How much force does it take to cause a 70-72 A Body steering shaft to collapse? I've just gone through three shafts that should have been fine to discover two of them are anything but fine.

The first one is the original out of my '70 Cutlass. It has been in loose storage around my shop for the last couple of years and may or may not have been dropped on it's end a time or two accidently. After reassembling the steering column I found that once the locking plate was installed the shaft was so short that almost none of it was protruding out the bottom bearing retainer and it was impossible to connect the lower shaft to it.

After some digging around, I located another 1970 steering column in my parts pile (A floor shift column I forgot I had, and which could have saved me some other challenges, but that's another story!). As I had cleaned and painted the other column, I pulled the shaft from this one, found it measured maybe 1/2" longer than the first, and installed in the assembly I'm using. There was more spline visible, but again not enough to fully engage the lower shaft and get the lock bolt through the groove in the upper shaft. Once again, I suspect that storage wasn't kind to the shaft.



Fortunately my Oldsmobro has a '72 parts car with a column still installed, so we pulled that column out. I compared that column against the one from my '70 to confirm measurements from the top of the column to the bottom, etc, and found both to be the same length. The correct amount of shaft was protruding from the column. I removed the steering shaft from that column and found it again to be longer than the other two.

From left to right are the original from my '70, the spare I found in my pile and the unmolested '72 shaft.



The correct shaft protrusion (in the '72 steering column assembly):



With this third shaft installed in my '70 column, things are "correct". This shaft had plastic buttons or flanges over the pins on one side, while the other two shafts did not. Does their absence on the two shafts indicate that the pins have sheered due to column collapse?



Am I correct in concluding that unintentional mishandling, even if not overly rough, and moving these around in the shop and storage can generate enough shock to collapse them by up to an inch? Once collapsed, are they garbage or still salvageable?

 

The shaft can be pulled back out. The column has the energy absorbing part that is not serviceable. A simple drop on the column will push the shaft in, like a frightened turtle!

 

Fascinating!! I thought it was only the lower shaft (column to gear) that was collapsible. I don't have many pictures from my column rebuild, but it does look like the column shaft can also collapse. I can't tell if there are plastic pins on that shaft like the lower shaft. In my case I had a '71 and a '72 column.
You can probably pull them back to the correct length, but the shaft is compromised. I don't know if it's likely to collapse again or what.
I expect Joe or one of the other guys might have more detail. Brian (507olds) also rebuilds columns, so he might have a better idea.

 

The lower shaft has pins too, both parts appear to be collapsable.

I'm using the shortest shaft (original from my '70) as a bit of a test subject. It can be stretched out and shortened with mild persuasion but doesn't move freely. Before I did anything, I used a small drill bit to drill into the pin in the hopes it would score the inner shaft and I could see the movement, but it didn't seem to leave a mark. Scratching my head on that one.

There are 2 circlips on the shaft that seem to prevent it from moving in either direction (top portion of main steering shaft) and the connection to the lower shaft would theoretically hold the lower portion of the main shaft in place under normal operation but yes, I'd be leery about comprised function without input from one of the more knowledgeable people! I was lucky to have a good spare handy otherwise I might have used one of the others at least short term.

 

Are you referring to the under dash support for the column? I'm not sure where else in the column would be energy absorbing.

 

I thought there was a section that was expanded steel under the shifter bowl. You are making me think I'm confusing my makes though, which is a real solid maybe

 

You're assuming that steel mesh feature applies to later columns/years....it doesn't. They stopped that feature sometime in the later '60's I think. 70-72 Olds Abody columns don't have that feature. I've seen the steel mesh feature on a '67 Cutlass column, for example....so it must have changed sometime after that.

 

The expanded mesh was used in 67 and 68. Seen here with the plastic sleeve covering it:


Begining in 69, a telescoping column tube was used like this:

The smaller diameter gets forced up into the larger diameter tube on impact.

 

It wasn't an assumption, it's just a blurry memory! Either way the column still collapses.