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944 Rear Hatch Glass Repair
 
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Pelican Technical Article:

944 Rear Hatch Glass Repair

William Miller

Applicable Models:

Porsche 944 (1983-89)
Porsche 944 S2 (1989-91)
Porsche 944 Turbo (1986-89)
Porsche 944S (1987-88)
Overview

The 944 is equipped with a glass hatch that is surrounded by an aluminum frame. This frame is supported by 2 gas pressurized struts (attached at each rear corners) and two hinges at the front. When the hatch is in the closed position the strut place "reward" tension on the glass. Over time this tension cause the glass to be pulled loose from the forward portion of the frame. This will ultimately break the seal and cause water to enter the vehicle. I’ve heard of cars having this problem in less then a year. Shame Porsche, shame.


The glass is supported in an aluminum frame with a rubber seal and retaining clip "trim". The trim is designed to "hold" the glass against the seal and frame. The seal has no adhesive so the only thing that keeps the glass from pulling loose is friction.

I contacted several local glass shops but none were willing to work on it. Every shop said to buy a new hatch from the dealer! With very little to loose (it’s my brother-in-laws car) I decided to attempt the repair myself. For the investment of a couple hours and less then $10.00 in materials it’s well worth the effort. The hatch now fits correctly and should last for a long time given proper treatment.

The affected car is a 1985 1/2 944 with unknown mileage (the speedometer was previously replaced). This car has the "rode hard put away wet…" look and feel. The glass had separated from the forward frame and caused a 2-3mm gap. My B-I-L had sealed the gap with silicone to minimize the leak.

 

Process

Warning (disclaimer)! This repair is performed at your own risk. Don’t blame me if you break or crack the glass. I felt it was worth the risk (not my car) to attempt the reseal. If you are not willing to accept the idea of buy a hatch DO NOT attempt this.

Because the frame will most likely be bent the hatch will need to be removed. Begin by removing the rear portion of the headliner. Mine was held in with 7 screws. Remove the forward portion of the hatch seal by pulling it towards the rear of the car. Carefully peal back the headliner (it is held in place by the seal) to gain access to the allenhead bolts retaining the hinges. This car had the head-liner cut to get to the screws, don’t try this at home. Loosen all 4 bolts but do not remove. Remove the retaining clips on the hatch struts and disconnect the wires for the defroster and wiper motor if equipped. With the help of an assistant, (have them support the hatch while the bolts are removed) remove hinge bolts and washer plate under the bolts. Disconnect the hatch struts and CAREFULLY lift the hatch off the vehicle. Pretty strait forward.

Stand the hatch on it’s tail on a soft surface (an old sleeping bag works very well) and support it so it can not fall over. With a flat blade screwdriver carefully pry the trim loose from the inside. Start from one side and work slowly. It’s comes off fairly easily but don’t get in too big of a hurry. The frame is soft and will bend easily. Continue working your way across the frame till the trim is removed.

Now determine if the frame is bent along the end where the glass has pulled loose. This example was bent very noticeably at each hinge point.


To straighten the frame I used 2 1/2inch extensions, a big pair of channel lock pliers and a 3/4inch piece of wood. See drawing .

While holding the fixture in place squeeze the frame back into position. Ensure that the extensions do NOT contact the glass and check you progress repeatedly. It’s helpful to have another set of hands to support this fixture.

When you are sure you have the frame straight and the glass fits to your liking. Gently pull the frame away from the glass and thoroughly clean the seal. Apply of generous bead of Silicone based sealant. I used DAP® brand 100% Silicone rubber sealant (black) from my local Ace hardware store. Don’t worry about making a mess as it can be easily scraped off with a razor blade when cured.



While the silicone was wet I applied clamps and straps to hold the frame and glass in position until the silicone setup (overnight). Use extreme caution when applying clamps to the glass. You really don’t want to crack the glass! (that would be bad) Allow this to dry over night before proceeding, give your buddy his beverage.

After the silicone has cured remove the clamps and trim away any excess silicone.

 

Reassemble

Reinstall the trim to the front of the hatch. You may need to do some tweaking to the trim piece if it was damaged (twisted etc) during removal. After getting the trim started I seated it using light blows from a dead-blow hammer. A rubber mallet would work equally well.

