Does anyone know where I can get access to the GM issued instructions and diagrams for fitting Sports (bullet style) mirrors to C3 Corvettes?

I understand that Sheets 18 and 19 of the AIM have this information (pages 254 and 255). These were posted on this forum a while back, but I can't find them anywhere now.

Thanks in advance.

 

Have no clue where you got those page numbers. However, from my copy of the 77 AIM.

 

Excellent. Thank you.

 

I’m in the process of doing this right now on my 73.
Its more involved that just swapping the mirrors which was what I thought before I got into doing the job.
One of the issues is drilling the holes in the door.
Another issue is drilling the holes through the metal door frame big enough to install the nuts but also big enough to pass a socket to access the nuts.
Depending on the washer size attached to the nut and the diameter of the socket I’m looking at having to drill 9/16” or 5/8” holes in the metal door frame.
Besides the mounting holes in the fiberglass you’ll need to bore a large hole to pass the cable adjustment assembly through.
It doesn’t come apart so don’t even try.
Another issue I found was that at some point GM changed the mirror mounting studs from SAE to metric thread and I had to locate metric washer spinning nuts to fit the studs on my later model NOS sport mirrors.
Several vendors sell the free spinning washer nuts but they don’t specify 1/4-20 or M6-1.0 threads.
You will need to remove the window glass to drill the holes and mount the mirrors.
I actually have two threads covering what I need to do and the multitude of questions I’ve had to ask.
There are also several good videos you can Google to help you out.


These are the M6-1.0 threaded free spinning washer nuts I found that fit my sport mirrors.
They are a GM nut used for several different make and model GM cars and trucks.
Here are another set of mounting diagrams that were from Wilcox.

 

Oh one other tip.
The gaskets between the door panel and the mirrors must be mounted with the thick side towards the top.
If they are mounted wrong the inside edge of the mirror is too close to the window and may interfere with the window operation.
There is no left or right side specific gasket.

Here is a picture from the 77 AIM that shows some additional details regarding the hole placement and sizes for the drivers door.

 

Thanks OCB. Yes, the drilling of the holes is the key issue for my 74 convertible install as well, even more so in my case, because the car has already been painted.

There appear to be two options for the vertical positioning of the mounting holes (relative to top of the door skin) - either through the upper metal door frame, with nuts attaching the mirror onto it, or, through the fiberglass below the metal frame. In the latter case, a backing plate would be needed to spread the load and prevent the fiberglass from cracking with vibration. The AIM diagrams showing the positioning 1.55" - 1.60" below the top of the door panel, seem to suggest drilling through the metal frame.

Interestingly, there is no information suggesting the fore and aft positioning of the mirrors. From my setup trials, I think that a position about half way between the original mounting location of the old blade mirrors and the front edge of the door panel seems optimum.

 

Keep in mind that the area behind the door fiberglass skin is a sealed off cavity with no openings and to install any type of backing plate would need to be fed in through the only opening which is a small access point where the door handles are installed.
The only other option would be to cut a large enough opening in the door frame to be able to insert and install the reinforcement plate.
Interestingly enough the 77-82 AIM’s don’t show any metal backing plates either molded into the fiberglass or as a separate piece installed.
It appears the 77-82 sport mirrors mounting nuts were torqued directly against the fiberglass door skin.
The oem nuts do have a thin rubber gasket bonded onto the washer.

 

I'm not suggesting that, if fixed through the metal frame, a backing plate would be required - the frame itself serves as a backing plate and spreads the load. A backing plate would only be considered if fixing was through the fiberglass BELOW the metal frame.

Having worked with fiberglass extensively on aircraft, I definitely would not recommend torquing up nuts directly onto the glass - I can't imagine why GM would opt to do that.

 

If you are going to tie the mirror studs into the door frame, which I did, you'll have to provide clearance for the door glass.

 

I was looking at some old threads and came across one where DUB had a simple process for swapping out the threaded plates for the earlier chrome style mirrors.
He used two wires that allowed him to pull the steel plates from the door handle opening into position, then he removed the wires from the plates after he started the mirror mounting screws.
I’ll try and find the thread again.

 

Under paint and body work
Chrome outside mirror Aug 13 2017 by Dub.

 

Hey Peterbuilt,
It could be but the link you posted won’t open for me.
This is the thread posted by DUB from 2017.
https://www.corvetteforum.com/forums...t=Mirror+plate
It does show pictures and has the details of how he was able to position the plates.
This copy was in C3 General, same date.