What's the current approach to rear glass delamination?
12-27-2013, 10:14 AM
#1
Rennlist Member
Thread Starter
What's the current approach to rear glass delamination?
My coupe's rear glass is perhaps 60% delaminated from the top edge: the rest seems good. Of course it will only get worse. What is the best approach to repairing this problem these days?
12-27-2013, 11:46 AM
#3
Burning Brakes
subscribed...I have two hatches both are starting to separate and make noise..I talked to the local porsche factory body shop and they were only interested in adding sealant around the edge. This is something I am not comfortable trying on my own and it seems there are no shops willing to take it on
12-27-2013, 12:52 PM
#4
First off...there is much shade under my tree. Novice...never done this before (working with hatch) I just cant afford to pay anyone to do it so I leap with not much to lose.
So much for the disclaimer.
I cut mine out and used 3M Window Weld. A very long story short I will spare you...these are just some thoughts as I have to do this again in the next few weeks....
- Looking back I would have added window weld to the existing sealant around the edges if and only if the frame of the window was not bent in ANY WAY
In my case the PO had slightly bent the passenger side of the frame around the hinge.
- In this case I would cut it out ON THE CAR ( I did not ).
On the car locked in place would have helped me the first time; but I did it on a table instead. Once the glass was set in the frame deformed just from the weight so back on the car when closed there were stresses at different points when closed.
Also, I did not realize I had one shot at dropping the glass on the frame, if slightly off in anyway (which mine was) it was not going to be 'adjustable' not in the very least.
Took a month of sitting in the garage to start pulling apart. So much for attempt #1
For attempt #2...I will mask off the car in the rear and do it on the car with glass holders from ace hardware. Setting the glass down on the locked frame so as not too create any stress points where it will pull apart. BUT it is a messy job so masking is a must. I will take pics.
Have pics of the first attempt that look so good you would have thought it would have worked, but on the car locked was a different story.
So much for the disclaimer.
I cut mine out and used 3M Window Weld. A very long story short I will spare you...these are just some thoughts as I have to do this again in the next few weeks....
- Looking back I would have added window weld to the existing sealant around the edges if and only if the frame of the window was not bent in ANY WAY
In my case the PO had slightly bent the passenger side of the frame around the hinge.
- In this case I would cut it out ON THE CAR ( I did not ).
On the car locked in place would have helped me the first time; but I did it on a table instead. Once the glass was set in the frame deformed just from the weight so back on the car when closed there were stresses at different points when closed.
Also, I did not realize I had one shot at dropping the glass on the frame, if slightly off in anyway (which mine was) it was not going to be 'adjustable' not in the very least.
Took a month of sitting in the garage to start pulling apart. So much for attempt #1
For attempt #2...I will mask off the car in the rear and do it on the car with glass holders from ace hardware. Setting the glass down on the locked frame so as not too create any stress points where it will pull apart. BUT it is a messy job so masking is a must. I will take pics.
Have pics of the first attempt that look so good you would have thought it would have worked, but on the car locked was a different story.
12-27-2013, 01:33 PM
#5
Guys, it isn't *that* hard to separate and reseal a hatch, just make sure you use the right products and take your time.
The main thing is DO NOT USE SILICON BASED PRODUCTS TO TRY AND PATCH IT. If you do that, it will fail in a short period of time and the glass doesn't seem to like to stick when you go back and use the right products.
The only products I will consider using for this job are the 3-M Window Weld products, which consists of 2 tubes of the adhesive (part # 08609), and one bottle each of 3M™ Single Step Primer (P/N 08681 or 08682 for prepping the frame and 3M™ Glass Cleaner, P/N 08888. Also, get a package for application swaps for the primer, it makes the job go MUCH easier. You may laugh at my suggesting that you use the 3M glass cleaner but if you bring a hatch to me and suggest I use anything else, I will refuse to do the work. You will most likely have to order the glass cleaner as most body shops carry a generic that they claim will work "just as good". Maybe other people have had better luck with other products, but I haven't. If you want to do this ONE time, get the right products. In addition, a generic adhesive cleaner, roll of 3" blue painters tape and a handful of latex rubber gloves are needed.
Cut the glass out, which is the hard part, but if you have a friend help and a lot of utility knife blades around (swap them out regularly) and work carefully, you can remove from the car, remove all the trim and separate a badly delam'd hatch in about two hours once you know what you are doing. First time I did it, it took me about two days but I was working by myself.
Don't remove all the adhesive from the frame if you can avoid it as it makes a great base for the new adhesive. Trim it down so its fairly smooth and them coat it with the single stage primer. If you have areas that are showing a lot of metal, I think its best to take a wire wheel to the frame and remove all teh old adhesive and then prep the frame with an epoxy aluminum primer, let it cure a couple of days and then use the primer. Don't bother using the primer on bare metal, it won't hold.
Once the frame is prepped, put it back on the car and position it so that its aligned properly. DO NOT ATTACH THE HATCH STRUTS YET!
Put on a pair of latex gloves at this point, and then clean the glass with the 3M glass cleaner and then use the primer to coat the outside 1" edge of the glass. Let it dry.
