How To Remove Urethane Fixed Windshields

Tags: Auto Glass

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http://www.howtopaintcars.com/wp-content/gallery/example-repairs/windshield-removal.jpg?i=1571351474There are a variety of different ways that windshields and other fixed windows are held in place in new and older vehicles. Classic Cars prior to 1970 are likely to use a bitumen tar like substance that is placed in the windshield channel in a 1/2 inch cord shape and then the windshield is pressed in place. You will also see vehicles that have a rubber retaining molding. This is often used on late 80’s and 90’s trucks and vans.

New vehicles and classic cars that have been restored will use a Urethane Adhesive which is injected into the ledge around the windshield opening with a caulk gun. It is a nice material to work with because it will take out any imperfections in the leveling of the opening and it will cure into a flexible material that will protect the glass from shock while holding it securely in place.

In all honesty after many years of watching people struggle with removing glass I have to say this task is best performed by a professional that is dedicated to glass repair. Not only do they have the tools to perform the work they also do this work many times a week while an auto body mechanic may only do this once a month and a hobbyist may only replace two or three in their lifetime.

With this thought in mind there are times when replacing a windshield yourself is a reasonable task. If you purchase a windshield from a junkyard that does not offer instillation or if you are removing a damaged windshield to perform body work.

Tools you will need to remove a Windshield

http://www.howtopaintcars.com/wp-content/gallery/shop-tools/handled-windshied-cutter.jpg?i=222862422The tools that are needed to remove a windshield are pretty basic. Although there are a lot of companies out there trying to sell tools to make this job easier most professionals still use hand tools. If a service comes to your home or business to replace your windshield on your premises they are not going to be bringing sawsalls or rotary hammers with wide spoon attachments and they definitely won’t be hooking up any air tools.

On the other hand if you are a professional working inside a shop you might find some technicians make use of these power tools in special situations.

The main problems when removing a piece of glass are cutting through the Urethane bead and dealing with the weight of the glass.

Glass can be very heavy and difficult to work with so it is to your advantage to purchase at least two suction cups that can be used to help lift the glass and position the new glass. It will also allow you to pull the glass away from the frame as you cut the urethane bead we will cover that later.

Second you need something to cut the urethane bead. There are two tools that you will need a handled cutter with replaceable blade and a breakoff blade cutter / utility knife with a 1 inch wide blade that can be extended and broken off.

The final tools you will need are the ones to clean the urethane from the opening channel and apply the new bead of urethane. Various razor blade tools should be used rather then abrasives to remove the urethane however if you are performing rust work a wire brush works well. A heat gun will also help remove the final urethane before you start grinding.

How to remove the window

The way and direction you work is important so that this job is easier.  Many technicians who do not perform this work that often just jump in and start trying to cut away any urethane they can without thinking how it will effect the job.

http://www.howtopaintcars.com/wp-content/gallery/shop-tools/pneumatic-windshied-cutter.jpg?i=923774052The first thing you must do is remove the trim around the window opening. Sometimes this can be a little difficult because they often get glued in but they do pull out relatively easy from the front side of the glass without too much work. They can also be replaced if you damage them and they are not required to hold the glass in place after the urethane cures.

Start at a seam or end of the molding bead and use a ice pick or other tool to pry the end up. Heating the molding is not normally necessary just pull the bead up like you are removing masking tape after paint has cured. Keep your hands close to the surface of the window (where it is coming off) when pulling .. don’t continue pulling on a long end of the molding or it will stretch. This is hard to resist when the molding is coming off in the center of the window so use milk crates or something to stand on to let you get into your work.

Once the molding is off you want to start cutting the Urethane Bead at the top of the window.. you will then work down the sides and the bottom will be the last part cut off.

Before you begin cutting you want to protect the paint around the window with 2 inch masking tape. Two layers is a good idea.

Insert the cutting edge about 3 inches down on the front window post on the side of the window. You will work your way up around the corner of the window on one side of the car then all the way across the top to the other side and down around the top corner of the window.

