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Glass separating from the rear hatch

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Old 07-23-2004, 11:29 AM
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Stan944
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Question Glass separating from the rear hatch

The glass in my hatch started separating, and it rattles while driving.
I want to remount it (although I have some doubts about doing this job myself).
I did a search, and foud lots of good info, but have some questions:

1) This job has to wait a week or two. Is there a danger of complete glass separation, i.e. can I actually loose the glass on the highway?
2) There are many screws mounting the the rear (rubber) spoiler, locking bolts, the side trim, etc. Many of them are coroded, and I may break them while I try removing them. I don't know how to state the question, but will it be a major pane if I break a screw?
3) It's recommended to use 3M Window Weld Urethane Auto Glass Sealer. I can't find this product here. I found 'Urethane window seal/adhesive' made by Diamond Seal (OEM approved). My guess it's probably almost the same product. What do you think?
4) One write-up says to also use 3M Super Fast Urethane Primer. Is it really needed? Again, I can't find it here.

Any other tips?

Last edited by Stan944; 07-23-2004 at 02:17 PM.
Old 07-23-2004, 12:05 PM
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Peckster
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That product must be available here, but you won't find it at Canadian Tire. I'd ask 3M or an autoglass shop. I'd also use the correct prep, you don't want to have to redo the job.

I used silicon seal and it's worked well, but my glass was just starting to separate.

There are ways of dealing with broken screws if it happens.
Old 07-23-2004, 12:18 PM
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BeerBurner
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Pelican Parts has a proceedure for doing this that seems rather simple and inexpensive. I'll be trying it out in a few weeks myself.

Of course, I can't help but get the feeling that it probably won't be a permanent solution. But hey, I'll give it a shot anyway and hopefully I'll get lucky.

BB.
Old 07-23-2004, 12:20 PM
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ibkevin
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Stan,
My hatch is head'n down that road too and I'll start some searches myself. I've read that it is IMPERATIVE to keep those fastener holes aligned throughout the assembly and set up time. Use something like cocktail swizzle sticks!
Guys have broken the surface tension of the glass by filing the holes and the glass has imploded!!
Old 07-23-2004, 02:31 PM
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Stan944
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Thanks,
When I glue the glass to the frame, should I press it hard, or there should be a lot of glue/seal in between? There is about 1 mm thick layer of old glue now.
Old 07-23-2004, 02:49 PM
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AndyK
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Question: If I have no leaks, but am hearing a rattle...does it mean my glass is separating?

I'd love to find a reasonably priced 968 rear hatch w/wing and end this rattle!
Old 07-23-2004, 03:45 PM
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Chris_924s
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Andy- the rattle may be coming from a myriad of places. Have someone drive for you with you in the back seat / hatch area and see if you can pinpoint the source of the rattle. It may just ba a loose piece of hardware and NOT the hatch (My microswitch in the hatch rattles due to some plastic fatigue- this is the only way I found that one!) You can usually see hatch separation.

I know the windshield glass is sealed with Sika-Flex from the US factories (GM specifically)- it is difficult to work with, messy and requires activation and compression to seal properly. I have no idea what Porsche originally used but it looks the same.


Hope this helps.
Old 07-23-2004, 03:48 PM
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johne
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Andy,
It could just be that you need to adjust your hatch springs. They are located under your spoiler. It is easy; you just use a flat head screwdriver and a wrench and extend or shorten the spring. If your hatch is rattling you probably need to extend the spring. Just extend the spring enough to stop the rattling though. Because if you do it too much then your hatch will not fully close and will pop open when you are driving down a bumpy road. Not really dangerous but it can be quite surprising.

Regards,
John
Old 07-23-2004, 03:58 PM
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Mongo
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i gotta check that procedure out. I"m going nuts with mine. The glass is overlapping the metal trim on the passenger side top of my hatch which is really scary. Your glass won't come flying off your car don't worry. I've only seen 1 absolutey horrible incident involving that and that was with a 77 911S targa at an autcross where the glass just launched off the car in a corner and exploded when it hit the ground

Andy
Old 07-23-2004, 04:13 PM
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dave120
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Andy: My hatch rattles too sometimes. Already adjusted the hatch pins, that didn't solve the problem. Look at the top of the glass near the roof and see if its separating there. Mine doesn't leak yet but it makes enough noise to be annoying sometimes so I'm going to get it re-sealed soon. We had a place do it on my brother's car a few months back though and it's already coming apart again, and his actually leaks now. Makes me not really want to get mine done by the same people...
Old 07-23-2004, 04:30 PM
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AndyK
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I had Tom R back there a few weeks back. We didn't pinpoint the rattle. Now it's worse...and it doesn't sound like glass. It sounds like it should be the spare tire, or, the compressor, floating around in the spare tire well. Only, it's NOT those things.

Ahhhh!
Old 07-23-2004, 05:27 PM
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Andy-is your rattle kind of a loud metallic clacking sound? Mine does it at the weirdest times...sometimes on relatively smooth roads and sometimes never on rough roads. It sounds like mine is coming from a metal part or something hitting the body somewhere and can be very loud. I have no spare, pump, jack, or anything in the storage wells. I've adjusted the hatch pins at least 5 times now with no change. I'm starting to think it might be in the hatch release servo or rear wiper motor. It drives me nuts I've got to find it soon. It's intermittent on mine which makes it even more annoying. I don't think mine is from a glass separation problem either. I hope someone comes up with a solution for an all too common problem with these cars.
Old 07-23-2004, 05:30 PM
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AndyK
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2Tight--yeah, I think we have the same problem!
Mine does that...sometimes on smooth roads, sometimes not. It sounds like when someone jumps off a diving board...and you hear the board rattling...you know?? VERY frustrating!
Old 07-23-2004, 05:31 PM
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Check to see if the hatch release motor is loose and rattling- just a thought. Things may look tight but when the RPM's reach a certain level a harmonic is established things rattle.

Is this rattle at a specific RPM level?

OK, I'm thinking outside the box again..
Old 07-23-2004, 05:47 PM
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KuHL 951
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Originally Posted by AndyK
2Tight--yeah, I think we have the same problem!
Mine does that...sometimes on smooth roads, sometimes not. It sounds like when someone jumps off a diving board...and you hear the board rattling...you know?? VERY frustrating!
Good description Andy...what worries me is you can almost feel it through the car. It sounds almost like the pitch of a very dry hydraulic lifter...clack-clack very metallic and sharp. It is positively from inside the cabin, not under the car. Stopping and reclosing the lid doesn't seem to have any effect, it just goes away for awhile. I'll check all the mounts again and maybe pull the cover off the hatch release motor.

Chris-it doesn't seem to be rpm related or a resonant frequency thing at all. Once it starts it's there for awhile and then something will shift and it will stop sometimes for the rest of the day. Amazing thing is with hard driving on poor roads it never seems to be a problem...still haven't found what conditions triggers it but OMG it's so loud at times.


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