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Posted by: Thack May 19 2006, 08:22 PM

How hard is it to replace and install a windshield by oneself?

Posted by: wbergtho May 19 2006, 09:10 PM

Buy 1/4" butyl tape at any bodyshop supply company and clean the channel thoroughly before install. Treat any rust spots w/ POR 15. Roll the butyl tape off the spool onto the windsheild channel being careful not to touch it with your fingers. Once butyl tape is completely around the channel, snip or cut off the excess. No need to set the butyl tape as your windshield will set it in as you install it. Get a friend to help you hold the windshield and carefully center it and gently press into the butyl tape. Once windshield is holding in place, carefully push the windsheild firmly around the perimeter...all the way around to seat it properly into the butyl tape. DONT PUSH TOO HARD TO AVOID CRACKING IT! You will see the butyl tape flatten as you push. Use only enough force as necessary. Re-install chrome trim...done!

Bill

Posted by: So.Cal.914 May 20 2006, 01:32 AM

Don't forget to put plastic setting blocks under wind screen, you do not want glass to metal.

Posted by: thesey914 May 20 2006, 03:07 AM

What do these plastic setting blocks look like and where do the go? I haven't heard of these and didn't see any when i took the screen out?

Posted by: william harris May 20 2006, 09:06 AM

The plastic (actually rubber) setting blocks are for the back glass, not the front windshield. Factory manual has diagram of tool (wood block works) used by factory. This is to maintain the proper gap between the glass and the windshield while the bond cures. First, I recommend very strongly not to use the butyl tape install method. This is not a structural bond and the modern adhesives are much, much stronger. I got local glass company to install with modern sealants for $75.00 labor charge. Well worth it in my book. If you decide to tackle it yourself, send me your address and I will mail you the spacer used by the glass company (small plastic spacer they placed between glass and cowl) when they set the glass. Good luck if you go the butyl tape route, remember the windshield is the only thing between you and the road in the event of a crash.

Posted by: thesey914 May 20 2006, 11:14 AM

William, so you're saying that if butyl is used is is TOO strong and will crack the glass or something?

Posted by: So.Cal.914 May 20 2006, 02:14 PM

No what he is saying is butyl has been replaced by silicones. And they do work better for sealing against water, and impact.

P.S. We always used plastis blocks between glass and metals. glass will settle in time and you don't want your wind screen up against metal.

Posted by: wbergtho May 20 2006, 02:43 PM

I recommended the butyl tape method as it was the method that was accepted at the time. If it worked well then...it still works well now. He also asked if it could be done by one's self? Using newer more modern methods aren't necessarily a bad idea, but you would more than likely have to bring your car to a auto glass Co. to make use of the new adhesives. I just drove my car over 150MPH on the freeway yesterday and I can attest that my butyl installed windshield is performing flawelessly as they did back in the 70's.

One more piece of advice that I forgot to mention is buy a new package of plastic windshield clips (quantity 19) so you don't have a problem re-installing the windshield chrome.

Bill

Posted by: So.Cal.914 May 20 2006, 05:22 PM

Butyl worked really well on the back window. Silicon can be purchased at a

glass shop or a hardware store.

Posted by: Thack May 20 2006, 07:37 PM

I'll probably install myself and find a shop to put a new black rubber molding set by glue instead of chrome trim.

Posted by: aircooledboy May 21 2006, 08:21 AM

AHHHHHHHHHHH!!!!!!!

NO SILICONE!!! NEVER EVER EVER EVER!!!!!!!!

Silicone is the worst possible choice for any non-engine related automotive application. It will not only trap water, it attracts it, which means big honking rust problems in short order.

A windshield install is not as simple as it used to be. When I was working my way through school, I was an autoglass tech for several years. Back then (late 80s, early 90's), a butyl install would have been the method of choice for a 914, and was similar to the factory seal. Now, there is some question about whether it is a good choice.