Trim off the tip of both tubes of the adhesive at an angle so that it has about a 1/2" opening, and then you and your friend each start applying the goo, I suggest both starting at the top center and work around until you meet at the bottom center of the frame. If you do it right, you will each have just a little left when you get done. Be generous in applying the stuff, and make sure you get only on the hatch. If you get some on the painted surface, have the adhesive cleaner ready to go so you can wipe it off before it sets up but you will have time to get the glass in place first so don't stop what you are doing to clean it up.
Once the adhesive has been applied to the frame, put on a new pair of latex gloves (you WILL get adhesive on your previous set of gloves) and then pick up the glass and place it directly on the frame. If you can get another helper, have someone lay inside the car and put their arms up so they catch the glass in the center and then slowly lower it into place while the folks outside the car guide it so that it "docks" into the frame rather than catching one edge and adjusting it. Once its in place, push it firmly down to make sure you have a good seal all the way around it, and make sure its positioned properly. You can slide it around to adjust as necessary but you shouldn't have to do too much of it. You can use a putty knife to smooth out any adhesive that bulges out and to fill in any gaps. Once this is done, take 3" blue painters tape and tape from the center of the hatch down to the body in various directions to hold it down. Let the car sit for at least 24 hours before moving it. Make sure the windows on the door are down before shutting the doors as that can create enough pressure to cause issues before the adhesive has cured if you close a door hard enough.
Once the adhesive has cured, installation, as they say, is the reverse of removal. If you need to do any clean up, a razor blade will take car of excess on the glass but the trim usually hides it well enough.
I have done a number of these reseal jobs and the only ones that failed were because these instructions were not followed.
By the way, if you need a temp repair, black duct tape at the top of the hatch is the single best method I have seen. It hold the glass in place, seals it so it minimizes leaks and doesn't look terribly obvious.
The main thing is DO NOT USE SILICON BASED PRODUCTS TO TRY AND PATCH IT. If you do that, it will fail in a short period of time and the glass doesn't seem to like to stick when you go back and use the right products.
The only products I will consider using for this job are the 3-M Window Weld products, which consists of 2 tubes of the adhesive (part # 08609), and one bottle each of 3M™ Single Step Primer (P/N 08681 or 08682 for prepping the frame and 3M™ Glass Cleaner, P/N 08888. Also, get a package for application swaps for the primer, it makes the job go MUCH easier. You may laugh at my suggesting that you use the 3M glass cleaner but if you bring a hatch to me and suggest I use anything else, I will refuse to do the work. You will most likely have to order the glass cleaner as most body shops carry a generic that they claim will work "just as good". Maybe other people have had better luck with other products, but I haven't. If you want to do this ONE time, get the right products. In addition, a generic adhesive cleaner, roll of 3" blue painters tape and a handful of latex rubber gloves are needed.
Cut the glass out, which is the hard part, but if you have a friend help and a lot of utility knife blades around (swap them out regularly) and work carefully, you can remove from the car, remove all the trim and separate a badly delam'd hatch in about two hours once you know what you are doing. First time I did it, it took me about two days but I was working by myself.
Don't remove all the adhesive from the frame if you can avoid it as it makes a great base for the new adhesive. Trim it down so its fairly smooth and them coat it with the single stage primer. If you have areas that are showing a lot of metal, I think its best to take a wire wheel to the frame and remove all teh old adhesive and then prep the frame with an epoxy aluminum primer, let it cure a couple of days and then use the primer. Don't bother using the primer on bare metal, it won't hold.
Once the frame is prepped, put it back on the car and position it so that its aligned properly. DO NOT ATTACH THE HATCH STRUTS YET!
Put on a pair of latex gloves at this point, and then clean the glass with the 3M glass cleaner and then use the primer to coat the outside 1" edge of the glass. Let it dry.
Trim off the tip of both tubes of the adhesive at an angle so that it has about a 1/2" opening, and then you and your friend each start applying the goo, I suggest both starting at the top center and work around until you meet at the bottom center of the frame. If you do it right, you will each have just a little left when you get done. Be generous in applying the stuff, and make sure you get only on the hatch. If you get some on the painted surface, have the adhesive cleaner ready to go so you can wipe it off before it sets up but you will have time to get the glass in place first so don't stop what you are doing to clean it up.
Once the adhesive has been applied to the frame, put on a new pair of latex gloves (you WILL get adhesive on your previous set of gloves) and then pick up the glass and place it directly on the frame. If you can get another helper, have someone lay inside the car and put their arms up so they catch the glass in the center and then slowly lower it into place while the folks outside the car guide it so that it "docks" into the frame rather than catching one edge and adjusting it. Once its in place, push it firmly down to make sure you have a good seal all the way around it, and make sure its positioned properly. You can slide it around to adjust as necessary but you shouldn't have to do too much of it. You can use a putty knife to smooth out any adhesive that bulges out and to fill in any gaps. Once this is done, take 3" blue painters tape and tape from the center of the hatch down to the body in various directions to hold it down. Let the car sit for at least 24 hours before moving it. Make sure the windows on the door are down before shutting the doors as that can create enough pressure to cause issues before the adhesive has cured if you close a door hard enough.
