Volume Check
The power-steering pump is a less complicated animal but still deserves the same level of blueprinting. Tom Lee explained that the factory Chevelle pump is a sound piece that delivers adequate pressure (about 1,250 psi at peak) for low-speed or no-speed turns. Volume, not pressure, is the important factor in matching an older pump with a newer, faster-ratio steering gear. Charlie Hutchinson led us through the teardown and reassembly. The Chevelle uses a vane-style pump that's pretty simple in operation, so it's straightforward to rebuild. After Hutchinson pulled it apart, the shaft was bead-blasted and polished. A new seal was installed in the housing for good measure. Hutchinson checked for excessive clearance between the rotor and the liner and found tolerances to be within spec, so they were lightly sanded and the pump was reassembled with new O-rings and seals.
The size of the flow control valve (FCV) orifice dictates how much fluid volume is pumped through the steering gear. Additionally, the FCV contains a spring and a check-ball to cut off the maximum pressure the pump will generate, for example, when the driver spikes the pressure at full lock during a parking maneuver. Aiming for a 2.75 gpm flow rate, Hutchinson drilled out the orifice in the FCV to 0.148 inch (#25 drill) on a lathe. The 1,250-psi cutoff pressure was verified on an in-house test machine, and while it can be changed with shims or springs, we left it alone. Pumps are bench-tested on Lee's own test rig, and ours flowed exactly 2.75 gpm as expected.
 The pitman nut gets a uniform...  The pitman nut gets a uniform micropolishing so it slides smoothly in the bore. The pitman shaft and input shaft are polished in the areas where the seals ride for smooth, leak-free operation. |  The side cover supports the...  The side cover supports the upper end of the pitman shaft, and after hard use, the bore can distort. If Lee's go/no-go gauge bottoms out in the side cover, it's worn too much to use. |  Valenzuela measures the drag...  Valenzuela measures the drag on the front bearing/seal to verify it's within 4-6 lb-in. Turning the adjuster plug with a spanner wrench preloads or unloads the bearing. |
 The Saginaw power-steering...  The Saginaw power-steering pump is simple in operation and tough as nails. The critical parts are the rotor (A) and liner (B) and flow-control valve (C). |  Hutchinson lightly sands the...  Hutchinson lightly sands the bottom of the liner to promote a good seal inside the pump. |  Hard use really hammers the...  Hard use really hammers the thrust plate inside the pump (left). Slight scuffing on the thrust plate (right) is acceptable, but less wear is better. |
 The liner installs one way...  The liner installs one way only--with the arrow-shaped indentation pointing upward. The pump will absolutely not work if the rotor's installed upside down. |  Another Lee-designed test...  Another Lee-designed test rig confirms the flow-control valve's 1,250-psi cutoff pressure. |  Hutchinson verifies that the...  Hutchinson verifies that the pump is pushing 2.75 gpm on Lee's in-house dynamometer. |