Author Topic: Rear Window Install - Butyl Tape or Urethane Caulk?  (Read 5796 times)

kboehringer

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Rear Window Install - Butyl Tape or Urethane Caulk?
« on: October 22, 2014, 08:58:17 PM »
TAC Guys,
I'm getting ready to install a new rear window with defrost into my T/A.  The old window was scratched to heck and I couldn't get most of the scratches out.  I found a nice rear window without any scratches (and defrost) for $20 local.

A few years ago, when I was just starting on this car, I removed and installed the rear window using urethane caulk.  Unfortunately, it didn't work out too well.  The window "sunk" and the trims fit against it poorly.   I BELIEVE the factory used butyl tape for these?  It is my guess that the window will be less likely to "sink" again and may maintain the proper relationship to the opening and the trim using tape?   When I installed it in the past I did use the spacers with the urethane that were "supposed to" help maintain the gap.  It could have been the Georgia heat or some other mistake on my part but I do NOT want to screw this up.  Any advice would be appreciated......



The opening prep is almost complete.  I've removed ALL of the old adhesive and the new glass is spotless clean.  A small amount of corrosion has been removed, the area primed, and top coat Martinique Blue has been applied.  I only need to paint the rear edge (visible under the lower glass when installed) black to match the interior color. 

They sell butyl in a variety of widths and thicknesses.  Which one is correct for a 2nd gen?  Did I screw something up with the urethane?  What is the best? When you did it, how did you keep it from "sinking"?

Any advice appreciated.......

Kurt

P.S. Local window installers won't install it as it isn't their glass.  They don't have new rear glass but still won't install mine. :-?

leonpiper69

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #1 on: October 22, 2014, 09:29:39 PM »
While you CAN use butyl it is not recommended for rear or front windows. It just doesn't have the holding strength.

Always use the urethane. I always use 3M Window Weld. It can be hard to get a thick enough bead. When you use it you always feel like you won't have enough when you lay it on so you lay it down thin and that causes it to sink in.

It takes practice to really know how thick of a bead to it will support the glass right.

Honestly it might be worth checking with a local glass guy to see how much he would charge to install it.

Not that you can't do it. But when you add up the cost of the correct materials (urethane and primer, don't forget primer) how much extra is the cost of having a pro do it? Might be worth it to you, might not. Just something to consider.
74 firebird

kboehringer

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #2 on: October 22, 2014, 10:06:49 PM »
Honestly it might be worth checking with a local glass guy to see how much he would charge to install it.
Leonpiper,
Thanks for the response.  I've tried the local guys.  None will install the glass as they didn't provide it.  I've even offered that I expected no guarantees but they still won't do it.  Gonna have to do it myself.

P.S.  I grew up in Levittown, Mill Creek to be exact.  Went to Lincoln Elementary, B. Franklin Middle, and Woodrow Wilson H.S.  Still have a sister & bro in that area.

Kurt

leonpiper69

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #3 on: October 22, 2014, 11:06:58 PM »
We live in Whitewood (just around the corner). We have been here 5 yrs but are just stationed here so probably moving somewhere in the next couple of yrs.

That stinks that none of the local will help you out. I have always managed to get hooked into the local car scenes wherever we end up so luckily I kinda always knew someone who knew someone.

When we were back in IL at Scott AFB I could give the local safelite guy a few bucks and he would do it in his off time. Even hear I used to have to search the safelite guys truck when he came on base and we chatted and he gave me his card and said he would do it on the side. The key is to talk to the installer and NOT the office managers.

If there are any local body shops, I would try walking in and chatting someone up and paft out asking if they know anyone who is a glass guy who will do it in their off time for some cash, it can't hurt.

The only reason I really suggest the pro's for glass, is it comes down to cost vs reward. If I save a few bucks doing it myself but I am to happy with the end result then it could have been the same cost or less to pay a pro vs paying for materials twice.

Heck sometimes it's cheaper in the long run. When I narrowed a 9" it was cheaper to pay to have the housing ends welded than buying the tool (the alignment bar cost 400 dollars and they charged me 100 to weld it). So even though I might be able to do something, sometimes it is worth it to farm it out.

I wouldnt give up on trying to find a guy. If you talk to a body shop guy, tell him will give him cash and don't even want a receipt.

 
74 firebird

richchsr

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #4 on: October 23, 2014, 12:28:41 PM »

Grand73Am

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #5 on: October 23, 2014, 08:34:29 PM »
A Fisher Body Manual for your car gives the procedure for replacing the "stationary" glass, meaning the windshield and back glass on these cars of course. So, if you have a copy, it has some good info. If not, I can't spell out the whole thing, but I can tell you that they say to use a bead of urethane that is 3/8" high and 3/16" wide. Supposedly the urethane tube nozzle will be marked with lines where you cut the nozzle to achieve those dimensions. I'd figure the glass will settle to about 1/4" high. They say that's the max height you want.

In the book, they apply the urethane bead to the inside edge of the glass instead of the pinchweld, which I guess makes sense, because that's where you want the urethane to be. It would take extra care not to disturb the urethane when handling the glass though.
If you squirt it around the pinchweld instead, you could miss the edge of the glass when you sit the glass in. Not a disaster, but an inconvenience. A pre-adhesive fitting of the glass to the hole and some marking could insure the adhesive placed in the pinchweld would be in the right place. 

