I Want to Lift My Tacoma

snowboard704 · Mar 28, 2017

devinzz1 said: ↑

the truck is only so heavy. if theres 1200lb of weight it will compress the spring 2". if its preloaded 600# it will move it 1".

dont even think of it as preload as much as just moving the shock body down.

most harshness of a lifted truck is from lack of up travel and castor numbers being thrown off.
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jberry813 said: ↑

The spring is what provides lift. Shock just does dampening.

With Billy's, if you set the coil at 1.75" for example, it will add 1.75" of lift because it preloads (compresses) the coil. Billy's set at 0 basically has zero preload. Any other setting will preload the coil...and lift the truck.
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jberry813 said: ↑

Two problems with your thought process:

1) The 1.75" setting IS NOT compressed 1.75". 1.75" is the overall lift of the truck provided by the preload of the spring. Look at the notches themselves on the shock body...it's not 1.75", it's far less

2) Preloading the coil lifts the truck because you are raising the static spring rate, which in turn will raise the ride height of the vehicle. Essentially you have more stored energy in the springs than you have weight pushing down on the springs by the vehicle. Keep in mind that preloading does not change overall length of the shock.
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jberry813 said: ↑

Compressing the coil makes the SPRING shorter. It doesn't change the overall length of the COILOVER. See below. The middle coilover has zero preload and the right coilover has some positive preload. Yet the length of the coilover does not change. You can compress the spring all you want, it doesn't change the length of the shock. The coilover still has the same top and bottom mount points. The shock shaft doesn't magically get longer or shorter.

Stop thinking in terms of inches and start thinking in terms of weights.
Lets assume your springs are 600 lb springs. That means it takes 600 lbs of weight to compress the spring by 1". And a pair of springs would mean it takes 1200 lbs of weight to compress the springs 1 inch.

Now assume you put exactly 1200 lbs of weight on the pair of springs. That would mean you compressed the springs exactly 1" and (they would settle by 1"...meaning the vehicle is 1" lower).

Now...for the sake of argument, let's assume you preload the springs by 1". That means you have 1200lbs of opposing force pushing up on the weight added to the springs. Since you preloaded the springs 1" (and as such they have 1200 lbs of stored energy), adding 1200 lbs of weight to the springs does not make them settle at all. You have effectively negated the weight with the stored energy of the springs.

Adding preload does the same thing. You are countering the weight that is pushing down on the springs by providing stored energy in the springs to push back up.
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jberry813 said: ↑

Ride quality is an artifact of shock valving paired with spring rate and load. Valving a shock based on a loaded vehicle will make an unloaded vehicle feel excessively stiff. Valving a shock for an unloaded vehicle will make a loaded vehicle blow right through the valving and cause excessive shock travel/bouncing off the bump stops. Factory shock valving is typically somewhere in the middle, but erred to the loaded side particularly on full size trucks that are designed for large payloads.

By the same token, too much preload on a coilover can have negative felt perceptions of ride quality. Store too much energy in the spring and you'll typically blow through rebound valving making the truck feel excessively bouncy.
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I Want to Lift My Tacoma

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#21 snowboard704 Well-Known Member

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