New Porsches have done away with "vent" glass as have most modern cars so this feature should be on the Neo914. Apparently this has been done by someone in AK but was too much custom work such that it required constant adjustment and the fabricator would not duplicate them based on these problems. The person telling me the information guessed the donor glass came from a Jeep. Miles claims one was done with Miata door glass but they come with a vent window like the 914…?

Installing them will require a triangle "filler" so the front rail will have enough space to be mounted and there will be more than a "point" of the glass in the rail. There are two metal pockets that strengthen the hinges and there is a door stop mechanism which will interfere with a rail at the forward side of the door. Since the door is relatively short, there is very little room for structure below the window to firmly hold the window upright in extension. Some doors actually bond a mount up on the glass for the lifter. If I can’t find an existing side glass that works I'll go ahead and cut a plexiglass piece to develop the lift mechanism. If there is enough interest I’d consider having them manufactured. I’ve got tooling estimates and they can produce them out of tempered or laminate glass. A kit may not be feasible since the door will require cutting and fabrication to fit the glass, rails, and mechanism. It would likely be a complete door with core charge.

The door and various pieces, including an electric window motor from a Mercedes...

Here’s the door glass pieces, notice the "notch"...

I traced a single piece template of the two pieces. The dimensions are ~33” long and ~17” max height...

I test fit the template on dozens of cars at a dismantler and found very few modern cars have windshields with the positive angle or rake of a 914. Every car including commuters had lower rake and wide radius’ between the front edge and top of the glass. I began to look at 70’s and 80’s coupes of which only a SAAB has a more upright rake. Need to make a more rigid template!

VW, Volvos, and BMWs had lower rake. I didn’t’ have a chance to look at Jeeps…Matching the front rake AND rear angle is the challenge. I actually found something close within ½” but the A-pillar has a sharp radius and the front corner is not cut off which is necessary for rail fitment.

What about MR2 or Fiero or similar? Saw many of those at local dismantlers.
-B

heh damn if they aren't! I was told the glass was out of a Miata door... can't be so.




M

QUOTE (Brent @ Sep 5 2005, 12:00 AM)

What about MR2 or Fiero or similar? Saw many of those at local dismantlers. -B

Fiero had alot more rake and radius at the top of the a-pillar plus it is wider. No MR2's at Commercial St. PNP but it's interesting how many cars have much more lower rake than the 914's. Even the upward seated cars (taller) have more windshield rake, dam stylists...

QUOTE (Neo914-6 @ Sep 5 2005, 05:09 AM)

dam stylists...

You should see their hair.

QUOTE (Neo914-6 @ Sep 5 2005, 02:09 AM)

[No MR2's at Commercial St. PNP

I saw two there just three weeks ago. It was in the Toyota section, just after entry. Maybe, this is a diff place... the one off 13th and Berryessa By the Flea Market? I was checking the engine vent ducts. One gold one and one red one. I can meet you there tomorrow. Still 50% percent off I beleive.
-B

QUOTE (redshift @ Sep 5 2005, 01:08 AM)

heh damn if they aren't! I was told the glass was out of a Miata door... can't be so. M

Can anyone substantiate this:

QUOTE

The major problem you will face is glass support. The factory in late 72 decided to go with solid glass to cut cost. What they found was that less than 2 inches of glass was left in the door when the window was rolled up. This was not enough support and let the glass move in and out not letting the window seal. So they built a big T looking brace then they had to box the upper structure of the door to support the brace.  They found it would cost more to re-tool their equipment to make the changes than it would save in the long run

Hi Felix

I have been looking into this for about 10 years, and have came to the same conclusion, retro fitting something else.
I plan to rake my widshield...if you can PM me to whats close (car model) for a rake. Also what is the blue car? It looks like a RX7 ?
I have the CHT catalog. Inside they have many models of universal fit regulator/motors, lots of hardware including glass mounting and rails with squeagys. Thats the route I,m taking but I think you are going for a more OEM mod.

