just like the title says....how does spring preload adjusting work, does it have anything to do with spring rate?? Forgive the ignorant question.

 

It has everything to do with your spring rates. Preloading the springs means you compress them in some way prior to applying the weight of the car on them, which compresses them more.

A linearly rated spring will (theoretically) compress one measurement of distance for every one measurement of force applied, and is rated by the force required to compress them a given distance - eg. 10kg/mm, meaning it takes 10kg to compress the spring 1mm. Every additional 10kgs will theoretically compress the spring 1mm, until the entire spring binds completely. Other factors come into play that make it impossible to produce a truly linear spring.

 

Preload adjustment can be used to fine tune both compression and droop of the damper stroke. Increasing preload (Raising the collars) increases compression stroke while reducing droop. Reducing the preload (lowering the collars) decreases compression stroke while increasing droop. That is of course if your maintaining the same ride height via the lower-mount adjustment...

For a street car, you shouldn't really need any preload. You should just raise the preload collars enough that the springs are snug on their perches at full droop.

 

thank you so much guys, I am asking this because I want to learn exactly how to set up my car for the track in addition to utilizing my coilovers full potential. No point shelling out the cash for a good coilover if im not going to use them. It will be a street car, however I would like to be competitive during weekend racing ........so this leads me to a few questions.

1st. So would a 10kg/mm spring become an 11kg/mm spring with an additional 1mm compressed using the spring rate adjuster?

2nd. If this is the case, what is the purpose of buying specific spring rated springs if you can adjust them to the required. (I have an idea of the answer but humor me please I do not want to work on assumptions)

3rd. Is increased compression stroke more desirable to have? why is this?

Thanks again guys

 

1. You are not adjusting the spring rate - the rate remains the same, hence being a linear rate spring. Progressive springs will have their rates change intentionally as they are compressed.

I think the general consensus is that linear springs are preferred for performance and track use. A progressive rate spring, in theory, provides a low rate when you want a compliant ride (the initial rate is low), and a high rate when you want performance (as the spring compress, the lower-rate coils bind and the high-rate coils begin working), but in practice it's not always ideal.

 

Just remember this - for all practical purposes, the length of a linear spring will ALWAYS be the same when the car is sitting on the ground and the spring is compressed w/ the car's corner weight, no matter how much or how little preload you have placed on the spring while the suspension was at full droop.

Preload can appear to alter the spring rate during initial loading, as it takes more load to begin to move a preloaded spring. But once you move beyond the preload amount, the spring acts the same way regardless of preload.

 

thanks all for the comments its really clearing some things up

So now knowing that spring pre load does not affect rate.....its all to do with increasing or decreasing compression stroke while lowering or raising the vehicle...... (should have read that a little more closely.)

So ok now that i know this....and i know im beating a dead horse but I want to be sure....... in what situations would you want to increase or decrease the compression stroke??

 

When you need to increase droop. More droop at one end of the car allows more weight transfer to opposite end (during braking or acceleration).

 

isn't there a point where raising the collars no longer effects the compression stroke though?? Wouldn't all you be doing at a certain point by raising the collar is put tension on the spring?? or does that tension always raise the car allowing more travel?

 

ok did some digging and now i totally understand the preload theory. A short hypothetical example, correct me if i miss anything. (I know its probably unrealistic)

a spring is a 10kg/mm spring. once the car has its weight placed on it (really light car), it moves down 3 mm meaning there is 30kgs placed on the spring. You decide you want more compression stroke so you jack up the car again, move your pre load adjustment collar up 1 mm or place 10kgs of pressure on the spring. When the weight of the car is once again placed on the spring it only moves down 2 mm or 20kgs. With the additional 1mm which was pre loaded previously the total movement of the spring is 3mm or 30kgs just as before, however you now have an extra 1 mm of shock travel. To adjust the extra height of the vehicle out, all you do is move your height adjustment down.

This sound about right guys??

 

Yes that is correct. The car (in your example) is still putting 30kg on the spring, but the spring did not start to move until the car got past 10kg on the spring.

Without separate height adjustment, you would just be raising the car up, which would obviously give you more compression travel.

 

Thank you PatrickGSR94 and all those that contributed, very much appreciated....now i need to decide what spring rate is optimal for my set up....

 

This is all new to me as well. So one can only set preload on a coilover set if the coilovers have a separate height and preload adjustments? The preload adjustment collars you guys are talking about is NOT the same as the collars to raise/lower the car correct? OR am I confusing myself?

Reason I'm asking is because I have Megan coilovers and all I see are the collars to adjust height.. you can only do preload adjustments on high end coilver setups?

 

For coilovers that look like this^:
- upper gold collar adjusts preload
- lower gold collar locks upper preload collar
- lower mount in blue adjusts ride height
- colar in red locks blue lower mount in place.

Idealy you just want the gold collars barely snug against the spring. If you add preload and start to compress the spring, you will have a very very tough time adjusting ride height while the shock is on the car. This is because you are supposed to spin the shock body up or down in the blue lower mount. If the gold collars are pushing too hard against the spring, they won't let the shock body spin, and you won't be able to adjust ride height....

Another good reason not to run any REAL preload on the springs...

So for the 10 millionth time, don't bother messing with preload (unless your racing)...

 

I took a quick look at the megan racing site and most of the Honda full coilover systems have the height and preload adjust features, not sure if i missed something though....if you look at the picture that was posted previously, height only is adjusted using the lower mount colored in blue and on top of that the red ring locks it in place.....high end coilovers will have this, versatility and adjustability are things most race teams would be looking for to fine tune.

 

lol there are quite a few coilover setups with the separate height/preload adjustments that I wouldn't really consider high-end *cough* Ksport *cough* Megan *cough* D2 *cough*

 

Agreed. They are just there to fill a niche in the market (cheap racey looking parts)...

I especially like how D2 used pics of those Mercedes DTM touring cars on their website. Eventhough their actual sponsor was "D2 Vodafone" the European cellular company! ROFL!!!

 

Ahhh I understand now. Thanks! Oh and by the way.. I just have the cheap Megan coilovers, not the complete coilover/shock setup so no wonder I don't see the preload adjustment collars.

 

i got a question... i kinda know how preload works but im kinda confused how it would affect ride height.. say i have the preload collars on so that they are snug with the spring and i like the height im at... if i increase the preload(compressing the spring) then will the ride height actually change?? thats the only thing im confused about...

 

If you don't adjust the lower perch to compensate, then yes it will raise the ride height to increase the preload.

 

ok... thanks... i thought it would but i wasnt sure... and everyone else agrees correct?? haha i just wanna make sure cuz i've heard mixed things..

 

Yes that is correct. In order to adjust only preload, you have to re-adjust ride height. Now you guys see why these types of coilovers are overly complicated for street cars... lol

 

yeah they could be.. i was just wondering cuz i wanna see how the ride would be if i adjusted the preload but wanna keep the height the same so i just wanted to know

 

The ride wouldn't be any different at all, unless you had the spanner wrenches and man-handles the perches up to put 500+ lbs of preload on the spring. Then it would feel like you had solid suspension until the load from the car exceeds the preload amount. Tires will be much more likely to break traction, and it'll pretty much jar your teeth out.

 

alright koo thanks...