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Pelican Technical Article:

Installing Window Glass


1 hr per pane


Depends on which window you are installing




Thick sturdy cord

Applicable Models:

Porsche 911 (1965-89)
Porsche 912 (1965-69)
Porsche 930 Turbo (1976-89)

Parts Required:

New rubber for the window

Hot Tip:

Proceed very, very carefully, and don't rush this important job

Performance Gain:

No more wind in your face

Complementary Modification:

Replace window seal, replace front dash pad
101 Projects for Your Porsche 911

This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.

Make no mistake about it, reinstalling glass into your car is not an easy task. There probably isn't a Porsche shop out there that won't admit to breaking at least one windshield trying to install it. The trick is to have plenty of patience, and to make sure that you don't put any excess pressure or loads on the glass. However, the process of installation requires that you push slightly on at least part of the glass. As the glass ages, it can become very brittle, and may crack a lot easier than a new windshield. Unfortunately, you may end up doing everything right and still break your windshield.

The procedure for the installation of the front windshield is similar for the other panes of glass in the car. The main difference is that the front windshield is very large, and has an increased tendency to crack because it's much longer. The length of the glass may actually magnify stresses and forces placed on the windshield. The side windows and rear glass are less susceptible to cracking. However, the rear window needs special consideration because of the defroster wire that is running through the seal. For the remainder of this project, we'll concentrate mostly on the front windshield, and then give hints and tips on how the other panes are different.

The first step in installation is to attach your rubber seal to the edges of the glass. It's really not a wise idea to recycle an old seal, as these were probably damaged in the glass removal process, and will not seat properly. Always use a new seal. I also recommend that you only use OEM German rubber when replacing your seals. I've found that most of the cheaper, reproduction seals are of an inferior quality. It's not worth it to save a couple of bucks, only to have the seal leak on you at a later date.

Before you install the seal on the glass, make sure that you place the windshield on a scratch free surface. An old rubber tire with a blanket tossed over it makes an ideal candidate. When you fit the seal to the glass, make sure that the orientation of the seal is correct. The groove for the aluminum bezel always faces towards the outside of the windshield. Using a bit of soapy water on the edges of the windshield may help with the installation of the seal.

When the windshield is to be installed into the car, a strong cord is used to properly pull the edges of the seal inwards. The cord must be inserted into the inner ridge of the seal prior to placing the window on the car. After the seal is properly mounted on the windshield, thread the cord into the channel groove of the seal. Refer to the diagram that accompanies this project for a better indication of where it's supposed to go. When the cord is completely wrapped around the outside perimeter, make sure that it overlaps itself by about 8 inches.

Now, attach the aluminum trim bezel to the seal. The trim actually helps hold the seal to the glass. If the aluminum trim became bent or dented, straighten it out as you install it. It will be much easier to fix any dents or waves in the aluminum trim now than when it is installed on the car. Install the upper and lower clips that cover the gap between the two trim pieces.

Once you have the trim and the two clips installed, it's time to place the windshield onto the car. Before placing the glass in the car, make sure that all remains of the previous rubber seal have been removed from the lip of the mounting surface. Sand and paint any rusted areas that you find. Water has a tendency to seep into the windshield area, and once in there the water may become trapped and corrode the metal.

Before you place the windshield, coat the seam/recess where the seal is about to mount with some dishwashing soap to ease the installation of the seal. The soap will be able to be washed off later with some water. Now, place the glass into the car, with the lower edge going in first. Position it back and forth until the glass is centered in its recess. Then push the top of the windshield into place. Remember not to use so much force that you crack and break the glass. Patience is a required virtue here.

Move the glass around and check the gaps on all sides to make sure that it is properly positioned. Now, from inside the car, start to pull the cord out, while an assistant applies pressure on the outside of the glass. The trick is to make sure that the seal is pulled over the lip by the cord that you are pulling from the inside. If the cord doesn't pull the seal over the lip, then the windshield will not seat, and you will have to start over and rethread the cord. Make sure that you don't damage the headliner when you pull the cord out (it's very easy to do this).

The pressure applied on the windshield from your assistant is most necessary for the bottom edge of the glass, as the weight of the glass makes pulling the cord out just a little bit more difficult. It should be apparent that a weak cord for pulling would not suffice in this situation. Nylon cords like the ones used for starting lawnmowers are excellent for this task. Once the cord is completely pulled out, the windshield should be completely seated.

Once you have the glass in place, make sure that the aluminum trim is properly seated. Press it in or tap it lightly with a plastic hammer if it is not. Double-check to make sure that the seal is properly seated all the way around the windshield. If it is not, then you might be able to use a small screwdriver to pry the seal into its correct orientation. This potentially may damage the seal and the glass, so exercise extreme caution. Check the headliner inside the car, and tuck any loose folds or excesses back in under the seal.

The installation of the rear window is a little different than the front. The rear defogger wires should be threaded into the seal prior to attaching it to the car. Be careful not to damage the fragile contacts on the rear defogger window. Make sure that you place the glass into the car with the top lip first, and then the bottom lip. With the installation of the rear window, there are more sections of headliner to potentially damage. The side windows are installed in a similar manner to the front and rear glass.

Proceed with caution at every step, and make sure that you have a patient assistant. If you do break any glass, vacuum it out of your vents before you turn them on. Use appropriate gloves when handling the glass. Even thick-edged glass like the windshield can cut you if there is a small chip on them.

