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Bored, question stumping thread.

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Old Apr 1, 2008, 02:28 PM
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Bored, question stumping thread.

I have a freind who is a genius when it comes to mechanics on a car. We were talking today and I was trying to ask questions to stump him and it was impossible.

THEN!!!! I asked him "what if you let a car sit for a whole year, and during that whole year some of your springs are compressed inside the head... how are they ok a year later?"

He did not know....

I can pop out with these questions all day haha

so, how bad is that for the springs? eh??
Old Apr 1, 2008, 02:32 PM
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idk but i wish i had a friend who knew about cars. i know the most out of the ppl i know and im a newb.

but ide say if you leave a car for a year without at least turning it over ever once and a while you dont care about the thing anyway
Old Apr 1, 2008, 02:37 PM
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I don't think the spring tension will be affected very much, but letting an engine sit like that not prepped can cause small rust spots in the valves and when started again cause valve leaks.
Old Apr 1, 2008, 02:39 PM
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I wouldnt let a car go a year without at least starting it once in a while.

Some springs would have to be compressed.

However in reality it would be fine cause you would drain the oil and fill with new coating alot of the springs and rockers anyway. It would be noisey for a little
Old Apr 1, 2008, 02:57 PM
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Being in the Army and having deployed for over one year I can attest from my own experiences and my fellow Soldiers' experiences that it is possible to leave your car for a whole year without starting it and being able to restart it after that timeframe without any undo ill effects. Of course doing proper preventive maintenance is paramount.
Old Apr 1, 2008, 03:19 PM
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^ what he said
Old Apr 1, 2008, 03:46 PM
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Originally Posted by j14mp
I have a freind who is a genius when it comes to mechanics on a car. We were talking today and I was trying to ask questions to stump him and it was impossible.

THEN!!!! I asked him "what if you let a car sit for a whole year, and during that whole year some of your springs are compressed inside the head... how are they ok a year later?"

He did not know....

I can pop out with these questions all day haha

so, how bad is that for the springs? eh??
Its NOT bad for springs it follows Hooke's laws of linear elasticity which basically we would define an elastic range upon which the spring could be deformed by some force and would return to its origional position. Steel is a good common elastic material that follows hooke's law. Rubber however does not follow hooke's law because its stress dependent and sensitive to temperature and the rate of the loads applied.

So simply put if the spring was not beyond its elastic range then its going to return to its origional position since the material has not been deformed by the stresses imbued upon it. You can change that elastic range of a material by increasing or decreasing the temperature though these temperatures in steel's case would be a lot higher than your typical operating range.
Old Apr 1, 2008, 07:42 PM
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^^So valve springs NEVER loose spring rate? I disagree
Old Apr 1, 2008, 09:08 PM
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Originally Posted by 1d10t
^^So valve springs NEVER loose spring rate? I disagree
Well of course they will fatigue but its the repeated cycles of strain not just a constant load that will ultimately cause a spring to loose its elasticity.
Old Apr 2, 2008, 01:39 AM
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Originally Posted by RoadSpike
Well of course they will fatigue but its the repeated cycles of strain not just a constant load that will ultimately cause a spring to loose its elasticity.
I have to agree, I have worn out many spring mattresses from repeated poundings
Old Apr 2, 2008, 07:32 PM
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LOL! It would take a long time for real fatigue. Valve springs are under pressure at all times. I did enjoy reading the theory, good stuff.
Old Apr 2, 2008, 11:03 PM
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Originally Posted by RoadSpike
Its NOT bad for springs it follows Hooke's laws of linear elasticity which basically we would define an elastic range upon which the spring could be deformed by some force and would return to its origional position. Steel is a good common elastic material that follows hooke's law. Rubber however does not follow hooke's law because its stress dependent and sensitive to temperature and the rate of the loads applied.

So simply put if the spring was not beyond its elastic range then its going to return to its origional position since the material has not been deformed by the stresses imbued upon it. You can change that elastic range of a material by increasing or decreasing the temperature though these temperatures in steel's case would be a lot higher than your typical operating range.
oh wow.. that was fancy. Your banned from this thread haha I feel like a brainless dog being told "BAD DOG!" in a freindly voice and me still smiling.

New question....

IF you loose your front right wheel and your going ehhhh lets say 130 mph on a day with VERY little wind. Do you think theres any way the car could keep going straight? Im saying If there was a fat couple making love on my drivers side back seat and me weighing 350 lbs (which I dont) and there being some air resistance to hold the car off the ground yet not enough weight on the passenger side to really weigh it down..... thats a decent question haha.. I thought of it REALLY fast.
Old Apr 2, 2008, 11:19 PM
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Originally Posted by j14mp
oh wow.. that was fancy. Your banned from this thread haha I feel like a brainless dog being told "BAD DOG!" in a freindly voice and me still smiling.

New question....

IF you loose your front right wheel and your going ehhhh lets say 130 mph on a day with VERY little wind. Do you think theres any way the car could keep going straight? Im saying If there was a fat couple making love on my drivers side back seat and me weighing 350 lbs (which I dont) and there being some air resistance to hold the car off the ground yet not enough weight on the passenger side to really weigh it down..... thats a decent question haha.. I thought of it REALLY fast.
Well do you want me to answer this one?

I would say for this question it truly depends on the car setup. Air resistance isn't so much a factor at 130mph but our cars tend to make some downforce in the front area which would certainly be attempting to slam the car into the ground. The friction and resounding jolt may be enough to spin the car i highly doubt any average driver would react fast enough to counter the pull quickly enough to coast to a stop.

EDIT:
Grrr forgot to mention that one of the reasons I believe the downforce will win is the 60/40 weight ration to the front and the principal of leverage on that corner. The centerline of that car is basically going to run from the front left tire center to the rear right center putting the just right of your lap in the drivers seat and onward. Since your heavy couple is much closer to the centerline their weight will likely not be enough to counteract the forces involved in the front.

I also do not believe the rear wing will be applying enough for to stop it

Last edited by RoadSpike; Apr 2, 2008 at 11:38 PM.
Old Apr 3, 2008, 05:19 PM
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Originally Posted by RoadSpike
Well do you want me to answer this one?

I would say for this question it truly depends on the car setup. Air resistance isn't so much a factor at 130mph but our cars tend to make some downforce in the front area which would certainly be attempting to slam the car into the ground. The friction and resounding jolt may be enough to spin the car i highly doubt any average driver would react fast enough to counter the pull quickly enough to coast to a stop.

EDIT:
Grrr forgot to mention that one of the reasons I believe the downforce will win is the 60/40 weight ration to the front and the principal of leverage on that corner. The centerline of that car is basically going to run from the front left tire center to the rear right center putting the just right of your lap in the drivers seat and onward. Since your heavy couple is much closer to the centerline their weight will likely not be enough to counteract the forces involved in the front.

I also do not believe the rear wing will be applying enough for to stop it

BANNED!!!! haha jp that was a lame question anyways..

WHAT IF!!!!! You were on a dyno and had a helium tank feeding air in through the intake... WHAT would happen???
Old Apr 3, 2008, 06:01 PM
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Originally Posted by RoadSpike
Its NOT bad for springs it follows Hooke's laws of linear elasticity which basically we would define an elastic range upon which the spring could be deformed by some force and would return to its origional position.
Just to put it a little more simply:

Materials have two ranges of deformation: elastic and plastic. At some amount of deformation X, you cross from elastic to plastic. Less than X, you're in the elastic range it it'll go back to it's original length. You go past X, you're in the plastic range and it'll stay at whatever amount you deformed it.

Go play with a steel paperclip now


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