What gauge is automotive sheet metal?

Alloy sheet is typically 22 ga. or thicker…double-sided.

All steel (car) instruments are made of stamped/drawn sheet metal, which is about .085″ thick.

Flip top pedals for brake and clutch are often 1/8″ sheet metal…often have a “wood grain” texture on the back side to hide the steel edges that come from machine cut holes in them. ford appears to use 1/16″ or thinner….

Thinner gauge was used when things were expensive, as it provided more “total product”.

Now that fuel efficiency is emphasized, stuff uses heavier gauge stuff…probably has to do with body stiffness required by emission standards. some cars now use aluminum instead of steel for body panels.

The main difference between different grades and thicknesses of sheet metal is the hardness…which affects how pliable or resistant it is to dents. harder stuff tends to be more brittle, too….which doesn't make it ideal for structural applications (like car bodies where thin material can flex a little and absorb impact of minor fender benders)

Grade refers to the amount of “beauty impurities” in the alloy…and has little bearing on strength. there are some exceptions like leaded steel, which was made softer than unleaded steel. when lead was added to molten cast iron during casting, it would melt at lower temperature than pure iron. this allowed mold makers to use higher temperatures when making sand molds. the higher temperature caused the impurities to be flushed from molten cast iron into sand mold, which was lower in temperature than mold so it didn't cause further solidification of cast iron…producing a stronger structure upon cooling while still soft enough for easy removal from sand.

So grade is an indicator of purity and not strength. grades go from 1 up to 4 as purity increases….1 being purest alloy, 4 being most ‘impure'.

It's possible to have steel with different grades on each side (back & front) if it's welded together.

Stronger alloys are harder and make better (more expensive) cutting tools…but are also more brittle (may chip or crack)…and probably harder to stamp or machine.

Geometry of sheet metal is also important…flat panels can be made out of thinner gauge material than round tubing, etc….since flat panels are easier to form with less material.

It's possible that some alloy sheet parts in cars have been replaced with aluminum for weight savings and/or corrosion resistance….but it would have to be a pretty trivial part not to warrant use of thicker steel everywhere else on car. anodized aluminum in sunlight will heat up slightly and expand, causing little cracks at surface (similar visually to how rust forms). these tiny cracks (crevices) are perfect for holding water moisture inside them. then when rain gets the water inside these crevices…moisture will flow into cracks and follow them to any structural joint/panel in car that is not separated from ground by rubber or vinyl bushing, etc. ….iron can rust away pretty quickly this way since metal structures of cars are air-exposed (unless paint is very thick and well-protected)

Silver painted parts are often anodized aluminum…as it's cheaper than painting the item silver, but also provides some sun protection for whatever alloy was used to make part.

But now you can get special paints with special additives that prevent corrosion….whereas those additives make paint thicker so your clear coat peels off when used on a car door. most modern paints don't do that anymore….so it might be possible to use them on exposed parts of car.

Alloy can be superheated and then welded without oxidizing it. so if something breaks, you can usually fix it in the field with a torch….unlike aluminum which burns totally away when heated (instead of oxidizing)….and has to be fixed by replacing whole part instead of welding a spot to repair damage.

Aluminum is used for some serious structural stuff…because it's very strong/lightweight and cheap compared to any other materials that can be used in its place (everything else would either crack, bend, or fall apart quickly). there are alloys that are stronger than steel made from titanium and vanadium…but they're just too expensive for general use and not as strong in comparison to aluminum. aero/space is the only place i know of where titanium is commonly used…but it's also expensive there (maybe 2-3x more than steel for same part)….and that has nothing to do with strength issues, but rather because they use so much of it in their structures.

Aluminum can be superheated without oxidizing (though if light gets inside metal at high temp, then oxidation might occur). i think this is why aircraft window frames may have some kind of coating on them (paint or polyester resin)…because even though airplanes fly through air most of time…air has oxygen and other light elements like carbon dioxide in it too. once you open a window on an aircraft with oxygen in it (even if cabin is under pressure)…light will get inside window frame and cause oxidation to occur.

Never seen aero grade metals used in cars, but i have seen some alloys made from chromium that are super strong/lightweight…but they add expense due to chromium content, so even though they're lighter than steel….they might not be worth using at edge of car where weight savings are really needed (like along roofline for example)….because steel may be just as light for less cost.

Figure automobile has about 40-100 pounds of aluminum paneling….not sure what percentage this represents…but a typical car weighs 4,000-5,000 lbs. a 40 lb reduction on 4,000 is only 1%….so easy to achieve this by using less steel in most structural areas of car and shaving off weight there instead.

But there are probably some other alloys that can be used for panels or engines where aluminum would not work due to corrosion/oxidation issues.

Does anybody know what alloy is used for most sheet metal parts on car? (if you know it's aluminum…then just say that). i think a lot of this stuff should have been put out of production years ago….as it's so easy to damage in parking lots when shopping carts hit these parts while driving through them. too many dents/dings get made into bodywork because auto makers didn't upgrade sheet metal alloys. i wonder why body shop premiums aren't higher for these dents?

In fact, the best material to use in parking lots would have been nylon…which is completely unaffected by shopping carts/parking lot damage….and also doesn't rust because it's a thermoplastic polymer which melts when hot and reforms into solid piece (can be shaped or molded). so i think if you want your car protected from shopping cart damage…car manufacturers should start making everything out of nylon! (i know this stuff isn't light enough for exterior panels, but it could be used for engine mounts, drive shafts, control arms etc)….think how happy people would be to not get bent fenders/inner wheel wells from shopping carts dings in parking lots.

This is why i know we're headed for doom as a society…as nobody wants better products like nylon that last longer and are virtually maintenance free. instead they want cheap stuff that breaks easy, so more profit can be made….(how many people have gotten rid of their cars since 1980 due to rust problems?)…and then when stuff breaks they just throw it into landfill because they don't want to fix what's broke. maybe if there was no landfill problem we'd see different desires….but all the bad buildings/structures we've built in past 100 years will come back and bite every one of us in ass 20-50 years from now!

Btw, reason aluminum is used a lot in cars is because it's very strong for its weight…not because it costs less than steel.