The venerable Saginaw steering box has been in use for many decades and is found on a wide range of four-wheel-drives. A lot of 'wheelers with older rigs probably have one bolted to their framerail, doing its duty with competence each day they drive.
We have a Saginaw power-steering box of early-'70s vintage that finally blew a sector-shaft seal and had been weeping fluid for quite a while prior to that. So, we figured it was a good time for a teardown.
We sourced a rebuild kit from West Texas Off Road, and it included a complete set of seals with a heavy-duty top seal, and the input and output shaft bearings. With the box removed from the truck, we were ready to dive in.
A rebuild can be done with mostly common handtools. In any case, rebuilding a steering box requires patience and the assembly of many small parts and seals. Cleanliness and attention to detail will help ensure the result is a quality rebuild. Follow along as we show you the basics of how we cleaned, inspected, and reassembled our aging Saginaw.
For those of you who would rather not rebuild your own box, the folks at West Texas can do it for you. While they're in there, they can also tap the box, machine internal components, and add fittings for a hydraulic-assist upgrade. Other hydro-assist parts are also available if needed. If you have any doubt of your ability to rebuild a critical steering component such as this, leave the job to someone who's well experienced.
1. After the pitman arm has been centered in its rotational travel, it should be removed. Then the C-clip can be removed from the sector shaft using a set of snap-ring pliers. | 
2. The four bolts are removed from the cover on the top of the steering box. | 
3. The sector-shaft assembly should lift out of the housing. If necessary, tap the lower end of the shaft with a soft-face hammer to get it to pop up. Fluid will pour out of the box, so have a catch pan ready. |
4. Using an awl or similar tool, the steel retaining ring can be pushed from its groove and pulled off the inner bore. Rotate the stub (input) shaft in a left-turn direction to push the end plug out of the housing. | 
5. Pull the rack piston out of the housing bore. More fluid will come out, and a set of steel ball bearings will fall out or into the inside of the rack piston. Be careful not to lose any. | 
6. Remove the C-clip from the adjuster plug. Each C-clip in the steering box will be replaced with a new piece. |
7. Using a brass drift or punch, loosen and remove the locknut from the adjuster plug. | 
8. Using a spanner wrench (or similar tool), unthread and remove the adjuster plug and rotary valve assembly from the housing by pulling on the stub-shaft end. | 
9. Here you can see the adjuster plug and rotary valve assembly, along with some more exiting fluid. |