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Selective Steering

Getting the most out of your steering and tuning it to your preference

Eric Flavin - July 26, 2012 10:00 AM

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This is one of the reasons we started this project. The puddle of fluid was left after less than 12 hours.

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A further reason was the amount of play in the steering. As you can see, that is a significant amount.

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A further reason was the amount of play in the steering. As you can see, that is a significant amount.

 

 

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We began by removing the fluid lines from the back of the power steering pump.

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Have a catch pan ready because all the fluid from the reservoir will pour out.

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With the pump out of the car, it was obvious most of the leaking was from the front of the pump at the reservoir seal.

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Remove all the brackets from the pump as well as the other bolts and the output fitting. All of these hold the reservoir to the pump. There are several parts behind the output fitting that are spring loaded so be careful not to lose them.

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Use this sleeve to hold the piston in the vise.

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A 7/16-inch wrench removes the bolt where the shims are. The number of shims determines the amount of pressure the pump will put out. No shims yields about 1,350 psi and five shims yields 700 psi. This pump is set at 1,000 psi.

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A 7/16-inch wrench removes the bolt where the shims are. The number of shims determines the amount of pressure the pump will put out. No shims yields about 1,350 psi and five shims yields 700 psi. This pump is set at 1,000 psi.

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We went with five shims because the steering was over-boosted for our taste.

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While you have the pump apart you should have a look at the vanes. If they are significantly worn, it’s time to replace or rebuild it. Check the inside of the housing where the vanes contact it for scoring or wear.

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Next we cleaned up the reservoir, including knocking out the dents that it had acquired over the last 400,000 miles of use. Getting the inside clean was of particular importance. We don’t want any junk passing through the pump and box. Now is the time to paint it to look like new.

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The main O-ring seal on the front was the cause for most of the problems. All the seals will be replaced, since most of them were hard and cracking.

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Reassembled and looking good.

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Our attention is now turned to the rag joint. You can see how oil soaked it was. A lot of play was in this one part.

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The pins had to have their heads ground so they could come out the hole. Once reassembled they were tack welded so they would stay in place.

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This is a straightforward job but will make a big difference in the overall feel of the steering.

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Our alignment target was between +3 to +5 degrees of caster, 1/16-inch toe in and -.5 degrees of camber. Speedway Motors offers this magnetic bubble caster/camber gauge, or a digital model, for home use by enthusiasts.

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This is why we couldn’t make our caster target. Worn bushings are often the reason for an alignment issue. The suspension will be the next thing to rebuild.

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It goes without saying that the steering system is one of the most critical systems on a car. Keeping it in tip-top shape is vital to safety.

Steering also plays a very important role in the enjoyment of your car. If there is slop in the system, the ratio is too slow, the power assist isn’t right or it just doesn’t do what you want it to do when you want it to, your opinion of the car is affected.

The status of our steering was rather dismal after many hundreds of thousands of miles and a few years of neglect. It has always been over-boosted and the ratio is a little slow. It also has developed a few leaks and a significant amount of play. Our goal was to restore the steering to top condition (including fixing all the leaks), while drastically improving steering feel (effort) and steering response.

The first goal is straightforward enough. All the leaks need to be identified and the appropriate seals and gaskets must be replaced to correct the problems. In the power steering system, sources for leaks will be the pump, hoses (and connections) and the steering box. Thorough inspection indicated that all the leaks were coming from the power steering pump and reservoir.

Goal number two was approached from two separate areas. The first is power steering assist. The three factors that dictate the steering effort you experience are pressure and flow of the pump, along with the torsion bar in the spool valve. These have been listed in order of their ease to change/modify to your particular preferences. The pressure output of the pump is quite easy to change and is detailed in the photos. Flow for a pump is measured in gpm (gallons per minute) and while it is only a fitting change on the back of the pump, most of the lower flow fittings also have different hose end requirements, so it is not a direct bolt in.

Finally, the torsion bar in the steering box spool valve can be changed but that requires specific equipment and expertise from a rebuilder so this is usually not an option (see sidebar). You can generally yield acceptable results by adjusting the pressure. If you are ordering a new gearbox, you can discuss the steering effort you would like with the sales staff. The good folks at AGR got us exactly what we needed.

The other area is front-end alignment. Positive caster is the one adjustment that plays a big role in steering effort. Adding more positive caster increases steering effort along with high-speed stability. Older cars are typically set at between one and two degrees positive while new cars range from five to seven positive. Since we wanted more steering effort we dialed in as much as we could, which for the time being, was only one degree positive. Once the suspension is rebuilt we will be able to get much more.

An additional area of “adjustment” is the steering wheel diameter. Reducing the size of the wheel will increase steering effort and increase response. The increased effort comes from reducing the amount of leverage you have because a smaller diameter equals a shorter lever. Response is increased because angular movement (the number of degrees the wheel rotates) is greater per unit movement at the wheel rim. So if you move a smaller wheel one inch, it will rotate through a greater angle than a larger wheel moved that same one inch.

The final goal was to improve steering response. The two factors contributing to this are overall tightness (lack of slop) of the steering linkage and alignment. Steering ratio and tire aspect ratio (sidewall height) can also contribute to response but we aren’t going to deal with those at this point other than to say the lower profile tires make for a more responsive and crisp feel.

Identifying and removing all of the play and slop in the steering linkage requires examination of all the individual joints and components. While upgrading to a rack and pinion unit would remove four of the joints (areas of play) that just isn’t an option for some cars. For that reason, we stuck with the steering box and its inherent flaws.

Given that, our option is to put the original components into top shape. We found that several components were very worn and contributed to unwanted movement. The center link was predictably worn but the tie rod adjuster sleeve was one area that was a bit unexpected. But after so many miles, it’s not unreasonable. The idea is to check all components regardless if it is a typical wear item or not. As previously mentioned, AGR offers steering box options for nearly everyone’s needs. Our box is a quick ratio (2.5 turns lock-to-lock), three bearing output, direct bolt-in Saginaw-style unit. It performs very well and we are pleased with it.

The rag joint is a common item that can degrade and introduce significant play into the steering. We found that ours was quite loose and that the steering fluid leaks had contributed to its degradation. Now with all the play addressed as best as possible, we can focus on the alignment.

The toe setting can be fine-tuned to fit your personal preference for steering response. While you want to keep the toe setting within a range that doesn’t abnormally wear the tires, you can still change the steering characteristics quite a bit. If you want very responsive steering you can set your toe at zero. Adding toe-in will reduce the response and make the car feel a bit more stable. For the moment, we are trying to get the car to feel stable and controllable so we went with 1/16-inch toe-in. We may revisit this at a later date and move to a more zero toe setting as we get the suspension and tires up to a greater performance standard.

Overall, the combination of all these small improvements, changes and repairs have contributed to a substantial difference in how the car drives and feels. It indeed behaves more like a modern car than a dated family cruiser.

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