Hello all,

is there data somewhere about the various setups for rear shocks, including dampers and springs, for a -6 car (with heavier engine).

The car I purchased was equiped with Adjustable Koni ref: "8241-1050 SPORT 9510".
The springs progressive type, are 10.8mm thick, exterior diameter 110mm and around 360mm long when extended.

The dampers doesn't look in good condition and can be compressed by hand very easily.
Every used koni shocks I've seen on 911s were like this, though, where old Bilsteins remain quite hard to compress by hand.

I don't know either if the springs are ok for my setup or if I can find some harder springs.

thanks for your help.

Original springs were very soft at about 55 lbs. Replacement springs start at 100 lb and are a good choice. Your Koni shocks are probably bad. They should have even resistance through the range, both in and out. Koni 8241-1050 SPORT are still available for about $250 each US price. Bilstein shocks are about $156 each US.

PSI is a very well regarded rebuilder, but even they suggest buying Koni replacements that are still available.

https://performanceshock.com/index.php?main...roducts_id=3965

Fwiw, Koni red (non-sport) + 140lb rear springs is a nice combo in a 914-4, and the same 140lb springs still seem "about right" with a small six in the same car.

Everyone has their preferences/reasons, but I prefer Koni (non-sport, so red not yellow) to off-the-shelf Bilstein HDs in a street car.

Keep in mind Bilsteins are height adjustable as made.
Konis are not. You'll have to buy additional parts to adjust rear height with Konis

I'm with Pete on Koni red preference on a street car.