dohc

Anyone ever auto-xed with Edelbrock IAS shocks? Did you find that they worked fairly well or were they just too soft?

What springs are you using?

Sam Strano? Unbalanced Eng?

Anyone?

Arctic2002ss

Since you are on the subject, is anyone here running them? I have them on my truck and they have been great. How are they on an f-body?

Sam Strano

iTrader: (41)

What's fairly well? Are they anywhere near as good as you can get. No. Are they something I'd run? No (but we sell them).

dohc

With a stiffer front spring (500lbf/in), did you find that they provided enough damping on your typical auto-X track or do they leave you seasick?

The literature says that they are really nice and stiff in comp unless until the "inertia valve" is activated, is that how they feel, or is that just marketing hype (valve activates too early).

Can you get them with different recoil damping for different rate springs?

Koni FSD's are kinda along the same line, have you tried these?

Sam Strano

iTrader: (41)

Great marketing.... FSD's are intended for ride more than anything, but with decent control. They are in no way intended to be a replacement for something like a Koni Sport shock, and BTW, they freak out when you encounter a bumpstop and a sudden frequency change.

I'm guessing you are looking at these based on price, correct? You would be way better off with a Revalved Bilstein. Anytime someone tells you they can do it all, be very worried. And BTW "inertia activated", that just means at a certain piston speed the valve blows off and softens the shock, and it only works on one side of the piston, can't even readily determine if that's the bump or rebound side.... And they also claim that the shocks "reduce body roll". Bzzzzzzzzzzz, wrong, shocks don't reduce roll, they only change the rate at which is happens. Bars and springs are what effect the amount of roll.

dohc

FSD's are moot anyway, as I just found out that they don't make them for our cars.

No, not so much price. It would be quite stupid to have the damper blow off in rebound, the springs have a set rate (unless progressive, but who uses progressive springs for a perfomance vehicle?), so there's no need to change the rebound damping for a specific spring rate. Unless your vehicle is loosing mass at a fast rate (large fuel tank, thirsty motor), there is no reason to for semi-active rebound damping.

Your right, dampers only effect the transient rate of pitch, but unless your in a long constant radius corner and your acceleration stays constant (ie. no gas or brake or wheel scrub slowing you down), your pitch angle will be quite effected by damping rates.

Pitch angle is load transfer moment divided by wheel stiffness, so as stiffness goes up, pitch angle goes down. If you look at the equation for dynamic wheel stiffness, it does incorporate damping coefficient into it. This holds true for both recoil and compression, but in reality, compression has a much larger effect on pitch angle. Rebound should only be high enough to quell the heave frenquency (dependant on vehicle mass and spring rate mostly).

For ride quality, you want only enough compression damping to control the mass of the unsprung components, but for handling you want the dynamic wheel stiffness as high as possible. (Ignore tire stiffness and damping for now)

Outside of active or semi-active suspension, you just have to pick the best comprimise.

The theory behind IAS dampers and those like it are that rebound damping has little effect on pitch, so it there's no need for it to be semi-active, while compression damping should remain high until a large enough input acceleration is encountered to require a lower comp. damping rate. The mechanism for how that happens varies. Personally I think the IAS valve is the most effective.

The theories there, just seems like the execution leaves something to be desired. I'm guessing the comp. damping isn't stiff enough before the valve activates, and the acceleration input at which the valve actives is set too low. Edelbrock probably designed it for there core customer base, which is hot rods and cruisers. Most of whom won't run springs that are stiffer then stock.

If it was revavled by an auto-xer or road course nut, then I bet it would work awesome.

BTW, do you know what the front spring rate is for the F-bod IAS? What are the spring rates for the rear in the kit?

Thanx for your input so far.

dohc

Sam ?

Sam Strano

iTrader: (41)

They use Eibach springs, nothing special there. The shocks are valved by god knows who. I've never seen a damping curve on them, and the vehicles I have the most experience with them on are trucks, and never once haven't Bilstein's better better in comparison. Better control all the time, and still better over the sharpest bumps (because they have shim stacks on BOTH sides of the piston, not just one and a LOT more experiene in this realm.

dohc

Hmm. I might just pick up a used pair and throw them on the dyno at work. Cut them apart too just to see how they work. Looking at the cross section in the marketing package it does look like its the rebound side that blows off . That makes absolutely no sense to me.

Anyway, Sam, when you revalve the Billy's do you open the orifices up at all or just swap the stacks? I haven't worked too much with shim style valving myself, though we are getting into them more because our customers keep demanding shorter deadlength.

Sam Strano

iTrader: (41)

Bilstein does my valving, I only spec the rate changes I want. Sometimes that's a shim stack, sometimes it's also a different piston.