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Tech Tips :: C4 Related Tech Tips :: Early Convertible Top Installation and Glass Retrofit
possible for novices to install a glass window top to their early C-4
convertibles. I should know, I am as novice as they get!
Corvette owners that can no longer stand their plastic window, here is my
experience in converting the vinyl top to cloth with heated rear window.
First, let’s start with the supplies and parts you will
Stayfast Cloth Top – Robbins:
Video – John’s Corvette
Weatherstrip Release Agent – Zip
tubes of 3M Black Super Weatherstrip Adhesive – available at Wal-Mart and
3M Fast Tack Adhesive – 1 Tube 3M Part Number 08031 – Pep
Beers consumed – 1 six pack
Convertible Top Retrofit
Kit, 86-93 that permits these years cars to upgrade to the glass window
12522961 Convertible Top Retrofit Kit
Weatherstrip – 5 Pieces (required):
17987731-LH - Horizontal piece at
top front of door window
10273003-LH - Vertical piece
at rear of door window
14092676 - Back
The following piece is easy to replace if you need to while
your doing all the others:
10268887 windshield weatherstrip
following two pieces are really not needed if yours is in good
10269867-LH - Horizontal piece at top rear of door window (not
Wholesale Office - Parts Department
Time to complete
Removal of old top: 2 Hours
Installation of Retrofit
Kit: 3 Hours
Installation of new top: 6 Hours
Sharp razor cutter for trimming
Assorted slotted screw
Drill and lots of sharp bits
Pop rivet installation
Assortment of small (1/2”) brushes for spreading glue
nose pliers, straight and angled
Small scrapers to
remove old weatherstrip adhesive
Lots of Rags
Lots of Beer
The videotape that shows you how to remove and install a
new top was most helpful. I do not think I could have done it properly
without it. I had a VCR/TV in the garage to watch it as I was going though
it. This video will NOT show you how to install the retrofit kit. It will
show you how to go thru the job and get it on straight.
I choice to
break the job into three parts, removing the old top; install retrofit
kit, install new top. So I was able to complete the job in a long
Make sure that all the drill bits you use are sharp.
Otherwise you will get elongated holes and other problems. Also use fresh
razor blades when you go to trim the convertible top under bow 5. You must
be very careful and not slip or you get to buy a second top. I changed
razor blades about 3 times. A fresh blade will cut through the excess
material like butter without any frazzling.
Make sure that you
have an electric soldering iron with a fresh tip that has never been used
before to make small cuts in the stays (which is the material that hold
together the bows). The defroster wires go through these slits. If you
just cut it the material it will unravel.
weatherstrip looked pristine and was the original 11-year-old stuff. But I
knew it was original and was not sure if it would survive removal and
replacement. I do not think it is possible to reuse the crappy GM
weatherstripping if it is old. I went ahead and order all new stuff. Good
thing I did. Even though the weatherstrip (except for the windshield
piece) I had on the car looked great, it disintegrated upon removal!!!!
I had ordered the seven pieces needed for complete replacement for
the top. If yours is in good shape, there are two pieces that do not need
to be removed. These are the pieces that are on the top rear of the
window. This would have saved me more than $60.
Be sure to use a
zip lock bags to bag and mark where all the little parts go. Otherwise
they will beam up to parts heaven.
You will no doubt find at least
one screw that the GM torque monsters will have secured down to 1,000,000
ft/lbs. I had to drill out once screw in this job. You may also need to
find those little plastic screw like devices that secure down the
weatherstripping. It seems that they have a habit of ‘beaming up’ and
cannot be found.
The GM instructions for the retrofit kit are very
lengthy. There is one section which described installing some bumpers to
bow #5. The illustration on this step was not clear. You will need to
carefully examine the overall drawing on the first page to see where this
part really mounts. The installation of the retro fit can be confusing.
Take your time and remember – MEASURE THREE TIMES AND DRILL
The rivets that the GM kit supplied were steel rivets and
were quite rusty. You will need superior strength (i.e. many beers) to get
these rivets on securely. I also knocked down all the rough edges of these
four rivets with a file and coated them with silicon seal to prevent
anything from snagging against them and cutting the headliner or top
material. These are the rivets that connect a spring to bow four. There
were also several smaller steel rivets that were supplied to connect
bumpers to the bow #4 headliner retainer. I replaced with some fresh steel
rivets rather than struggling with rusty ones.
They also provided a
small amount of double-sided tape that was too old to be useful. I could
not understand what its purpose was anyway, so I did not use
There was one main shock I had after the top almost fully
installed. I only step I had left to do was to install (and glue) the top
to the front bow. But before I did I figured that I would see how the top
came down and stored in the storage compartment. When I tired, it seemed
the top would not go down far enough to allow the compartment to close! I
was appalled! I spend over an hour going over the retrofit kit
instructions to see what I had screwed up. Could not find a thing. I tried
closing it a dozen or so times. Slowly up and down, up and down, slowly.
BIG TROUBLE!!!! Or so I thought. But even though I was about my wits end,
I decided to plow forward. Good move! As soon as the front of the top was
properly installed, it went right down into the compartment – no
Cleaning up the weatherstrip retainers to get off all
the little bits of glue is the most time consuming and messy part of this
job. The 3M Release Agent will do it. I was told that you can also use
‘decal remover’ for this purpose. You need to soak the stuff several times
to get it all out. BTW – unless you like shrieking in agony – wear rubber
gloves because little cuts on you hand do not mix well with this chemical.
I found that a combination of using flat screwdrivers of various sizes
flowing rubbing with a rag sprayed with the chemical will help scrap the
goop out of all the channels. I also used denatured alcohol to wash
everything down before reinstallation.
You may also want to obtain
a roll of thin black double-sided tape to apply to the back of certain
weatherstrip retainers. Evidently GM uses it on some of them and the tape
will not survive this process. I just used a very thin bead of the 3M
I also ran 400 grit sandpaper of the back of the
weatherstrip before gluing it down.
top needs time to adjust to the frame. Robbins suggests leaving the top up
and in the sun for 5 to seven days. The creases created during shipping
show when the top is up. Hopefully, this will disappear with the sun’s