Shrinking coil springs

i don't see 200 degrees having any effect at all on steel tbh. 600 maybe?

just by some lowering springs.

sounds like a variation on the "heat it with an oxy-torch" method of lowering which causes the steel to become more brittle and increase risk of spring snapping.

Just get the grinder out and cut 'em - or buy lower springs.

Sounds like a bad idea to me, heating metals enough to remove their elasticity will make it more brittle unless it is done properly. I.e. left in the furnace to cool very very slowly. Cool it quick your setting up stress points by aligning the atomic structure. This will make it far more brittle. When cooled slowly the atoms have time to rearrange into a random pattern which reduces the ease of crack propergation and brittle fracture.

in the oven aint gonna do a thing but curse word you off ,

the way to do it is cut em down so they a bit longer than you want , then heat top coil with a blow torch, only 3/4 tho , flat it down so it replicates how it would have sat before ,

let it cool on its own!! never chuck water on it!!

ive done many a car like this and has been fine for yers , also makes em stiffer,

this is what ive done and if you do it yourself then thats your own risk

all springs are cut. Even factory ones...

They don't grow on trees magically in the right length.

And that's the point; a chopped spring changes it's stiffness and thus it's rate.

I thuink the idea - and I see that 200° is too low - of putting the compress4d spring into an oven is to avoid exceeding the temperatures that alter the material. Let's call it 'controlled torching'. In theory this should prevent the steel from getting brittle...

coil springs (or any other steel spring) is an medium to high carbon steel alloy (steel in turn being an alloy of iron)

it can have many combinations of things added to help it act as a spring, that allow it to be tempered reduces it likelyhood of fatigue...
usually containing chromium and silicone and manganese etc..

ok so I'm no metallurgy specialist so please do not take everything I say as word of god..
but I will tell you what I have learnt first hand.. ive made coils springs. reshaped them radial compression and extention. made leaf springs etc..
and sucessfully welded them..

everything from springs in car instriments a few mm in total size upto road car springs with lots in between ie gun firing springs, lock/catch springs etc..

basically there is 3 things you can do to spring steel using heat..

hardening
tempering
anealing

to make a bit of suitable bar springy.. it needs to be tempered..
but to be tempered it needs to be hardened..
(i wont go into exact temperatures as it can be slightly different due to different alloys)
the bar would need to be heated to a cherry colour red but then cooled rapidly in water.

this will harden the bar

basically hardened its great to use as a cutting edge or chisel etc but very brittle..
a file run across it will slide effortlessly and cut minimally..
but if you try and bend it it will resist and then snap with very little distortion.

ok thats rubbish for a spring then..

so next you will need to heat it again to around 700 to 750c or around straw colour to metalic blue, and held that heat for a bit before cooling much more slowly than you would to harden.
in sand or woodchips. can also work well in oil...

voila you now have a spring steel bar....

ok so this sounds easy but it can take a bit of practice.

what I have missed out is annealing..(to make soft and malliable)

basically you heat it up again to near cherry colour and let it cool natrally in air slowly..

what I'm really trying to cover here is that by cutting a spring or heating a spring to reshape it you are not always going to make all the nuns and kittens don there safety helmets and run for the hills...

if you don't induce much heat or its very localised when you cut coils its fine.
if you heat then to let them compress to length then you quench them with cold water they will prob snap!...
but let them cool naturally they will prob go soft and flat but they shouldnt snap..

ok so I don't expect everyone to suddenly heat all the coild springs in sight thinking its fine

ANYTHING YOU DO ON A CAR CAN BE DANGEROUS IF YOU ARE NOT SURE WHAT YOU ARE DOING!

but saying that don't be affraid to experiment safely in a safe enviroment and always distruction test before contemplating modding your road car..

ok one last thing...

coldworking springs...
firstly remember school?
"hookes law" wiki it if not familiar

lots of people say you should never cold work springs..
but in truth lots of moddern coil springs are cold formed from the factory.. its simply faster...

so yes you can force a spring beyond its elastic limit and into its plastic behaviour stage to cold form it.. difficult with coils as they will coilbind long before there elastic limit and difficult to pull safely..

but works well on leaf springs..
reversing eyes or decambering is no problem..
however do it once not over and over again they WILL fatigue then can break...

and and just a last one....

aviod stress risers..
when making/modding springs always avoid stress risers..
any nicks/cuts/grind marks/scratches/rust pitting on the surface of a spring can lead to a brakage
always sand and polish if you can all surface of springs and radius any edges.. (again avoiding much heat if existing spring)

ok hope that helps some. hopefully I'm not "teaching granny to suck..."etc..

si

excellent post B-8-D

It's refreshing to see someone else who understands the metallurgy of carbon steels.

Springs are very dangerous things if you don't know what you're doing.

My advise is, if you don't know EXACTLY how to re-temper/anneal/harden, or have the proper equipment to do so, then for safety's sake, leave it to the professionals

Bending leaf springs is one thing, This is another matter.

Think of teh kitties