Once the adhesive has cured, installation, as they say, is the reverse of removal. If you need to do any clean up, a razor blade will take car of excess on the glass but the trim usually hides it well enough.
I have done a number of these reseal jobs and the only ones that failed were because these instructions were not followed.
By the way, if you need a temp repair, black duct tape at the top of the hatch is the single best method I have seen. It hold the glass in place, seals it so it minimizes leaks and doesn't look terribly obvious.
12-27-2013, 01:45 PM
#6
Slide it around...hahahaha that is what I thought. As soon as it dropped it set using 3M but hey someone else may have different results. Don't forget to mention that the top of the frame has a cover that is press fit. If one does not pay attention to the height of ones set then one will not be able to get the cover on the hinge side of the frame re-attached as it sits over the glass and the frame.
It actually was not that easy for me...and from google the jury is still out of how well Window Weld holds cause it is clearly not the same consistency as factory, which is why I guess you said to leave as much of the original as you can as we both know it is a far superior product even at 20 years old, eh?
It actually was not that easy for me...and from google the jury is still out of how well Window Weld holds cause it is clearly not the same consistency as factory, which is why I guess you said to leave as much of the original as you can as we both know it is a far superior product even at 20 years old, eh?
12-27-2013, 01:53 PM
#7
I've done plenty of hatches and promise that I know exactly what I am talking about. Unless you waited too long to get the glass to the frame, it will move easily enough when you first set it into place.
Window Weld works EXTREMELY well for this application, I have a hatch that I resealed ten years ago that is on my 951 with zero signs of failure at this point. There are several others that I did that are still out there with ten+ years on the reseal job that are still holding as well. The failures I have had were caused by previously silicon'd glass or not following the instructions I posted.
By the way, cutting the glass out of the hatch goes MUCH easier with it off of the car. Once you have the glass out, if the frame got tweaked, you can" adjust" the frame to fit properly again before you put the glass back in. Once the glass is glued back in, you will no longer be able to do this, so its worth taking your time to fit the frame back on the car.
Window Weld works EXTREMELY well for this application, I have a hatch that I resealed ten years ago that is on my 951 with zero signs of failure at this point. There are several others that I did that are still out there with ten+ years on the reseal job that are still holding as well. The failures I have had were caused by previously silicon'd glass or not following the instructions I posted.
By the way, cutting the glass out of the hatch goes MUCH easier with it off of the car. Once you have the glass out, if the frame got tweaked, you can" adjust" the frame to fit properly again before you put the glass back in. Once the glass is glued back in, you will no longer be able to do this, so its worth taking your time to fit the frame back on the car.
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12-27-2013, 02:01 PM
#8
That's what I want to hear cause I am going to try it again. It was easy off the car you are right but I thought that may have been something I did wrong going into this blind.
"Once you have the glass out, if the frame go tweaked, you can" adjust" the frame to fit properly again before you put the glass back in"
-Yeah I think I screwed that one up the first time. You are giving me confidence, when I am scared I procrastinate...why t has taken me so long to attempt it again
"Once you have the glass out, if the frame go tweaked, you can" adjust" the frame to fit properly again before you put the glass back in"
-Yeah I think I screwed that one up the first time. You are giving me confidence, when I am scared I procrastinate...why t has taken me so long to attempt it again
12-28-2013, 11:29 PM
#10
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I redid my hatch about a year ago and used the 3M products. Followed the directions as carefully as possible. The bond failed at about 9 months to a year after the reseal. The 3M primer which was pointed on the underside of the glass, pulled away from the glass. This was not a failure of the urethane adhesive but a failure of the primer bond to the glass. Very frustrating. I am not alone as I have read accounts of exactly the same failure of the 3M system- the primer bond to the glass. One guy tried at least twice with exactly the same failure mode. I called 3M to ask about the failure and they said that the primer is not supposed to dry overnight on the glass (which I did) . Rather I should have applied the adhesive and set the glass within two hours of painting the primer on the glass. I need to do mine again but given my experience with 3M and reports of other failures I am looking at Sika products as well as products by BetaSeal (Dow Chemical) . I have a lot of respect for 3M products generally but am wary.
Lastly, the easiest way to separate the glass from the frame is to take the hatch off and then use a torch to heat the frame enough (not too hot) to cause the adhesive to "melt" . One guy says that he can separate a hatch in about an hour using a torch. For more details go to the 924/944/968 forum and search for "rear hatch torch" and you will get plenty of detail.
I am planning on doing my hatch this week but need to decide on an adhesive system. Any more experience with 3M or Sika or Betaseal?
Don
Lastly, the easiest way to separate the glass from the frame is to take the hatch off and then use a torch to heat the frame enough (not too hot) to cause the adhesive to "melt" . One guy says that he can separate a hatch in about an hour using a torch. For more details go to the 924/944/968 forum and search for "rear hatch torch" and you will get plenty of detail.
I am planning on doing my hatch this week but need to decide on an adhesive system. Any more experience with 3M or Sika or Betaseal?
Don
