Lighter weight 'convertible' targa top

[X1/9Cruiser]

My winter project for the X this year was a lot easier and less expensive than some of my other projects from years past. Tired of lugging and stowing my 25 lb. insulated targa top, I bought a spare top on eBay along with some convertible top material and trunk liner material. Tools I used were an angle grinder, hacksaw, sanding block and file, 3M Spray adhesive, clothes pins and some epoxy type glue. The finished convertible targa top weighs 14 pounds and is a whole lot easier for me to stow.

The pic above shows the amount of fiberglass I cut out of the top. I used an angle grinder to make the long cuts and it made short work of cutting the fiberglass. The convertible top material is already glued and tucked in to the sides, front and back. I used clothes pins to hold the top material in place until it set up.

In this pic, the trunk liner material has been glued to the inside of the top.

Here's a pic of the top mounted on the car. Total cost for the project was around $250. including the top and it took me about 10 days of working in the evenings for an hour or two. Most of that time was waiting for the glue to set up. All in all I'm very happy with the results and I think it was money well spent.

 

[JimD]

It looks really nice in the picture. Well done. Your next one will only take 5 hours, then the next maybe 2 hours. You will be in full scale production soon.

I posted the weights of some of the various tops I had on hand long ago to the original N54 forum, so I will add them here for reference.

Saratoga top = 16lbs
78 Stock top - no headliner = 20lbs
86 stock top - with headliner = 25lbs

 

[kmead]

Winter project, does that mean you have yet to go down the road with it?

If you have been out and about, how is the sound level?

Very cool, it looks great. More pics are always appreciated.

 

[lookforjoe]

Looks great! Got any daytime pics where we can see the outer form?

Also, any links for the materials you chose? I'm ready to lose 10lbs

 

[Dr.Jeff]

I like it, well done.

 

[X1/9Cruiser]

Looks great! Got any daytime pics where we can see the outer form?

Also, any links for the materials you chose? I'm ready to lose 10lbs

Joe, here's a photo of the top off the car. Unfortunately, time and the weather aren't cooperating for much more than a spin around the block. The car isn't as quiet with this top as with the insulated one but the insulated one sometimes seems to trap noise in the car as well. I didn't notice
any unusual wind noises or anything like that. As for material, this is what I used but being convertible top material, there's a huge selection
of materials and colors to choose from:
https://www.ebay.com/itm/STAYFAST-C...e=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
And the trunk liner here:
https://www.ebay.com/itm/Black-Char...var=521370938974&_trksid=p2060353.m2749.l2649

Here's another photo as well with the top off the car. The chrome you see is just where the paint wore off the chrome and my finger prints are visible too, gotta wash the top at some point. I'm painting some of the exposed fiberglass now and need to repaint the chrome areas as well.

What I did was to wet sand down the top smooth with 80 grit, then masked off the areas to cut, did the cutting (outside), cleaned the dust off with a garden hose and then started gluing the top material using the spray adhesive. I glued the first 10 inches or so of the driver's side and let it dry overnight. Then I sprayed the passenger side the same way and stretched the material over and let it dry. I then did the front, then the back. Then I trimmed the material and began tucking it in, one side at a time. Then I glued the middle part of the top (the arches). Lastly I did the trunk liner material. All in all a relatively simple job that the average DIYer can easily do.

 

[lookforjoe]

Thanks for the process detail - I was curious as to the best practice for gluing & tucking the outer skin to the inside. I presume you stretched it under where the seals, etc., screw in place for added rigidity?

I've done many a Volvo wagon headliner in the past, but with those you basically spray, stretch, adhere & repeat, working pretty steadily from one end to the other, from the center outward.

 

[Dr.Jeff]

For a 'summer' top, I'd be tempted to just cover the outside with the cloth material and not add the inside lining. Not sure how much lighter that would make it compared to having the inside lining, nor how much difference it would make with noise. Perhaps an even better option for a 'summer' top might be to cover the outside with a mesh fabric, like the shade covers for picnic umbrellas, also with no lining. That would allow air flow for added cooling but still block the direct sunlight giving shade. Might be cooler overall than no top or an insulated one.
Something else we've talked about is making a foldable or collapsible or rollup top of some kind.
Excellent project, thanks again for sharing.

 

[X1/9Cruiser]

A couple of thoughts....the inner liner fabric (trunk liner) weighs almost nothing at all. You can almost see through the stuff but it does give the finished look I wanted. I did want a top that was water tight in case I got caught out in the rain but its real purpose is more a sun screen than anything else. As for the best process for gluing, stretching, etc. there might be a better method to doing this...I'm certainly no expert but I think the results I got are good-the fabric is taut. And yes, I took off the side hardware (rain channel bits) before I even started the project and tucked the convertible top fabric up underneath where they attach but only after the convertible top fabric was fully glued to the top surfaces.

 

[Dr.Jeff]

the inner liner fabric (trunk liner) weighs almost nothing at all

Good to know. I was thinking of the heavier rubberized lining with a backing. Looking at your link for it, I now see it is a light product. And it certainly looks nicer with the lining.

Thanks for all the details. Your result looks fantastic. I imagined getting the outside fabric tight and smooth would be difficult, but you certainly mastered it.

One question; you said "Then I glued the middle part of the top (the arches)". How did you do that after the fabric had been stretched over and glued around the sides?

