Cutting Coils: Let the hate flow....

[renfield90]

Originally Posted by wparsons

Where did I say the force needed to fully compress the spring increased by cutting it? It would be decreased because there would be less length to compress.

Originally Posted by wparsons

Assuming the spring is completely linear, just cutting some of the spring off won't change the spring rate at all.

It'll change the total force needed to fully compress the spring, but not the spring rate.

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And you're wrong - this isn't a matter of opinion, but one of physics and math. Spring rate will go up if you reduce the number of coils in the system. See the equations and links posted by Gunman.

[Calum]

Originally Posted by renfield90

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And you're wrong - this isn't a matter of opinion, but one of physics and math. Spring rate will go up if you reduce the number of coils in the system. See the equations and links posted by Gunman.

He's not wrong, the formula you're using is incomplete.

[wparsons]

Guys, go look at the stock springs. If you're cutting enough out to only lower it 1/2", you're not cutting the active coils.

[Ashikabi]

Originally Posted by wparsons

Guys, go look at the stock springs. If you're cutting enough out to only lower it 1/2", you're not cutting the active coils.

Any decrease in dead coil length will turn some of the live cool into dead coil to replace that now missing length. For .5 inches it won't make a big difference in spring rate but it will some. Probably won't even be noticeable

[SkAsphalt]

Is this guy dead now?

[wparsons]

Originally Posted by Ashikabi

Any decrease in dead coil length will turn some of the live cool into dead coil to replace that now missing length. For .5 inches it won't make a big difference in spring rate but it will some. Probably won't even be noticeable

That's not how dead coils work. They aren't the same rate as the main part of the spring, they're just used to locate the spring and take up space so the spring isn't rattling around with the shock fully extended.

[Gunman]

You don't cut the closed end of the coil off, you still want that to locate the spring. You would trim coil from the open end. The small bit at the end of the open coil that sits against the helix is the "dead" portion on that end. It will always be at the end, regardless of how much you trim off, because that small section at the end will always sit against the helix.

[MrDinkleman]

Originally Posted by fumanchu1

Yes, yes it does... ask me how I know

In the interest of collecting information, can you let us know how you know? I've cut springs and never had any problems... I used an abrasive wheel: cut a bit, let it cool, repeat. About 1/2" on either side of the coil got red hot but no more. Quenched it when I was done, just because didn't want to wait for it to air-cool.


Funny story: a friend of mine tried to cut his springs but he only had a hack saw. He spent hours on one spring and was able to knick it about 1/8". When he heard I had the abrasive wheel, he brought his springs to me and it took me a few minutes to cut them.

[Futaba]

Originally Posted by pushrod

lol, I love how we're discussing a way of saving <$300 on a $25,000 car with potentially adverse consequences.

Insert "cutting corners" joke, it's funny because in cutting corners he'll be cutting corners.

[Calum]

Originally Posted by MrDinkleman

In the interest of collecting information, can you let us know how you know? I've cut springs and never had any problems... I used an abrasive wheel: cut a bit, let it cool, repeat. About 1/2" on either side of the coil got red hot but no more. Quenched it when I was done, just because didn't want to wait for it to air-cool.


Funny story: a friend of mine tried to cut his springs but he only had a hack saw. He spent hours on one spring and was able to knick it about 1/8". When he heard I had the abrasive wheel, he brought his springs to me and it took me a few minutes to cut them.

You know the word quench, but do you know what it does to the steel? When you quench something it makes it harder, and more brittle.

[Ashikabi]

Quenching would not be good here

[fumanchu1]

Originally Posted by MrDinkleman

In the interest of collecting information, can you let us know how you know? I've cut springs and never had any problems... I used an abrasive wheel: cut a bit, let it cool, repeat. About 1/2" on either side of the coil got red hot but no more. Quenched it when I was done, just because didn't want to wait for it to air-cool.


Funny story: a friend of mine tried to cut his springs but he only had a hack saw. He spent hours on one spring and was able to knick it about 1/8". When he heard I had the abrasive wheel, he brought his springs to me and it took me a few minutes to cut them.

Aside from the incessant bottoming out, the added NVH, the less stability in corners, overall shitty ride and dampening? Don't get me wrong it was functional but the adverse effects far outweigh the benefits of buying a set of springs that can be found for as low as 100$. It can/should be used as a temporary fix or something you do on a beater (which is what I had done it on), not something you do permanently on a 30k almost brand new car.

[MrDinkleman]

Originally Posted by fumanchu1

Aside from the incessant bottoming out, the added NVH, the less stability in corners, overall shitty ride and dampening?

LOL. Never had any of that happen. As long as you didn't get stupid crazy with the chop saw (i.e. cutting more than a coil or so) cutting springs was fine.

Originally Posted by fumanchu1

Don't get me wrong it was functional but the adverse effects far outweigh the benefits of buying a set of springs that can be found for as low as 100$. It can/should be used as a temporary fix or something you do on a beater (which is what I had done it on), not something you do permanently on a 30k almost brand new car.

You're forgetting (or don't know): there were no $100 springs in the 1970s, especially for J-tin.


So, how much did you cut and how, that would cause those symptoms you describe? Oh, and I guess "quenching" is not quite the correct word since it has a specific meaning in metallurgy. I should have said I would spray the spring end after the red glow went away to cool it faster.

[fumanchu1]

Originally Posted by MrDinkleman

LOL. Never had any of that happen. As long as you didn't get stupid crazy with the chop saw (i.e. cutting more than a coil or so) cutting springs was fine.


You're forgetting (or don't know): there were no $100 springs in the 1970s, especially for J-tin.


So, how much did you cut and how, that would cause those symptoms you describe? Oh, and I guess "quenching" is not quite the correct word since it has a specific meaning in metallurgy. I should have said I would spray the spring end after the red glow went away to cool it faster.

I could see the usefulness of doing it in the 70s but today with the cost of new springs there is virtually no reason on should do it