Trunk Drop Off Plugs

[Gene-73]

Anyone have a good solution for the trunk drop off plugs?

I was able to source the original looking plugs but unfortunately the hole on the reproduction drop off panels are too large. The hole measures 1.07 inch and the plug is 1.05 inch (at the tabs) so they just fall right out. Would prefer something rubber that can be easily removed if needed.

The hole also has that strange cutout at the bottom so the plug needs a larger head to cover everything. Any ideas?

[Wallington]

Mine were like this, albeit with underbody spray over them. Assume it's what you may have already tried at 1". Usually, a slot like that allows the new plug or seal that is oversize to be screwed in, until the lip is on the inside, like a large blanking grommet.

https://www.firebirdcentral.com/1970_1981_Firebird_Under_Rear_Seat_Floor_Pan_Plug_p/she-71.htm

[Gene-73]

I've tried a 1" rubber grommet and it fits pretty loose. Also, most that I've found don't have a large enough outer diameter to cover the slot. The other issue is the metal is fairly thin here so that's another dimension criteria.

I suppose the firebird central plug you provided the link for could work if it was seam sealed in, although the plugs I have could work that way too. The ones I pulled off the car were green in color just like the replacements I bought. The plug is probably correct, it's the hole in the repro drop off panel that is probably oversized.

[Wallington]

Good info on the green plug, I can't recall seeing one. Wonder when they changed over.

[roadking77]

Im pretty sure mine were gooped in place with seam sealer. Were these ever intended to be removed (as a wash out) or were they in place like the holes in the floor to allow drainage from the primer dip? I would almost guess the later?
Now, they make a  bit more sense as a wash out, I got some rubber plugs at the local auto part store but they were small, maybe 1/2" at the largest. Perhaps you could look there.

OR, not simple for me but should be a breeze for you, why not 3D print a set?

[Wallington]

This is on my '78.

Firebird trunk dropoff drain plug RH by Aus78Formula, on Flickr

[Gene-73]

This is on my '78.

That looks similar to the firebird central item. Now that I look at it again, I assume the tabs on the back hold it in place. That looks like it might work.

OR, not simple for me but should be a breeze for you, why not 3D print a set?

3D printing could be an option. There is a type of filament that is flexible called TPU but I don't have any on hand. The price of a spool of filament is about the same price as the firebird central plugs. But I might just give that a shot.

[Wallington]

Yes, the ends are like a spring steel tab so they pop in and stay in place. But I bet even a perfect fit needs sealing up to keep in place. Mine are all gooped up then sprayed over.

[Gene-73]

Here's what I came up with. Probably a little over-engineered but I like being able to remove them easily if necessary.
For about $7 in parts, I bought the following:

• 1 1/2 inch stainless steel fender washers (qty 4)
• 1/4-20 stainless steel flange head bolt (qty 2)
• 1/4-20 brass threadsert (qty 2)
• 1 1/2 inch neoprene washer (qty 2)
• 1/2 inch neoprene washer (qty 2)

Two of the stainless washers I cut down to 1 inch wide to fit through the opening with a small tab left sticking out and bent inward slightly. This goes on the inside of the panel and the tab fits inside the hole slot to keep it from turning while you tighten down the bolt. Neoprene washers to keep the water out, and stainless parts to avoid rusting. Also a little thread locker to keep it from loosening up.

 

[pancho400cid]

Nice!

[Wallington]

Neat job.

Just saw this on another site, probably the same floor plugs listed elsewhere, but for a 1" hole. That may make them still far too small for the oversized hole in your panels.

https://pontiworld.com.au/usgmsp/product_info.php/products_id/12224

[Maxthe222]

Is it bad to just leave them open and unplugged? If I leave my T/A outside, they'd hold water, right? So wouldn't it be good to leave exposed?

[roadking77]

I would almost imagine they were there originally for the factory primer dip to allow excess to drain? Much like the plugs in the floor pan. If everything around the wheel well is sealed good there really should be no need for them (technically). After the fact they are good to have to clean that area out though. I would not want to leave them open, that only invites more trouble in my small mind.

[Wallington]

It might help initially to get the water and moisture and mud out, even poor boiling water down the sides and blast out with air gun to loosen up. But stopping the water getting in is the main issue, especially on a project that just sits, as water does the same. Trunk seals are cheap, or throw a tarp over that section.

[NOT A TA]

You wouldn't believe all the weird stuff I've gotten out of cars through (or with the help of) those holes over the years. Stuff slides over the edge between the trunk pan and quarter panel and drops down in there. I used to find beer bottle caps, roach clips, hair barrettes, scissors, wrenches, twine, and other stuff.

 I need plugs for my 67 Camaro I replaced all the lower trunk area sheet meal in.

[Wallington]

Yes, mine I found my missing jack retainer plate and wingnut, along with various nuts or screws, and several 70's US coins. I used attached hose to a vacuum cleaner and those spring-loaded claw tools. Most couldn't be seen, just playing around and pre-phone camera with flash. Might have to try that again.
No rare SD-403 paperwork though!

[roadking77]

I found some wrench sockets in mine.