Karpellarpy

iTrader: (3)

So I'm installing koni SA's with stock springs on the lower perch, and was comparing them to the stock deCarbons. A couple of things I noticed. First, the koni's have less compression than the deCarbons, and even when set on full soft, have more rebound. Also, it seems like the compresson and rebound of the deCarbons are close to being the same. So here are my questions, why would I want less compression than stock? I'm running an 18" torque thrust 2 wheel that's heavier than stock. Seems like I would want more compression to ensure I don't hit the bump stops. I'm guessing the lack of compression would work better with a higher spring rate? Can anyone confirm or explain? How will this effect the ride? Second question, I would expect shocks to have a lot more rebound dampening than compression since it will take more force to control/slow the compressed spring. So why do the deCarbons seem to have equal compression and rebound? Are they just tired and the rebound used to be greater, or are they like that new?

z28bryan

iTrader: (7)

I'm not an expert but I'll answer from the homework I've done, so take it with a grain of salt. I've heard the koni compression is less than a lot of shocks too. But it's ideal for the ~stock unsprung weight. I'm not sure if the torque thrust wheel weight should make that much of a difference, but give it a shot.

Your decarbons are probably worn and old. They were never valved very good in the first place.

Karpellarpy

iTrader: (3)

My deCarbons are old, but they still gave me plenty of both compression and rebound dampening when I was playing with them. Like I said, they even have more compression dampening than the new konis. Everyone says that deCarbons aren't valved very good, I'm looking for what makes the valving not very good. Why are the konis 'less compression' characteristic considered better valving that deCarbons. How is 'good valving' determined? I'm not picking on you, I appreciate the reply, just looking for some more in-depth tech.

JD_AMG

How are you measuring all this? With a shock dyno?

For me, the stock decarbons (which mine were the "better" WS6 ones with less than 40,000 miles) were terrible because they were overly jarring stiff, and jittery over bumps, while also being way too loose/jelloish when pushing the car, and would be somewhat floaty/disconnected at higher speeds.
I put Koni SAs on the car, with no other mods and there was an immediate night and day difference. The ride quality was very solid, firm but almost never jarring(only jarring over the biggest/deepest potholes), and no where near as rough as with the decarbons. The Handling, feel, control, balance was drastically improved the car was significantly "tighter" feeling in all situations. For example I could push the car with the tires roaring while the car stayed perfectly neutral and controlled, even over rough roads, where as stock was all over the place, and often would have snap-oversteer. I could rocket out of a corner sideways and the car wouldn't be wallowing around like a drunk, I could easily control it drifting.
So with all this I would say the less compression settings are for a far better ride, while also helping handling on rougher roads (so the car is skipping all over the place like the stock shocks did). The upped rebound is for added stability, less pitch/roll/squat and a much more solid feel.

Im sure Sam can chime in (or you can PM him to get his attention) with some real technical stuff.

z28bryan

iTrader: (7)

Once again, my knowledge about setting compression and rebound correctly is amateur at best... though the ideal compression is usually less than the rebound. Rebound is what the stock shocks and most shocks are pretty weak at. Too much compression is bad for ride quality and handling. You want to let your suspension travel work, otherwise it can cause you to skate across the pavement when pushing the car hard.

In the end it's all personal preference, but the koni compression setting is pretty good for probably 95% or more of the cars out there.

Sam Strano

iTrader: (41)

First, what you feel/see when running shocks by hand is not valving, but the effects of gas pressure. deCarbon's and Bilstein's are high pressure shocks, Koni's are low--the difference between about 360 psi of Nitrogen vs. about 120. You are not working the shock at speed, and certainly not as hard as the car does. Basically you are getting a result that seems like one thing, but isn't. The faster they extend would indicate not more, but less rebound (more rebound makes the shock extend slower). Again, it's not really indicative of what is happening on the car, but if you turn the Koni's up they should extend somewhat slower... but you don't manipulate compression with those so they won't compress any faster.

That's about all I can say here. As always those Strano Performance Parts Koni customers are free to call me if you want more detail. All part of the sale with me.

Karpellarpy

iTrader: (3)

Thanks Sam for the correction, I did reference rebound backwards, as a function of speed instead of dampening (even though I know better). I'm not using a shock dyno or anything, i was merely messing around with them off the car by hand. You say my result is invalid, so is the unadjustable compression of koni's less than the deCarbons? Is the softest rebound setting on the koni still a higher dampening than deCarbons? Is the compression equal to the rebound on a deCarbon, and if so, why would GM do that since it seems to me that you will always need more rebound to control the energy/force in the compressed spring.

Sam Strano

iTrader: (41)

I have no idea why GM does what they do on shocks... that's the one thing they've historically screwed up overall as far as I'm concerned.

The Koni's have much more rebound, though if you turn them all the way down you're looking at something similar to the SS/WS6 shocks when new (which are upgrades over stock Z28, Formula shocks). You do want more rebound control, and you've got it in spades with those shocks. Compression forces are different, but not radically so--a bit softer in the rear pretty similar in front.