Cutting springs

bravenrace wrote: In reply to Zomby Woof: It's only dead if it's a closed coil, which you shouldn't be cutting anyway. An open spring design has no dead coils, and in either case when you cut with a torch there is a heat effected zone that does in fact extend into the working part of the coil. The bottom line is that in the vast majority of cases, cutting with a torch is going to weaken the coil, and there are other much safer and better ways of doing it that don't.

If it's on the top, or bottom, once the car is on the ground, it's a dead coil.

Zomby Woof wrote:

bravenrace wrote: In reply to Zomby Woof: It's only dead if it's a closed coil, which you shouldn't be cutting anyway. An open spring design has no dead coils, and in either case when you cut with a torch there is a heat effected zone that does in fact extend into the working part of the coil. The bottom line is that in the vast majority of cases, cutting with a torch is going to weaken the coil, and there are other much safer and better ways of doing it that don't.

If it's on the top, or bottom, once the car is on the ground, it's a dead coil.

Sorry Angry

and that right there is why 90% of the time i think ZW is pretty smart.

I've heated and rebent the coil to a closed one. Just be quick and keep the important stuff cool. It works fine.

Spring manufacturers say a torch is bad idea and recommend using a saw or cut off wheel.

Personally, I just can't see a reason not to heed that advice.

In reply to Zomby Woof:

A dead coil is a coil that does nothing. If it compresses, it's not a dead coil. Closed springs have dead coils, open springs do not. It doesn't matter if it's installed or not.

In reply to tuna55:

Sorry fishy, but ZW isn't correct on this one. And I mean that in the most welcoming, nice and non-argumentative way.

Get this book if you want to know the facts concerning coil spring design:

link

A guy on the mercedes forum took springs from a V8 r107 and cut them down 2" to put on his 280sl, I think I'm looking to do the same as short spring are pretty expensive for my car 500-700$ for a set of 1.5" lowering springs.

That being said I think you could find a set of lowering springs for a w123 for probably 250$ if you look around. Keep use posted and good luck!

This is a photo of brittle metal. It cracks like ice.

That's all I got.

The number of active coils in a spring is the number of coils that are free to compress under load. Normally this is equal to the total number of coils minus two (i.e. minus the coil at each end). This is because the coil at each end is fixed against its spring seat and therefore unable to compress.

When calculating spring rates on existing springs you never measure the coils at the end.

In reply to ditchdigger:

I'll explain this one more time. Some springs have closed ends. This is what you are referring to. Other springs have open ends. Closed ends are dead coils, inactive. Open ends are active coils. So on a spring that has open ends, you do in fact consider them in calculating spring rate, because they do compress when installed.

Open spring end:

Closed (and ground in this case) spring end on top, open on bottom:

bravenrace wrote: In reply to ditchdigger: I'll explain this one more time. Some springs have closed ends. This is what you are referring to. Other springs have open ends. Closed ends are dead coils, inactive. Open ends are active coils. So on a spring that has open ends, you do in fact consider them in calculating spring rate, because they do compress when installed.

I think ditchdigger has got this one - we all understand ground vs open ends, but that isn't what he (they) are explaining

After I did a lot of weight reduction on my SC, it sat way too high in back. I used a Harbor Freight porta-band to remove 1/4 coil at a time until I got it sitting where I wanted it. It cut the spring like butter, and it was still cool enough to touch.

I knew cutting the spring would increase the rate. These were open-end linear-rate springs, and I didn't mind a firmer spring rate at all, so win-win.

foxtrapper wrote: There was an old practice of running a torch up and down the coil spring, while still in the car, and letting the car as on that to lower it. The results were...interesting.

I've lowered well over 20 cars (about a dozen of them mine) this way since 1985. Never had a problem and still do it to this day, lolol.

bravenrace wrote: Coil springs are heat treated. The vast majority of the time, when they are torched they lose their hardness. This happens whenever the springs are not normalized afterwards. This allows them to fatigue over time and fail. Bad idea for a long term street car.

Wow. For a guy telling everybody else they're wrong...

No. Springs are definitely NOT heat-treated. That would make them brittle. In fact, all calculations for springs/bars/etc is based on a general constant for the elasticity of steel. Plain ol' steel. Therefore, if cutting a spring with a torch, all you have to do is let it cool all by itself, with no pressure on it, and it will maintain its spring rate. Be happy to refer you to a couple of material books, since you think that's so handy...

bravenrace wrote: Bad idea for a long term street car.

Disagree. My '79 Civic CVCC is a current 5 year daily driver on heated springs. All my cars have been daily driven on heated springs. I have never once replaced a suspension related item in my life.

Literally never.

In reply to pstrbrc:

Springs are made from a really high-alloy steel (used to be 9254 chrome-silicon) that isn't brittle when heat-treated. There is no steel that could stand up to 300,000 psi as-annealed and that's a fairly typical working stress level for a spring.

If you want to test this, anneal one of a pair you get at the junkyard - heat it to 1500F or so for half an hour, then let it cool down slowly in sand. Then compare the spring rates. They'll be quite different at higher force levels!

qdseeker wrote:

bravenrace wrote: Bad idea for a long term street car.

Disagree. My '79 Civic CVCC is a current 5 year daily driver on heated springs. All my cars have been daily driven on heated springs. I have never once replaced a suspension related item in my life. Literally never.

I would go thoroughly inspect all of the wear items in your suspension then.

Coil springs are heat treated after they are wound. Heating them in your garage is asking for trouble, or at least ruined springs.

You can take any heat treated metal you have and anneal it, but I doubt any of us could reverse that at home.

I've cut springs with a hacksaw. Yes. Hacksaw. Didn't feel heat-treated to me.

I've also cut springs with chop saws, zip discs, AND a torch (though not all at the same same time). I use the torch to heat the cut half-coil end and then bend it to a "closed" coil. Despite YEARS of road use, they have not failed, snapped, sheared off, or killed anyone.

I won't torch-to-sag-them - I haven't mastered getting that done evenly.

Take the information you find here, and make your own decision. Nobody has a gun to your head either way.

I am a big fan of the heating coils on the car school of lowering. Early efforts failed because they didn't heat the coils evenly. Torches are too finicky, but bonfires underneath the chassis are much more consistent.

Nice and low. Good for weight reduction too.

The cutting spring thread, the automotive world's equivlent of an abortion thread

Hyrpercoil's Website says: Coil springs can be either "hot-coiled" or "cold-coiled". Cold-coiled springs are more precise, but only if they are wound from pre-heat treated bar stock. Many racing springs are cold-coiled from annealed "bundle stock", then quenched and tempered after coiling. This method produces a less accurate spring and can result in surface imperfections.

qdseeker wrote:

bravenrace wrote: Bad idea for a long term street car.

Disagree. My '79 Civic CVCC is a current 5 year daily driver on heated springs. All my cars have been daily driven on heated springs. I have never once replaced a suspension related item in my life. Literally never.

And over 30 years of playing with cars, the ONLY springs I've ever seen that broke were ones that someone had heated up to sag. As an example, friend's '76 2002 had it's springs heated up to lower it, and it made it the 20 minute drive to my shop to get painted and as it came into the driveway, 2 springs snapped in 4 places causing the car to set down on the tires on that side. My torino GT when I got it had heated springs, which I removed, When taking them out, I noticed that both of them were split and cracked down in the compressed, heated section.

Not evey set of heated springs I've seen have become brittle and broke. But every set of springs I've seen get brittle and break were heated.

I've cut many springs, I will NEVER heat them up to sag them. Just too much risk.

I am sorry but there is no way in hell I am cutting a spring with a torch or heating them to sag. The original intent of the question was to figure out why people said it was a bad idea to cut springs. I didn't realize people cut them with torches.

93EXCivic wrote: I am sorry but there is no way in hell I am cutting a spring with a torch or heating them to sag. The original intent of the question was to figure out why people said it was a bad idea to cut springs. I didn't realize people cut them with torches.

You'll be completely fine then. Just don't cut them too short.