Get your buddy to help reinstall the hatch. It is helpful to have a small screwdriver to center the hinges with the bolt holes. (Why are these back seats so small, or maybe I’m just too fat?) Loosely tighten the mounting bolts so the hatch can be adjusted to fit. When you are happy with the alignment tighten the bolts and temporarily reconnect the struts, your buddy will start to complain about it getting heavy (blah blah blah). Reinstall the head-liner and connect the wiring. When reinstalling the hatch seal pay attention to the forward corners. On this car the seal didn’t contact the hatch and had to be "persuade" to fit correctly. It had not been seated correctly for quite sometime as the carpet was soaked! I’m guessing I’ll be putting in a new seal before too long.

You may want to leave the struts disconnected for several day’s to give the silicone time to completely cure.

If you’ve got a pulled out hatch give this repair a try. It’s not difficult and is a lot cheaper then replacing the hatch.

William Miller

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Comments and Suggestions:
Gordon Comments: I forgot to mention that the $100+ "additional gasket" Porsche's terminology, not mine had shrunk. One end of the gasket was silicone RTV'd in place one can see by the impressions on the gasket where it should go and allowed to cure. Then the gasket was then stretched, the other end RTV'd and clamped with a vice grip. The nylon washers were also RTV'd in place.
May 25, 2015
Gordon Comments: Using the vise bolted to the floor worked well. The frame was "taco'd" in a damp kitchen sponge before placing it between the vise jaws. The heat gun set on "high" was set vertically on the floor with the frame resting on top of it which left both hands free. A sharpened scraper was then used to remove the sealant from the L-channel. Once a strip was started, the sealant end could be grabbed with a gloved hand and gently pulled away from the frame as the heat gun was slid down the frame. The stretching of the sealant at the point of contact helps break the seal. The narrowslots in the frame were scraped out as well. Finally, the channel was cleaned to bare metal with a drill motor driven 2" wire wheel brush.

That done, the 3rd light/wiper wiring harness was reinstalled on the frame and new connectors crimped onto the five wires. The hatch locking pins were rebolted onto the frame, the frame hinges reattached to the car and the hatch frame locked. During this process I noticed that the gasket, while still supple, had shrunk away from the top corners - in spite of a 1" gap at the bottom where the two edges join had previously been filled with silicone. A replacement gasket was ordered and the old one will be kept to splice into any future shinkage gaps.

The glass was dry mounted to check the frame alignment. The frame was elongated, so three 2" x 27' ratchet strap flat hook straps were purchased. The straps were installed to check fit and then the glass was removed for cleaning and priming. An additional strap from the a sailboat was also used as well as several C-clamps. The frame was cleaned with acetone and primed with 3M 08682 also. One 30ml container was just enough for this job.

Once the frame was primed, 1/4" dowels wrapped in teflon tape were inserted into the screw holes. A few of the dowels had to be honed with a bench grinder in order to fit the holes.

Ironically, most of the time spent on this project thus far was on the part of the system where the sealant stuck, and virtually no effort expended on the delaminating problem area: the leading edge of the glass. As mentioned below, the sealant and primer both separated from the leading edge of the glass, in part I believe because the glass is smooth. A Dremel drum sander was used to roughen up the sealing areas - 7/8" width and the edge - from heater band to heater band. The glass surface to be sanded was elevated by placing a 4x4 under the carpet supporting the hatch.
May 24, 2015
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Gordon Comments: After consuming three course sand paper rolls, the sanded area looked like frosted glass. Whether or not this will make a difference in adhesion is debatable, but the effort was relatively minor.

3M 08609 Window-Weld was applied to the frame. This material dries a bit too quickly to my mind. Tightening the four straps on this stretched frame was like playing Wak-a-Mole - tighten one strap and one ends up with a frame or glass bulge in another. The only thing to do is to focus on the leading edge of the glass as that is where structural adhesion is critical. The rest is mostly just water sealing.

The Window-Weld was allowed to cure for 30 hours and then trimmed with a razor blade. The vehicle was then put back together. The hatch mushroom pin receivers had to be adjusted and a U-shaped aluminum shim installed on the leading edge of one of the hatch pin bases to make it fit properly.

I will use the struts immediately. The car is driven only once per week, and since it is garage kept, both the hatch and hood are left open when not in use. This was originally done to disengage a battery switch and preserve the struts, but now delamination is another motivation.

