68 Wiper Door Overide Knob

[Jeff P.]

My wiper door won't shut or work so I'm starting to look at threads to troubleshoot the problem. The car is a 68 ,5 star Survivor.
I took the bracket under the steering wheel off to get access to the switch. I removed the knob and switch. My question is ,does anyone have an idea when the all black knob changed to the silver or chrome center. This knob and switch looks very original. But could have been changed in 48 years. Car is a March build. Thanks, jeff.

[Mike K.]

Re: 68 Wiper Door Overide Knob

Jeff,
You are referring to the wiper override knob which is located at the lower edge of the drivers-side dash.
The Judging Manual calls out only round black plastic knob with grooved edges, and originals have no metal insert in the center.
Aftermarket or service replacements sometimes have a stainless insert. The Judging Manual does not call out anything else
different or a change and when. Refer to page 21 of the 68-69 Judging Manual, 4th edition. Hope this helps.

[Joe L.]

Re: 68 Wiper Door Overide Knob

My wiper door won't shut or work so I'm starting to look at threads to troubleshoot the problem. The car is a 68 ,5 star Survivor.
I took the bracket under the steering wheel off to get access to the switch. I removed the knob and switch. My question is ,does anyone have an idea when the all black knob changed to the silver or chrome center. This knob and switch looks very original. But could have been changed in 48 years. Car is a March build. Thanks, jeff.

Jeff-------


Do I see a small screw on the side of the nose of the knob?

[Jeff P.]

Re: 68 Wiper Door Overide Knob

Thank you Mike. I was familiar with the judging manual but thought there is always room for change. I would like to know when the change over to the stainless circle occurred.
Yes Joe, there was a small Allen screw to keep the knob on.

[Joe L.]

Re: 68 Wiper Door Overide Knob

Thank you Mike. I was familiar with the judging manual but thought there is always room for change. I would like to know when the change over to the stainless circle occurred.
Yes Joe, there was a small Allen screw to keep the knob on.

Jeff------

I have not seen one of these knobs with the screw. The known original on my 1969 does not have a screw. There is some type of spring mechanism inside the knob orifice that retains it to the shaft of the switch. Also, the knob on my very late 1969 does not have the stainless or chrome insert. So, I doubt it was added in 1968. That being said, your knob just looks to me like it could be original.

So, why do any of the knobs have this metallic insert? After all, on a Corvette the knob faces downward and the insert, which is ornamental only, cannot be seen. Well, this knob was also used for the windshield wiper switch for some 1964-65 Chevrolet trucks. However, for that application I expect the face of the knob could be seen. But, with that being the case, I would have expected that all of the knobs would have had the insert.

By the way, the knob was always GM #1991024 both for the 68-72 Corvette applications and the 64-65 truck applications.

[Jeff P.]

Re: 68 Wiper Door Overide Knob

As always Joe,very informative. Ill try to touch base with some 68 owners.

[Douglas L.]

Re: 68 Wiper Door Overide Knob

If it helps, my Jan 15 68 build car has the stainless insert but no set screw.

Doug

[Jeff P.]

Re: 68 Wiper Door Overide Knob

Thank you Doug. Hopefully some other 68 owners will chime in.

[Kurt B.]

Re: 68 Wiper Door Overide Knob

Jeff,
My May 10, 1968 build car has the gloss black plastic knob with no stainless steel insert and no attaching screw on the side.
Kurt

[Joe L.]

Re: 68 Wiper Door Overide Knob

All------


Something I wonder is if all of these knobs had the insert and, in some cases, the insert has just fallen out. It's even possible that happened to mine. I just don't remember if it's always been the way it is now. After all, it's not like I looked at it a lot.

It's also possible, of course, that the insert was deleted from the part via a change to the part specifications, perhaps sometime in later 1968 or early 1969. So, it would be nice to hear from 1968-72 owners, not just 1968.

[Edward B.]

Re: 68 Wiper Door Overide Knob

There is some type of spring mechanism inside the knob orifice that retains it to the shaft of the switch.

Joe, I found a thread on a TRUCK WEB SITE that showed an NOS 1991064 knob (and I'm assuming you made a typo in your reply #5 showing 1991024 instead of 64), and you can see the spring mechanism in the last picture (also attached here).

And for the record, my car was built October 21st, 1969, has the stainless (?) insert, but no set screw.

Ed

[Ralph S.]

Re: 68 Wiper Door Overide Knob

12/10/69 does not have a set screw or the stainless steel insert.

[Kurt B.]

Re: 68 Wiper Door Overide Knob

Joe,
I just looked at my knob from my 68 again, and it is very smooth on the surface and has no indentation where an insert might have been or fallen out, neither is there any sort of residue to indicate that something like a stainless insert might have ever been there. The face of the knob is flat and even with the sides; no indentation.
The flat face portion of the knob is very smooth and has the same shiny appearance and texture of the rest of the knob so at least on my car, it appears there was never any sort of insert.
Kurt

[Joe L.]

Re: 68 Wiper Door Overide Knob

Joe, I found a thread on a TRUCK WEB SITE that showed an NOS 1991064 knob (and I'm assuming you made a typo in your reply #5 showing 1991024 instead of 64), and you can see the spring mechanism in the last picture (also attached here).

And for the record, my car was built October 21st, 1969, has the stainless (?) insert, but no set screw.

Ed

Ed------


Yes, I meant to type 1991064.

I have an NOS example of the knob and it's exactly like the one you have pictured. Note the parts group 16.067. This is the "group of prime use" for the part and is the parts group for the truck application (parts groups above 15 are truck-only). I expect it got assigned to that group because that was the first use for the knob.

[Terry M.]

Re: 68 Wiper Door Overide Knob

No metal insert and no set screw on my end of January 1970. Never had it either I did look.