Ultimate Rear Window R&R Thread

[Superman]

I've read through the technical article on headliner replacement, which involves removing the glass, here:

https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/68-Headliner/68-Headliner.htm

The glass removal/replacement article is here:

https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/79-Glass_Removal/79-Glass_Removal.htm

Here are two threads that are instructive:

Is a rear window seal replacement THAT daunting????

Race Prep Backsliding -- Re-installing a rear windshield

Apparently, if you do it right, R&R'ing the glass is generally not difficult (if you use a new, OEM gasket).....except for the rear glass. Rear glass has wires threaded though the gasket for the defrost. I've got a new gasket, and two old ones with the wires still in them so I can use them as a guide. What I don't know is the ORDER of the tasks.

With front glass, you put the gasket onto the glass, then install the trim into the gasket, then the rope around the lip and go. At what point do you run the wires? Before installing the gasket onto the glass? Just before you install the glass/gasket/trim combo into the frame of the car?

Now....bear in mind that the wires go into the gasket through a hole that needs to be cut in the lower left corner, and they each come out through different holes in the gasket, which (each) also need to be cut to meet the connectors on the glass. Bear in mind also that the wires are still in the car. So....the electrical part of this job needs to either be done with the glass/gasket/trim assembly located at the car's window frame (where the wires are, which has got to be a PITA) or the wires need to be removed from the car.

I read an article which seems to suggest the wires be disconnected at the engine compartment fuse box (and presumably removed from the car so that the complete rear window assembly, with electrical, can be assembled at the bench. Do I really need to remove this entire harness, carefully, from the car (finding the termination points for the other ends of each of those wires, and then reconnect each of those wires after rear window installation is complete?

[ed mayo]

I always do this job by disconnecting the wires from the plug in the engine bay and pulling the harness out with the glass. To try and install the seal, the wires, and the trim with glass resting on the package tray will only lead to frustration.

[RDM]

What Ed said.

I'm doing this for a Targa window right now, and I installed the wires into the new seal before putting the seal onto the glass. I figure that trying to put wires in with the seal on the glass would cause...the seal to come of the glass, so I'm skipping that step!

[Superman]

Thank you both, very much. In order to remove the wires from the plug at the engine bay electrical panel, will I need a special tool? Will the plug itself not fit through the opening in the firewall?

I am also interested in whether that wire loom will be in the way when I rope the glass into the car. Even if so, it's probably no big deal. As I mentioned to the group above, glass actually goes in pretty easily if a new (OEM!) is used.

Further, John Walker says the rope should overlap at the top, not the bottom, and that the glass/gasket/trim assembly cannot be set straight into the frame, as if ropeless, at one edge (like the bottom edge for example). Every inch of the lip must be pulled in using the rope.

And finally....I hear that certain goop can be used, after the installation, to seal leaks if necessary. My plan is to use silicon to lube the gasket and improve the likelihood of a good seal. I assume the goop, if necessary, would still seal the leak despite the presence of silicon. Or, alternatively, I could use soapy water. What do you guys use?

[75 911s]

In my research 3m Auto Bedding and Glazing compound 08509 is a popular choice.

[ed mayo]

You didn't say what year car, but most that I've seen use a two prong flat plug that can be separated with a very small flat tip screwdriver allowing the the wires to be pulled out. When installing just push the wires thru the hole in the deck first, then rope in, passing the rope past the wire harness when you get to that corner.

[Superman]

Originally Posted by ed mayo

You didn't say what year car, but most that I've seen use a two prong flat plug that can be separated with a very small flat tip screwdriver allowing the the wires to be pulled out. When installing just push the wires thru the hole in the deck first, then rope in, passing the rope past the wire harness when you get to that corner.

Thank you!

[Superman]

Here is that plug, in one piece and in two.





Here are the exposed connections from that plug, and also the rubber grommet that protects the penetration in the firewall leading to the window frame. The grommet can be pushed upwards into the car and the wires can come out of the car still attached to the old window gasket.




There is also a ground lug behind the fuel accumulator. The nut and washer have to come off.

[Superman]

Each electrical connection on the window is a spade connector. There are three connections on each side. The connectors look like a butterfly with two connectors each. So.....six spade connectors on each side of the glass. Of the three on each side, the center circuit is a single circuit. The top and bottom circuits are connected by a jumper wire. For example, one of the power wires goes to the defrost strips at the bottom of the glass. The other power wire goes to the middle strips. The upper strips are energized by a jumper wire that goes from the bottom (energized) connector to the top connector. I had to modify mine since one of the critical spade connectors broke off. 40 year-old glass.

SAVE the gasket and remove it with the wires still embedded. This will be a template for how you will install those same wires into the new gasket. To do this, use a box cutter to remove the gasket lip inside the car. With this lip removed, the glass/gasket/wire/metal trim unit can be removed intact. You will need to poke some holes in the gasket for the wires. Use sharp nosed pliers to pull the wires through the holes you made. When you install the gasket, be careful not to break off the spade connectors at the edge of the glass like I did. But first.....

Use the glass as a template for bending the metal trim into proper shape. This works. The metal trim has to be shaped properly. It is EASY to bend. This means it will not be shaped properly when you receive it. It also means you will be able to easily bend it into proper shape. The metal trim has a hookie thingie that grabs onto the rubber gasket inside the slot. This MUST be entirely engaged into the gasket when you install the glass. It snaps when it engages, which you can feel with your hand. Run your finger along the edge between the metal trim and the gasket. If the trim is not fully engaged somewhere, you can feel it easily.

Yes, the wires need to be disconnected at the plug, which is pictured above, and the entire thing removed from the car. You do NOT want to fight with this while it is still on the car. This is bench work.

I mis-heard John Walker. The rope needs to be overlapped at the bottom, not the top.

Now....this all seems complex to you and it is challenging. However, the hard part is next.

You need three people to install the glass into the car. At least. One person at the bottom and two people to manage the to corners. Situate the glass/gasket/wire/trim setup just below the frame. Lube the gasket and the frame it goes into. As the person at the bottom moves the glass upward, the people at the top guide the lip of the gasket toward the center of the vents at the rear of the roof. Slowly. Carefully. When you are there, the people at the top press their fingers against the METAL TRIM, not the gasket or glass. They push the setup into the frame while trying to keep the gasket lip from folding under. You may need a hooky tool to tease the lip upward. Push it home (into the window frame) against the METAL TRIM while the person at the bottom pushes upward and pressed the glass down into the bottom part of the frame. If the metal frame is allowed to tip upward, you start over. If you can get the setup into the frame with the metal trim still engaged into the gasket, and with the lip of the gasket poking upward, then you are ready to have someone press onto the glass/gasket while you rope it in.

It took three guys and ten tries over two weeks for me to be successful. My advice: Subcontract this to an actual competent glass guy. I'm a DIY guy. There is almost nothing I will farm out to the pros. This is one of the rare exceptions.