The whole process takes two hours and makes a classic car immeasurably safer
Classic cars are never quite as good as we thought they were back when they were new. That 500-hp Chevelle you had in high school really only made 260, and it handled like dump truck. Add 40 to 50 years into the mix and it is bound to be significantly worse off for wear, especially the steering. Manual steering is not awful when properly set up, but when a manual gearbox gets some age on it, the slop comes in fierce. If your steering box has more than an eighth of a turn of play, then it might be time to rebuild it.
Rebuilding a manual steering gearbox is not difficult and is much cheaper than buying a new one. Plus, if you have a valuable classic, keeping the original versus installing a replacement maintains the value of the car. This was the situation for my 1966 Corvette, as I was keeping it stock. Instead of converting to power or rack and pinion, I opted to rebuild the original Saginaw manual gearbox with a kit from Borgeson (p/n 921039). The kit comes with everything you need to rebuild a worn gearbox including bushings, gaskets, bolts, and the most important parts: the worm and sector gears.
This is a recirculating ball gearbox, which is essentially a giant double-grooved ball bearing assembly. The worm gear—the part of the gearbox that is connected to the input shaft—is a machined block that has the gear teeth on one side and two machined grooves inside the block. Metal ball bearings ride inside the block, providing the bearing surface for the grooved input shaft. As you turn the steering wheel, the bearings spiral through the worm gear block, moving the block up or down the input shaft. This movement is translated to the sector gear, which is attached to the pitman arm. As the ball bearings roll on the shaft, worm block, and each other, each component slowly wears down. This is where the slop comes from.
Eventually, you have to turn the wheel to take up the extra space that is left behind from the wear. This can become significant and that is dangerous situation. Yes, you can compensate for the play, but this also leads to lane drifting as the steering system will wander left and right without the tension inside the gearbox. The solution is a complete rebuild with a new sector and worm gear assembly.