Coil Springs?

[Brian Gray]

i watch free height mainly. springs vary ever so slightly from week to week but when you start noticing changes in free height its time to pitch em.

think about whats happening with your car if that spring starts loosing height halfway through a race. it is going to have dramatic influence on your initial setup.

if you start to notice from week to week your car is just not consistant check the free length of your springs. always take an initial measurement the first time you install a new spring and keep record of the changes you will find some interesting data in that alone.

[Brian Gray]

if you want top end springs call draco. you will not find better.

[TheJet-09]

Hey @Lizardracing, it was Keith Masters that said that about springs losing their rebound ability. Seeing as he has more racecar knowledge in his pinky than I do all together, I believe it. I can't give you a formula or anything to back it up, but just food for thought. Maybe springs are like humans...I'm older now and it takes me a lot longer to get up off the couch? Sorry, that's the best I could come up with.

[Sprint76]

Lizard, it's similar to shock hysteresis if you're familiar with that. Memory foam is an extreme example of this. The material provides a certain force as you push it in, but as you pull away, it stays compressed, so it's exerting less (or no) force on the "rebound".

I'm not convinced this is necessarily true (significant) with spring steel, and you would need some pretty sophisticated equipment to test it accurately. I attached a rough chart of what a spring exhibiting this behavior would look like on a spring dyno capable of testing it.

[72Dubya]

I remember seeing in another thread where a racer used a scale pad in a press to check his springs. Has anyone tried this and compared their results with a true spring checker?

We use the scale pad/press method and it was giving us the same readings as a friends rater.

1. Put one scale pad on press, connect it, zero it out, adjust press height to spring.

2. Place spring on scale (if using a spring that is not flat on both ends, you can use a stock lower to hold it level). Put a spring cup in top of coil. Rezero scales

3. Run press down to coil, maintaining zero on scale. Measure free height of coil.

4. Slowly press coil down one inch from what the free height was. Rezero scale. DO NOT RELEASE PRESS!

5. Press coil down one more inch from previous height. The reading on your scale is your coil rating.

[Lizardracing]

Thank You Sprint76 and Jet, that is interesting and informative.

Not all spring manufactures rate their spring the same way id your comparing two older one however if you check them when new it's best to keep doing it the same way for repeatability.