SloopJohnB@mac.com

I did not change springs. LOL..I subsequently bought a set of Voghtlund red-violet (30-60mm) springs that are still sitting in my garage in the box...I decided not to drop wifey's car considering the scrapes on the front underbelly and the many local speed bumps/humps.

I installed the Konis right out of the box; hopefully they were set at the factory at some middle setting. Nevertheless, they were much stiffer than stock in compression and rebound wasn't adjustable anyway IIRC. Rebound was not so tough that the car ratcheted downward with rough roads (one of the lesser-known issues with dual-adjustable shocks and noobs).

mithrilG60

You're correct that Koni yellows are dampening adjustable only, rebound is a fixed rate. I hear you on the lowering, I debated for quite a while on whether or not lowering would be a good idea given how low the belly pan and lower front lip is from the factory. Eventually I gave in since it doesn't make a lot of sense to me to install a stiffer sport shock and not match the springs.

The Eibach ProKit is a 30mm drop, only 10mm more than the stock sports suspension, so it keeps the car within alignable specs and isn't super aggressive. The Eibach's are also meant to have a much nicer ride quality than some others, H&R specifically, so it shouldn't result in my back getting destroyed by expansion joints on the way to and from work. The days when the idea of winding coils down to their lowest setting and scrapping over every little hump held any appeal at all are well well in the past! lol.

Just Me

i'm not arguing against replacing dead shocks with good new ones. In that case i might suggest either Bilseins or Koni FSDs (softer).

But a) he said they were ok and b) said he wanted to improve handling.

So, i restate =- they are a terrible way to improve handling. What you want is a matched, critically damped spring/damper set. If they are dead, you no longer have that. Then, yes, replace.

G

Just Me

Shocks.or. more accurately, dampers, damp oscillations. period.
Using a damper to stiffen a car's handling is very inefficient, and result sin over-damping.
A proper damper should resist all motion. But exert no upward (spring) force.
Its objective is to keep the suspension motions controlled,and the tire patch in contact with the road, and the force - and thus friction - constant.

For some racing situations you might over-damp in order to keep the suspension very "quiet" - but note this will also result in tires literally in the air more often, unable to maintain contact with the road. For stability this may be desirable. Stead state adhesion tends to decrease when friction goes to zero. And the Cf of air is pretty much zero.

So are shocks important? yes. But should you Change damper without changing the spring accordingly? No. (except to repalce worn out units with a suitable replacement)

And the minimum weight transfer with minimal impact on ride quality will occur from lowering the center of mass and point of rotation.

Everything else is 2nd order magic.

G

Just Me

not really. A damper simply resists motion. So, when you begin to squat or dive, yes, it will resist, but it will NOT push the car back up. And whatever resistance to squat and roll you get with a stiffer than usual shock comes with two penalties:

1. more impact harshness at times you DONT want it
2. over-damped, which means that it does not return to rest in minimum time - which tends tom simultaneously hurt both handling and ride.

You can certainly give yourself a more jarring ride. But it wont translate into truly better handling. And who wants that?

(note: lots of people apparently, but its mostly confusion - equating harsh with good adhesion in all conditions)

A better result would come from incrementally stiffer and lower springs, combined with exactly matched dampers, in a kit.

I do suspect that your dampers, bushings and tie rods have all deteriorated in the last 55k miles. If so a refurbishment may yield real improvements - but dont go stiff just for stiff's sake. Note also the Audi will never handle like the lighter, better balanced, BMW. Its nose heavy.

G

devinsixtyseven

You guys (except Glen) are killing me with your shock talk .

I have yet to see a damper offered for these cars which allows you to tune the valving yourself. You might get to play with the bleed, but not the valving.

The valve in a shock has shims for compression and rebound, and bleed, which affects both. It doesn't all have to be in the same place, either...a monotube will have a floating valve on the end of the shaft, with bleed and shims all incorporated on the valve, and twin-tube designs usually have a valve fixed to the bottom of the assembly, and not all the components are necessarily colocated.

The shim stack dictates how much force is necessary to open the valve to free flow. This requires high shaft speed...not vehicle speed, shaft speed. Think speed bumps, frost heaves, curb climbs (remember, aim for 35*), washboard, pot holes, bridge seams. When someone says "the valving is stiff", they're almost certainly referring to the shims. The shims are part of what allow your car to feel tight in a corners, *and* suck up sudden changes in the road surface.

The bleed valve allows a certain amount of fluid to pass through an orifice in the valve at any given time. It's always open...it's just a hole. Some shocks let you adjust the size of the hole, but remember this hole goes both ways. That "certain amount" is critical...the bleed valve will not allow more than a certain flow volume. Anything more is forced against the shims. This is low shaft speed...body roll, brake dive, acceleration lift.

When you mess with the adjustments on what's available on the market, unless you're actually opening the shock and changing the shims (ie King, SAW, IVD, Bilstein 7100+, etc), you are only changing the bleed valving. A tiny amount of bleed adjustment can make a *huge* difference in feel and handling, but the downside is it affects *everything* about the shock.

Rebound damping should be critically damped, period. Like Glen said, the shock packs up if it's overdamped for the spring...that means the rebound valving (the shims, not the bleed) is too stiff to allow the spring to extend the shock in time to react to the next impulse...so the car "sits". Do this on a rough road, and you'll find yourself on the bumpstops and quickly out of control. It's not a good feeling. Worse yet, when the car hits a pothole, rather than allowing the tire to meet the bottom, the entire chassis drops in to the hole. Better hope you're not overdamped on the compression side, because the exit is going to f-ing hurt. This is a good way to break suspension mounts, as well as rattle loose all sorts of things on the chassis.

If you're always on good roads, you can overdamp the shock a little...but don't go much past critical. If you really want it stiff, run a stiffer spring with the correct rebound valving for the spring, and ease up just a little on the compression valving, to accommodate the stiffer spring. Add swaybars, and it will handle like it's on rails. Just be aware that since the chassis hasn't changed weight, the stiffer spring will be very noticeable exiting potholes, over heaves, and of course over speed bumps. Go too stiff, and the chassis will porpoise on some repeating road seams (concrete paving, bridges), because the suspension frequency is incorrect for the chassis.

If this is a daily driver...critically damped, lower CG, swaybars. You could pick a wheel with less backspacing, too, but I'm not sure how that will affect the chassis' Ackerman angle. C5 has a tight turning radius.

devinsixtyseven

OBTW...the "stiff on pothole exit" bit can be overcome to some degree by a dual rate coil and a shock with internal bypass. I know we can get dual rate, I don't know about the bypass.

A bypass just allows a given amount of fluid to pass the valve in a particular region of shaft travel. Some are just like an additional bleed valve, some have a check valve and only affect rebound or compression. A dual rate setup would ideally have less resistance near ride height, and more resistance near full compression, when the stiffer spring rate has taken over. I don't know how exactly the dual rate products are set up, but these are questions worth asking.

...You all know how much easier this would be, if Audi hadn't chosen those backassward lower shock mounts, with the eye on the arm and the fork on the shock? Every single high quality rebuildable shock I can think of uses an eye mount on the shock, and assumes the fork is on the lower control arm.