my brand new koni shocks (the yellow, adjustable kind) did something strange in the last few days.

the shocks were installed right before the WCR. i set all four to full soft for street driving.
everything was fine, set the ridehide, got the car balanced and drove it at the WCR and for a week after that without any problems.

then, a couple of days ago, i walk up to the car and the drivers side rear is visibly sagging.
i think to myself "self, WTF?". i look under the car, shock looks fine, springs look fine, collar is still where it's supposed to be.
hmmmm ...

i try the push down on the fender, and nada. it moved maybe 1/4" down but didn't come back up at all.
so, i go to the other side and all is well. push down, comes back up. normal.

today, i take the shock off the car and the rod does not move at all. i turn it upside down and press down on it using my full bodyweight.
after a few seconds, i hear a loud "POP" and now the shock moves normal ...


put it all back together, and all is well as of 10 minutes ago.

anybody had anything like that ever happen to them???
Andy

Sounds like a bad strut. They are gas filled right? I would think that should not ever happen with those.

Makes me wonder how long they sat on the shelf before you got them & also the environment they were stored in. I know CA has no humidity compared to here but if things sit long here they lock up. I have to send my calipers to E for a rebuilding. Sat too long & rusted up & would not release. I'd guess it's got to be that or improper assembly of the strut at the factory. I can't think of any other reason for the strut to lock up like that. My .02.

Call Koni in the morning...

Gordon: 859-586-4100 x343

can that happen when it gets bottomed out too much? i dunno...

on a brand new shock? with 250lbs springs? and 6" ride-height?

man, i sure hope i didn't bottom out too much ...
Andy

sounds like it's maybe a sticky valve inside the shock, so it works sometimes and then gets stuck shut and doesnt let the gas through (letting the shock move).

Andy,

Are you running jounce bumpers? If so, how long are they? If not, it's easy to see how this would happen.

That's a twin tube damper if I'm not mistaken. It is possible that the piston rod got jammed into the base cage and snagged the top of the rivet or something else.... which is why jounce bumpers are required for dampers that do not have internal jounce bumpers (most dampers do not).

I can't understand "sticky valve". I tune twin-tube dampers here at work. I've built them before, too. The valve stack is deflection disk technology. The disks cover holes on the piston or base cage and as the fluid is forced through the holes, it delfects the disks. How can that "stick"?

Even if there was crap in the fluid, this is not the failure mode associated with that.

Also, the gas pressure is there to prevent cavitation of the oil. If the gas pressure leaked out, the damper still works, but under higher speed reversals there is a gap in damping while the air bubbles pass through the holes. This is not the failure mode associated with that failure either.

are you talking about the 3-piece rubber stops? if so, yes, i'm running those. i was told (by someone in the know) that it was safe to cut them down to 2 pieces on the koni shocks, which is what i did ...

Andy

Be careful about people who are "in the know"

I'm not familiar with the 3-piece part, but cutting it down may have cost you a damper. Got any pics?

With as much travel as there is in the rear of a 914, I can't understand why you'd want to shorten it. But, whatever......

I'd recommend getting some of these: Koni jounce bumpers

Make sure you have a sufficient amount of travel (on the rear of a 914 you should have at least 1.5") before the damper can hits the jounce bumper.

Did you talk to Gordon?

that would be Rich Bontempi from HPH ...

the rubber stops that came with the koni's are 1 piece but have three distinct "ribs", roughly 1" per rib.

the reason to cut them down was mainly to gain some more shock travel in the *front*. which has worked perfectly so far.

the rear has waaaay more travel than 1.5" before the shock would hit the rubber.
Andy

Okay... I think I've seen these and they're not the short ones I was thinking of. 2/3 of a short one could cause trouble. If these are still 2" you only lost some progressivity.

If you had plenty of travel in the rear already, why did you cut them down?

The symptoms of your damper problem sounds like it was bottomed-out, but with 2" of jounce bumper that's probably not what happened.

I agree with Kevin. Who really does know.
Shocks don't like to be bottomed out.

250 pound springs? So what ........ the shock canprogressively "hold down the car" While you are driving and you won't know the difference.
It only takes once.
Put a zip tie around the shock piston next to the shock seal.
Go for a drive and see where the zip tie is. You will be amazed at how close it will be to the bump stop.

Thats fricking wierd,

When the gas shocks first came out (yes, I am that old), a friend of mine had them on his Camaro. Try as I might, those shocks wouldn't move when I pushed down or jumped up or down on his bumper.....

And, I am not small.

Ken

I have a sagging problem on the drivers rear koni shock too. But it feels like my mounting perch has come loose. When the car on jack stands I can freely move the spring several inches up and all around. the pass side is firm. I haven't taken it off yet to look at it.