Thanx for the research, I think this is a viable mod.
Later

QUOTE (MecGen @ Sep 5 2005, 01:49 AM)

Hi Felix I have been looking into this for about 10 years, and have came to the same conclusion, retro fitting something else. I plan to rake my widshield...if you can PM me to whats close (car model) for a rake. Also what is the blue car? It looks like a RX7 ? I have the CHT catalog. Inside they have many models of universal fit regulator/motors, lots of hardware including glass mounting and rails with squeagys. Thats the route I,m taking but I think you are going for a more OEM mod. Thanx for the research, I think this is a viable mod. Later

I seriously contemplated raking the windshield then you would only need to match the width and the b-pillar rake. I wish there was a database the windshield companies would let you view...

New is not out of the question but I'd have to "invest" in tooling...

QUOTE (Brent @ Sep 5 2005, 01:37 AM)

QUOTE (Neo914-6 @ Sep 5 2005, 02:09 AM) [No MR2's at Commercial St. PNP I saw two there just three weeks ago. It was in the Toyota section, just after entry. Maybe, this is a diff place... the one off 13th and Berryessa By the Flea Market? I was checking the engine vent ducts. One gold one and one red one. I can meet you there tomorrow. Still 50% percent off I beleive. -B

That's the one, I missed those MR2's. I believe the b-pillars are straight on them, though. May meet you if I can find an hour. I'd like to pull one of the glasses to check what's inside the door...

I can go and do the dirty work for you. I will take many picks with my new point and shoot.
-B

QUOTE (Neo914-6 @ Sep 5 2005, 05:41 AM)

QUOTE (redshift @ Sep 5 2005, 01:08 AM) heh damn if they aren't! I was told the glass was out of a Miata door... can't be so. M

Hey, I WAS JUST TOLD, I NEVER ACTUALLY LOOKED AT A MAYNOTAUGHTA!



NO! I CAN'T LOOK!


M

QUOTE (redshift @ Sep 5 2005, 05:05 AM)

QUOTE (Neo914-6 @ Sep 5 2005, 05:41 AM) QUOTE (redshift @ Sep 5 2005, 01:08 AM) heh damn if they aren't! I was told the glass was out of a Miata door... can't be so. M Hey, I WAS JUST TOLD, I NEVER ACTUALLY LOOKED AT A MAYNOTAUGHTA! NO! I CAN'T LOOK! M

So you made ME look at it!!

QUOTE (Brent @ Sep 5 2005, 02:06 AM)

I can go and do the dirty work for you. I will take many picks with my new point and shoot. -B

Brent, that would be great, I'd pay you for it since It would allow me to have something to visualize and plan the mounts.

My daughters having a play date so gotta make sure they don't get hurt or hurt each other.

Here's the planned end result for those who missed the Neo914 thread...

If you change the rake of the windshield, the targa top won't fit correctly.

It will if you add material to the hoop, and section out the top.






M

What about the curvature, isn't that a crucial factor? If you could find an oversized window with the right curve it might be possible to have it ground down along one or more edges to meet your needs. Might be cheaper than having new windows made.

Do you guys find yourself staring a little too closely at all the other cars on the road looking for donors?

I do.

The MR2's were promoted to the compactor! I can't believe they were gone so quickly. There was still quite a bit for the vultures to pick clean.

I did take several picks of Rx7's there. They have many generations available.

Did you also catch the 944? The rear flares are in great shape. Never saw that done in a teener before. Someone scavanged only half of the calipers. I wonder why?

-B

Uhhmmm... Mr2... Miata... ... Mr2... Miata...

You know, It may not have been a Miata?

I may remember the wrong thing.. is that scary, or 'ok'? ... ok, well I am going to go now..

Uhhmmm I looked on google, and I am positve.



M

That I remember it wrong.. it absolutely is the Mr2.. jees..

QUOTE (jonwatts @ Sep 5 2005, 01:00 PM)

What about the curvature, isn't that a crucial factor? If you could find an oversized window with the right curve it might be possible to have it ground down along one or more edges to meet your needs. Might be cheaper than having new windows made. Do you guys find yourself staring a little too closely at all the other cars on the road looking for donors? I do.

Just don't stare and crash. A piece of posterboard would make a nice, relatively stiff template. Have you looked at how this mod has been accomplished on other vehicles?

It seems to me that if the curvature of the glass was right, this suggestion is the hot ticket

A hot rod guy would make aluminum templates, wussies.


