires are off the ground. Support the car with jack stands and then grip the left front tire and cycle the steering lock-to-lock several times. Large bubbles will appear in the reservoir and the level will drop. Keep adding fluid until all the air is removed from the system and the fluid level is at the proper level.
Next, start the engine and check to see if the level drops. If it does, refill to the proper level and then drive the car around the block using plenty of steering input. Check the level again. If it’s okay, the system is complete and ready to run. Never start the engine with the steering box or pump empty of fluid as this will pump air into the system. The air in the hydraulic system is what creates that nasty growl. The only way to remove the air from the system is to let it sit for perhaps days to allow the air to escape.
Another tip Padelford offers is to avoid the use of automatic transmission fluid (ATF) for power steering. Lee offers its own dedicated fluid that not only can handle higher temperatures, but is designed more as a hydraulic fluid without the friction modifiers and other additives found in ATF.
Lee Power Steering also highly recommends the use of an inline-power-steering fluid filter. This filter is located on the return side between the steering box and the reservoir. The filter uses a typical cartridge element that screens roughly 95 percent of all dirt larger than 10 microns. A micron is equal to 0.000039-inch! This prevents debris from potentially damaging or locking up the steering box. The filter has sufficient capacity that most performance cars – even those driven daily – may need a filter change only once in their lifetime.
Padelford also mentioned the older, Saginaw tower-style power steering pumps, called P-pumps, tend to suffer from a poor reputation. But, he feels they are in fact a good match for the Saginaw recirculating ball steering boxes. The newer T-style, more compact version pumps used on later model cars have also attracted a following. Either pump works well, although Padelford recommends choosing a cast iron over an aluminum body T-style version. He says aluminum can wear prematurely and introduce metal shavings into the fluid.
Track day cars and Pro Touring machines that see plenty of autocross duty tend to abuse their power steering more than a daily driver. For these applications and even for the street, Padelford recommends also running a remote reservoir for several reasons. First, the tall reservoir is designed to remove air from the fluid before re-entering the pump. This reduces overall operating temperature. Plus, its aluminum body and location separated from engine heat contribute to reducing the fluid’s operating temperature.
It’s best to avoid allowing the power steering fluid to exceed 250 degrees F. Coolers can be added, but often are not necessary with an efficient pump. If the fluid exceeds 250 degrees F in competition, it should be changed as fluid breakdown is likely.
As you can see, there are several opportunities to improve steering response and feel in almost any car. While the majority of this story was aimed at GM vehicles, Lee does work on all domestic brands and imports as well. If high-performance driving is something you look forward to, a simple steering box upgrade might make a world of difference. You will feel it every time you get behind the wheel.
|Application||Ratio||Turns (Lock-Lock)||Effort (lbs)|
|Late OE||16:1 V.R.*||3.5-4.0||30-35|
- V.R. stands for variable ratio where the on-center ratio is 16:1, but as the wheel is turned, the ratio quickens to 13:1 at full lock.
- Some boxes can have internal stops that will limit the number of turns with a given ratio so these numbers are approximations across various vehicles.