Repro direct connection trunk lid spoiler- any ideas on mounting without drilling?

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MRGTX

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I just got my repro spoiler (bought from the usual guy on Ebay) painted up and ready to mount.

I don't have a spare trunk lid and drilling holes in my car is something that I really, really prefer not to do. Can you guys recommend any kind of clips or adhesive mounting system that would hold the spoiler reliably on the trunk lid?

I thought about epoxying in some pieces to serve as mounting points for automotive grade trim adhesive...this seems like it's going to be a big pain in the rear (no pun intended) to get right.

Thanks!!

The pic below is from many moons ago, posted by @74360duster
It looks like this thing is attached without the screws/rivets but I believe it's just held in place with a clamp.

DSCN0994.jpg
 
The problem you’ll have is surface area, as you know that spoiler is totally hollow and the only parts that sit flush on the trunk are the screw pockets.

So, what I would do is get a couple of thin strips of aluminum. Thin enough that it’s easy to bend but thick enough that it’ll capture some threads. Use the screw pockets on the spoiler and screw the thin strip of aluminum to the backside of the spoiler, then flush the protruding screw points so the part that goes ro the car is flat. You’ll probably have to use 3 or 4 pieces so you can leave out the part that goes over the rib in the trunk.

Then use a 3m body tape between the aluminum strips and the trunk lid.
 
The problem you’ll have is surface area, as you know that spoiler is totally hollow and the only parts that sit flush on the trunk are the screw pockets.

So, what I would do is get a couple of thin strips of aluminum. Thin enough that it’s easy to bend but thick enough that it’ll capture some threads. Use the screw pockets on the spoiler and screw the thin strip of aluminum to the backside of the spoiler, then flush the protruding screw points so the part that goes ro the car is flat. You’ll probably have to use 3 or 4 pieces so you can leave out the part that goes over the rib in the trunk.

Then use a 3m body tape between the aluminum strips and the trunk lid.

This seems like a better idea than affixing pieces with epoxy to do the same job. I'll have to think about how to do this without leaving a gap....
 
I would just drill the holes and attach it as designed, while making certain that no water has access to your trunk. Filling those holes down the road should you change your mind is easy. You're going to have to repaint the trunk either way you choose.
 
This seems like a better idea than affixing pieces with epoxy to do the same job. I'll have to think about how to do this without leaving a gap....

Yeah it will look like it’s been attached with screws but no holes in the deck lid. The biggest thing is you need enough flat surface area so the body tape has some good grip.

I don’t think the gap would be very big, I know I was planning on gluing some rubber washers to the backside of the screw pockets to keep the screws from cracking the spoiler on mine. So there’s a bit of a gap between the pockets and the lid already, the metal strip would take that up and as long as you kept it relatively thin the edge gap should be small.

The original DC spoilers were just attached with plastic push rivets, that’s why they’re always cracked at the pockets when people attach them with screws.

I would just drill the holes and attach it as designed, while making certain that no water has access to your trunk. Filling those holes down the road should you change your mind is easy. You're going to have to repaint the trunk either way you choose.

Yeah that’s what I’m doing. Got some nice stainless steel screws for it, use some RTV on the backside to fill the hole as they go in. My deck lid has all the hand depressions from being closed too hard over the years in that spot anyway, I’m gonna cheat and leave them there since the spoiler will cover all of them and pulling them will be a pain since they’re covered by the inner structure on the backside. If someone wants to remove the spoiler later they can weld up the little holes and pull the dents while they’re at it.
 
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There is a lot of aero force on the spoiler. I would be inclined to just use the screw holes. The deck lid is a very common part that would be easy to replace if you don't want to fill the holes later, but even that isn't a consideration if you are planning to keep the spoiler.
 
For those curious, this is how the original mounted. Not my pictures, not my hand. Borrowed from another thread here somewhere and archived

Instructions
ducktailspoilerinstall.jpg

"mounting clips"
130803-MP_Rear_Spoiler-P4120358-04.jpg


The holes you drill are small, I mean, if you can't weld up a 1/4" hole then you probably can't take the dents out of my deck lid either. The holes for the screws I'm using will be less than a 1/4" anyway, the push rivets used by the original DC spoiler would have been larger.
 
I bought some stuff from my lumber company. They called it mastic. It is like a double sided tape but black and available in rolls of different widths. Thickness is approximately 1/16 inch or less. Super sticky. You might want to check something like that out.
Yote
 
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The holes you drill are small, I mean, if you can't weld up a 1/4" hole then you probably can't take the dents out of my deck lid either. The holes for the screws I'm using will be less than a 1/4" anyway, the push rivets used by the original DC spoiler would have been larger.

