 Checking spring rate, Am I doing it right? |
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| bondo |
 Jan 8 2006, 09:17 PM
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#1
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Practicing my perpendicular parking  Group: Members Posts: 4,277 Joined: 19-April 03 From: Los Osos, CA Member No.: 587 Region Association: Central California  |
I set the spring with a metal plate on it next to a wall. I made a mark on the wall at the top of the plate. I added 25 lbs, 50 lbs, and 230 lbs (me), and marked the wall accordingly. I then did the math to calculate pounds per inch, and I get around 120 lbs per inch. (for example, it deflected 1.9 inches when I stood on it)
All the measurements started with a nearly completely unloaded spring, which is not the situation it will see in a car. Is the spring effect linear, or do I need to install them in a 914 and see how much it dips when I jump in the rear trunk? |
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| bondo |
Jan 20 2006, 06:19 PM
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#2
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Practicing my perpendicular parking Group: Members Posts: 4,277 Joined: 19-April 03 From: Los Osos, CA Member No.: 587 Region Association: Central California |
Ok, I measured the spring and used this formula to calculate the theoretical spring rate. (theoretical because not all alloys that are used for springs are the same) It comes out to 160 lb/inch. It also can't be exactly accurate because I measured the paint, which has some thickness.
Of course I'm not the type to be satisfied by math.. so I rounded up a spring tester.. of sorts. The displacement accuracy is .001.. the force accuracy is 1%. This is the sort of thing that satisfies me. (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) Attached image(s) 
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Posts in this topic
bondo Checking spring rate Jan 8 2006, 09:17 PM
SirAndy Jan 8 2006, 10:38 PM bondo http://www.914world.com/bbs2/ht... Jan 9 2006, 10:00 AM Borderline That's the principle. You should be in the ba... Jan 9 2006, 10:09 AM bondo ... Jan 9 2006, 11:01 AM ppickerell Aaron is right. Get the spring under some load at ... Jan 9 2006, 11:29 AM bondo Jan 9 2006, 12:09 PM ppickerell Ooops, My bad, the springs I make are so f'in ... Jan 9 2006, 12:27 PM bondo Ok, I tried it with more weight. I added weight in... Jan 17 2006, 04:17 PM Mueller Jan 17 2006, 04:31 PM bondo <... Jan 17 2006, 04:53 PM Mueller Jan 17 2006, 04:57 PM bondo <... Jan 17 2006, 05:29 PM bondo I think I may have figured out where the 1/4" come... Jan 17 2006, 06:59 PM bondo Ok, here's the pic.. this is 300 lbs. Half the... Jan 17 2006, 07:28 PM
bondo Here is the graph of the data. (I did the graph a ... Jan 20 2006, 06:22 PM |
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