Additional notes:
1. The 3rd light/wiper electrical connector is located behind the left rear quarter panel carpet.
2. The left and right trim piece nuts were removed/reinstalled with a flat head screw driver slotted with a Dremel cutting wheel. Do not over-tighten the nuts on reinstallation as it distorts the rubber.
3. All threaded connections were coated with Permatex 81343 anti-seize lubricant prior to reinstallation as two of the M5-0.8-20 screws had to be drilled out/removed with vice grips.
4. During the frame/glass separation process, one of the heater contacts popped off. Fresh solder was melted onto each of the two contact prongs and while hot the contact reapplied to the heater element. The glass was propped up against a wall so that the working area was horizontal.
5. In hindsight having a 1/2" wide aluminum strip welded to the trailing edge of the hinged portion of the hatch frame would provide more surface area for bonding.
6. In spite of purchasing a $25 can of 3M 38984 solvent, it was used only for cleaning my hands, so do not bother.
7. If the hatch becomes delaminated again, I will spend the $2k to replace it.
May 24, 2015
  Followup from the Pelican Staff: WOW! Thanks for sharing this info and the details. We know it takes some time to share stories like this, they really help the Pelican Community. - Nick at Pelican Parts  
Gordon Comments: Casey, I was referring to the frame to which the glass is sealed, not the trim. My four pieces of trim are fine.
May 11, 2015
  Followup from the Pelican Staff: I got ya. I just remember on one I did that replacing the upper trim was necessary, and that memory confused the issues here. Let us know how it goes. - Casey at Pelican Parts  
Gordon Comments: I forgot to mention that I clipped off the five terminals and removed the wiper and heater wiring harness prior to using the heat gun. Why did your system remove my parentheses in the previous comment?
May 10, 2015
  Followup from the Pelican Staff: I am not sure why the parenthesis were removed. I'll ask our tech team if they have any ideas. - Casey at Pelican Parts  
Gordon Comments: After in intensive search of local glass and Porsche repair shops, my local Porsche dealer recommended someone who has made this repair in the past. This person wanted $2000 the cost of an OEM replacement and one month to complete. So with nothing to loose, I decided to attempt to repair my '87 944S myself.

In my case, the whole front edge of the glass separated from the frame with no obvious frame distortion. There was no residual sealant nor primer on the glass where it delaminated. I was not so lucky delaminating the rest of the glass from the frame. Even a sharpened putty knife just bounced off of the sealant when hammered. So I used a heat gun set on high to heat the glass and then shoved a putty knife from the inside to separate the glass from the frame. I followed this putty knife with another which poked completely through the glass and frame to keep tension on the delaminating area. I grabbed both ends of the second putty knife and dragged it along as I went I have read several hatch repair articles and the heat gun approach has never been mentioned. Once again, the sealant stuck to the frame - the glass was relatively clean. Now I am stuck with having to remove the sealant from the frame I wish that Porsche sold the frame separately :/ . Tomorrow I plan to bolt my workbench vice to the garage floor to hold the frame steady while I heat the frame to peal off the residual sealant.
May 10, 2015
  Followup from the Pelican Staff: Sounds like you've got a tough one there. Be patient and keep on working at it. In response to your trim statement...did you need a new top trim or the sides? We sell the top trim separately. PN 477853313A =0 - Casey at Pelican Parts  
emsman Comments: mrunlawful have any more pics of the final product?
June 16, 2014
  Followup from the Pelican Staff: Let's see if he has more to share. - Nick at Pelican Parts  
clayton Comments: my 1985 944 hatch keeps popping up, i tried replacing the pins to know avail,what else could be wrong.
May 6, 2014
  Followup from the Pelican Staff: With the hatch open, can you manually close the latches? Then check if they hold close. They may not be locking. - Nick at Pelican Parts  
BacT3R1a Comments: I ended up with this issue, few days after installing new support shocks.. Then i saw the glass out of the upper frame!
So i took it off myself, it only weighs 52.5LBS, took the trim molding off the top, the glass and frame were in alignment so i cleaned the glass and rubber seal with paint thinner, applied a nice bead of clear silicone, squeezed both pieces together and reinstalled the top molding back and tapped it in with a rubber mullet and the excess silicone came out, glass was in place and 5 hours later, its back in the car, but this time, i'll leave only 1 new and one bad shock. One support shock holds the glass pretty well, 2 is overkill to me.
Remember, patience is a virtue!
December 5, 2013
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
mrunlawful Comments: I custom built an exact duplicate hatch glass out of fiberglass painted to match, then did my final body work. I have a rear camera inside my vehicle facing out a hole big enough on the hatch I made. Must say never have to worry about breaking it ever
February 21, 2013
  Followup from the Pelican Staff: Thanks for sharing, it looks sweet. We appreciate it.
- Nick at Pelican Parts
 
speedster Comments: Do you know how the pins or rear bolts that are in the the hatch adjust Thanks John
September 8, 2011
  Followup from the Pelican Staff: Here is some info from the forums:

