The statement "Pre-load "ONLY" changes the resting point" is completely wrong.

At the same time I don't understand your vague post. It seems to me like your saying that preloading is there only to put the piston at the optimum position, which is also incorrect.
You preload the spring to corner balance your car, all 4 corners will then have pistons sitting in the different parts of the shock, am I correct? If so, then your statement of preload doesn't make any sense.


I could have mistaken what you wrote as talking about raising your rideheight on a coilover without an adjustable bottom bracket such as a KW coilover, which, in that case is not called preload at all.
Unless you're talking about putting in preload to put the piston in an optimum position in the shock considering droop, but then that usually means you probably want to raise your spring rates anyways. Most times you want to decrease preload to put the piston in an optimum position, not increase it unless you have really soft rates. Even then it would be pointless because your starting rates are going to be stiffer and the spring would be there just to pick the car back up from compression.

I dont think you understand what I meant in my post either. There is no technical definition of sweet spot buddy. I am saying the sweet spot of the spring.
Just to let you know it does not matter what Afco's website says, if you dyno a spring you will see that it has an arc to it. and therefore in the first bit of compression the spring rate is way lighter than the spring rate listed for the spring, at the same time as you compress it near coilbind it stiffens up way past the listed springrate. In between that is the sweet spot of the spring, where the rate is dead on. So yes, you can preload to match spring rates.

Anyways this is a pointless argument because there are so many reasons why you would preload it. In fact if you look at circle track racers, which is what afco mainly caters to, they will get a 14" 125lb spring and preload it to coilbind and back it out maybe 1.2 inches, so the standing height of the spring is about 5".

Also why are you posting up an afco site? I browsed through it real quick and I don't see anything about preload. Again it doesn’t make sense. If you read it you will see that when they put the spring on the spring checker they will disregard the first parts of the compression of the spring, and that’s what Im talking about.

So in other words I don't understand your post at all.
-I still don’t know if you even know what preloading means.
-you obviously didnt understand what I posted
-why afco?

 

What happens when you increase preload.

 

Preload only changes the resting point of the piston

http://www.afcoracing.com/tech_pages/spring.shtml

 

I feel the term 'preload' should be banned from all discussions of coilovers. What you're doing is changing the height of the bottom spring perch. Any given spring is the same height when the car's weight is resting on it, regardless of the lower spring perch height. By moving the lower perch upwards you also move the upper spring perch upwards, along with the rest of the car.

If you had some suspension where the shock had zero or minimal droop travel from ride height, then raising the spring perch would preload the spring at ride height. But I think we all agree that that would be a pretty f-ed up suspension setup. (unless it's needed to fix something else that's pretty f-ed up)

 

OMG thank you

the term should not be banned but instead people should be educated on the matter.



A 1000lb spring with a 1000lbs and 1-1 mr will compress 1 inch, a 500lb spring with a 1000lbs will compress 2 inches. Yes I know it won't be perfect but it's close enough.

For 1000lbs not to be able to compress the spring you would have to have 1 inch of preload for the 1000lb spring and 2 inches for the 500lb spring. Nobody will set their suspension up like that, instead you adjust for the correct amount of bump and droop if you are travel limited. You do this by preloading the spring or in cases with high spring rates it would be negative preloading (not sure if that's the correct term) and that's when helper springs are used to keep the spring captured.

 

Even that is confusing. Can you imagine someone that's new to this trying to figure out how to 'negative preload' a spring?

The lower spring perch sets ride height for any given spring. If your car is lower than desired, raise the lower spring perch. If your car is higher than desired, lower the lower spring perch. If you ever put new springs in with a different spring rate, you either:

1. Do the math with corner weights and suspension geometry to determine optimum lower spring perch height.
or
2. Take a guess, put the car on the ground to measure ride height, and then adjust the spring perch as per the above.

I'm going to guess 99% of people do the second version. I certainly do!

 

Sorry for not being clear.