Sheet metal screws through firewall and footwell. Correct?

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Grigio330GT
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Sheet metal screws through firewall and footwell. Correct?

Postby Grigio330GT » Fri Dec 08, 2017 4:20 pm

Much of the interior trim in my 330GT is held in by sheet metal screws, and many of these protrude through the floor, firewall and footwell housings on my car. Over the years, it seems that anytime someone worked on the interior trim and had to remove these screws, they would subsequently re-install the screws without re-using the old hole. This has resulted in multiple holes all around the various screws. This is an example from the driver's footwell:
footwell walls.JPG
footwell walls.JPG (81.12 KiB) Viewed 957 times


So this leads to several questions:

1. What is correct- are sheet metal screws really just supposed to protrude through? Or are there maybe pems that are supposed to be there? I should have been more observant over the years, but have never carefully inspected other 330s I have see
2. If it is correct - is there any place I can find out how many/which screws the factory drove through?
3. I plan to patch all the "extra" holes with epoxy - (JBweld). Any other suggestions?
4. Would it be terrible to bond m3 weldnuts to the firewall (boss facing out), and use a machine screw?
Slab_base_weld_nut.png
Slab_base_weld_nut.png (211.07 KiB) Viewed 957 times
Dave Michael
330 GT 7895

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330GT
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby 330GT » Fri Dec 08, 2017 8:18 pm

From my experience, Pininafarina (body maker) used metal plates that were spot welded or riveted to the backside of the piece that the screw fastens to:
SplashShield12_small[1].JPG
SplashShield12_small[1].JPG (8.19 KiB) Viewed 942 times

The plate was typically about 1/8" thick and had a machine screw thread (usually 4 or 5mm) tapped in the middle.

If the metal being fastened to was steel and thick enough, a nut was just welded over the appropriate sized hole. In other cases, a square nut was captured in a spot welded or riveted on box. This allowed the nut to move around to accommodate slight location variances. Examples of these are nuts that hold the headlights in, attach the grill to the body and transmission tunnel to the firewall and floor.
Regards, Kerry
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http://www.parrotbyte.com/kbc/ferrari 250 PF Coupe 1643GT, 330 GT 2+2 8755GT, 308 GTS 23605

Grigio330GT
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby Grigio330GT » Fri Dec 08, 2017 9:15 pm

Kerry

Thanks for the note. My car has a few of the captured nuts you mention, but not for all of the carpet button and trim screws. Those are the ones that I am trying to figure out. In any case it sounds like your car does not have any sheet metal screws sticking through the foot-well housing (under the brake booster)

Dave
Dave Michael

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tim
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby tim » Sat Dec 16, 2017 12:57 am

Greetings... On 5769, the carpet snaps are secured by what appears to be sheet metal screws on the firewall. The panels are coated with under coating and the pointy end of the screw sticks through maybe 1/8 inch. Not real evident due to the thickness of the under coating. The snaps on the floor are also secured with what looks more like a small shanked wood screw into the floor panel which is thicker. On the trans tunnel, what looks like self taping machine screws go through into a tinnerman or "speed" nut. Hope that helps.

Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS

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tyang
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby tyang » Sat Dec 16, 2017 8:04 am

Hi Guys,

In my opinion (you know what they say about opinions!) Sheet metal screws that were used for interior pieces like carpets and trim panels were often cut flush with a pair of side cutter pliers after they were screwed into place and if they protruded far out the other side. There's only one place these sheet metal screws can poke through, and it's at the transmission tunnel. ( In fact, I cut myself just this week from one of these screws because my upholsterer didn't cut one of these screws down! ) The floorpans are double layered, so rarely do you see a screw poking through. Screws like the ones to hold the transmission tunnel in place were capture nuts with threaded screws. The screws holding the splash shields were also threaded, but the receiving threads were tapped into the support structures. Certain screws did have support backing sheetmetal as pictured previously, but I can't think of where I saw them.

Tom
'63 330 America #5053

enio45
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby enio45 » Sat Dec 16, 2017 5:58 pm

I know this is about 330 cars, but i can tell you that on the 250 Ellena i have, all the screws for the tunnel that go in the floor
are sheet metal screws with no captured nuts, and are not cut off on the back side etc.....

the firewall on the other hand has 4 holes with captured nuts type for the front edge of the tunnel to secure to
Ed Montini
330 GT 2+2 Series II - 8289
58 Ellena - 0855GT - orig drivetrain

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330GT
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby 330GT » Sat Dec 16, 2017 7:51 pm

tyang wrote:Hi Guys,

...The floorpans are double layered, so rarely do you see a screw poking through. ...

Tom

The later (interim and series 2) 330 GTs have a fiberglass floor. The carpet snap screws go through and stick out underneath. I've never scarred my hands on them, but if I ever do, I'm sure that the cut-off wheel will be wracking off the ends post haste.
Regards, Kerry
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Suebian330
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby Suebian330 » Mon Dec 18, 2017 5:59 pm

The backlayered metal strips you find as I remember only for the mud shields inside the fenders. It is tapped M5. See pic
DSC01327.JPG
DSC01327.JPG (36.79 KiB) Viewed 800 times
[b]Suebian330

#8741 330 GT2+2[/b]

Suebian330
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby Suebian330 » Mon Dec 18, 2017 6:10 pm

May be now pic in better size
DSC01327.JPG
DSC01327.JPG (23.59 KiB) Viewed 799 times
[b]Suebian330

#8741 330 GT2+2[/b]

Grigio330GT
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Re: Sheet metal screws through firewall and footwell. Correct?

Postby Grigio330GT » Wed Dec 20, 2017 8:19 am

My car has all the correct machine screw bosses for the major hardware. It’s just the carpet trim screws that’s protrude through the footwell walls. From everyone ones responses, it seems that is not correct - the screws should be very short so they go through only the 1st layer of the double wall. So I will patch the engine-bay side of the foot well with epoxy and then find the appropriate short screws for the inside....
Dave Michael

330 GT 7895


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