1. Open hatch and tighten the hatch pin(not the nut), so the pin moves up. Do this more turns then you did when you loosened it. (both sides) Try closing the hatch. You want the hatch to close and NOT lock. So if the hatch closes and lock, open it and tighten the pins more until they don’t lock when closing the hatch.

2. Now the hatch should close and not lock on both sides. Open the hatch and loosen the pin a full turn on both sides. Notice that the pins have more wear on one side of the flat part of the head than the other. Try to align the pins so that this extra wear is facing the front of the car.

3. Close the hatch and see if it locks. If it doesn’t lock, keep repeating step 2 until the hatch locks. If one side locks and one side doesn’t, keep repeating step 2 for the side that doesn’t lock, until it does.

4. Now you can tighten the nut on the top of the pin. Make sure the pin doesn’t rotate while doing this.
- Nick at Pelican Parts
 
stilespj Comments: William,

As Bill said: "Great write up by the way!"
I'm in complete agreement.

Bill, thank for the tip on the 3M products, I'll give them a try just ordered them.

My hatch glass is coming loose at aroud the passenger side hinge area. It is sliding back and making opening the hatch a bit difficult. Time to fix it.

Paul
August 2, 2011
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Bill Dunster Comments: William, Great write up by the way!
June 10, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Bill Dunster Comments: Hi I am a PPG industries automotive coatings employee. My sons rear hatch has been rebuilt recently. 3m makes a primer and urethane that will bod to glass. Silicone has an acidic property that will corrode aluminum and steeldont use to reseal your windshield either it will rust the metal the part numbers for the 3m is 08609 window weld urethane and 08681 primer. it will run you around $50.00 in materials but is the reccomended products from 3m. Happy hatch rebuilding!
June 10, 2011
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Fluidplay Comments: The extensions are just a way of supporting the frame in areas where the frame is bent allowing you to apply pressure to the damaged or "bent area in an attempt to straighten the frame before re-installation. I would use something like a C-clamp to apply this force as you would have more control over how much movement in the material is required to straighten.
December 31, 2010
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
randy Comments: Hey thanks I'll try this right away. It will probably save me $140.00 to do it myself. I have another hatch if needed already. But I prefer the hatch with the brake light in it.
April 7, 2010
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Paul59 Comments: you have just made my life a whole lot easier... Thank you
March 5, 2010
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
chocko Comments: It will also help if you purchase a new aluminum top bracket.
January 19, 2010
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
boxcar Comments: thanks Cliff, I'll take a look.
SO far I found an early model hatch. basically am still at square one.
Early hatch is a temp for time being car use and is in place on new gasket. It is now exhibiting separation at leading edge of hatch. Plan is to mitigate fit problems on temp.
Then,take my old apart and straighten/reseal with modern glass adhesives. Have seen a 3m urethane product listed in conjunction with a primer, but there are others I'm sure.
July 5, 2009
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
Cliff_87_951 Comments: "BOXCAR", you leak in the pass seatwell could also be coming from the battery tray which is another common problem. Remove your battery and check for and rusted out areas.
June 23, 2009
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
boxcar Comments: sounds practically easy. after just finding a 1 inch pond in the 86's pass seatwell, and insuing seat and carpet removal-and box fan drying I'm ready. don't want any substantial mold growth so i hit these areas with some 30% bleach solution-since they were all pulled up. also should order the big seal William mentioned first...so a little lead time before game day. none of those rubber parts live more than 20 years. the met blue 944 gets to live in the garage for the mean while.
May 15, 2009
  Followup from the Pelican Staff: See this reply from Cliff_87_951:

"BOXCAR", you leak in the pass seatwell could also be coming from the battery tray which is another common problem. Remove your battery and check for and rusted out areas. - Nick at Pelican Parts
 

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