The reason is that new urethane compounds provide a dramatically stronger bond to the frame, and thus more structural rigidity in a roll over. No question that is a good thing. Modern standards require a minimum retained bond of 70% after a roll over. Urethane can do that, butyl ain't even close. Unfortunately, 5-10% is a comon average for a butyl seal after a roll over. So, if urethane is so superior, why the question? Well, because modern cars rely on the structure of the windshield bond to protect the occupants in a roll over, but 30 year old sports car don't. Nobody in 1970 Germany considered the windshield frame a structural issue for a second. The sealants used at that time simply couldn't do that. So, we have a built in roll bar in the targa bar instead.

Sooooo, the question is, do you really need the added strenght of a urethane seal? I used to say "no", but after a long talk with by buds at the glass shop, I have changed my mind. Seems to me, given that there is no down side to urethane, it is a no brainer. Unfortunately, as I learned checking up with my glass shop buddies just last week, the modern urethanes are probably not a DIY proposition. You will only be able to get the right stuff at an autoglass shop, and application is not as straight forward as popping a tube into a caulk gun and lettin' er rip.

If you think must do the install yourself, I would reconsider. Having a shop come to your location and doing it will not cost that much ($100ish), and is the better choice. On the other hand, the chances that a butyl install would ever bite you in the ass are very slim. For me, often carting the offspring around in the vroom vroom, that is a chance I'd rather not take.

Posted by: Elliot Cannon May 21 2006, 09:47 AM

When I decided to have my car painted I decided I would install a new windshield myself. I called four auto glass stores asking to buy butyl tape. They all told me no one uses butyl tape any longer. When I finally decided to let them do the installation, they used something (not silicone) in a caulking gun. They first painted a black primer on the glass and on the window frame, laid down a bead from the caulking gun (not silicone) then put the glass in place. The price was $165 total. Many shops include installation with the price of the glass. It was worth it in this case to let the pros do it.
Cheers, Elliot

Posted by: wbergtho May 21 2006, 10:44 AM

You can buy a roll of butyl tape for $15. Put the thing in yourself and save a $100! Oh...I almost forgot to say....don't roll your car over.

Bill

Posted by: 736conver May 21 2006, 02:43 PM

QUOTE(wbergtho @ May 21 2006, 11:44 AM)

Posted by: william harris May 21 2006, 04:50 PM

That is the point. The exact same thing happened to me! As I was preparing the car for paint, I have my 15 year old son helping me remove the glass. The rear glass was a real bitch, had to saw it out with a guitar string and broom handle. Came to the front glass, popped off the chrome, touched the windshield and it literally fell towards the hood. There was absolutely no seal at all. That decided it for me.

Posted by: Rleog May 21 2006, 05:18 PM

QUOTE(william harris @ May 21 2006, 06:50 PM)

That is the point. The exact same thing happened to me! As I was preparing the car for paint, I have my 15 year old son helping me remove the glass. The rear glass was a real bitch, had to saw it out with a guitar string and broom handle. Came to the front glass, popped off the chrome, touched the windshield and it literally fell towards the hood. There was absolutely no seal at all. That decided it for me.

Posted by: Thack May 21 2006, 05:35 PM

It looks like the chrome trim also acts to secure the windshield. There is no big mystery about poly-urethane as a sealant. I'll at least take out my chipped glass and replace the dash pad then decide if I want to put in the new glass. Thanks for all the input. I learned a lot.

Posted by: Mike D. May 22 2006, 12:38 PM

How Apropriate, I removed my old pitted windshield yesterday and need a new one.
I'll just let someone else do it after I prep the surface.

Elliot, do you have the name or PH# of the people you used? Do they come to you?

My windshield was stuck in Good. It must have been replaced by some PO. I'm going to go ahead resto the dash and fix a few other things while its apart.

Posted by: aircooledboy May 22 2006, 02:07 PM

QUOTE(Thack @ May 21 2006, 06:35 PM)

Posted by: anderssj May 23 2006, 07:45 PM

Strongly agree with aircooled boy--never use silicon product for the windshield as it gives off acetic acid as it cures (smells like vinegar), and the acid gives rust a head start.

Modern urethane adhesives are the way to go, applied as outlined in the earlier post.

Best,