GM Convertible coupe, roadster, or open car with folding windshield Mirrors

[chistech]

A while back I posted in my 32’ olds forum about a pair of mirror mounts I made for my car. As most of us know, our 30’s cars leave a lot to be desired in the “rear” view mirror market. Most of us have tried the spare fender mounted tire type mirrors but they never seem to work that good and if they’re even close to giving you a look behind, you need to twist your neck like an ostrich to see anything. 
    I ended up designing and milling out of 1” aluminum, mounting blocks that can easily be attached to the lower windshield post side frame swivel bolt by simply removing the knob, putting on the bracket, and putting the knob back on. Easy on and easy off makes them perfect for show cars.

    I went about designing and fitting them to my car without ever writing any dimensions down figuring I’d just copy my brackets to make more as there was a lot of interest in them from other convertible owners. Well, after a gentleman saw them at the grand National in new ulm, he begged me to sell them to him so off they went. This meant I had to do some more designing, at least on paper this time but I did, and decided to make up twelve pair. I ordered two bars of aluminum and a half dozen set of mirrors (for now until they sell), some socket head machine screws and went to work mass producing them. At least mass production as far as hand making them on my vertical mill. Here’s a couple pictures of the original passenger side block and mirror assembly I made.

[chistech]

Last night I decided to try and make up some mounts out of a 24” piece of 2”x1” aluminum bar stock. I set my design based on working with square dimensions so it would be easier to locate each block sing my digital read out. I ended up using a 1 1/4” end mill and a 1 1/2” end mill for the majority of the work. Here’s the initial layout on the mill. The 1/8” deep 1 1/4 holes are for the post knob to recess in when tightened. I first located my 1/2” hole for the post in the first block, set my digital readout to “0” on the X axis, tightened the lock for the Y axis once the height of the hole in the block was set, then simply spaced and drilled all the others exactly 2.000” apart. Going back to 0 once all the holes were drilled, I installed the 1 1/4” end mill, set the quill to 5/8” depth, and milled the smaller of the two holes in the back side of the bar. The face of this hole sits on the face of the special lock ring/spacer that the knob usually tightens against. Again, moving to each corresponding hole exactly 2.000” , each block was starting to take shape. I then repeated the process with the 1 1/2” end mill, milling the larger hole to clear the diameter of the windshield post bulge in the casting.

[chistech]

Turning the bar stock on edge, the hole that mounts the mirror to the block was located. It was first drilled to a depth providing enough shelf for the head of the socket heads to seat on and tighten the post of the mirror. Then a hole just greater than the thread diameter was drilled completely through the block. Again, each hole was drilled the same size, one after another based on the 2.000” advancement, the the drill size changed and done again. Each hole was also leveled at the bottom with an end mill to provide a flat surface for the head of the socket screw. The bar then got flipped 180d, located the center of the first drilled hole, zeroed on the digital readout, then using a 7/16” end mill, a shallow recess was milled for the serrated post of the mirror to seat in and “bite” into the aluminum when tightened. I didn’t take pictures of that process but these pictures show the holes.

Edited October 14, 2021 by chistech (see edit history)

[chistech]

The mount has two angled lugs that fit into the area that is intended as a stop for the windshield frame when it’s folded down. I determined that I had to leave 5/8” of material to the backside on the front of each block. I then determined I could use the 1 1/2” end mill to mill the block out and it would remove 1/8” from the front face of each block which is not a problem plus it would set the line to saw each block apart. Again, working on my 2.000” advance, each block was milled with the quill set for depth.

[chistech]

I cut one block off the bar, put it on the car, and determined the angles needed to interlock the block at the front of the post. With the angles determined, I returned to the mill and rotated my vise. Because everything was done on the 2.000 registration, I used the mirror mount holes on the top of the bar as stops for cutting the angled area out. I simply put the drill in the hole, tightened the vise with the drill against the jaw face, then milled the area, loosened the vise, removed the drill, moved it to the next hole, repeating the whole process. After changing the angle of the vise for the lower section of the block, The Whole process was repeated again. Once done all blocks were separated from each other with a hand hack saw (yup, sold my metal bandsaw years ago because I didn’t use it much!), then sanded to clean up the edges on my 12” disk sander. All the blocks then got slightly milled to a consistent size and all edges were done with a round over bit. They are now done and ready for my neighbor to polish. This is just the passenger side and I have to do the drivers side next.

[chistech]

The rounding over of the edges using a stop block then the finished machining process blocks, ready for polishing.

[Laughing Coyote]

Looks like a lot of work, but fun work.  With all that machine work and pictures I thought I was on the wrong thread. 

[chistech]

I now have multiple sets of mirrors made up and available to purchase. As most know, these are hand made by me on my vertical mill then hand polished by Brass from the Past. They are not polished on the backside that can’t be see and there might be some tooling marks or imperfections but in no way interfere with the attachment or function. The mirrors are polished stainless steel with the drivers side a conventional mirror and the passenger side a convex mirror. These are easy on and easy off, guaranteed to fit the 31-32 GM cabriolet and convertible coupes with folding windshield. If for any reason one doesn’t fit well because of a too heavy rechrome on the windshield post, I will machine it to fit your post if sent back to me. The price is $239 including shipping in the Continental US. Those of you from out of country, request a shipping quote. Please note, these are made up but polished at time of sale so allow a couple days from payment received to shipping. PayPal is accepted.