Listers,
I got a ton of replies on my questions about the TR4 top with
lots of good advice. The biggest thanks go to Brian Schlorff.
Brian runs Power British Performance Parts. He took time from
his business to measure new Robbins tops in his stock to make
sure mine was normal. He also shared some of the professional
tricks of new top installation. I will try to recount the
process for those who will be attempting it in the future.
Based on my recent experience (with Brian's help) I think
installing the top is well within the skills of most TR
gearheads. If you did your own interior, panels, seats or
tonneau cover... this was only a little harder.
I purchased a new Robbins top from TRF. The quality was
excellent but it seemed about 1" too narrow across the front edge
where it slides under the capping. It occurred to me to use a
heat gun, but I was afraid use it. If I damaged the top or
installed one fastener... I was stuck with it. The local "auto
trim shop" wanted 8 hours of labor at $50 and hour... so that was
a last resort. He actually looked it up in a Robbins dealer
guide.
Here's how I went about it:
1. Use your old top as a reference if possible. Install it and
take careful note of the position of the front snaps and the hook
that attaches at the top of the windscreen side. Make sure you
know how each snap is placed and account for any mistakes from
the PO. First install the metal strips in the pocket sewn into
the front edge. You can steal this piece from your old top or
order a new nicely shaped replacement from TRF. Make sure your
hoodsticks are up but in the relaxed... pulled forward position.
2. Place the top across the hoodsticks. Insert the front lip in
under the capping as far as it will go. Mine was a little tight
from a new windshield rubber gasket. I used a rubber mallet to
make sure the lip was fully engaged. Start out at the front on
the side of your choice. We want to install the snap fastener at
the forward corner. There is a natural spot where the edging
makes a turn. Feel with your fingers to position the male snap
on the capping right in the corner with enough room for the full
circumference of the snap head. Now check that the side piece
that meets the window glass top and the slanted windscreen line
up. They should unless things are real strange. Mark the center
of the capping snap on the top vinyl with a ball point pen. The
pen makes a noticeable mark but can be rubbed off when you
finish. If you plan it right all your marks will be under snaps.
Using a hand punch make a hole in the top just big enough for the
snap cap post. Take the top off the car and take it to a work
table with a large surface. I used a maple hardwood stool off
the edge of my work table as a hammering backstop. You can find
your own solution for this, but you need a hard surface for the
hammer tool. If you lucky you can buy the hand squeeze tool.
Using the snap installation tool and a hammer, install the snap
female fastener in the top.
3. On the other side the lineup can be as much as an inch short.
Place the new snap fastener in the same spot as the other side...
double checking the line up of the side piece. We are going to
custom stretch the front edge using a heat gun. I used a hobby
heat gun left over from my model airplane days. This puts out a
lot heat for shrinking polyester film used in skinning model
airplanes. I had to be careful not to over-heat the vinyl. I
good strong hair dryer will work as well or better. Heat up a
section from the middle over to the other side until the vinyl is
hot to the touch but don't go too far. Then grab the short end
and pull hard on the vinyl. You should gain about a 1/4 inch
toward your goal. Next heat the center section and pull..
another 1/4 inch should come toward the right spot. Finally...
heat the section closest to you and pull again. My snap rolled
on to the capping male post after this process.
4. The next step is to start at the rear by finding the center
of the rear window on the new top at the bottom and marking the
centerline on a piece of masking tape along the edge where the
LTD (lift the dot) fasteners go. Also put tape on the rear
capping between the two center posts. Mark the center line on the
masking tape. Now you can visually line up the spot-on center
position for the first set of LTDs. Lineup your two center lines
and use a wide piece of masking tap to hold the position. Feeling
with your fingertip... use the pen to mark the north/south
position of the two center male posts. The center hole of the LTD
should be 23 MM from the back edge of the top. Mark the east/west
line so you have a cross target. Now use the LTD backing plate as
a guide. There are small marks on the backing plate that you line
up with the cross-hair target. The hole cut out is actually
offset a little... sort of oval. Trace the hole with the pen.
Use a hand punch to shape the hole. place the LTD back plate in
place again using the cross-hair lines and holding it in the
middle cut the four slots for the LTD tabs. Use a very sharp
Exacto knife with a common #11 blade. This is easier with a
helper. Don't forget to position the "dot" aimed at the 9 or 3
o'clock position pointing in the direction of the door seam.
5. Continue this procedure for the two LTDs on either side of the
first center ones. When you are finding the N/S line for these
next posts, stretch on the material just a little... just to take
up a little of the natural vinyl shrinkage (but nothing like the
front edge routine). You can punch the inner set first and put
the top over the posts to set the next set. This brings you to
the LTDs at the bottom of the space between the back windows. Do
the snaps that turn the radius one at a time jumping from side to
side. The last run to the door can be done all at one time on
one side... but I would recommend two at time or you can get too
far ahead of your self and miss-punch something. Pull on the
material and mark the N/S line. Use the MM ruler for the E/W line
and do all the LTDs.
6. The last tricky part is the u-shaped hooks that are installed
on the front edge of the side flap. Place the hook on the tab on
the windscreen... under the rubber sealing gasket. With the
hoodsticks only half relaxed and the front edge and snaps
installed... hold the flap in place where it lines up with the
windscreen. Don't be tempted to pull it down too far as this will
pull down the top when the hoodsticks are set and the top is
stretched. My old top has an ugly pucker from this bad fitting of
the hook. Position the u-shaped hook on the outside of the flap
and trace a circle inside the loops on the hook. I punched these
holes a little off the marks to make it a little tighter fit than
my pulling on the flap would allow. Remember the u-shaped hook
goes on the inside. The special rivet snaps can be installed
using a big pair of vise-grips. Place the post on the inside and
the "button" on the out side and set the vise-grips so that when
you squeeze them to the lock position the button gets pressed
onto the post but not crushed too much. You can do the first one
in degrees until it looks right. Use the flat front edge of the
vise-grip jaws.
7. One more thing. The hoodsticks must be positioned so that the
front bow lines up with the front seam so that the overlapping
tabs that grab the top don't pull anything but down. If these
are miss-aligned the front bow makes an ugly pucker in the
surface of the top. The measurement from the back edge of the
tall post to the center screws of the holding plate on the rear
bow is 21 1/4 inches. I laminated a piece of vinyl, from the
scraps leftovers from the panel set, to the end of the cloth
strap and lined up the hole with a new LTD facing toward the
doors. The top looked like a million bucks when the hoodsticks
were set. The rest of the snaps are pretty straight forward if
you got this far. Brian Schlorff recommends leaving the top on
the car for a 10 days or so and leaving the car out in the hot
sun to "set" the top.
I hope this is helpful to others who are thinking about a new
top.
Brian Sanborn
62 TR4 CT16260L - Groton, MA
My TR4 Restoration Web Site
http://www.net1plus.com/users/sanborn/Home.html
E-Mail: sanborn@net1plus.com
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