OK,
I'll try. Hopefully someone will jump in soon.
First, realize I haven't had to take the wheel off in some time and memory retention for an ol'salt like me is weak at best.
My steering wheel has a "cap" in the center. I believe the cap is secured by a set screw. Removing the cap exposes the shaft with a large nut holding the wheel in place. There may even be a "key" that secures the wheel to the shaft. You need to remove this nut in order to remove the WHEEL.
Assuming that the 170 is like my 222 then I'm somewhat sure this is how it works. (remember, by me stumbling around, the experts will chime in, less I give you wrong advice)
The rusted screws you see underneath hold the "steering box" in place. This is true for both cable and hydraulic steering (I think
)
You may not have to remove the box, only the wheel (this I really don't know) but a picture or two would help so we can see what you are trying to accomplish. Even though I owned an 86 170 I'm fuzzy on what you are doing. Again, a pic or two would be worth one or two thousand words.
This is a good (and extremely knowledgeable) group of people and that includes the ones that don't own a CCP
I'm sure they can direct you to wherever you wish to go.
Good luck.