V2Rocket

Howabout the rearview mirror glue? Designed to hold non-porous metal to glass, in constant sunlight and heat...and readily available.

I am going to try a local shop this weekend, but might experiment with my spare hatch with the rearview glue...


For those who have been around 944s and their hatches longer than I, let me run this by you as my understanding of the failure.

We know the glue is susceptible to UV/sunlight and degrades. The glue was applied to a sort of paint on the glass designed to protect it from sun. This degrades, allowing sunlight to reach the glue, causing it to fail.

The issue with the hatch struts is this - although the struts are connected to a sturdy part of the hatch frame, as a whole the frame is very flimsy.
With the window closed, the struts are trying to expand, pressing against the mount on the hatch frame with all their might. They of course cannot expand because the hatch is locked down by the pins.

However, the pins are not a precise fit, there is quite a lot of wiggle room for the hatch to move about there. The only really fixed part of the hatch assembly is the hatch hinges, securely bolted to the roof. This part of the frame does not move, rather, the rest of the frame and glass is pushed away from it (the flimsy hatch frame can bend and flex enough to allow this to happen) which we see as the "gap" from glass to upper frame. This is exacerbated by the lifting of the hatch to open it - the struts pushing where they push vs the fixed hinges flexes the frame at the big bends which allows the glass to work loose further.

While we can mess with all the glues in the world, what might be the surest solution would be a solid restraint to prevent the glass from migrating away from the hinges...I am thinking of two straps of sorts, strips of metal connected between the hinges and the pins and run under the glass, that would be under tension. The struts could push all they wanted on the frame, but the top of the frame and the bottom of the frame will be connected so they cannot deflect and migrate apart.

Alternatively (or additionally), we could explore other options of keeping the hatch open, that do not apply pressure while not needed. The broomstick is one, but I like 12v linear actuators...

whalebird

Spencer, I've considered the same idea. However, instead of running strips of something from hinge to pin, My idea was to fabricate a rigid "turnbuckle" type of thingy that could be attached to the frame flange where the strut itself attaches: a drilled hole with a tiny heim joint. From there a piece of thread stock from the heim joint to the hinge. I noticed this is an almost straight shot along the interior glass contour with minimal intrusion into the storage area. The biggest challenge is an attachment to the frame in the area of the hinge. I considered drilling/tapping small holes in the frame in the area of the hinge where the hinge and its weld would offer more bite for a fastener. Then just fab a bracket that bolts to the inside frame to receive the thread stock with another heim joint or whatnot. I need a spare hatch to play with. alternatley, a simple "hook" of sorts could be fashioned to grab hold of the frames exterior lip (which has a nice groove in it) and protrude into the car across the seal that could receive the thread stock. This would have to be thin so as to allow the seal to function, yet rigid enough to carry the tension of the struts. A thin section of stainless like a brake backing plate may do the trick. If a simple "hook" as described were placed just inboard the hinge at the top and held in place with tension from the thread stock and heim joints AT the strut mount, it would consume almost all of the force that's transfered through the glue as original.
My only reservation with this is the rist of injury these links would pose in a crash. It seems they would be pointed straight at the occupants head.
I hope my idea makes sense as described. I could probably draw a picture in the dirt with a pocket knife easier than type it out.
I feel certain a simple reliable aperatus would prevent hatch delamination, and sell like hotcakes if it were a no drill/weld install.

ehall

Good thread. Great info here!

afx

Anyone have any updates on how well these Sitka products have been working, or even the 3M ones?

Would be great to hear about how it has held up in the long term with specific products.

Just got a new 944 with the hatch coming apart and will need to do this soon.

tj90

Im actually thinking about the welding tab idea that Dandy Don has. DD, any updates on the success of this modification? Would you still consider a strip across both hinges? Im thinking that maybe its better to have both hinges to "float" relative to each other... I dont konw if a more solid connection will stress the glass or cause creaks or noises. How thick are the aluminum tabs that you used. I see that the strut mounts use a thick piece welded to the frame.

It seems that the Sika products are giving everyone good results. I need to order the kit.

Finally, I installed new struts and noticed that the act of closing the rear glass at the spoiler lifts the glass as well. Its like the struts are a fulcrum point. I wonder if it would help to close the glass directly over the struts to minimize the stress that the glass to frame seal has on it.This motion seems worse than the deck lid sitting there in a closed state.

