Blazer Spare Tire Carrier
When the GM engineers looked at spare tire locations for the 2-door Chevy Blazer, its short wheelbase made for a
difficult design compromise. The underside of the vehicle has no room for a full-sized tire. So they offered two
solutions:
Time + Wear = Noise
May 2012
Inside Mount
Outside Mount
Neither option is ideal. Cargo space gets eaten up with the inside mount, and the outside mount requires the spare
tire carrier to be swung out whenever you want to open the tailgate. On stock ZR2 Blazers like mine, you can't even
open the rear glass without swing open the carrier, because the tire is in the way. Plus, it blocks the rear view.
Another common issue with the outside spare is the carriers occasionally come unlatched, which usually results in the
carrier swinging open all the way while you're driving down the road.

I addressed these issues with help from the ZR2USA website, first by lowering the spare tire mount and then by
adding a secondary latch. The square metal plate in the photo below is the lowering kit. It's just a metal plate mounted
to the carrier, with studs positioned a couple inches lower. Washers are used to space the tire further back, which
helps provide enough gap
from the rear glass that it can
be opened without having to
swing out the carrier.

The secondary latch is visible
on the left side of the latch
plate. It's an ingenious little
device plumbed into the stock
latch mechanism. If the stock
latch somehow releases (or
wasn't closed properly), the
secondary latch catches and
prevents the carrier from
swinging open.

Unfortunately, neither of these
products are available
anymore, although the
lowering kit would be pretty
easy to make with plate steel,
studs, a drill press and a
welder.
Secondary Latch
From left to right: 1) Carrier open; 2) Carrier closed; 3) Latch unhooked by squeezing the latch handle;  
4) Carrier tries to open; secondary latch engages.
The main weakness of the outside-mounted spare tire is the weight of the wheel and tire on the carrier. If I had to
guess, between the wheel, tire and carrier, there's at least 100 pounds mounted to the rear quarter panel. When the
carrier is swung all the way out, the hinge and brackets are supporting a pretty large load.

A couple things can cause problems here. First, if the carrier breaks free from the latch while the vehicle is in motion,
odds are it's going to swing open rapidly, all the way to the stops. The force of this can actually dent the quarter
panel. If you do a lot of off-roading, all the bounding and jostling may even cause the body panels to crack.
The pictures above are probably extreme examples of
how the carrier brackets can damage the body. I'm not
sure what conditions this Blazer was driven in, but I
would guess there was some off-roading involved.
There's really no good way patch-fix this. Most carriers
that end up this way probably aren't carrying a spare tire
anymore.

On the left is a more common example of what happens
when the carrier swings out all the way to the stops.
We'll see below why the body panels can dent so easily
when this happens. There just isn't much support behind
those panels.

I've seen plenty of Blazers
without the tire on the carrier,
probably because of some of these issues. When
Blazer owners give up on the carrier, most spare tires
end up taking up room in the cargo area. Others end up
on the roof rack. Neither method is ideal, although that
roof rack looks pretty cool.....
On my Blazer, the carrier started rattling and thumping pretty severely. Before I figured out what the noise was, I
thought something might explode back in the rear passenger side quarter panel area. When the noise disappeared
with the spare tire removed, I knew it must be the carrier mounting brackets. The mounting bolts were snug but not
super tight, so I torqued them down a bit. That only made the problem worse.

After a long period of Internet research, using forums like
s10forum.com, zr2USA.com and blazerforum.com, I couldn't
find much help. Nobody had any photos of what the carrier mounting brackets connected to on the other side of the
body panel. The best I could find was a diagram (click on diagram for larger view):
Some of my Internet research pointed to the hinge
pins and bushings as potential noise makers, but
my hinges had very little play. The inside brackets
(#6 and #7 in the diagram) had to be the problem.

When I took apart the inside body panels and
exposed the inner part of the rear quarter panel, I
saw only this:
The inside bracket was sandwiched between the
inner and outer body walls. I could just barely make
out the bolts poking through the rear-facing part of
the bracket, but not good enough to tell anything
about what was going on in there.
You can see that the bolt threads into what is
basically a nut welded onto the inside bracket.
The reason I chose to expose this particular bolt
was because that nut thing was pushed in slightly.
With the carrier removed and the M10x1.50 bolt
threaded about a third of the way into the nut,  
the bolt would move just a little as I jerked on it.
The other bolts did not give very much when
threaded into the other 5 holes (the brackets
appear to be tack welded to the outer body).

When I exposed the bracket, the lower left corner
had a small gap between the bracket and the
outer body wall. Not much - probably about 1/16"
of an inch. On a hunch, I shoved a nylon washer
into the gap, put some electrical tape around the
bracket to make sure the washer stayed put, and
then gave it a test drive.
Outside bolt holes. The one of the right had been pushed in just a bit. This can be fairly
common, especially when the carrier opens all the way to its stops. There's a lot of
weight pushing against the body and the brackets. For as much weight as there is on
these brackets, I was surprised how not beefy this is.
Washer shoved between the bracket and the body wall, with tape to keep it from falling out.
All back together, with subwoofer and amp (out of sight behind the sub)
Like magic, the noise went away. Apparently the flexing of the body wall against the inner bracket was enough to
cause some rattling and thumping. At some point I will spot weld the bracket for a more permanent solution.
To improve my view, I drilled a small hole to locate the upper bracket (#6) and then made it bigger with a 1.75"
bi-metal hole saw. With a larger opening, I could see the front-most bolt sticking through the opening. It looked like
this: