Carpokes Porsche Forum

I have a question. The rear vinyl window on my '99 986 is developing a couple hair-line cracks. I'm wondering if anyone else has, or has had, this issue on an older convertible top, and if they have found a suitable remedy/product to keep such cracks from expanding?

Thanks
Bob Priddy

@rfpriddy

Hi Bob,

I'm going to relocate your post and question to the '986, 987, 981 Boxsters & Caymans' sub-forum where more Boxster owners might see it. I'll leave a shadow copy that will remain for a few days here where you originally posted, so it'll be in two places.

By the way, welcome to Carpokes! Join in the conversations if you wish - lots of good people here.

Hey Bob,

I have no idea whether or not there is any specific product available that will fix or stop cracks from expanding on a vinyl window. Plastics break down and get brittle over time, especially when outside in weather. Cracking is plastic's middle name I think, especially when it gets old after going through many years of extrmeme temp and weather changes. I would guess that the cracking will only get worse

Putting some kind of silicone glue might work to slow down the growing cracks but no idea if it will actually do that nor for how long, assuming it even adheres decently (doubtful). Plus, glue will make it impossible to see through wherever it's applied and will look bad. The wrong glue could damage the plastic even more.

Using some heavy duty clear 2" wide packing tape similar to what I linked below might be your best bet. I've used this stuff seemingly forever for shipping and for fixes for which the tape was not intended and it often works just fine. At the least, it's a good temp fix for misc needs that will not leave residue when removed.

https://www.amazon.com/Scotch-Shipping- ... 4191&psc=1

Tim, Thanks for the info. These are hairline cracks, caught early, and are no more than 3-4 mm long, and in the typical Boxstger fold location, I have previously used Performix VLP Vinyl/Leather repair.... Works pretty well. However, not perfect, per se. So I was wondering if anyone else had tried a different/better product. There is a tape advertised online that is specifically for vinyl repair, and has received a thumbs up from a Boxster owner. However, tape tends to eventually cure and peel. After a few "asks" on this topic, I believe I will stick with the Performix VLP product, and to that point, I would recommend it to others as I have not received a reply from any Porsche forum that offers a better solution. Many thanks for your input. Kind regards, Bob

rfpriddy wrote: Fri Aug 11, 2023 8:39 am Tim, Thanks for the info. These are hairline cracks, caught early, and are no more than 3-4 mm long, and in the typical Boxstger fold location, I have previously used Performix VLP Vinyl/Leather repair.... Works pretty well. However, not perfect, per se. So I was wondering if anyone else had tried a different/better product. There is a tape advertised online that is specifically for vinyl repair, and has received a thumbs up from a Boxster owner. However, tape tends to eventually cure and peel. After a few "asks" on this topic, I believe I will stick with the Performix VLP product, and to that point, I would recommend it to others as I have not received a reply from any Porsche forum that offers a better solution. Many thanks for your input. Kind regards, Bob

Excellent feedback Bob. I kind of figured there might not be a lot of fixes available and as one who knows nothing about vinyl repair for rear windows in convertibles (or vinyl repair anywhere for that matter), I wanted to get you some kind of feedback even if it was of the shade-tree mechanic variety. And yes, in my mind's eye I was picturing much larger cracks - I envisioned yellowing, brittle vinyl with big cracks - it was a mental conjuring!

Since you mentioned that it is a not uncommon problem for Boxsters, maybe this thread and your response will help others who are unaware of the Performix product, so thanks for that.

The original rear window in my '01Boxster developed a half inch crack after about 15 years. I used Tear-Aid type B (for vinyl), cut out a little piece, and it held up for many years. I finally had a local interior shop used by my Porsche dealer replace the rear window.

The rule of thumb is vinyl rear windows on a Boxster will last about 10 years, anything more than that and you're doing good. The best way to prevent cracks is to stop and chop the fold when the top is half open before opening all the way, so the vinyl rear window folds smoothly

geoff wrote: Fri Sep 15, 2023 8:06 am The original rear window in my '01Boxster developed a half inch crack after about 15 years. I used Tear-Aid type B (for vinyl), cut out a little piece, and it held up for many years. I finally had a local interior shop used by my Porsche dealer replace the rear window.

The rule of thumb is vinyl rear windows on a Boxster will last about 10 years, anything more than that and you're doing good. The best way to prevent cracks is to stop and chop the fold when the top is half open before opening all the way, so the vinyl rear window folds smoothly

Thanks for posting and sharing that info! And welcome to Carpokes!

Tim - '22 992 Turbo S - Carmine Red
Actually, my 1999 986 has its original window. The cracks are hairline at the corner fold areas. And, it has not yellowed. I do follow commons sense vinyl window rules, never open below 40 degrees, do the "Boxster Chop" to insure ease of the fold and use Plexus vinyl conditioner. As noted above, I have found the VLP product a solid resource as neither crack has advanced... one for more than five years and the other is recent. Also, there is a shop near me that will replace the vinyl for about $700... Thanks for your comments and support, Bob

Where are you located? The plastic window in my 2001 Boxster has aged so badly that I can't see through it. Found an interior shop that would replace it for $1500. That is a lot of money for an old top.

I’m in the denver metro. I have a place that says they will put in a new window for about $800