Coilover spring preload questions

[ron in sc]

If a coilover has a spring with a spring rate of say 600lbs will moving the spring upward increase the preload? I would think yes. This would be done to raise front end of vehicle.

If the preload is increased as stated above would that decrease the amount of rebound and compression the shock was previously capable of?

Would it be best to not preload spring so you get the most out of the compression and rebound properties of the coilover?

I have no real experience with this type of spring and shock comparison so no flaming please.

 

[eddiebx]

Raising or lowering the collars should not affect the actual spring preload, unless you raise it so high that the shock does not compress anymore with the vehicle's weight on it. But you would've also went waaay past the coilover's recommended adjustment range too, so as long as you stick to the manufacturer's instructions on raising the coilovers, the preload should not be affected

 

[1engineer]

Ron although this thread http://www.toyota-4runner.org/5th-gen-t4rs/135713-weight-increase-vs-spring-rate-increase.html was calculating for a different issue it might help to read through it. In that case weight was added to the truck. In the case of nosedive weight is added by shifting mass caused by deceleration. Anyway it's a good read.

 

[Jeremy556]

Yes, the threaded collar on most coilovers adjusts preload. Spring preload has no affect on the shock's damping, however it does increase the effective spring rate and reduces available suspension down travel.

Ideally, you would have a spring with a rate that is perfect for your desired static ride height (sag) and no preload. That is usually not feasible, hence the preload adjustability.

 

[eddiebx]

Hmm after reading the responses I think I might've mis-read what you meant by preload. What I was trying to say is probably much better understood with pictures and formulas, lol

Here's a good link that has a nice write up if you're interested in reading it: Coilover Spring Preload Explained | ZoomSquared

Basically, what I meant is, say an un-preloaded spring compresses 4" when you rest the weight of the vehicle on it; if you go and adjust the collar to preload the spring by 1", the vehicle will only compress the spring 3" when you rest the weight on it.

The total compression on the spring is still 4" (regardless of preloading or not), so the spring force should end up about the same, and thus probably dampen all the same as far as the shock is concerned?

At least that's how I best understood it, maybe [MENTION=66316]1engineer[/MENTION] can explain better and tell me if I got it wrong

Mechanical anything is not my forte, lol.