Compressing Factory Coiled Springs

[021chopsho]

Im curious to know how this process is carried out,

Ultimately Im wanting to offer this service to a small local crowd of people in New Zealand whom are all enthusiast with lowering of the suspension.

Advice that would point me in the right direction as to heat treating to retain original spring characteristics, heating temperatures, post cooling, tempering methods etc any related info would be much appreciated!!

Thanks, Jono

 

[israelkk]

It will be safer and cheaper to design new springs to your specifications. Tampering with already finished spring may (probably sure to) destroy its short and long time properties. I assume you want the same force and/or rate of the spring but in shorter compressed length/s. This can be done only by using either thicker spring wire, different number of spring active coils, and even spring material. If you know the exact properties of the current spring then you can design new springs with different dimensions for the same properties. Since you already agree to invest in accurately controlled heat treatments and secondary operations then all that is needed is to design and coil the springs.

 

[GregLocock]

I'd listen to israelkk, but would point out that scragging springs is done very commonly by automotive OEMs in production.

It's done to a finished spring, roughly speaking just overcompress it without damaging the end coils in particular.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Dudely7]

Its really hard to predict the outcomes if you havent experimented with this alot.

If I were to offer economic lowering services, an old prefered method is to cut a certain mount off the spring with a hot flame (oxy acetylene torch) and use the heat to quickly force the cut end down,for a factory seat, let the spring cool slowly,then finish the cut end. I know it sounds scary but lots of professional suspension designers can vouch for this method.

But its pretty hard to determine how much to cut,considering all the factors (ratio of the suspension,added stiffness of new shorter spring, unpredictability of the new flattened end)

http://books.google.com/books?id=rY2ujnNrhf0C&pg=PA33&lpg=PA33#v=onepage&q&f=false

 

[Tmoose]

I think Pressing the hot coil into my asphalt driveway could result in a powerful theft deterrent via the resulting distinctive "Circle C" brand.

Dan T

 

[evelrod]

I've done a few "lowering jobs" in the distant past the way that Dudely7 posted...I think the first was on my 1949 Mercury when I was 16 (my dad went ballistic when he saw what I did to a new car...a "new" car to him).

I've scrounged the "yards" for springs...too laborious.

Last time on a new '83 Turbo Coupe, I had new springs wound up by a custom shop. That's the way to do it. Not terribly expensive and much less labor intensive.

These days, sadly, everything comes in a "kit" requiring only $$$ to achieve just about any results one would wish.

Rod

 

[NormPeterson]

". . . retain original spring characteristics,"

I'm not even sure that you want to do that. Reduced clearances in 'bump' suggest that a somewhat higher spring rate would be preferable.

Even if you did manage to arrive at the desired ride height by only heating and collapsing a coil or two, when that/those coils go solid ,the spring rate will have gone up anyway and the strains and energy per unit volume in the rest of the spring will also have gone up.

If specifying a custom spring is not an option, I'd start with replacement springs of similar ID/OD and end configurations that are stiffer and/or longer free height and a higher rated load and cut them down.


Norm