I bought a used pair of good used rear Special D Red shocks off of a member here and installed them about 300 miles before MUSR. I used Koni's web instructions and set them at a medium setting. The were tight on the fender push down test with no bouncing and the car was handling good

The trip to MUSR was 1000 miles one way, and by the end of the 2nd day, I was doing the bouncy bouncy uppie downie on both sides. equally, at the rear.

It seems unlikely that they would both leak down at the same time. With 2 days of highway driving, is it likely?

Could my setting be wrong i.e., not locked down somehow?

Is there a machine that can test the shock, in a shop?

If they need rebuilding, is there anyone outside of Koni that does the rebuild?
Thanks guys for the help.

Bill,

I have Koni Special D's circa 1980 on my 73 2L from my rolling resto back then, that I only put 20k on before it got whacked & put on blocks in my garage in 5/85, so I need to redo mine too.

From other members here & prelim research on their website, I understand that Koni does rebuilds/restos of them in-house, including a repaint to original colors. IIRC they warranty their rebuilds for a good period too.

What may have happened with your new/old set, is that the rubber seals inside were old & brittle, but initially okay without use after sitting for who knows how long, then when you drove with them they broke-down enough to allow blow-by. IIRC they stopped selling the SD's in the late 80's & started calling them HD's in the new colors scheme.

They're great shocks & many prefer them over the Bilsteins for top level shocks on 914s, although I've had no direct comparison - but they were hugely better then my OE 170+k mi old Boges back in 1980 when they were replaced!

Thanks Tom. I've never seen the inside of a shock but the old brittle rubber makes sense. Group buy on rebuilds anyone??

Koni's guarantee was "lifetime" as long as you have the original receipt.

I like Koni's but... that flame may be dwindling.

I have them on the 914 but the 911 now wears Bilsteins. I had a "box" of Koni inserts that have gone bad and... no Bilsteins.

The Koni's feel great. Had them on my 911 prior to the Bilsteins and loved them. Personally, I've yet to experience a failure on one of my cars. But now... the pricing is getting stupid. $200+ "per" insert while the Bilsteins are hanging in what I would call "normal" territory. They're making it hard for me to recommend them any more.

Regarding your original question; I tend to think Tom's right. They probably gave up the ghost. A lot of times the fluid can be in one area of the shock making it feel firm but, once the normal driving process gets started the valving seems to show it's age.

There was a user here who found a guy in TX that did them on the cheap. That's yet "another" nail in the Koni coffin... they're damned expensive to repair vs. a Bilstein. If you find the thread... the guy seems to do a decent job for less money. Just get the insides fixed because the paint is basically "Chevy Engine Block" orange... FLAPS.

I recently had my GT shocks restored by TrueChoice and the bill with all of the parts was $425.00. Probably a bit much for most people but a reasonable price to save these: