Coil springs

[oldtinsmith]

1. Are the springs cold-wound or hot-wound? If they are hot-wound (and your wire diameter is not ~.700" or larger) then find another spring. Hot winding ruins the heat treatment of the wire, reduces the fatigue life a bit and also produces less consistent springs.
   
2. What wire material are the springs wound from? You are looking for either chrome vanadium or chrome silicon. Preferably, chrome silicon.
   
3. Are the springs stress relieved after winding? This is an easy procedure and is done by most companies so as to almost be assumed. But you wouldn't want to assume now would you??? ;-)
   
4. Are the springs shot-peened AFTER winding? As, most engine savvy people know, this done to rod beams to increase the compressive stress at the surface of the metal. Well, the same is true for springs. Shot-peening is also one of those procedures that is done more often improperly than properly, so make sure to stay with a reputable manufacturer or an aircraft peening operation if you try to have this done yourself.
   
5. Are the springs pre-set after winding? Pre-setting springs is a process whereby the spring is smoothly compressed from both ends until it stacks solid. It is then held at that position for a predetermined amount of time and then released to free length again. Pre-setting is an invaluable process used to combat what is commonly known as "spring sag" or the springs taking a set.
   
6. Are the springs epoxy powder coated? This finish protects the spring from nicks which could cause stress fractures. It also makes the springs look pretty trick as well and you car definitely get bragging rights at the local shindig ;-). Also DO NOT, under any circumstances buy springs that have been chrome plated as this causes hydrogen embrittlement of the spring wire and will most assuredly cause the spring to fail while you are in the middle of your annual trek across the Rockies. As far as I know, no company has been selling chrome plated springs for a LONG time, but it's always better to know about these potentially life threatening things beforehand.

I know that the questions above are for new racing/competition springs. My question is: do springs "settle continually" over their life time or do they "settle to a point" then stop?

Doug

[BMR Sales]

Doug,

I will just State for our Springs. BMR Springs are Cold Wound, Chrome Silicon, Stress Relived, Shot-Peened, Pre-Set & Epoxy-PowderCoated. Our Springs will take their "Set" and then are Guaranteed For Life against Sagging>

http://youtu.be/4vDSOpONcDs

[oldtinsmith]

Thanks TC! ... How long do they take to "set"?

Doug

[BMR Sales]

The "Set" is more about the car, but a good 30 Hour Drive will do it

[oldtinsmith]

TC, that's the answer i was looking for!!! I'm pretty sure the time will vary somewhat per vehicle. Thank you!!


Doug