So, it was a beautiful day for a cruise! 70+ degrees! Took the wife out for a spin, stopped to put in some fresh 93 octane, and I go to start it back up and the "start" position didn't seem to want to return to "run". I had to do it manually, and all was well for the rest of the ride.
When I get home and shut her down, it appears the switch has some play in it that it didn't have before. It moves in and out about 1/8".
Is this the rack gear?
Am I looking at a steering column tear down?

 

I'm sure Jim Shea will see this thread and if I leave something out he will add to this.

There is a rack in the steering column that controls the pull back motion of the key cylinder. Sometimes the teeth wear on this rack and bind up cylinder from coming back. You could also have a problem with the cylinder and key, or you could have an issue (I doubt) with the actual switch at the bottom of the column.

I think I would remove the rod from the switch first just to eliminate the lower column ignition switch as the source of the problem and then I would tear the top of the column apart to see where the problem is.

Willcox

 

Well, after doing some reading on Jim's papers, I went out this morning and first disconnected the battery.
The spring action seems to still work, the only real issue seems to be that the locking cylinder moves in and out about 3/32". This is causing some sort of binding and requires the key to need to be moved all the way back into the run position.
While it doesn't seem to operate smoothly, I'm sure somethings wrong, but exactly what, I'm not sure. It look's like taking the upper column apart is very close to brain surgery. Has anyone else had to do this?
I checked the ZIP website and p/n's SC-432 & SC-517 might be all I need.
Well, lots of patience too....

 

One thing I noticed leading up to this was that after I gassed up yesterday I noticed that when the clutch was depressed to the floor(after I started it up) I had a light grinding sound underneath the car. While that sound was going on, the voltage meter was going nuts. I'm guessing the starter wasn't fully disengaged due to the ignition cylinder not returning to the run position all the way.

 

Be carefull to return the key as quickly as possible so you won't damage the starter and or flywheel over this.

My 75 has had the same problem for about the last 6 months, just haven't gotten around to fixing it yet, hopefully this week.

Get the plastic horn insulator first, before you tear into the column if you decide to, part is almost guaranteed to fall apart.

 

 

The key lock cylinder in the off position will move in and out approx 3/32".

I took mine apart yesterday. I was very fortunate, in that no one had been in there before to butcher it.
Same symptoms as yours. Nothing in it was broken, although the lock cylinder itself was worn a bit, but still operated freely by itself.
I found that each moving part, rack, sector, etc had some friction resistance, both from a little galling on the aluminum where the parts met and also from some very little buildup of old grease and dirt on the mating parts. I sanded all the mating surfaces with 600 grit wet and dry and polished with alum wheel polish. The parts move and slide much, much more smoothly now, even with no grease. When assembling I will use some teflon grease, best light grease I have found.
Got a new key cylinder lock assembly with 2 keys from AutoZone for $12.99. Good insurance for that little a price. Any GM from that era is the same. Also had a new sector gear and ignition switch on hand, so will install them. The spring action in "start" in the old switch seemed as strong as the new.
Polishing etc might be overkill, but the last one I did was so smooth a baby could operate it.

I'll try and post some pics later tonite or tomorrow.
Hope this helps a bit.

 

You absolutely will need this part
GM 7808385 available still from GM or Corvette Central for $7.95 or most other venders (various prices).



This is only $9.95 at AutoZone.



Here are some problems I found in this column, but nothing broken.







Sanded and polished all mating surfaces, parts and housings, don't show all the pics, took about an hour. Will use a fairly lite Teflon waterproof grease. Should be good for another 40 years.

 

Here's three pics that show how the individual parts come together. Everything just slides together(metal on metal). The spring back action comes from a spring inside the blue ignition switch on the left.