Your comments are appreciated. Im new to the 944 world so Ill be learning from everyone on RL.

Regards,
TJ90

superloaf

Thinking about tackling this and wondering if the Sika is still holding up as the best adhesive to use? I found the Sika ASAP Superkit online for $18; how many kits are needed? I figured this product would cost much more so it's refreshing that it's so affordable.

http://www.chemical-concepts.com/sik...00-ml-ctg.html

Thanks for the ongoing thread about this problem which affects every single 944 owner....


*EDIT--Ok, should have known that was too easy. The kits are only sold in minimum 24 quantity.

alordofchaos

Sooooo..... group buy?

jbob

i am looking to solve an old leaky hatch. I would be interested in any group buy or definitive writeup. it's funny that we all share a similar nagging issue

tj90

Put me down for a group buy. If it helps, I would like to suggest each of us buys 2 kits. Still affordable - you'll have extra just in case you need to do it again in near future - and we could order with only 12 people in case response is slow.
Tj90

951Tom

Has anyone looked into or heard of using Dow 795 adhesive? It's designed for structural glazing of glass to window frames when there is no mechanical fastener used. It's used extensively in the marine industry for attaching port & hatch glasses to their frames. No primers are needed just a clean surface. The only negative thing I found is a 14-21 day cure cycle. Based on Dow's info sheet, it sounds perfect for this application.

jbob

Is everything but the adhesive choice basically a method that everyone is basically doing similarly? clean metal and glass with a straight razor and then glue and clamp for X days? I like that idea of creating more of a large glue area via a tab. I would love to see some pictures or hear what is currently the state of the art. that marine adhesive sounds potentially beefy

superloaf

Group buy sounds good but I wish we had an expert or even glass shop person to assist. I was reading some of Sika's instructional info and there are so many different primers, cleaners, and even adhesive depending on whether you're working with glass, metal, rubber, plastic, or even for blocking UV etc that it's quite complicated. Sika makes a lot of different adhesives so I'm not even sure if the ASAP is the best. Some have to be heated first so I can say we wouldn't want that added complication. I guess a few different adhesives will work so there I go overthinking it all but it would be nice to have opinions from experts.

I emailed CRL (Sika distributor) to ask who would sell the kits individually and although they sent me some places, they all sell by the case. My problem is I'm in Nashville working on my car (timing belts, oil pan gasket, rod bearings) so I have the time and place right now which I don't have in LA. A group buy would probably take longer than I have right now but still interested....

pdxfj

Just so happens I'm having a new windshield installed in my car on Monday. Since making the appointment and getting the necessary weatherstripping from Germany I have noticed my hatch is starting to come apart as well.

I have chatted with the most experienced person in the shop (25+ years) about the windshield. I am going to make a point to chat with him about my hatch and what he thinks of the different adhesives available to do the reseal.

Will let everyone know what he says.

KVDR

I'm taking my delaminated hatch apart next week. I would love if someone posts a solution before then.

I haven't taken a close look at the area yet - but has anyone considered modifying the hinges, drilling through the glass and using bolts? The 80's Camero looks to have a similar configuration, but I'm sure there are others.

tj90

@YYC - DandyDon above welded tabs to the hinge points effectively increasing the surface area of the bond. I reached out to him as well as PM him and he didnt respond. I think I am going to go that route despite not hearing back from him.

My glass is so bad after installing new struts that Ive got a gap across the entire top edge. Im really limiting my miles with the car as Im concerned about the glass.

The camaro idea is a good one but I dont think youlll find many willing to drill on tempered glass. I am anxious to get this fixed but I dont want to disassemble unless I have the repair kit in my hand.

I am sure there are several ways to skin this cat - Sika, Dow... I am partial to Sika products. However if there isnt enough interest I will start looking into alternatives. Im sure DOW has an equivalent to the superkits (if anyone knows cross reference, please chime in). A quick search on Amazon yielded results of various urethane products and primers in single count quantities.

Regarding Sika group buy, lets have a count of hands -
TJ90 - 2 kits....

If this doesnt go anywhere in the next few days, Ill need another solution as I want to drive my car!