Prepare the window glass by placing it on a tire or soft, flat surface.
Figure 1

Prepare the window glass by placing it on a tire or soft, flat surface. Attach the seal all the way around the outside of glass. You may have to stretch and pull the seal to get it to fit. Once the seal is in place and the bezel installed, insert the cord into the groove that mates with the edge on the body. Make sure that you have about six to eight inches of overlap when the cord is inserted completely around the entire window.

This diagram shows how the seal holds the glass to the edge of the window frame.
Figure 2

This diagram shows how the seal holds the glass to the edge of the window frame. The installation cord is inserted into the seal where the lip of the chassis is located, as indicated by circle number four on the diagram. As the seal and glass are pushed against the lip on the body and the cord is pulled out, the edge of the seal (indicated by the dotted lines) is pulled over the lip into its final position. Make sure that the seal is firmly in place all the way around the edge of the window after the cord has been completely pulled out.

Installation of the glass can be a tricky process, especially with older glass.
Figure 3

Installation of the glass can be a tricky process, especially with older glass. While an assistant applies pressure from the outside, pull the cord out on the inside, forcing the seal to the inside of the pinch weld lip on the body. If the seal doesn't properly seat against the body, carefully try to refit the seal using a small screwdriver or appropriate plastic tool. If you can't pull the seal over the lip, then remove the window and try again.

Comments and Suggestions:
KDRGibby Comments: I can't even get a local shop to help with this project I bought the OEM brand seals and local experts say they are crap, won't seat properly and they will waste their time and won't make any money. Where are these seals manufactured? Does Porsche actually make these seals? Anyone have trouble with them lately? I can't get them to stay on.
December 12, 2017
  Followup from the Pelican Staff: I am not 100$ sure. Porsche should make them. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need. - Nick at Pelican Parts  
Tom Comments: I am installing a new rear windscreen seal on my 1973 911E coupe. The old seal has a material on it that looks and feels like plumbers putty. It is not an adhesive. Does the installation require a sealant to affix to the mating surfaces and what is recommended?
October 26, 2016
  Followup from the Pelican Staff: Most likely butyl tape or "dum dum". - Nick at Pelican Parts  
Nico Comments: I have to install a new front windshield on my 87 911 coupé. All is ready and in place seal, cord, trims. I wonder if injecting a mastic-type sealing compound after having completely installed the windshield was necessary as it is mentioned in Haynes 911 repair manual 10-14-11 p247. It seems very hard to do as it may be hard not to break the seal.
July 22, 2016
  Followup from the Pelican Staff: Haynes may be using info suggested from Porsche, I can't add insight to their process as I don't know for sure their source. In the current factory literature, Porsche recommends using a urethane to install the windshield, that may be why Haynes mentions an adhesive. - Nick at Pelican Parts  
andy Comments: Recently installed new glass with Porsche OEM seals. Back glass lower corners are pulling back and folding into opening. This is exactly what was happening to 25 year-old original rubber. I've seen this on many older 911's, any remedy?
April 23, 2016
  Followup from the Pelican Staff: The seal needs to be pulled out and placed on top of the body, to see if falls back in. If it does, the glass may not be centered, too small, or the body has erosion. - Nick at Pelican Parts  
Msteel3 Comments: 1980 911 sc targa. I need to install rear window trim. Anodizing has come off. I ordered and received the trim today. Is it possible to replace my window trim without window removal?
January 25, 2016
  Followup from the Pelican Staff: GOing by memory, the window has to be removed. - Nick at Pelican Parts  
aircool6289 Comments: Just wondering - my '89 3.2 has the alum term in the rear seal and front - if I wanted to buy a new seal, can I go with the the one that does not have the moulding - are they interchangeable?
December 30, 2015
  Followup from the Pelican Staff: Great questions. I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need. - Nick at Pelican Parts
rich Comments: I'm searching for a how-to for the rear targa glass. I need to install one today. I would like to know if you start from the bottom and pull up the vertical targa bar sides or start the gasket at the top and pull down.

I'll check the general forum and see if anyone has a helpful post. Thanks for the info posted here.
April 22, 2014
  Followup from the Pelican Staff: We do not have a tech article for that procedure. If we get the chance to perform the repair, we will be sure to document the procedure. For now, you can grab a repair manual. - Nick at Pelican Parts  
Red911 Comments: I wanted to replace my headliner in my car 78' Sunroof SC. One of my largest concerns was installing the windows after I installed a new headliner. After having read the procedure outlined here in this article I found it not be a bad job after all. The windshield took me 10 minutes to install with out any assistance. The rear was a bit more work took me several try's but it finally went in nicely. The quarter panel windows were the fun ones, I definitely needed an extra pair of hands for those. After numerous try's I finally figured out the trick to start them, then they went it fairly easy. Still messing with the chrome strip on the left quarter window, it refuses to stay in the groove but I am sure it will stay at some point.
January 27, 2012
  Followup from the Pelican Staff: Thanks for the heads up - Nick at Pelican Parts  
realgren Comments: Addition: for those who have the integrated antenna in the windshield mine is an 87. The wire comes out from the bottom passenger side of the glass.
While someone holds the glass tilted slightly forward, clip the wire making sure not to loose the section that remains in the car. I used a little piece duck tape.

Reassembly: the wire on the windshield will come out from the seal upwards. When putting the glass back in the car, make sure to reattach the wire. I crimped the 2 ends using a females - female 16 gauge join.
November 27, 2011
  Followup from the Pelican Staff: Thanks for the tip - Nick at Pelican Parts  

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