Convertible top window replacement experience

[landrovered]

My rear window on my 01 Boxster S was yellowed and finally cracked pretty badly. With summer thundershowers just around the corner I needed to solve the problem.

Things are still a bit tight around here financially so I decided to go the sew-it-yourself route.

After looking at many different suppliers I bought the Kal GLas .40 Mil plastic from Sailright in Indiana. It was only $39!!! with shipping it came to $48... perfect for the eternally cheap like me. http://www.sailrite.com/Kal-Glas-40-Gauge-Vinyl-Window-Material-29-x-68

The window material is DOT approved and quite thick, it is good to unroll it and let it relax overnight before trying to work with it.

I decided to remove the top with the frame rather than attempt to do the work "in situ". This was a good idea and I highly recommend doing this rather than visiting the chiropractor. http://www.renntech.org/forums/index.php/topic/18782-oh-man-someone-cut-the-plastic-on-my-top/

You will need black outdoor UV treated polyester thread, a pack of large needles as well as two thimbles, tweezers, a pack of razor blades, a glue gun and some straight pins, a big towel, some scissors and a few folding chairs and a work light. I got black silicon sealer for the waterproofing.

I used the razor to cut the old window out of the top. Pulled the threads out with the tweezers. Flipped the top upside down on the table with a towel under the window cut out to keep the new window from being scratched.

DO NOT CUT THE NEW MATERIAL TO THE SIZE OF THE OLD WINDOW, I did this and it made the job a lot harder than it had to be. Leave at least two inches of extra material all the way around the size of the old window.

You can pin or as I did hot glue a few points around the window to get it to stay in the proper position for sewing.

I did check with two local upholstery shops to see if they couls sew the window in fro me and the price would have been around $100 for the service but neither of them had a sewing machine with a long enough arm to clear the rear frame of the top and sew the top of the window.

After the window is pinned or glued in place flip the top over using three chairs and a forth for you to sit on at the rear of the window.

I started sewing along the bottom edge of the window, the material is very thick and you have to push hard on the needle to get it to go through. Make sure you get large thimbles because the ones I got were a bit too small and they started to really hurt after a while.

You will poke yourself and curse for the first ten minutes but then you should start to get the hang of it.

It took me about two and a half hours to go all the way around.

Trim the extra window material from the inside of the window after you have finished sewing.

Seal the threads on the inside with black silicon, this also keeps the threads from unraveling. Also I ran a very thin bead of black silicon around the edge where the top meets the window on the top side. This keeps water from running down the window and collecting at the seam and then running into the car through the threads. It also makes the seam neater to the eye in case your stitches are not perfect.

Replace the top and the window should be a bit tight because it will relax and stretch a bit once it is on the car for a while.

I am rather pleased with being able to see out of my rear view mirror for less than fifty bucks.

Given my "druthers" I would replace the top but this is a good stop gap method and if you didn't know that I had done the job you will not notice the minor imperfections in the sewing because of the black thread.

So...a new top is better but this works just fine if you are patient and don't mind pricking your fingers a few times.

[Mike_Yi]

Thanks for the great write-up. I'm thinking about doing this, but it sounds like one of those jobs where it is such a hassle that it's worth paying somebody else to do it.

[Spinnaker]

You did a nice job to avoid the big buck cost of having to have the window replaced by a shop.
I have purchased items from Sailrite before for the boat and they are a good outfit to deal with.
Instead of using thimbles, you might have tried using what sailmakers use to push needles through thick material. It is called a sailmakers palm. Sailrite carries them also. It makes pushing the needle through hard to sew items a lot easier.
http://www.sailrite.com/Palm-Adjustable-Right-Hand
I know it is too late for you this time, but maybe someone else will see this and know what other options are available for them.

Now all of you know why I chose my user name.

[Jake D]

Awesome, thanks for the links. My window also cracked a few weeks ago and the top is in great shape. I may just have to go this route for the time being. Could you provide any pics to show how it turned out?