Point taken but if one doesn't know how to weld at all, it might look a bit more daunting. I may go this route eventually. If this was an original/new condition spoiler, I would be much more inclined to mount it as intended. This fiberglass repro is fine but it's far from perfect. Between my two jobs, I invested absolutely as much time as I'm willing to spend sanding, priming, sanding, etc. I hit it with the same Blitz Black that I used on my hood and it will look great from 20 feet but still maybe not quite good enough to permanently alter the sheet metal of the car if I decide that it's not good enough.

While nothing about my car is especially rare or "collectible," After 26 years (a few years more than half my life at this point), I have an irrational loyalty that compels me to do the least invasive mods possible while still improving the car. I will cut/drill/etc. but only after exhausting every "non-surgical" possibility first.
 
Point taken but if one doesn't know how to weld at all, it might look a bit more daunting. I may go this route eventually. If this was an original/new condition spoiler, I would be much more inclined to mount it as intended. This fiberglass repro is fine but it's far from perfect. Between my two jobs, I invested absolutely as much time as I'm willing to spend sanding, priming, sanding, etc. I hit it with the same Blitz Black that I used on my hood and it will look great from 20 feet but still maybe not quite good enough to permanently alter the sheet metal of the car if I decide that it's not good enough.

While nothing about my car is especially rare or "collectible," After 26 years (a few years more than half my life at this point), I have an irrational loyalty that compels me to do the least invasive mods possible while still improving the car. I will cut/drill/etc. but only after exhausting every "non-surgical" possibility first.

Hey sounds good to me! Just throwing out options. My point about showing the stock mounting was more about showing what DC thought was adequate, if plastic push rivets will do the job I wouldn’t give a second thought to using 3M body tape as long as you can get a decent amount of surface area.

My car is so far past returning to stock I don’t worry about changing stuff too much anymore. I mean, I don’t chop stuff up just to do it, but if someone wants to return my Duster to a stock ‘74 /6 auto car then welding up some body panel holes is gonna be real small potatoes.
 
I see this keeps popping up. The simple way of installing these is to make a fiberglass mold of that area on your trunk. They make silicone sheeting that has a "sticky back" on one side that you can apply to your painted truck lid to lay up fiberglass on. I'd cover the rest of the back of the car with the heavy weight trash bags. The most important thing is to 'NOT' mess up you paint. then fiberglass away. Probably best to vacuum bag the wet fiberglass, but that's beyond what most people can do.

Once you get the top of your trunk lid mold made you can cut it down so it fits flush to the bottom side of what ever spoiler you bought. Most of the fiberglass aftermarket spoilers are poorly made and they don't fit flush to the truck lid anyways, because the fiberglass pulls and shrinks in deferent directions when it cures. I guess you could stick the spoiler on by putting double sided tape onto the bottom piece you just made. Or you could fit a metal or aluminum framework on top of the trunk mold to bolt it on.

It takes some fitting, you might have to cut the trunk mold you made in half because it shrunk, but you actually have something that can make a structure that the spoiler can be bonded to.

Or just drill a bunch of holes to mount whatever you bought. And when it sits in the sun it will take a different cure and have even more flaws pop up.
SPOILER.jpg
Spoiler Rear.jpg
Spoiler 3_4.jpg
Spoiler 4_3.jpg


No matter what, now you made your trunk heavy and it won't stay up.
 
That'll look nice, this may be a day late and a dollar short but, if you use the fiberglass foot idea which is a good one, use epoxy resin in lieu of methyl methacrylate or vinyl ester ( boat resin). Most epoxies won't cure as fast but they shrink far less. When repairing fiberglass ALWAYS use epoxy for this reason. Boat resins consume up to half of their bond strength in shrinkage. I agree with Tru Blu's 3m tape idea, epoxies are tenacious bonders however, once hard the bond line can be shocked with impact whereas a 3m tape type product bonds tenaciously and has a ton of flexural strength.
 

So, what I would do is get a couple of thin strips of aluminum. Thin enough that it’s easy to bend but thick enough that it’ll capture some threads. Use the screw pockets on the spoiler and screw the thin strip of aluminum to the backside of the spoiler, then flush the protruding screw points so the part that goes ro the car is flat. You’ll probably have to use 3 or 4 pieces so you can leave out the part that goes over the rib in the trunk.

Then use a 3m body tape between the aluminum strips and the trunk lid.

This worked out pretty well. There is a gap which is most noticeable on the sides but it’s more or less acceptable.

D12869F8-A027-48E5-88B4-9CA329E2FB11.jpeg
 
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