Rear glass replacement!!

[Furiac]

1979 450slc broken rear window glass needs replacement. I would like to replace the back glass myself, but need some technical assistance. Any help would be greatly appreciated!!

[fonzi]

Stuff out there on the internet talks about how this is a two person task that required a lot of lube and patience. The trim must go in with the glass and rubber or it won’t go in at all. It can’t be installed afterwards.


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[meltedpanda]

Im not sure Id tackle that job, it is tedious, you need the right tools and know how. I opted to have a pro do mine, it was on a 300SD but I can tell you that watching him Im glad I chose that route. That said , nothing ventured nothing gained .... good luck

[daantjie]

On the W116 at least the trim on the rear window goes in afterwards by way of external clips on the window frame. The front is a much bigger job and for the front yes you must install the trim BEFORE you install the glass with the gasket.
There is a very good clip on youtube on the 116 glass install albeit for the front, but a lot of the methodology is the same. Patience, lube and a second set of hands (ha-ha, sounds like fun but it's NOT!) This is a huge job and best done in warmer weather so there is more flex to all components. Good luck.

[Rick76]

The SLC is the opposite of the W116.
Clips on the front and trim in the rubber on the rear. Trim must be installed before installing window.

When inserting the trim in the rubber use a lubricant that will totally evaporate such as isopropyl alcohol. Leave it at least overnight so the alcohol evaporates completely. Anything you use to make the trim pop in the rubber will make it pop out when you try to install the assembly in the vehicle if any traces of it remain.

Pay particular attention to the corners that the trim is fully seated in the rubber. I've seen a lot of installations where the corners are not properly seated.

Never hit the trim with a rubber hammer as it will fracture the delicate aluminum anodized surface that will show up when in sunlight.

Check for any rust and repair. Mine had the paint cut through to bare metal where the factory workers had used a knife to cut the headliner where it wraps around the window opening. Rust in spots had progressed almost to where it would show up with the installed window.

And then there is the topic of sealer which seems to bring out a variety of different opinions.

When pulling the ropes starting at the bottom, the helper must push down as well as lightly pushing in as the window has a tendency to creep up causing it to be uncentered in the opening.

Are you using a new seal? From MB or aftermarket?

Where did you get the replacement window?

[daantjie]

Originally Posted by Rick76

The SLC is the opposite of the W116.
Clips on the front and trim in the rubber on the rear. Trim must be installed before installing window.

When inserting the trim in the rubber use a lubricant that will totally evaporate such as isopropyl alcohol. Leave it at least overnight so the alcohol evaporates completely. Anything you use to make the trim pop in the rubber will make it pop out when you try to install the assembly in the vehicle if any traces of it remain.

Pay particular attention to the corners that the trim is fully seated in the rubber. I've seen a lot of installations where the corners are not properly seated.

Never hit the trim with a rubber hammer as it will fracture the delicate aluminum anodized surface that will show up when in sunlight.

Check for any rust and repair. Mine had the paint cut through to bare metal where the factory workers had used a knife to cut the headliner where it wraps around the window opening. Rust in spots had progressed almost to where it would show up with the installed window.

And then there is the topic of sealer which seems to bring out a variety of different opinions.

When pulling the ropes starting at the bottom, the helper must push down as well as lightly pushing in as the window has a tendency to creep up causing it to be uncentered in the opening.

Are you using a new seal? From MB or aftermarket?

Where did you get the replacement window?

Learn something new every day
Yes on the sealant, this is an area of differing opinion. Service manual says to install a bead between the glass and the seal (outside) once installed. Other guys only run sealant in the frame before the unit is installed. This can be a bit messy but I think gives a better seal than just doing the outside. For sealant, the only one you want to use is "3M Glazing and Bedding Compound", the best for this job. Then use "3M Adhesive Cleaner" to clean up any areas of leakage and squeeze out together with a microfibre cloth. 3M is your friend This worked for me at least on my 6.9, and believe me the 116 is probably the hardest to install, especially the front seal is murder

[torsionbar]

Originally Posted by fonzi

Stuff out there on the internet talks about how this is a two person task that required a lot of lube and patience.

This is a family forum here, lets keep it G rated please!

