Selecting plastics for car underbody fasteners

Agreed, in this situation, someone could get hurt (or worse) and you dont want that to come back to your plastic fastners, and you. The price for proper fastners is far less than the price of life.

Hello landriamanjay,

I've had good experience using Dzus Hardware, button head 1/4 turn with D-handle are easy even using gloved hands. The 1/4 turn unit does not disassemble, the screw remains attached in open and closed position. It is a cam-lock type fastener with spring loaded retention feature.

www.racebolts.com

Dear Landriamanjay,

In general, Auto Industry prefers to use " HIGH TENSILE FASTENERS ". Strength & safety are considered as very important factors.

You mentioned 5 years life span. Better to go safe. If not, high tensile like 10.9 Quality Fasteners, please consider using 8.8 or 6.6 low tensile steel fasteners instead of plastic for your application. Please refer to SAE or DIN STANDARDS for more data.

Regards

P.Rangasamy

Thank you all for your prompt answer. I think your answers are full of wisdow and caution and show you have more experience than me (still at school). I could not locate a SAE specification but I did find a SAE paper on this exact topic. I should mention that this fastener would be used to connect/disconnect two parts hinged to the truck. It is not a structural fastener and in case of a failure it would not fall on the road/tires but would hang from the truck.

Because of what you told me and even if the Dzus fasteners look nice, I am however leaning toward a simple 316 stainless (Is 316 actually needed? I guess I better be safe than sorry, it would add about ~12$ to a ~100$ part) clevis pins. As far as I know, these have well know strength and vibration resistance. The absence of thread also eliminates the possibility of thread seizing/wearing down and it is one of the simplest thing to install. I should also indicate that the fasteners are holding composite panels so we don't have to bother with galvanic corrosion in anything else than the fastener.

I mentioned a little earlier that the parts are hinged. I was thinking of using some plastic piano hinges I heard of but I don't see a place where they talk about being of automotive grade or something like that. They do say they resist oil, salt water, solvents, UV and temperature as low as -40°F. For aestethic reasons I was sizing the hinges with a factor of safety of something like 25+. I also considered stainless (304 is the only type I saw) hinges but as I don't have much experience (and some mechanics here at work assure me they would seize) I fear a rusted hinge. The only SAE paper I found was about door hinges.

Have a nice day!

Lova Andriamanjay