1997 986 - DIY GLASS HOOD UPGRADE - USING OTHER MAKE GLASS WINDOW?

[tonyplymouth]

I have a spare hood for my 1997 986, in excellent condition except for the plastic rear window.  I'm considering up-grading it with a glass rear window as a DIY winter project.  I have a heavy duty sail-making sewing machine and learned a lot successfully sewing a new plastic screen in the working hood on the car.

My idea is to try and find another make of convertible car, with a glass rear window that is slightly smaller and of approximately the same general shape and curvature as the Porsche plastic window, perhaps Golf, Audi, Mazda, Jaguar etc.  These windows and hoods seem to be available used for a fraction of the price of a Porsche unit (of course!).   Then sew this window into the Porsche hood with probably some form of transition "frame" made from soft top material. 

Has anyone tried this route before?  What window was used and how successful was the project?

Meanwhile I carry a tape measure and I'm measuring the hood rear window of every convertible car I see parked up.  Haven't been arrested yet!

Thanks in anticipation of advice and comments.

[the baron]

It won’t work I don’t think, the plastic window is much larger than the glass window replacement, I doubt it will retract

[K.I.T.T.]

You also won't be able to put your roof in service position with a glass window slightly smaller than the plastic rear screen. There's a reason the 986.2 and aftermarket 986.1 roofs have a significantly smaller rear screen.

Edited November 15, 2021 by K.I.T.T.

[Boxob]

Agree the comments as above by @the baronand @K.I.T.T.. If you can find sheet TPU (as used on the BMW Z8) that can be sewn in. The benefit is its flexible in any temperatures you're going to get in the UK, it doesn't crease or mark (so no Boxster chop required) and it's optically as good a glass. It's the Holy Grail but just a hard to find. It's available in huge rolls at a huge price but I've not been able to locate it in rear window size! Whilst looking I did find half a dozen unicorns rolling around in rocking horse sh!te though.

Edited November 15, 2021 by Boxob

[½cwt]

The plastic/vinyl screen in the original 986 hood has to fold to allow the hood to open and retract.  Also you'd not be able to get into the top of the engine bay with such a large piece of glass in place.  I have had a new replacement vinyl sewn into mine (about £250-300) which makes it as clear as possible but it still folds and does show a crease line, otherwise an 2003 onwards (£800 upwards and second hand) replacement hood will get you as big a bit of glass as possible with a heated rear window and a different roof profile to accommodate an extra hoop to allow it to fold correctly, or an after market hood (£800 upwards) with a much narrower piece of glass, which many who have one say makes little difference it visibility even if it affects the design/look of the hood.

[Menoporsche]

3 hours ago, Boxob said:

Whilst looking I did find half a dozen unicorns rolling around in rocking horse sh!te though.

  Ah I remember those TPU hunts on BoXa...

[SuperPaulie]

This wouldn't work as it would obviously not be able to fold. That's the reason the glass replacements are smaller, so they don't have to. They actually look smart with the smaller window in my opinion, but only the BAS roof. At the risk of being unpopular with the sponsors, the CarHood window isn't positioned right in my eyes, looks weird.

BAS

Car Hood

 

 

[tonyplymouth]

Thank you the baron, KITT, Boxob, 1/2cwt, Menoporsche and SuperPaulie for those helpful comments.  All much appreciated.

I have been experimenting with different sizes of dummy rigid rear windows made of hardboard, temporarily fixed to my spare roof.  As you all predicted, a rigid window about the size of the original plastic window prevents the hood from folding down properly and explains why Porsche had to resort to a smaller window and an extra bow in the frame for later 986s.  

The plastic window is about 420mm high however I've found that a smaller rigid window about 310mm will work; this allows the hood to fold down well enough and also to be set adequately in the service position.  The main snag though is that a rigid window of this size can't be secured symmetrically in the aperture left by removing the plastic window; the bottom edge of the rigid window has to be fixed along the bottom edge of the aperture to permit folding to work.  Accordingly it will look rather odd unless I can devise some sort of surrounding "frame" which restores symmetry with the lines of the hood.  Besides I haven't actually found a used window as small as 310mm yet.  Therefore for the moment I'm putting this idea on the back burner.

As an alternative I'm thinking along the lines of fitting an inexpensive used glass window in my spare hood and using it as "winter hardtop", accepting that it can't be folded but will give me superior visibility astern in winter driving conditions.  My experiments suggest that a "winter hardtop" along these lines does allow partial folding and sufficient "service" room to access the 3 hood securing bolts each side.  Also as part of these experiments, I have found that I can remove and fit my hood in about 10 minutes now, with the help of a second person for the lift-out and lift-in operations.  How much I would actually use this "winter hardtop" is debatable though as one of the joys of a Boxster of course is to drive hood-down on crisp sunny winter days, but I like experimenting with the car ......

Thank you Boxob for suggesting TPU sheet.  In fact I used ordinary UV stabilised clear PVC material, as used in yacht spray hoods, for my working hood.  This is 0.7mm thickness, compared to 1.2mm thickness of the original Porsche window.  This made the window fairly easy to sew and more flexible when applying the "boxster chop"; in fact the chop is hardly necessary because of the extra flexibility.  The optical quality is pretty good too, certainly much better than the old original window but probably not as good as TPU and other modern materials.  As for durability, I have found that this material lasts for well over 5 years on my yacht, exposed 24/365 to the elements.  Whether it is worth fitting a plastic window on a DIY basis is debatable when many organisations can fit new plastic windows for around £200-300 but as I have said I like experimenting and DIY .......

[Menoporsche]

21 minutes ago, tonyplymouth said:

In fact I used ordinary UV stabilised clear PVC material, as used in yacht spray hoods, for my working hood.  This is 0.7mm thickness, compared to 1.2mm thickness of the original Porsche window.

I think finding a better material than OEM is really important here. As above, TPU seems so rare, but there must be other solutions as you demonstrate.

[Daboy3000]

I have this one.  Don't know who make it.  Looks great but I can't get to the engine!!

[edc]

Looking at the seal around the edge it looks like the BAS one. The Carhood supplied one seems to be recessed. 

[the baron]

21 hours ago, Daboy3000 said:

I have this one.  Don't know who make it.  Looks great but I can't get to the engine!!

You should be able to get to the engine, you just need to wiggle the screen up onto the roll bar loops and prop it up with a stick, it’s not as good as the original access but is workable, I have taken the Throttle bodies off so access is certainly there

[Daboy3000]

2 hours ago, the baron said:

You should be able to get to the engine, you just need to wiggle the screen up onto the roll bar loops and prop it up with a stick, it’s not as good as the original access but is workable, I have taken the Throttle bodies off so access is certainly there

I did give that a go, but didn't want to force anything, I'll give it another try.  Thanks

[SuperPaulie]

No matter what I tried I couldn't get my BAS screen over the hoops. Didn't bother in the end, just propped it up from the rear of the car with the wife's yoga mat and still had pretty good (cr*p) access to get to everything.

As a side note, the CarHood roof with the window recessed slightly, doesn't that thing just collect and hold water?