They also used glass primer around the edge of the glass and would also use it on paint like you have, before applying the urethane for better adhesion. Of course, that was in the 70's and I'm not sure primer is needed now with the modern Windo-Weld urethane. It might be primer-less. Something to check on anyway. 
Steve F.

kboehringer

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #6 on: October 23, 2014, 09:49:59 PM »
This should help
http://www.powernationtv.com/episode/DM2014-17/glass-tech-101
Rich,
Thanks.  This was a good help.  Even though the guy was using modern adhesives he did use the window primer on the glass and the body.  Pretty cool he was working on a T/A! :D
He did however put the sealant on the body and not on the window as described in the Fisher Manual. Obviously, it's a whole lot easier to lift and place the glass that way.
I found that Summit has the sealant but they show no listing for window primer.  I won't install it without the primer.....my PPG store may have some...
Thanks again,
Kurt

kboehringer

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #7 on: October 23, 2014, 09:58:16 PM »
So, if you have a copy, it has some good info.
Thanks for reminding me!  I have one for '79 & one for '75.  I've read the entire chapter #11 (stationary glass) and I'm going to give this a try again on my own.

I was able to find one guy that said he would install the window.  He wants $150 and offers no guarantee & no warranty on leakage.   I figure the supplies will cost me about $30.  If he had said $100 I would have bit the bullet and given him the C note.   Looks like about 30 minutes (or less) for a guy that does this on a regular basis.  I think $150 is more than a little high since I had a brand new window installed in the front for only $170 a year or so ago and that included the new glass.  The guy's storefront is also less than 2 miles from my house.  Not exactly a long trip....

I'm gonna give it a shot again on my own.

Thanks again,
Kurt

Grand73Am

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #8 on: October 23, 2014, 10:22:02 PM »
So, if you have a copy, it has some good info.
Thanks for reminding me!  I have one for '79 & one for '75. 

I have the same ones, and a 73 manual too. I always get the factory manuals for any old car I get.

I've done a few of my own glasses, since I rather do it myself (and to save money), and they've been fine. 
Steve F.

leonpiper69

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #9 on: October 26, 2014, 09:51:00 PM »
So, if you have a copy, it has some good info.
Thanks for reminding me!  I have one for '79 & one for '75.  I've read the entire chapter #11 (stationary glass) and I'm going to give this a try again on my own.

I was able to find one guy that said he would install the window.  He wants $150 and offers no guarantee & no warranty on leakage.   I figure the supplies will cost me about $30.  If he had said $100 I would have bit the bullet and given him the C note.   Looks like about 30 minutes (or less) for a guy that does this on a regular basis.  I think $150 is more than a little high since I had a brand new window installed in the front for only $170 a year or so ago and that included the new glass.  The guy's storefront is also less than 2 miles from my house.  Not exactly a long trip....

I'm gonna give it a shot again on my own.

Thanks again,
Kurt

Yeah, that is WAAAAAAY too much money. Most the guys I knew back in IL would have done it for like 60 bucks (like you said about 30 bucks worth of materials).
74 firebird

brdzword

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #10 on: October 30, 2014, 07:34:32 PM »
I also plan on resetting my rear window on my 76 Formula.  I used the Butyl 3/8th thick and it sat perfectly.  Problem arose when the slowly slipped downward during the hot summer heat.  I forgot to use the rubber blocks at the bottom edge of the window and  they stop the window from sliding downward :( .  These are my new planned steps:

1.Pre-fit the window without the Butyl.  Put blue painter tape
   across the body and window at the bottom and top.  Slice
   the tape nice and straight.  This will give you a center point
   to line up your window before you set it down.  If you screw
   up too much to the left or right.  The window won't budge much
   once it makes contact.  Shift it left or right after setting it down
   will only compromise your seal.  Remember to place your
   properly cut stops to size/thickness at the bottom for even spacing
   at the bottom of window.  It should be equal to the top of the
   window spacing at the roof edge.

2. Use heavy duty suction cup handles (2).  I found mine for
    cheap at Harbor Freight.

3.  Use Butyl 3/8th and wrap it along the edge of the window
     *start from the bottom center and finish at the same point.
     *be sure to install the rubber stops at the bottom edge
     *be sure the rubber stops are a snug fit. Some stops are
       a bit to narrow, modification, alternate rubber blocks may
       be needed. You may have some good rubber laying in the garage
       that may be cut to size.  Just don't cover the drain holes.

4.  This may take 3 people.  Two to lower the window and one to
     navigate the blue tape lines and assure true center.

     Good Luck!

Question for you guys.

1. What do I use to remove the sticky butyl residue prior to installing fresh butyl?  I don't want to harm the rear window aftermarket tint.  I thought perhaps that WD might slowly work it off.

2.  I was considering placing 4-6  1/4in. perfect rubber blocks within the Butyl ribbon to keep the window from squishing downward too much beyond the original 3/8th thickness.  What do you think?
« Last Edit: October 31, 2014, 06:53:16 PM by brdzword »

Grand73Am

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Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #11 on: October 30, 2014, 08:36:43 PM »


1. What do I use to remove the sticky butyl residue prior to installing fresh butyl?  I don't want to harm the rear window tint.  I thought perhaps that WD might slowly work it off.




If it's a factory tinted glass, you won't harm the tint, since it's in the glass not on the surface. If the residue is fairly thick, you can carefully scrape it off with a new razor blade. What's left can be removed with some lacquer thinner.
Steve F.

Re: Rear Window Install - Butyl Tape or Urethane Caulk?
« Reply #11 on: October 30, 2014, 08:36:43 PM »
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