[Furiac]

Originally Posted by meltedpanda

Im not sure Id tackle that job, it is tedious, you need the right tools and know how. I opted to have a pro do mine, it was on a 300SD but I can tell you that watching him Im glad I chose that route. That said , nothing ventured nothing gained .... good luck

I would rather pay someone to to do it, but here is my problem. I live in a very rural place in Colorado and the nearest auto glass shops are 2 hours away. None of the shops have experience with this situation. They would be learning how to do it just as I would. Of course they have better tools, techniques and overall experience, but they probably won't take the time and care that I would while they fight this bear of an install. I don't care if it takes me 10 hours to do, they will be trying to make a buck and not take all day.

[Furiac]

Originally Posted by Rick76

The SLC is the opposite of the W116.
Clips on the front and trim in the rubber on the rear. Trim must be installed before installing window.

When inserting the trim in the rubber use a lubricant that will totally evaporate such as isopropyl alcohol. Leave it at least overnight so the alcohol evaporates completely. Anything you use to make the trim pop in the rubber will make it pop out when you try to install the assembly in the vehicle if any traces of it remain.

Pay particular attention to the corners that the trim is fully seated in the rubber. I've seen a lot of installations where the corners are not properly seated.

Never hit the trim with a rubber hammer as it will fracture the delicate aluminum anodized surface that will show up when in sunlight.

Check for any rust and repair. Mine had the paint cut through to bare metal where the factory workers had used a knife to cut the headliner where it wraps around the window opening. Rust in spots had progressed almost to where it would show up with the installed window.

And then there is the topic of sealer which seems to bring out a variety of different opinions.

When pulling the ropes starting at the bottom, the helper must push down as well as lightly pushing in as the window has a tendency to creep up causing it to be uncentered in the opening.

Are you using a new seal? From MB or aftermarket?

Where did you get the replacement window?

Thank you so much for the info, I watched the great YouTube video on the front window replacement with awe, but thought that mine might be a different animal.
I am going to order a new gasket from an aftermarket dealer. I have not yet removed the old glass so I don't know the condition of the gasket, but to be safe I will get the new one.
I got the "new" glass from a junkyard. They pulled it and had it ready to go so I did not see the process of removal.

[daantjie]

Do not get Uro seals they are total garbage. Get MB seals only. The fit and quality is far superior to any aftermarket ones.

[fonzi]

The windows often pop right out of older JY cars because the old seals have dried and shrunk. The part that makes a good deal is the part that makes it so difficult to install.


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[fonzi]

Originally Posted by Furiac

Thank you so much for the info, I watched the great YouTube video on the front window replacement with awe, but thought that mine might be a different animal.
I am going to order a new gasket from an aftermarket dealer. I have not yet removed the old glass so I don't know the condition of the gasket, but to be safe I will get the new one.
I got the "new" glass from a junkyard. They pulled it and had it ready to go so I did not see the process of removal.

Want to share the link to the video?


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[daantjie]

Here is the link, this guy is a beauty! Love that thick accent too:

https://www.youtube.com/watch?v=v4hAT0aSIyM

[torsionbar]

Originally Posted by Furiac

I got the "new" glass from a junkyard.

Yikes, you certainly have your work cut out for you then. Automotive safety glass is made up of multiple layers of glass and plastics laminated together. The inner plastic layer becomes hard and brittle with time and UV exposure, as all plastics do. Installing a curved piece of glass with rubber seal involves significant "muscle" to flex and force the glass into place, and it requires a lot of feel and technique to do so without breaking it. With your used glass, again, it is much more brittle than new glass, so it will be even more difficult to install successfully without breaking it. The two body shops near me that do euro cars both refuse to install used glass. They won't touch it, because of the high probability of breakage during installation.

Originally Posted by Furiac

They pulled it and had it ready to go so I did not see the process of removal.

The junkyard removal process is the same as the body shop or glass shop removal process. They use a box cutter to slice up the old seal, cutting the exterior half of it off. Then simply lift the old glass up and out. The old glass may be stuck to the old seal a bit, so some careful prying with a plastic tool may be required to pop it free.

[Furiac]

Originally Posted by daantjie

Do not get Uro seals they are total garbage. Get MB seals only. The fit and quality is far superior to any aftermarket ones.

Where is the best place for me to get new seals for this window project?