Not true.

When the vehicle's mass is resting on the suspension system, the springs are compressed and preloaded by the same amount of mass regardless of the static compression caused by either shocks.

The rougher ride quality you feel with the shorter shaft Z-shocks is most likely caused by the higher damping of the shocks.

 

No no no! Preloading springs causes a stiffer ride. Think about this, when the car hits a bump, the entire corner of the chassis goes up (to a varying degree). When that corner is at its highest point, their is no upward force on the shock. A spring/shock without preload will have extra spring/shock compression when the corner hits the road again. If the spring is already preloaded, that dampening will be reduced when the car goes back down, therefore less dampening --> stiffer ride.

Your logic would work if the weight (not mass) of the car on the spring never decreased. This would happen if the car never traveled up, only down and back to it's original height. This doesn't happen obviously.

If you still don't believe me, call Tein's technical support and ask them. They have one of the best technical support center of any company I know of.
562-861-9161

 

Sorry you're wrong man. Just think about Hooke's law, basic principles of spring force and compression.

F=-kx.
F= force
k= spring constant
x= distance from equilibrium.

http://en.wikipedia.org/wiki/Hooke%27s_law

 

On a coilover setup that is true. With the coilovers, springs can be preloaded to provide zero droop. In that case, the preloaded springs would cause significant discomfort.

However, I am talking in the context of using a shorter body Z-shock. With that setup, the springs are compressed the same amount no matter how much shorter the shaft or the body is.


I have tuned and tracked many cars, including a heavily modified 240sx and an Integra Type-R. I now track a Lotus Elise. All these cars run on coilover setups that I tune myself.

 

Gotcha on the coilover vs stock system. I was still thinking in terms of my 99 Acura's design (coil spring system).

Are you saying that the static ride height is only influenced by the spring, and that (by the same principle) the dynamic ride height (and preload) is also only influenced by the spring?

 

They are not compressed the same amount on a Z shock as a G shocks. They are compressed more on the shorter shock. I laid they all side by side with Freddie (mechanic and member of this site) for comparison. You are getting roughly 1/2-3/4 of an inch more travel on the G shocks than you would on the Z shocks.

 

Side by side. But on the car with all 3700lb. on them, would they compress the same?

 

That's exactly the point.

The length of the shaft and/or shock body do not affect the spring rate. It only dictates how much travel the suspension has before the piston shaft bottoms out.

The G shocks have more droop travel but less compression because of the longer piston. The Z shocks have more compression travel but less droop travel because of the shorter piston.

The key point is that as long as the same set of springs give the same ride height when installed on the same vehicle, it doesn't change it's stiffness regardless of piston length of the shocks.

 

I dont understand how they would compress the same based on the Z shocks are much stiffer to begin with and then the springs would be more compressed, therefore inital travel would be stiffer because you lost the initial softer linear rate.
Also, when going over bumps while driving the shocks/springs have weight removed and then applied over the course of a single bump. So when the shock has weight removed from it (rebound of a bump) you are losing that softer part of the shock/spring rebound. The Z shocks will be taunt throughout the whole process.

Either way, this is finally a good, informative thread.

 

I think it's like this:

Since the shock doesn't stop at the point where the car sits at static position, the spring is the only thing that determines static ride height. Shocks only stop movement when at their max compression I believe. Before that point, they are just two tubes that slide into each other at a slowed rate due to small holes (valves) on the inner tube.

I am not sure if the above applies to moving situations or not. If the Z shocks are stiffer (smaller valves) then they will not decompress or compress as quickly over bumps as the G shocks. Does anyone know if the decomp and comp are both slower on the Z shocks? Basically are rebound and compression both reduced? IF so, I think it stands to reason that G shocks will have reduced "preload" over the Z shocks, as the G shocks will expand more when the car is unweighted on that shock.

 

Are any of you running the sport suspension with the HP's? I talked to the tech dept at Tokico and they told me that there is no shock they make that can go with a 2006 g35 coupe with sport suspension and RAS. I have a pro kit in hand and would like to repace my stock sport shocks/struts with HP's so i dont have to pay double labor when the stock ones blow. If anyone has the part numbers for the aftermarket shocks that they used with a factory sport suspension it would be greatly appreciated as i am installing the springs in 2-3 weeks. I dont want to get halfway through the install with my mechanic only to find out that Tokico was correct and that i cant replace the factory shocks/struts with HP's. I also looked into the KYB's but they offer the same performance as the factory sports suspension so i feel its a wash. I am currently at 62k miles. thanks again for your help guys!!!

 

as far as I know, the only diff in sport suspension is the wheel size. 18s vs 19s.

 

Sport suspension has stiffer rear springs and shocks than non-sport, and stiffer front sway. But you should be able to run the Tokico D-specs, probably the Z versions since the Pro Kit will drop the car about 1". Just dial the compression and rebound damping up a bit to match the new spring rates.

 

ill be runnin some HPs soon. hopefully before zdayz cuz my LR shock is leakin and im startin to notice a big of a loose feelin when goin over uneven pavement/bumps while turning

 

Are these the right blue G-Shocks?