Floppy Miata Door Mirror Fix

Introduction

The following page is an account of how I repaired the floppy passenger door mirror on my 1990 Miata.  When I brought the car home the passenger side mirror would not hold a position.  The mirror was securely mounted, but there was not enough friction in the socket between the two parts to allow the mirror to stay in a set position.  It was so loose that it bounced on bumps.

After reading a post on the subject on Miata.net it seemed that there was supposed to be a bolt with a spring maintaining tension between these two units, and that when the unit was disassembled the bolt could be accessed and tightened.  Apparently this commonly breaks but can be replaced with parts from the hardware store.

A user going by "Brewester" posted the following for another user with the same problem:

You have to take out the mirror and while you're in there, you'll more than likely find a bolt that is too rusty to tighten. To remove the mirror, carefully use an x-acto knife to take off the black plastic retaining ring. With the tip of the knife in the groove between the ring and mirror body,keep going around the mirror to break through the glue, the ring and mirror will fall off the body. The little plastic housing at the base of the mirror is held on by little clips on the inside. Gently pry up and the cover should pop off. The bolt in ours broke so I went to the hardware store and bought a bolt and spring , its on the car and works great. Cheers

So I went about following the disassembly instructions.  Everything worked fine except that I found the thin knife blade wasn't enough.  I hade to use a thicker piece.  I peeler that I had sitting around worked very well.  I didn't use a cutting motion but simply forced the edge straight in.  Since the peeler was thicker than the available space this broke the glue.  As you can see in the pictures the black trim on my mirror was already cracked, which made it easy since I had a starting and finishing place to work around instead of taking it all off at once.

I also had to scrape out some gunk that was holding the mirror in place, but there was no glue there and it came out fairly easily.  The mirror was stuck to some foam behind it.  It turns out that this is because there was paint on the foam.  It seems this isn't the first time this mirror has been cracked open and there is un-even paint inside the mirror.

Now to the real problem.  NO BOLT!  My mirror is held on by a rivet.

I realized that there was nothing I could do with the rivet, so I continued by drilling the rivet out.  which resulted in the following pile of components.

I then decided that I would simply come up with my own system, so with stock components in hand I went down to the local hardware store.  I got a stainless bolt, matching nyloc nut and assorted washers (I couldn't find stainless washers and had to settle for plated.  I also found a spring that you see below.

As you can see I also bought pair of plumbing washers that just happen to almost perfectly match the hard rubber "ball" that goes inside the socket.  My thinking was that this softer piece would provide more friction.  Here's the two pieces side by side (original on the right).  If you want to try the same part you can make out the "Home Hardware" part number in the picture above.

Well I did some test fitting and not everything worked as hoped.  The rubber piece above did have more friction, but because the hole in the middle was too large it wouldn't actually move with the mirror and thus you couldn't make adjustments.  I also found that in order to make enough tension between the mirror and base for the mirror to hold position I had to crush the spring completely flat.  I'm sure Mazda had something stiffer, but that wasn't available at the local hardware.

So I decided that I had to use something else.  The solution was a common rubber grommet (like you see in a firewall) that fit neatly over the bolt.  This worked much like a spring with a very high rate, and was more compact.  I also realized that the corroded and rough socket in the mirror base was making adjustment difficult and the mirror wouldn't want to sit in certain positions.  So I broke out the dremel and cleaned the socket up, both inside and out.  Know the stock "ball" piece moved freely in the socket and when the new pieces were test assembled they held the mirror well.  You can see the pieces below.

Above you can see a square washer.  I made this from a fender washer, by simply cutting it to fit.  As you can see below there is a square recess that the factory pieces fit in.  The plan is that once finished I don't want to ever take the mirror completely apart again.  So I will weld the nyloc nut to the square washer, then put some glue to retain the nut in the pocket.  This way I can completely remove the bolt in future and the nut won't fall out.  I can also tighten or loosen it without needing to put wrench inside the mirror housing.  Here's the test assembly below.

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