M

QUOTE (redshift @ Sep 5 2005, 05:02 PM)

A hot rod guy would make aluminum templates, wussies. M

Y'all I just need a template for rough measurements. I've found one close so now I can make a rigid template or buy it for trial fit. Besides they don't allow bringing in "parts" into this yard, I have to be somewhat

Yes Jon most glass is curved...

Might want to take a look at early - mid 90's subaru's ... My wife has a 93 legacy and they have the big window without an upper frame.

I just eyeballed it tonight and it looks like the windshield has more rake, but it might be good to open up the doors and see how they supported the window glass without the upper door frame. I measured her glass at ~30 inches wide and ~17 high fyi.

Lemme know and if you want I can snap some pics...looks like a fun project.

Tony

QUOTE (Qarl @ Sep 5 2005, 12:48 PM)

If you change the rake of the windshield, the targa top won't fit correctly.

Karl,

Change usually prompts more change.

The BBR kits require more rake and they have to cut the front to back length of the top.

The guys who section the a pillar ala hot rods actually have to add top sections in both directions. The bad thing is it won't fit in the trunk and is heavier...

If I can keep the rake, I will. I like most of the profile and think it makes the 914 distinctive.

QUOTE (cha914 @ Sep 5 2005, 07:09 PM)

Might want to take a look at early - mid 90's subaru's ... My wife has a 93 legacy and they have the big window without an upper frame. I just eyeballed it tonight and it looks like the windshield has more rake, but it might be good to open up the doors and see how they supported the window glass without the upper door frame. I measured her glass at ~30 inches wide and ~17 high fyi. Lemme know and if you want I can snap some pics...looks like a fun project. Tony

Tony,

I wouldn't mind seeing the mechanism if you were planning on opening it up. That window is too short and tall. frameless glass requires alot more bracing so cars usually have larger doors with more space...

did you look at volvo 740/760's? they have a pretty upright front window also...

QUOTE (Aaron Cox @ Sep 5 2005, 07:55 PM)

did you look at volvo 740/760's? they have a pretty upright front window also...

I looked at earlier Volvos but I'll bet these have more rake. The newer the more rake. Even the 80's cars had more rake. You also have to look for coupes because the glass in 4 doors are too narrow.

Did you help Jason? I notice he hasn't posted his Boxster thread yet...

Felix,

First, you are wasting your time looking at any window that has a frame. Here's why: If you remove the 914's vent glass, you will have a frameless door window. Frameless windows require alignment fixtures on the glass as well as the door frame to get them into the right spot and hold them there when they close, and to keep them in the right general orientation when they are open. Framed windows are held in the right position by the frame as the window goes up and down, and don't need or have the alignment fixtures. The frame steadys the glass while the regulator raises and lowers it. A 914 is a semi-framed window, because it uses the front channel between the vent and the door glass as the primary guide when the window moves up and down. A semi-frame window, like a frame window, does not need alignment fixtures. The problem with looking at a framed window as your donor is that you can't add the neccessary fixtures to a door glass that wasn't made for them, because they are attached using holes through the glass, and you can't add holes to a tempered door glass. Thus, you won't be able to take a glass from a framed door and make it work in a frameless application because it wont have guide fixtures, and they can't be added.

Second, my educated guess is that you would not be able to put a fully functional frameless glass in a 914 door for 2 reasons: 1. You would have a nearly impossible time fab'ing the necessary fixture guides into the inside of the door cavity. Those fixture guides are usually part of a pretty sturdy framework stamped into the door's frame. I think that would require a ton of pretty precise support engineering and fab, and in the end, a 914 door is just too narrow to accommodate the whole deal. Assuming you get past that hurdle, you get to the bigger obstacle; 2. Even when fully raised, frameless door glasses have a large portion of glass below the top doorline that would not likely fit into the short 914 door body. Frameless windows need a good 20%ish of their glass mass to stay inside the door even when fully raised to provide enough leverage for the fixtures to hold the glass firmly in place. A stock 914 regulator rests within an inch or so of the bottom of the door when the window is all the way open. That means that when you add the needed extra glass at the bottom of a frameless glass, you would not be able to roll the window all the way down, because the glass will bottom out inside the door.