Has it rained since or have you sprayed it down with water to see if its sealed up?

Thanks

[Jake D]

Another question for you, what was your reasoning for using 40 guage vinyl? I'm looking for smoked or tinted vinyl since everything else on my car is black and I've always hated the clear back window with tinted sides. So far, I've only been able to find 30g tinted vinyl

http://www.allvinylfabrics.com/Clear-Vinyl/Smoke-Clear-Vinyl/30-Gauge-Smoke-Clear-Vinyl/276.aspx

[JoeFromPA]

So plain black silicone caulk is fine to use on the top material? Does it work to hold the fabric against itself?

This would be great, as the fabric on my top has come apart from a glued section where it meets the body in the back. If I can simply run a very thin line of caulk there, push the fabric into it or maybe weight it down while it dries....well, that'd be a much better solution than some of the glues I was weighing.

[nieuwhzn]

Great! Congratulations with your work and thanks for the writeup.
As our Boxsters are coming out of storage many need a new window. Replacing the whole top because of a cracked or ripped window is not only expensive but also kind of wasteful, with proper care the top can probably outlast the car.
I have to replace my window too and I'm planning to do it myself, so I have a couple of questions. My top seems to have had its window replaced by the previous owner already, but they did a particular bad job. The original window is stitched in between the canvas. In my top someone just cut out the original window, left the edge in between the canvas and stitched the new window to the inside of the canvas. Of course this really sucks because the sharp stitches are on the vinyl surface and will start cutting into the vinyl. I opened the top when it was pretty cold still (well above freezing, though) and the stress just pulled the stitches through the vinyl where the vinyl folds.
So, first question; did you stitch the window in between the canvas, just on top or did you put something over the vinyl to prevent the stitches from pulling through?
I know that your window is DOT approved, but 40 gauge sounds awfully thick. The usual stuff for campers, etc. is 16 gauge. Being this thick does your window fold easily?
What kind of stitch did you use? I think that for jobs like this a saddle stitch is appropriate. It works with 2 needles at a time and you use an awl to pre-poke the holes. The advantage of the saddle stitch is that the window is kept in place by 2 threads, so even when 1 thread breaks the other will keep the window in place.

Oh, dear this starts sounding like a quilting forum....

Forgot; where did you get your thread?

[nieuwhzn]

Originally Posted by JoeFromPA

So plain black silicone caulk is fine to use on the top material? Does it work to hold the fabric against itself?

Nope, caulk has no mechanical strength whatsoever. It only keeps things together if there is enough surface.

I don't think I would use black silicone caulk on canvas. It can become kind of messy and, in the end, I don't think it will adhere enough. People have been waterproofing canvas for a couple of hundred of years now and there are better ways to do this. In the army we used some kind of a green paste to waterproof our bags, etc. There must be something similar around for canvas. Maybe one of the sailors here can comment?

[JoeFromPA]

I've found it to have good strength in fixed applications, but yeah, thinking it through more I can see it tearing quickly after repeated lowering and opening making the canvas move and stretch.

Just need something to glue them together and be somewhat water proof/repellant. The canvas will overlap itself where the glue is, so it shouldn't be visible and it should shed water naturally.

[landrovered]

I'll see if I can answer a few questions...

1. 40 gauge is thick and since it was the only thickness with the DOT approval I went with it but I think that 30 gauge would be perfectly fine. I did see the tinted 30 gauge and was tempted but went with clear Kal Glas in the end.

2. The black silicon is meant to waterproof only and does stick to the edge of the canvas and the window material although the window is really slick and even the hot glue can be peeled off of the kal glas with a little work. I don't think you could glue canvas top material together with it, especially if it was under tension.

3. I cut the old window out of the top and cleaned everything completely before starting again. Since the material is 40 mil, I did not use a vinyl backing pad but for 30 mil I would recommend it so that the thread does not cut through the window material. I think that a black backing material would look better than none on the inside.

