Koni Yellow Shock Lifespan and Other Questions

[wstr75]

I have been watching BMWCurves thread with great interest as my car's rear suspension is in sad shape. My 2004 ZHP Convertible has 109K miles and I am the 4th owner. A previous owner put yellow Koni shocks on the car. They are not leaking and appear to be in good shape, however, it appears all of the bushings in the rear structures are worn out. I took it to an indy shop and when they dropped the lift in short, sudden increments you could see the rear arm structures wobbling and moving front and back with all sorts of loose motion. The other day when going through a long sweeping curve at 75 mph the car was clearly exhibiting rear instability.

The car sits lower than my neighbor's 2004 325 convertible by about 2".

Assumptions:
1. Let's say a previous owner put on the Koni Sport shocks (yellow) at 80K miles and thus the Koni shocks have 30K miles on them
2. Let's also say the previous owner also put on new springs as part of a shock/spring package and this explains the lower ride height
3. All rear bushing components are worn out and need replacing.

Questions:
a. How long do non-leaking Yellow Koni Shocks last? 30K miles? 50k miles? 75k miles?
b. In addition to replacing all bushing components, should the spring pads, shock related mounts, reinforcement plates and other components be replaced?
c. When the car is on the lift, is there a way to look at the springs to determine if they are aftermarket or OEM?
d. Any other components to replace?
e. The yellow Koni shocks are adjustable, yes? Where is the adjustment mechanism?

[BMWCurves]

I can only answer a few (since I'm now just doing this) but:
a. I've heard of cars with 80k+ miles on theirs and no signs of decrease in functionality. Plus they have Koni's limited lifetime warranty. The OE Sachs springs are supposedly only good for 40-50k miles.
b. I'm still wondering the same, but I plan to swap them all out because 1. I'll already be in there doing all of this and 2. peace of mind so I don't have to worry about those components for another 50k+ miles.
c. I can't comment because I don't know, but I would guess they would be black for stock equipment, while a lot of common after market springs are red or blue or some other bright color.
d. I'd check my thread about it.
e. They are adjustable. The front struts are adjustable with a knob in the front. The rear shocks are adjustable but you have to remove them from the car, compress the shock and engage the adjustment mechanism, set the desired rebound rate, disengage the adjustment mechanism, and then release it. Part of why I considered going Dinan or TC Kline rear shocks because they are modified Koni Yellows that you can adjust from the trunk with a knob without having to remove them from the car.

[wstr75]

William, thanks for this help. My rear springs are gray/black with a vertical white stripe. Anyone know of a kit that can be added to a Koni Sport rear shock to give it an external adjustment mechanism?

[slater]

Ground Control and TC Kline sell externally-adjustable rear koni yellows for our cars... also, the 80's Porsche 911 rear koni yellow shock fits and is externally adjustable.

peter

[BCS_ZHP]

On stock springs, they will be black and have several colored markings on one of the springs. I've seen white, green, red, blue, and combinations of two or three of those colors. Sedans are different than coupes, sometimes, and I believe the convs may be different too.

[wstr75]

My inclination is to keep the Koni shocks and the springs on the car while replacing all bushings and reinforcing the shock mounts in the front and back. If it continues to be loose after those changes, then I'll throw in the towel and replace the springs & shocks.