Interior Question #1

I browsed the internet for info on glues that are good for this discussion. It seems like peel strength , tensile strength, and elogantion are the most relevant performance indicators. The unit for peel strength is PIW which is roughly 1lb inch of width (not area because this is a peel test). Tensile strength is usually tested with a shearing force between two plates. Elongation is a test of distortion over time for a given constant force.

I checked the datasheet on a 3M epoxy (DP125, roughly equivalent to their "5 minute" stuff you find at the big-box home improvement stores.
Peel strength is dramatically sensitive to temperature: at 70°F it is 35 piw, but at 150°F it falls to less than 1/10th the original (3 piw). I realize 150F is hot, but perhaps that's realistic for a car parked in the Arizona sun for a few hours (black interior).

Sheer strength: at 70F it is 4300psi, and at 150F it is only 450psi.

So maybe this type of epoxy is not the best.
I'll see if I can find some data sheets on gorilla glue and construction adhesive.

John
 
John, thanks for the leg work. I get jealous when I hear engineering talk since I was once one but it was long ago. I had a Dynamics professor that said " You should only know as much as I have forgotten" Now I say " I should only know as much as I have forgotten".
 
John,

Your estimate of temps is about right. When I lived in AZ in the '60's, both Ford and GM had proving grounds near Phoenix. I knew a fellow who worked at the GM grounds. He said two hours in the mid day AZ summer sun brought the interior temps up to about 155 degrees F. That was about the maximum, as the car radiated as much heat as it absorbed after that!

Bavbob, being in MA, may only experience a maximum of about 125 degrees F or so.

Gary--
 
Gary Knox said:
John,
Your estimate of temps is about right. When I lived in AZ in the '60's, both Ford and GM had proving grounds near Phoenix. I knew a fellow who worked at the GM grounds. He said two hours in the mid day AZ summer sun brought the interior temps up to about 155 degrees F. That was about the maximum, as the car radiated as much heat as it absorbed after that!
Bavbob, being in MA, may only experience a maximum of about 125 degrees F or so.
Gary--
Click to expand...

What we don't know is the minimum strength required to keep the vinyl/foam trim stuck to the hard under-structure. 3 lbs per inch of width doesn't sound like a lot, but if the edge that's trying to peel away is 10", the epoxy should withstand 30 pounds of force. I'd guess that's probably enough.

The other thing that might be worth looking into is if there's a way to make the plastic skin of the trim a bit more flexible, but without stinking it all up with wintergreen oil. I would think the biker trick of soaking in alcohol + some non-odiferous oil would work. Maybe that's what those interior vinyl trim conditioners do?
 
Seems like 3M Scotchweld 2214 Hi-Temp New Formula is better.
It loses ZERO strength going from 70F and 180F. I didn't understand their data on peel strength (not in PIW units).
 
I will follow you guys regarding all differing strengths etc.
Living in the north west of the UK where everything is green, cold and damp most of the year - normal HT works a treat -
Now Phoenix Arizona is the polar opposite to the UK - would love to go there and have a good look round the aircraft boneyard ( if you can)... may be able to get rid of my thermal underwear and put on some shorts for a change and get a bit of sunshine.....
 
Well that's why I heated it to 170 then clamped it, to soften the vinyl instead of forcing it and cracking it. I got some additional play.
John, any numbers on 3M strip caulk which somebody used in some post and said it lasted a few years? Yes, car won't see much heat so not worried about high temp effects, I will not drive often and certainly not let it sit in the heat. Gotta be garaged as required by Hagerty.
 
On a previous E9, I used tiger seal, what they bond car body panels together with, and 4/5 speed cramps. Leave it for a decent amount of days, and it worked perfect. Don't use a glue that says "bonds everything", because it doesn't work, it's crap, it lasts about as long as the time to fetch it from the shop. Tiger seal was the only thing that worked.
 
It's a waiting game indeed, I released the cramps too early and after a day it started to peel away, so re-bonded it and left it out of sight for well over a week, and it worked spot on.
 
I heated it to 170F in an oven (wont say which oven), then clamped it quickly and stuck in oven for 10 more min, removed and let sit for 2 days. I got somewhere but not all the way. Maybe enough for glue to hold. Perhaps repeating the process will fatigue the vinyl more, not sure.
 
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