Sheetmetal Gauge comparasion

[Luis_gz06]

Is the sheetmetal on 67-72 chevytrucks heavier than 73 and up trucks?
I would also like to know about 50's and early 60's trucks sheetmetal. Were there all the same through 72 or different??

[WorkinLonghorn]

I'd like to know this too.I know my '69 is a tank compaired to newer models,but which year(s) did they start using thinner metal-if anybody here knows.

[bobthecop]

ttt

[Huck]

The earlier the year of the trucks, the thicker and heavier the sheet metal was used. Just try knocking out a dent on a pre 50's truck and you will see what i mean. Around mid 70s they even painted them without a protective primer and they rusted prior to delivery!!!! Some vendors say the new Tiwan sheet metal is the same thickness or weight as original butttt just sit on a new tailgate---it doesn't have the tack welds through the center as the originals did so not as strong. Try to stay original when possible and protect any sheetmetal you replace with a good paint sealer prior to install. Huck

[Luis_gz06]

Just heard from an old guy yesterday that 72 and below were all the same 20 gauge sheetmetal and 73 and up was all JUNK thinner metal!!!!! The only thing he said about old 50's trucks is that they were stamped differently than later models. Maybe thats why it might sound heavier than newer ones!!!

[Palf70Step]

Only thing I can add is experience. Since I mixed, matched and welded parts from an 84 stepside and my 70, I can say that the sheetmetal thickness on the bedsides, step fenders and front panels are the same.

[mbgmike]

Newer steel has a higher tensile strength than older steel. This allows Mfg's to use the thinner gauge.

[WorkinLonghorn]

Newer steel has a higher tensile strength than older steel. This allows Mfg's to use the thinner gauge.

Well,this may be true to some extent,but on my '69 my crew and I often walk across the hood,step up on the roof to load stuff into the front of the bed when it is almost full up (4 foot side boards). I weigh 220 lbs and with an 80 lb. load that's 300 lbs with each footstep-----and it is never a problem for the sheet metal. Try that on a 2007 model.

[MACO]

On newer vechiles the sheet metal is just there to hold the paint up!

[AKChevyman]

I think the new stuff might be the same gauge but it can't be the same density.(or tensile strength) My new repop tailgate weighed 10lbs lighter then my old one. Now it doesn't because I took the thing apart and welded in a 1'X1" tube in the top lip of the tailgate the entire length and replaced the side hinge pieces with the ones from my original. I should have just went and bought a take off tailgate.

[72-stomper]

Originally Posted by WorkinLonghorn

Well,this may be true to some extent,but on my '69 my crew and I often walk across the hood,step up on the roof to load stuff into the front of the bed when it is almost full up (4 foot side boards). I weigh 220 lbs and with an 80 lb. load that's 300 lbs with each footstep-----and it is never a problem for the sheet metal. Try that on a 2007 model.

Not possible

[shifty]

So, just as a general question: What gauge is the firewall in our trucks? I was wondering about this. I bought 16ga to replace whatever is there when shaving it. Is it actually 20ga?

[shifty]

Man, I'm at that stage still - can anyone tell me what gauge the stock firewall is, pretty please?

[RACINJASON22]

Man ya know what shifty I tried seaching for ya and guess what thread came up THIS ONE I tried. I don't know either lets see who comes up with the right answer.

[sevt_chevelle]

My 49 and 72 chevy trucks all measure the same on exterior gauge as well as all 3 70 chevelles Ive had. GM used 19 ga on exterior panels as well as other car makers.

16ga for a firewall is too thick, 18 would be a better choice as a thicker gauge was used for more structual parts.

Today's steel is lighter thinner and stronger. You have steel that is sandwiched between plastic, steel with different alloys and quenched at different temps and procedures.
The old steel is draw quality metal very workable, used because it took the molds/presses easily. Today they use ultra strength instead of draw quality because of better technology and because its alot stronger and thinner.

