OK, so I'm progressing with my 5 lug upgrade and jazzed that my car came with Koni red struts in the front. I finally get the inserts out of the old 4 lug tube and one has oil all over it. Damn. I figure I can get them rebuilt but then find out it will be $135 each plus parts and shipping. I'm guessing maybe $340 total.

As I'm doing my research it looks Koni only makes the yellow "Sport" strut now and it's supposed to be a better performance strut than the red. Performance Parts has the yellow struts for $190 each with free shipping. That's only $40 more than rebuilding the reds and I don't have to wait the 2-3 week turn around time.

The question is are there other options that provide equal performance at a lower cost? This is going to be mostly an autocross, DE, and occasional weekend car. Performance is more important that ride quality.

Don't assume they are bad because you see oil all over it. They actually put oil in there for cooling. The strut may still be good.

Oh, and I use Koni yellows and love them.

Koni all the way. Yellow is faster.

Yes, the inserts don't fill up the entire space inside the strut. Apparently you will commonly find lightweight oil, mineral oil or anti-freeze inside the strut. It probably helps conduct heat away from the insert as well as prevents regular water from working it's way inside the empty space and corroding the strut interior and the insert.

Some good links...

http://www.roadglue.com/wiki/index.php/911_front_suspension

http://www.914world.com/bbs2/index.php?showtopic=390

http://www.914world.com/bbs2/index.php?showtopic=57045


I have done a fair amount of research regarding insert options for a 911 Koni strut. Check out post #7 by me in this thread as it summarizes what I had found out...

http://www.914world.com/bbs2/index.php?showtopic=70929

Thanks. I'd never heard of fluid in the strut housing before. I only had fluid in one side but it was a very light weight oil. I guess the next question would be what is the fluid from the insert like and is there a way to test the inserts when they're out of the car?

Regarding testing them, I would let others with more experience comment on that. My guess is that if you are in doubt, it is probably cheaper to replace or rebuild them than have them officially “tested” (such as on a shock dyno). At a minimum, I would expect that you will be able to smoothly move the piston through it’s range of motion and that you should get resistance during both compression and rebound. If it doesn’t do that, I would think something is wrong.

One extra thing about Koni struts. Apparently the original OEM struts didn’t have a complete “sealed unit” insert as we know them today, but rather the strut body acted as the oil reservoir with the “insert” being the working internals of the damper. Today, most (all?) replacements are complete sealed units that just slide inside of the strut. And the fluid is either to conduct heat, prevent corrosion or both.

So I without photos, I can’t tell what style you have. You may have original Koni struts with the original internals, or maybe the previous owner had replaced the original internals with a sealed insert in the past. My Koni struts happened to have the original internals in which the oil was used by the damper itself. I am also assuming it is cheaper and easier to use newer inserts vs. trying to have the older style rebuilt.

Since I am in the same boat as you (but not yet ready to do the work), I started to wonder what type of fluid (if any) is supposed to be used for the newer sealed inserts. I did some searches here and on the Bird board today and it seems that there is differing opinions regarding what type (if any) of fluid you should put inside the strut when you put in a new insert. Some people say that the Koni instructions say to use Antifreeze. Some say the instructions don’t mention anything. Some say to not use oil as if water gets inside, it will not mix and the water that settles under the oil will cause rust. Some just use light weight oil. I don’t know what the right answer is. When I am ready to rebuild my struts (sometime in the next year), I will probably just see what (if anything) that the Koni instructions say. If they don’t say anything, I probably will call Koni or someone that specializes in Porsches and sells Koni (such as Paragon Products) to see what they say.

turn them upside down, put your weight on the end of the strut and move the shaft all the way in (hepls to put a piece of wood on the floor so you don't bang up the threads) ...

pick up the shock and the shaft should come up nice and slowly in a rather smooth fashion ...

if not, it's missing the oil ...
Andy

PS: there's a video here somewhere that i posted ages ago of how the shaft on a bad (empty) shock moves. you'll know right away if it's bad ...

PPS: yellow konis all around!

I took one that was fully extended and turned it upside down. When I pressed down on it the strut collapsed about 6" right away with little to no force and then slowed down with some resistance. I did that a couple of times and the shaft got coated with oil. I'd say this case is closed.

Yep it's bad.
one of the most common kisses of death is the shock gets bottomed out and smashes the piston against the bottom of the insert.
Normally from ride hieght being too low. and soft torsion bars.

Someday we will get a definitive source for the advance design insert to put in our struts.
Currently I am running a Koni race 1473 Universal strut. I had to shorten the strut tube and it came out pretty good I now have 1 1/2" extra suspension travel.
The shock is very agressive and can hold down the suspension (don't like that part. But the grip is prett awesome.