04 mar 2021
New ~ 2005
AMC used Saginaw (I think it is) steering columns in the 1960's muntil they switched to GM type locking columns. As they age they get sloppy, in two areas; the pivot for the shift lever, a simple roll pin that wears out the pot metal it rides in, and in the older automatic shifters, at least, the shift lever tip rides in a pot-metal channel that wears, and the shifter ges very sloppy and likes to pop out of park even when adjusted right.
There are two separate fixes here. My experience is limited to the 1963 Classic automatic transmission column shifter (the original text and photos below) and a 1968 American manual three-speed shifter. Both share the pivot/roll pin problem and have the same fix, improved on the '68.
Unfortunately I didn't take enough pictures here, but the task is simple. You'll need a drill press and a big vice or some way to clamp the shift-column section, lengthwise.
The shift lever is hardened steel, and the casting it is mounted in and pivots on is cast aluminum. A spring steel roll pin, a friction-fit in the level, pivots in the hole in the casting. years of use wears away the aluminum adding much slop and ambiguity. The inside, working tip of the shift lever doesn't hold the gear-selector components in position and the car pops out of gear or jams going into a gear.
The inner-pivot portion of the problem, at least for the '63 auto shifter, has a fix in the section below.
The idea is to drill out both the lever and the casting to accept a new, larger, pivot more suited to the task. The trickiest part is determining where to drill the hole. Since the bottom hole ovals badly it's hard to get a "center" from, and you don't want to miss, or the tip of the shift lever won't be centered in its channel.
Here's how I approached the problem:
For moderate wear the shift lever pivot fix is fairly easy. The limiting factor is the amount of wear in the casting; is there enough metal left for a tapped 1/4-28 thread in the bottom portion? If so, use this next section. If not, see further below.
This leaves the shifter visibly modified; the head of the new, improved pivot is visible. If you want to use a roll pin as per the factory setup, use the more invasive solution below.
...meaning there is not enough metal left to bore and tap for a 1/4-28 bolt, do this. I did this on my '63 Classic column and it worked great. The basic idea is to remove enough metal to install two steel inserts, which are then drilled out and used as the basis for the pivot. More work, but stronger than original.
In addition to the pivot problem above, the inner, working portion of the shift lever has it's own set of problems and why it is so hrd to get in, and stay in, the selected gear.
The soft castings are the main problem. The shift lever is steel, with a hardened tip that rides in a too-thin cast channel, and the pivot is a roll-pin. The hardened tip of the shift lever transmits the force of your arm onto the shift tube via a tiny contact point in the potmetal. Once that wears away, the force is instead applied to the pivot. Eventually the lower hole becomes oval, the lever moves all over the place, and the slop lets the hard shift-lever detent pop out of the gate inside the column.
The fix is in two parts, the pivot dealt with above. Below is the fix for the inner pivot/selector.
Photo #1 shows the steering column in the car, and photo #2 shows the unmodified shift-column section as indicated. All of the work is done in this part. The numbered items, described later, are: 1) the screw-access wells, 2) the shift-lever tip, 3) the channel in which the shift-lever rides. A drill bit replaces the roll pin while working on the bench.
The tip of the shift lever rides in a vertical channel with very narrow sides. Due to the shape it would be difficult to repair. But a fortuitous design feature makes for a five-minute fix!
It's hard to see in the photo, but the very tip of the shift lever sits in a slot, extending just beyond the screwheads to the left and right of it. The tip penetrates the channel only 1/16" or so; it travels up and down the slot as you pull the shift-lever forward to change gears. The tip wears the thin lip of the channel away quickly.
There are two circular wells that provide access to the screws that hold the shifter detent spring assembly in place, about 5/16" diameter and about 1/2" deep. The fix is simple:
As you can see in the right-most photo (assembled without grease for the photo) the rod tip now rides along the edges of the rods. Though the contact area is radiused, the rods are much harder (though still softer then the hard shift lever) and the force is transmitted to much more of the casting area than before. Mine was slightly tight initially, but I'd avoid removing metal.
Be careful that the dropped-in rods don't drop-out when you're working on the thing. Once the column is assembled, the shift gate in the next-higher column section (that contains the directional switch and horn slipring) prevents them from falling out when you tip the car on its roof (you might have other worries if that happens).
The tapped holes that hold the hard-steel shift gate were pulled; the screws are too small for the load. I deep-drilled, retapped, degreased and used low-strength Loctite. Before I did this it shifted slightly in operation, adding to the sloppiness.
(Be careful tapping aluminum with a 6-32 tap! (A shop I worked in called them "snap 32". It's gummy stuff, I almost broke off a bit and I was paranoid to begin with. I found I had to completely remove the tap every 2 - 3 three new cuts and clean the tap. Slow, but easy work.)