355 Those little rubber capped nuts...

..on the undertray.
Has anyone found a source for those?

 

The Ferrari part number is 64449900. They appear not to have a plastic dome any longer.
A number of suppliers seem to have stock.


https://www.ricambiamerica.com/64449900-nut.html

 

Nope

 

$9.32 each at Ricambi? Try Bell Metric, $0.51.

https://belmetric.com/acorn-nylon-locking-nut-a2-stainless-din-986/?sku=NA6NYLOCSS

 

....and paint the caps with Plasti-Dip

 

Which one is the correct size?

 

I have a few hundred made from china. Black nylon not painted. Pretty close, little shorter than the one on my f355 that I think are original. I’ll have to find them somewhere in my garage. If you want I can ship them to you. DM me.
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I don't understand why they have a rubber top. It's a guarantee that the stud will pop through the rubber top over time. Dumb design.

 

I have thought about this for quite some time. The Challenge cars would use duct tape to smooth the airflow under the panel. With this in mind::

My thoughts turn to an insert nut with a philips or torx torque=point that has a washer on the bottom of the nut (flange) to spread the load, and a disk the size of the contour of the hole at the top. So, you screw it on and you have a free flowing surface on the air channel....

 

These might fit:

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https://www.temu.com/4pcs-m4-m5-m6-m8-m10-m12-star-through-hole-knob-female-thread-nut-clamping-knob--knobs-knurled-thumb-nuts-g-601099528770571.html?_oak_mp_inf=EIuojJ%2Bm1ogBGiBjMjBmYTBjZmVjYWU0NGUzOWQ3YjQ2YWU3NDk1ODhmYyC5xLX7nDI%3D&top_gallery_url=https%3A%2F%2Fimg.kwcdn.com%2Fproduct%2Ffancy%2F469d38d6-3f86-4203-8749-195dcef91600.jpg&spec_gallery_id=2045117892&refer_page_sn=10009&refer_source=0&freesia_scene=2&_oak_freesia_scene=2&_oak_rec_ext_1=MTA1&_oak_gallery_order=817082410%2C358002051%2C2095497977%2C1300312298%2C1012277834&search_key=m5%20nut%20rubber%20cap&refer_page_el_sn=200049&_x_sessn_id=lxub4f8rv6&refer_page_name=search_result&refer_page_id=10009_1725761938321_9diskpiuc9

 

I'm pretty sure the originals are rubber capped to limit corrosion of the undertray studs. Doubt full metal will work. The nylon insert ones might (I'm uncertian how much thread length you need)

 

But if it was intended to protect the studs, why not just use a standard all-metal acorn nut?

 

My bet is they wanted a stealth black look. The washers that go with them were painted black from the factory.

 

I found these, but nothing in black.

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Anyone want to confirm the size needed?

 

No, that’s not dirt and I didn’t paint the washers black.
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If anybody can find someone who can reproduce these faithfully, in size and color, I am sure some of us on here would each buy a few hundred. I would.

 

Where from?

 

https://www.aliexpress.us/item/2255800058943474.html?src=google&gatewayAdapt=glo2usa

 

Right, Mitch. The amount of drag those nuts produce is negligible but certainly putting tape over them will prevent them from getting lost.

My Challenge car has a whole assortment of nuts securing my undertrays but it doesn't really matter to me at all.

Barry

 

Aren't all these nuts inside the recessed areas/cutouts of the undertray? They are not in the airstream in the first place.

 

.... and if they are in the airstream, maybe they act as vortex generators and help keep the air stuck to the diffuser

 

It's like the swimmers shave all their body hair in order to swim faster... Really, if you have to rely on having those caps on the small nuts to go faster, perhaps you need more .... brass balls.

 

On my car, some are and some aren't...


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