GSteg

iTrader: (15)

Can you elaborate? I want to be entertained

BenStoked

iTrader: (3)

adjusting preload changes the weight distribution. unless you don't drive your car (or drive it like a grandma), this is bad.
coilovers have two adjustment points 1) preload, 2) height.

little more info at 4:19, so just skip to there
http://www.youtube.com/watch?v=N89-Pr4jCpc

iridebmx

iTrader: (6)

EDIT: ^^^^^^^^beat me to it!

GSteg, maybe your being sarcastic or something but whatever.... it just show how much you don't know. and how you want to be "entertained" because you think the way you do it is right.

you are supposed to lower and raise the car with the 2 way adjustment. HOW??? you loosen the bottom ring and turn the whole spring to adjust height.

this is a clear explanation of why mr. smarty pants =)

FROM ZILVIA (member, sykikchimp) :

"""""There are 2 kinds of springs. Progressive, and Linear.

With progressive springs, as they compress the lighter rate coils compress, and force higher rate colis into action. Effectively increasing spring rate as they are compressed. Stock 240sx springs are progressive. (most stock springs are.) This type of spring is good for street driving b/c they are comfortable over small bumps, but tighten up as you start turning, or braking harder.

Linear springs are the same spring rate no matter how much they are compressed. Almost all coilover systems come with linear rate springs. Linear springs are much better for sport driving, b/c they are much mroe predictable, and make tuning your suspension much easier.

You can only preload springs with threaded shock body coilovers.

To preload a spring, you compress it b/w the upper and lower spring perches by adjusting the lower collar with the spanner wrench.

With linear springs:
When you put the weight of a corner of a car (probably around 700lbs) over your spring it compresses to absorb that weight. With 400lb spring, it will compress about 1 3/4". So, if you start with the lower collar so that it is just tight enough to hold the top of the spring against the upper perch this would be 0 preload. Raise the collar 1 3/4", and you now have 700lb's of preload. (arbitrary #'s for the sake of illustration.) Since you have preloaded the spring, the same weight as the car's corner, when you put the car on that spring, it will not compress at all, and will simply sit on top of the spring. If you were to hit a bump, the force would still compress the spring the same amount it normally would if you had set the spring to 0 preload. Now if you set the spring to say 900lbs of preload, when you hit the bump (say its a bump that generates around 250lbs of upward force), the spring will compress much less b/c the spring is already beyond the load specified to absorb the bump. Since there is only 50lbs beyond the preload, the spring will only compress about 1/8th inch, and the car will likely be launched over the bump.

You will likely never ever preload a spring beyond the weight of the corner of the car it is on for that exact reason. Springs are there to absorb bumps, if there are any bumps at all, this is a bad idea.

What good is preloading the spring then?

It can provide you with more suspension travel in certain situations. In the ideal world, having the spring at 0 preload would place the piston inside the shock exactly halfway through it's stroke (middle of shock) once the car's weight is resting on the spring. This is almost never the case. by preloading the spring, you can adjust the amount of rebound, or compression travel you have in the shock. If you preload like 200lbs, this will give you more compression travel, and will help keep your car from bottoming out when cornering. You have to be careful though, b/c you don't want to sacrifice too much rebound travel, or you could cause all sorts of other problems.

Progressive springs:
With progressive springs, preloading the spring does all the same things as linear springs, but it also increases the initial rate of the spring. So say you have a spring with a 200lb/in initial rate, and a 400lb/in max rate. (all progressive springs are rated this way.) Preloading 200lb's will compress the spring just under 1". Since the rate goes up with a function, it will have increased to probably somewhere around 250lb/in by the time you reach a 200lb preload. So now your initial rate is 250lb/in, with a max 0f 400lb/in.

You will likely never deal with this though, b/c very few coilover systems come with progressive springs, and remember you can't preload without adjustable spring perches. (coilovers)


-Charles"""""


SORRY to the OP and others, i just felt the need to prove a point.

