Chris, our customer, is an Assistant Professor and Automotive Department Head at a Pennsylvania technical college. We rebuilt the pump and gearbox for his 1973 Buick Century Regal. He posted a video of his checks of the power steering system after the rebuild. You'll see some typical pump pressures and flows in this video.
Some Fords, from 1965 to 1979 (Mustangs from 1971 to 1973) used Saginaw gearboxes, but not all of them. Those with Saginaw power steering gearboxes can be upgraded to the 12.7:1 ratio.
It's easy to tell if you have a Saginaw box in your Ford. Saginaw's have 4 hold-down bolts on the adjustment cover, the Fords have 2 bolts on that cover. If you've got the 4 bolt cover, your gearbox can be upgraded to the 12.7:1 ratio. (click the image to see full size)
Between 1968 and 1972, Saginaw gearboxes left the factory with a yellow sticker. We reproduce this original factory condition when we perform extreme detailing on a gearbox for vehicles in that range of years.
Customers often end up with a gearbox - but they are unsure of the vehicle it came from. Then, they want to know "can it be upgraded to a fast ratio?" One way to answer that question is to know what size gearbox it is.
Saginaw 800s come in two sizes; 3" and 3.25". When talking about 1960s through 1980s GM automobile boxes, most B-bodies (full size GM cars) came with the 3.25" box. A-body and F-bodies came with the 3" gearbox. The 3" can be upgraded to the 12.7:1 fast ratio, the 3.25" cannot. (The 3" box can be a drop-in replacement for the 3.25" and that's how full sizes vehicles are upgraded to fast ratio.)
To check your gearbox size, measure the round aluminum endcap (which faces the front of the car) as shown.
There are other ways to tell what gearbox you have, but sometimes you still need to know the size. Other ways to identify your gearbox will be covered in a future post.
A common mistake with rag joints (flexible couplings) is to think that loosening its "pinch" bolt is all that's required to remove the rag joint from the steering gearbox. Loosening the bolt is not enough, the bolt must be removed from the rag joint for it to slip off the input shaft. The same goes for installation - insert the bolt after the rag joint is positioned on the shaft.
1977 and up had a bolt head with 6 points, prior to 1977 they were 12 point bolts, so you'll need a 12 point socket for these.
PowerSteering.com's practice is to ship gearboxes on center. And as the heart of your steering system, its center position is important during installation. However its not difficult to tell if a gearbox is on center. The majority of steering gearbox brands, power & manual, have gaps in the pitman shaft splines that tell you if it's at center; the input shaft provides a clue too.
Most pitman shafts are indexed with 4 large spline gaps. When the spline gaps line up with the axis of the steering box, its on center. If they aren't lined up, it's not on center.
Furthermore, when at center the flat on the input shaft will be at top-dead-center. If there is a rag joint attached, the rag joint's pinch bolt will be at top-dead-center. See photos for examples. The input shaft alone doesn't tell you if you're at center, i.e. if its a 4 turn lock-to-lock gearbox it will be at top-dead-center in 4 places. (These conditions do not all apply to reverse rotation or 4 x 4 GM gearboxes.)
If you have a rag joint (flexible coupling) on your input shaft, the pinch bolt is at top-dead-center when the gearbox is at center, as seen below.