Same holds true with the old/new aluminum. Aluminum is a DREAM to work with, but the stuff they use today you cant touch. Today's AL is throw away...Eric

[shifty]

thanks, Eric.

i'm also curious to hear from guys who've shaved their firewall (Shane, where are you? ) and finding out what they went with for metal. I'd hate to think I got a big ass sheet of 16ga steel for nothing

[brak]

PM rokcrln He'd know

[RACINJASON22]

Shifty when I did the seach I read something about a honda hood Shane used
and it beung the same gage as the fire wall and got a pretty funny reply but there was no mention on actual #'s.

found it read herehttp://67-72chevytrucks.com/vboard/s...d.php?t=233488

[pat]

Does anybody have a micrometer?

[Luis_gz06]

I just guess all sheetmetal from 72 below were all the same!! 73 & up is lighter.

[RACINJASON22]

Originally Posted by pat

Does anybody have a micrometer?

I do but the truck is here and it is not or I would go check right now.

[Palf70Step]

Shifty, I have some old step bedsides, as well as an extra hood that I get my patch panels from. I cut pieces from the original bedsides of my truck to patch the firewall.

[GMC Jim]

I could be wrong but it comes to mind that 1/8" = 11 gauge; and 16 guage is 1/16" thick..........

[Richard H.]

Originally Posted by sevt_chevelle

My 49 and 72 chevy trucks all measure the same on exterior gauge as well as all 3 70 chevelles Ive had. GM used 19 ga on exterior panels as well as other car makers.

16ga for a firewall is too thick, 18 would be a better choice as a thicker gauge was used for more structual parts.

Today's steel is lighter thinner and stronger. You have steel that is sandwiched between plastic, steel with different alloys and quenched at different temps and procedures.
The old steel is draw quality metal very workable, used because it took the molds/presses easily. Today they use ultra strength instead of draw quality because of better technology and because its alot stronger and thinner.

Same holds true with the old/new aluminum. Aluminum is a DREAM to work with, but the stuff they use today you cant touch. Today's AL is throw away...Eric

Eric , There is a plant in Indy Called GM Truck and Bus that stamps The skin metals for there trucks. The first time I was in there was in 1972 and have made several return visits as an " outside" electrician. At any given time there are over 250,000 doors riding along on the carousel awaiting fabrication at the plant. They do stamp the firewalls and fender parts there also. Kind of neat watching the firewall being done , roll of sheet metal being fed into a machine that has a total wieght of 3200 tons and out the other end come a firewall with all the holes punched and all the fasteners welded and or crimped in.
I believe it is all the same size metal for these parts to eliminate plant confusion or error. Heavier parts like the radiator support are made some where else.

[sevt_chevelle]

Originally Posted by Richard H.

Eric , There is a plant in Indy Called GM Truck and Bus that stamps The skin metals for there trucks. The first time I was in there was in 1972 and have made several return visits as an " outside" electrician. At any given time there are over 250,000 doors riding along on the carousel awaiting fabrication at the plant. They do stamp the firewalls and fender parts there also. Kind of neat watching the firewall being done , roll of sheet metal being fed into a machine that has a total wieght of 3200 tons and out the other end come a firewall with all the holes punched and all the fasteners welded and or crimped in.
I believe it is all the same size metal for these parts to eliminate plant confusion or error. Heavier parts like the radiator support are made some where else.

Rich,
There is nothing like taking a tour throu a plant. One of the coolest was the fridage air(sp?) in Iowa where they make washers and driers.

Anyways theres some numbers for you guys
16ga .0598 right at 1/16
18ga .0478
20ga .0359

I dont have the numbers for 19 ga but around .040/.041

Ive never measured the "inside" metal on my 72 as I didnt have to replace any metal, but the floors on the chevelle where thicker as well the firewall. The floor braces, trunk braces and few other braces measured 16ga.

19ga is correct ga to use but since its hard to find most use 18ga unless there is lots of shaping involved then they switch to 20 ga because its easier to shape...Eric