GSteg

iTrader: (15)

Don't want to write a novel, but preload is a tool. Vendors on here and everywhere else have people brainwashed that preload is a bad thing, which is no surprise because most of them sell coils with dual heigh adjustments. It's a win-win because customers can slam their car further than coils that only adjust through preload, and it save manufacturing cost because most of them are using the same dampers, but with different mounts to accomodate the car.

In any case, changing preload itself isn't what causes weight distribution changes. You cannot change F/R distribution without physically loading/freeing up the corners. You can change cross weight by adjusting the corner height, but this can be done whether you adjust via shock body or preload.

Changing height by changing preload is only bad if you are trying to slam your car all the way down because your piston will slam against the base valve. Sellers will also tell you adding preload is also a bad thing, which is one horsecrap sales tactic. When used properly, preload can be a good thing. Food for thought, Formula F1 and most other high-dollar race cars do not have dual height adjustment. They adjust through preload, and they certainly don't drive like grandmas There is a reason why Penske, Moton, KW, Sachs, etc only have one height adjustment. When you can create dampers that perform, they will perform at all levels...not limited to just 3mm of preload or whatever they try to sell you.

I care about performance more than looks, and I ride my car at the height that is within safe margins, so single height adjustment works in my book. Quality over quantity. I see the word preload get thrown around so much nowadays that the meaning is eventually lost. Preload is now a negative connotation.

GSteg

iTrader: (15)

The information you provided is nothing new. My grief is that people are calling adjustment through preload a bad thing, which isn't always the case, unless you are trying to acheive a slammed look. Whoever wrote that is right on the dot...preload is a tool which can be used to your advantage if done correctly. I don't have my car slammed, nor do I have it preloaded 5 inches either!

iridebmx

iTrader: (6)

those coilovers use a different concept than double adjustment coilovers.... most of them have an extra compression chamber....


but to be honest i thought you were saying you just adjusted you suspension by preloading them and didnt know any better.

in a lot of cases esp for racing purposes adjusting and playing with the preload is ideal and most car if not all play with it when getting a corner balance for a day at the track or even to dd if they want that.


so touche' to you, i had a misunderstanding! i was wondering why a guy with 13k posts was saying that.

GSteg

iTrader: (15)

Yes I agree it's a misunderstanding. You asked whether I change my height with preload and the answer is yes, my car's height does change when I increase/decrease preload

In any case, people who have dual height adjustment should use preload to their advantage. I know some companies offer different spring rates (like BC Racing), but still recommend the same 3-5mm preload in all applications. If the piston is within the center region of the shock body after weight has been applied (using say 10k/mm spring), then it's definitely not going to be the at the center with 8kg/mm springs. This is a case where preload is a good thing because you can increase compression stroke. Obviously the 3-5mm preload suggestion doesn't work, which is why I always try to emphasize the usage of preload to set up the suspension correctly.

horent135

iTrader: (10)

Yay finally someone that really know about suspension. I have a question, sorry to jack thread.... I have dual adjustment (springs preload and height) Could I make the ride softer by changing the preload? Or that is all damper in works?

GSteg

iTrader: (15)

If your springs are truly linear, then no, preload will not change ride quality because the rate between force and displacement of the spring is still the same. Both springs AND dampers need to work with one another to accomplish a specific performance. You can have soft springs and shocks with high compressive force and it'll ride equally as bad a a car with stiff springs that are under-damped. This is why I don't worship damper ***** and I definitely don't see it as a substitution for proper suspension setup. It would be nice if you had seat time in a car that's properly set up. Not only is the ride surprisingly comfortable, but it can also turn better track times even though the car may feel like it's rolling (which btw is not a bad thing).

If you feel that your car rides too stiff, you can try getting softer spring rates. Most dampers can accomodate up to +/- 2kg/mm.

BartleDoo

iTrader: (1)

I adjust my right height with pre-load.

Oh and btw GSteg you're going to confuse a lot of people since most tend to believe that no body roll means the best handling. They fail to see what that would imply.