Here is where the professional trick comes.

Professionals have two hand cutters. The first is a shorter blade that cuts about half way through the bead and the second is a blade that will definitely pass all the way through the bead of urethane.

The good part about this is it is much easier to cut half the width of bead with a first pass. The hard part is it is very hard to line up the cuts.

The best way to do this is to keep your blade pressed close to the metal channel as you can and even if you are off some the first cut will relieve the stress on the urethane making it much easier to make your second full pass.

If you try to cut it all at once it can be pretty difficult to make the cut accurately and also it takes much more strength and you don’t want to slip and damage your paint.

 

The next trick will help you cut the sides away.

http://www.howtopaintcars.com/wp-content/gallery/example-repairs/windshield-rear-removal.jpg?i=1607555889Professionals will have special wedges they use at this point to very slightly push the top edge of the glass you just cut away away from the vehicle.

They are normally made of nylon and about two inches wide with a pretty sharp taper.

The idea is not to force the glass off / remove it with the wedges .. the idea is to add a little outward pressure that makes cutting much easier.

If you don’t have wedges which you probably won’t you can cut a hard nylon bondo spreader .. the real flexible ones probably won’t work.

Insert the wedges about a foot in from the side of the window.

NOTE
Before you start cutting the sides you want to secure the top edge of glass to the roof of the car. Use a few pieces of two inch tape but add a short loop to give the tape room to let the glass move out. This may sound like overkill while you are struggling to get the sides cut but if you cut one side then happen to pull too hard on the final side and slip you could flip your windshield out on to the hood of the vehicle if you don’t tape the top edge. It is a precaution well worth taking especially if you are working alone.

Cutting the bottom edge of windshield urethane

This part is where it gets tricky and where a lot of tool companies are making money trying to get you to use their tools.

In most cases you probably won’t be able to cut through the bottom edge of urethane with your handled bead cutter.

If you can get to some of the bead then go ahead and make a pass on it. If you can’t then there is an easy way to get it out.

The first thing you want to do is place a suction cup as far in to center of the top of the window as you can comfortably reach.

Now cut the tape that is securing the top edge of the window to the roof.

Using the suction cup you want to pull the glass away from the top edge of the car as far as you can. This will only be a few inches on some vehicles and on others you can go pretty far .. maybe even past vertical.

The idea is to pull the top part of the window far enough away that you can extend the blade of your utility cutter and cut the bead of urethane from the inside of the window.

You must be very careful when you do this and a helper is really recommended to hold the window.

If you can not pull the window out very far you can still support it against the top of the vehicle by placing some towels between the glass and the roof then taping the window back to the roof.

You can then enter the vehicle and make your cut from inside. BE VERY CAREFUL not to damage the dash pad.

Once the glass is cut away you can remove it using suction cups to pull it away from the vehicle BUT DO NOT try to carry the full weight of the window with the suction cups. A gloved hand is best. Reach as far center of the window as you can and lift up and away.

Final Note

http://www.howtopaintcars.com/wp-content/gallery/example-repairs/windshield-urethane.jpg?i=1164144173This is a very difficult job for a professional to perform on their own but it can be done.

A professional will probably take about 15 to 20 minutes to remove the glass. You can expect to take an hour working alone or almost that with a helper.

Note that the two man cord bead cutter is not suggested for urethane beads because it will not cut well. It is to be used with the older bitumen beads.

Also there is no need to heat your tools .. many people think that helps but it doesn’t.

It is a good idea to do this in a warm shop if you can or outside on a sunny day but glass gets hot and this could make it difficult to handle.

The biggest problem when doing this job is frustration.

I can not tell you how many guys I have seen resort to stupidity in the frustration of getting a window out. Some will sit inside the car and use their feet to get some glass out only to crack it.. or to make a cracked window a real pain to deal with.

Remember these things are in there tight for a reason.. getting them out is not going to be a 10 minute job especially if you are not doing this every day.

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