4. I Sprayed it with the hose to check for leaks. I did go back and hit a few minor spots with silicon and it is all good. Also it is a lot quieter while driving now.

5. I started to do a lock stitch (saddle stitch) and had a machine type needle (with the hole at the sharp end) but ditched that in favor of a simple stitch with a traditional needle and a knot at the end of the thread. It worked just fine and I went back into the old holes as much as possible. Thread came from Walmart.

I should have documented the process but honestly I was not really sure how well it would turn out so I did not take any photos. I will try to snap some after pics for you guys.

Scott

[stateofidleness]

clear gasket maker here!

talk about cheap... but it's been working a treat (bout 6 months now). just applied a small amount around the seam of by the crack (about 2 inches) and "smoothed" with my index finger. It's hardly noticeable (to non P-car owners lol) and it's been leak-free since application. It did well through the ice and nasty weather as well.

just another cheaper option for the even cheaper than cheap

[Spinnaker]

Originally Posted by nieuwhzn

People have been waterproofing canvas for a couple of hundred of years now and there are better ways to do this. In the army we used some kind of a green paste to waterproof our bags, etc. There must be something similar around for canvas. Maybe one of the sailors here can comment?

According to the local boating store, this is the stuff to use on seams.
http://www.amazon.com/Gear-Aid-Seam-Grip-Sealer/dp/B003TP2NT4/ref=sr_1_3?ie=UTF8&s=sporting-goods&qid=1300739198&sr=8-3
Haven't tried it, so if anyone has some experience with it, let us know.

[nieuwhzn]

Originally Posted by Spinnaker

According to the local boating store, this is the stuff to use on seams.
http://www.amazon.com/Gear-Aid-Seam-Grip-Sealer/dp/B003TP2NT4/ref=sr_1_3?ie=UTF8&s=sporting-goods&qid=1300739198&sr=8-3
Haven't tried it, so if anyone has some experience with it, let us know.

Looks good, thanks!
I only wonder how difficult it will be to remove if again another window needs to be put in?
This stuff seems also to be a good adhesive, what about using it to glue the new window to the canvas first and let it cure before starting to stitch? From what I read the main problem with stitching in a new window is to get a nice taut window without wrinkles. Hm, maybe that's less of an issue with 40 gauge vinyl.

[landrovered]

That is what I did with the glue gun, used it to hold the window in for stitching, a more flexible adhesive would be better than hot glue.

The secret to getting the window taught is not having it all the way open (stretched) when you lay it out and sew it. Have the canvas a little bit loose and then when it is mounted it will be nice and tight.

The 40 gauge material loosened up a surprising amount. If your stitch quality is good then you will want it a bit hard to close because it will relax over time. I know with Land Rovers, you have to use a hair dryer on the top to close it the first time.

[landrovered]

I snapped a finished photo for you guys to see.

I would not claim that is is perfect but it is certainly better than a cracked yellow window that the rain goes right through.

Cheers!

[nieuwhzn]

Looks great to me, congrats with your work!
Waiting for the weather here to get a bit better before attempting this myself, low temperatures and rain/snow/sleet every other couple of days. I don't care about cracking my window any further anymore, lower the top anyway, heater on full blast and enjoying the ride.

Btw, did your cat already figure out that the canvas top is a nice scratching post?

[landrovered]

We have four cats and they LOVE the soft tops on my wifes and my Boxsters. I bought a $20 car cover from Walmart that does an amazing job of keeping the cat hair off of the top. They don't seem to sharpen their claws as much with it on there. I guess because it is loose.

[Bala]

Old topic but have a question. What do you for canvas on canvas glueing? I'm planning to bring my old top back to life.

[landrovered]

I used a hot glue gun (not recommended, will melt in summer) to hold and then stitched over top. Check with an Upholstry company, I bet they could recommend something better.

[Eric G]

Big props to you sir, you may see more flaws the the rest of us...but I see a well done DIY project. It would be nice to see a few more pics of what you have done.