 

[lookforjoe]

Joe, here's a photo of the top off the car. Unfortunately, time and the weather aren't cooperating for much more than a spin around the block. The car isn't as quiet with this top as with the insulated one but the insulated one sometimes seems to trap noise in the car as well. I didn't notice
any unusual wind noises or anything like that. As for material, this is what I used but being convertible top material, there's a huge selection
of materials and colors to choose from:

Another question - is the canvas lined/backed? If I'm reading the description properly it suggests it is. If that is the case, how did you bond it without having issues with the backing material? I see other places that list waterproof canvas for significantly less money, that definitely has no liner.

Was one yard sufficient (can't measure mine at the mo)?

 

[Dr.Jeff]

Its been too many years to recall the details, but the last time I shopped for convertible top fabrics there were a huge range of choices. Traditionally "German" top fabrics were considered the gold standard, with a price to match. But I'm sure that has changed along with everything else in today's global market. I imagine if this type of top was a secondary one with limited use (normally kept in storage), the quality or fabric's durability might not be as critical as for say a true convertible (where it is always on the car) or your primary/only top.

Sorry if this is a bit off topic, but along the thoughts of a "shade" top for summer use. The woven mesh fabrics I was referring to is along the lines of the samples pictured below. Jeeps have something like this available from the aftermarket, I think they are called 'sunbrella tops'? Naturally this wouldn't be your only top, but an alternative for driving in certain times of year / weather conditions (depending on where you live). For me, in this scorching desert, it might be more of a winter top. But it allows for air flow and shade from direct sun/UV. The mounting would be the same as "Cruiser's" excellent job above (but without a liner).

 

[X1/9Cruiser]

Good to know. I was thinking of the heavier rubberized lining with a backing. Looking at your link for it, I now see it is a light product. And it certainly looks nicer with the lining.

Thanks for all the details. Your result looks fantastic. I imagined getting the outside fabric tight and smooth would be difficult, but you certainly mastered it.

One question; you said "Then I glued the middle part of the top (the arches)". How did you do that after the fabric had been stretched over and glued around the sides?

I forgot to mention how I 'glued' the arches. I used my caulking gun with black silicone caulk and ran a bead across the arch and then smoothed it
out with a roller and my hands. That was after everything else was glued down. There's enough play to make it work. Should be more than strong enough. Since there is little rain in your corner of the world, a mesh fabric might work well for you, but it would be a little trickier to keep it from moving around since you can't really glue it down from the top.

As for the convertible top fabric, its virtually identical on both sides and I'm not sure what the seller meant by it being lined. No issues gluing it. I think a piece 3 x 4 feet would be all you need to do the job though having a little extra material makes it a little easier to pull tight when you're gluing it down.

And Jim, no interest in building another one but they are simple enough to make and don't cost a ton of money

 

[lookforjoe]

I ordered a tan version canvas. I like that combo with a red car. Thanks again for the thread. Gives me something to address when it's too cold to do any work in the garage or outside.

 

[lookforjoe]

What I did was to wet sand down the top smooth with 80 grit, then masked off the areas to cut, did the cutting (outside), cleaned the dust off with a garden hose and then started gluing the top material using the spray adhesive. I glued the first 10 inches or so of the driver's side and let it dry overnight. Then I sprayed the passenger side the same way and stretched the material over and let it dry. I then did the front, then the back. Then I trimmed the material and began tucking it in, one side at a time. Then I glued the middle part of the top (the arches). Lastly I did the trunk liner material. All in all a relatively simple job that the average DIYer can easily do.

Another question if you don't mind - did you note the width of the roof you left for structural support? I can eyeball off your pics, easier (for me) if you know what the width was you left

 

[Dr.Jeff]

I also was kind of wondering how you decided how much to cut out of the fiberglass structure? Just for general reference.

 

[X1/9Cruiser]

I also was kind of wondering how you decided how much to cut out of the fiberglass structure? Just for general reference.

Dr. Jeff, I cut as much as I dared cut out in order to make the conversion worthwhile. Did I cut too much? Only time will tell. I did have a chance to drive the car briefly yesterday and no issues and top worked great. To answer Joe's question, measuring from the side edges I have approximately 4 3/8 inches of 'side' fiberglass until the cut begins. The cut at the back of the targa is approx. 5 1/8 inch. That's about all you can cut in that area. If you are unsure, or want to be safe, I'd say allow 5 inches of material or so. Of course, that will come with a slight added weight penalty. I also forgot to mention, if you look at the thin rib in the photo of the underside of the top, it's actually reinforced with a thin strip of fiberglass I cut from the adjacent panel. That basically doubles it up and adds strength to keep it from bowing inwards too easily. Hopefully that makes sense!

If either of you guys do this conversion, post some pics of your progress. Hopefully you'll be able to figure out some improvements to the process!

 

[kmead]

This is a great project and very nicely done.

Would it be possible to upload a larger (higher resolution) of this image:



The other images are quite a bit larger, this one tells a lot of the story.

Thumbs up!

 

[X1/9Cruiser]

Karl, unfortunately when I uploaded the images to my computer I deleted them from the camera and then to top things
off I resized the image in paint because it was huge. You can see what I call the 'rib' running top to bottom in the middle
of the pic. That's where I epoxied another strip of fiberglass over top of it to basically double its thickness and strengthen it.
As for how much material to cut out or not cut out that's a judgment call. The fiberglass is pretty strong and the metal
strips that are screwed down on the sides add to the strength. Let me know if there's anything else I can clarify.

 

[X1/9Cruiser]

Here's an edited image I did in paint.net. This is about the best I can do...