LocostUSA.com

got the trickier sheet metal peices out of the way. Can't wait to get the rest in, cause then its spatter and booger cleaning time and then paint!

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AWD Exotruck 525hp Subaru EJ22 http://www.locostusa.com/forums/viewtopic.php?f=36&t=19011

Uhhh... You ARE talking about activities relating to sheet metal and welding and NOT about personal hygiene, right?


JDK

got the contoured piece fit, took some grunt, 16ga lil more rigid than i thought. probably because I bought A1011

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AWD Exotruck 525hp Subaru EJ22 http://www.locostusa.com/forums/viewtopic.php?f=36&t=19011

I have a new concern. When i smack part of the chassis with my fist, or anything really, it sounds like i hit a large peice of duct work. Does anyone else have an issue with resonance. I really dont want to dynomat this entire thing to quiet it down.

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AWD Exotruck 525hp Subaru EJ22 http://www.locostusa.com/forums/viewtopic.php?f=36&t=19011

That's why so many do a bead roll on the flat pieces.

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

Someone (Perry I think?) runs a weld bead or two in the middle of panels in the same pattern as you would bead roll, to achieve a similar effect (reducing oil-canning).

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

Our bead roller couldnt do 16ga, figure it was for strength more than noise. Guess i'll research this weld technique

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AWD Exotruck 525hp Subaru EJ22 http://www.locostusa.com/forums/viewtopic.php?f=36&t=19011

The noise reduction is incidental. The bead stiffens the panel and stops it behaving like a wobble board (if you remember Rolf Harris and his aboriginal 'instruments').

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

The hole thing seems to make noise. I'll try and record it

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AWD Exotruck 525hp Subaru EJ22 http://www.locostusa.com/forums/viewtopic.php?f=36&t=19011

Maybe the same thing depending on how you look at it. The flat panel will vibrate like a drum skin, even a heavy 16 gauge panel. A crease or a bump from a bead roller or it seems a weld bead will break up the panel a bit and reduce the vibrating. If you make a panel twice as thick it's 8 times stiffer, so the creases they put on ductwork or all the shape they put into car body panels make them much stiffer. You won't find much flat metal in a car, except for the outer body work. Even then it tends to have curves...

The weld beads sound like an interesting idea. I wonder how much tension they'll put on the metal when they cool down...

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
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http://www.locostusa.com/forums/download/file.php?id=55428

Here's a pic of what I do to reduce 'oil canning'. Used on 2 builds now with no issues.

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Perry

'If man built it, man can fix it'
"No one ever told me I couldn't do it."
"If you can't build it safe, don't build it."

Perry's Locost Super Che7enette Build
Perry's TBird Based 5.0L Super 7 L.S.O
Perry's S10 Super 7 The 3rd
Perry's 4th Build The Topolino 500 (Little Mouse) Altered
Perry's 5th Build the Super Slant 6 Super 7
Perry's Final Build the 1929 Mercedes Gazelle

Following on from Horizonjob and Perry, the weld lines or panel beads will constrain the panel and allow only higher modes of panel vibration. These higher modes will be at higher frequencies, and probably have less energy (and be quieter) than the fundamental mode of an unstiffened panel.

The challenge for you is exterior panels where crossed weld beads would be visible, and not as 'attractive' as rolled beads.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

Sounds like a good time to practice stick welding

Got the sound, although sound quality sucks. It's lower pitched in person

https://youtu.be/zaPH98nvJZk

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AWD Exotruck 525hp Subaru EJ22 http://www.locostusa.com/forums/viewtopic.php?f=36&t=19011

Just for info, I used the MIG

Just listened/watched the video. Sounds like there are loose panels/tin somewhere. I believe your panels are stitch welded correct? There may be gaps between the structure/sheet metal between the stitches.
You need to have someone tap on the frame while you listen to locate the source. You can rig up a tiny funnel (2"-3" dia) with a 2 foot piece of rubber tubing attached to it. Use it like a stethoscope using one ear to locate the noise(s), keeping the funnel just off the surface as you move it along the metal. Word of caution: the sound can be very loud coming through the stethoscope.

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Perry

'If man built it, man can fix it'
"No one ever told me I couldn't do it."
"If you can't build it safe, don't build it."

Perry's Locost Super Che7enette Build
Perry's TBird Based 5.0L Super 7 L.S.O
Perry's S10 Super 7 The 3rd
Perry's 4th Build The Topolino 500 (Little Mouse) Altered
Perry's 5th Build the Super Slant 6 Super 7
Perry's Final Build the 1929 Mercedes Gazelle

http://www.locostusa.com/forums/download/file.php?id=56957

Another practice I use is to brake a slight crease diagonally both ways across the material (you can see this in the trunk/boot pic). This also prevents 'oil canning'.
For those of you that have furnace or AC ducting in the basement you will see this done on the duct work.

_________________
Perry

'If man built it, man can fix it'
"No one ever told me I couldn't do it."
"If you can't build it safe, don't build it."

Perry's Locost Super Che7enette Build
Perry's TBird Based 5.0L Super 7 L.S.O
Perry's S10 Super 7 The 3rd
Perry's 4th Build The Topolino 500 (Little Mouse) Altered
Perry's 5th Build the Super Slant 6 Super 7
Perry's Final Build the 1929 Mercedes Gazelle