Just my .02 based on my years in the auto glass trade.

Chris,

I am more confident because it's already been done but I believe the window did not fully retract which may support your 20% estimate. I realize finding an existing glass the right size is unlikely, then to make any glass rigid without a frame is more challenging especially in the small door. The first order is finding a glass with a close enough shape to utilize in designing the door frame and structure that it will need when fully extended. If I don't find one, a plexiglass piece will be used for development, weighted of course. It may take several iterations but it's a start...

good input!

To be honest, when you said you had a quote for making a one of a kind tempered door glass that did not make you faint, I was amazed. Last time I looked into doing that for a guy, it was about $1500 for the 1st door glass, $500 each after that, and no guarantees as to fit. And remember, you need to double that, since R&L door glasses have opposite profiles. I can ask my old buds at the glass shop if that has changed for the better. I am their "corporate counsel" now (I take care of all the employee legal problems, and I get all my glass needs at cost ).

We used to have a PPG catalog of all auto glass pieces and there was a drawing of each glass, but no dimensions as I recall. If that interests you, I can see if I can get one for you. Not sure how much help it would be to you here.

That catalog could be usefull as long as they are to scale. I could reference a known measured glass.

Do you know if there are any methods to cut or trim tempered glass? I know of a company with a good abrasive for removing scratches.

QUOTE

Do you know if there are any methods to cut or trim tempered glass?

Sorry bud, no dice. Tempering makes glass harder by "squeezing" the crystal structure of the glass together as tight as it can be, using heat. Once glass is tempered, any damage to the structure of the glass anywhere causes the structure in the rest of the glass to fail like dominos. That's why tempered glass is a kind of "safety glass"; its very hard, but if you crack it, it disintigrates into thousands of tiny much less dangerous pieces. Even trying to polish a chip in the edge of a tempered piece of glass is risky. Cutting it or removing anything more than about .5mm is literally impossible.
I'll see what I can find on the old catalogs.

are you sure it can't be cut with a water saw?


M

Yeah, I saw the Wonder Twins do it once. Or was it an ice saw?

Even the one-piece windows kits for bugs are a PITA and they have a frame.
I'll never do one again on my cars.

Just my opinion...good luck

QUOTE (redshift @ Sep 8 2005, 02:23 AM)

are you sure it can't be cut with a water saw? M

Pos-o-tive.

Any breach of the structure, and you have an instant 100,000 piece jigsaw puzzle.

If you ever have a garbage piece of tempered glass laying around, try this for a little fun: position the glass over a trash can (saves clean up later ), find the closest thing to a 90' corner on it, and tap that corner with a hammer. Don't wack it hard, just tap it. Any edge will do, but a corner is the ultimate weak spot on a tempered glass. You will be shocked at how little force is needed to "blow" the glass, and when it does, there will be 1000's of pieces, and not a single shard will be bigger than 5mm across. No matter how it happens, if you break the chain of the glass structure, whether by hitting it or cutting it, the result will be the same. KABLOOUUY!!!!

I appreciate the fact that you have 20 years of experience with glass, but if I had a tile wet saw I'd just have to see this for myself. Anybody have a wet saw and a spare vent window?

Have at it my man. Just make sure you've got a shop vac handy.

Well I got the RX7 glass to test fit angainst the door. Close in width, and both side angles but I knew the glass section under the vent glass would be a problem. This should help illustrate some of the challenges:

Here's the problem which is bigger than what cutting and welding can solve.

Another is the overall size vs. the door space to get the glass to completely retract into the door...

And yet another problem to solve is having the correct bend, the 914 is the flatter one is on top.

There may be the right shape existing but there are several features and dimensions that are needed. I've decided to go with a hard coated polycarbonate for the pre-production version called Speedglass It's used for racing for it's weight advantages but the coating should at least hold up to a door wiper.

First I'll fabricate a harder template of plastic or masonite to develop the lift mechanisms. Then get a pair of blanks and cut to size. If this is prod. reproducible, then I'll consider tooling. An alternative to tempered glass is laminate (like windshields) but still require the fixtures for the heating process.

Is there no possible way to heat up the glass without braking? that would allow it to be contoured less...