Let's talk Hydropneumatic struts!

[Scott Clarke]

I'm curious about how these performed. Does anyone have any firsthand experience with them on a running car? Were they like MFI: a great idea not commonly understood? Or were they simply something without merit that didn't work? Ahead ot their time, or an answer to a question no one asked?
-Scott

[304065]

Scott,

I don't have a set, nor have I ever seen a set, nor have I ever talked to anyone who has a set, nor have I ever talked to anyone who has seen a set, or talked to anyone who talked to anyone who had a set. . .

(well, you get the idea. )

I was reading the Frere book the other night and it mentioned that Porsche actually used them on rally cars as a reliability exercise, and the cars finished quite well.

I have had quite a bit of fun, after a few beers following a Club Race, telling people how well the Hydropneumatic Struts handled during the race. . .

[Scott Clarke]

John-
I (unwittingly) have a set. What's more, they have 3.5" caliper bolt spacing. Evidently, they were from a '69S with the hydopneumatic option! I thought I was buying conventional struts, and ended up with these. I was pondering my misfortune when I had the perverse idea that perhaps I could actually USE THEM. So, if they work well, perhaps it would be interesting to try to get them to go. I'd be the only guy on my block......
-Scott

[kycarguy 935]

I have a set of them also I removed off of a 1970 911T.

[69911e]

Scott: I drove my car for about a year (17 years ago) with the hydo. struts before I changed to a standard torsion bar setup. They were fine for simple street driving if you like a soft suspension. Most of them have lost some pressure by now and may make the car lean to one side. You would be much better off with a standard torsion bar suspension which allows you to customize it to your needs.

[304065]

Would one of you fellas post a picture of what they look like? That way I can cross that off my list of things to do and go back to looking for the green flash.

[Rot 911]

Hydropneumatic Strut:


Conversion kit that is no longer available:

[Grady Clay]

I’ll bet I had a pile of 100 or more of these struts.
At first we made adapters to fit Koni inserts but it quickly became apparent
the best for the customer was to install regular S-struts.
The outrageous additional expense was Porsche had installed Hydro-E-only
A-arms.
They didn’t have the splines for torsion bars and were
not reinforced as the standard A-arms.

To make an E as an S it took struts, A-arms, torsion bars
and all the associated pieces.
The only good news was they came with S forged brake calipers.

Here are some discussion diagrams:
“



"
(C) 1969 Dr. Ing. h.c. F. Porsche A.G.


Best,
Grady

[Oldporsche]

I had them on my '70 911E. I converted them to hold Koni's. I also used some 911T "A" arms and torsion bars. I was lucky, some '69 E's that came equipped with the hydropneumatic struts were not equipped with the sockets in the body to hold the torsion bars.

Good luck,
David Duffield

[Scott Clarke]

David-
How did you convert the struts to hold Konis?

Grady-
It sounds like this is a mod you don't recommend.

I might have to come to terms with throwing away Porsche parts. It is against my constitution.

[Grady Clay]

Scott,

Kurt V diagram is correct, some also needed the cross-member because Porsche didn’t include the retainer and stop for the torsion bar lever. Dumb ‘ol my memory. That image doesn’t include ball joints and the wedge pin attachment hardware. It appears the struts are the pinch-bolt type.

Yes it is very possible to make an adapter for any strut insert; Koni, Bilstein, Boge, and other. If you have the lathe skills this is a possible way to go.

I discouraged that approach because the cost was comparable and with the S-strut you have a known spare part, not a custom set of parts. Along about ’72, Porsche changed from the pinch-bolt attachment to the ball joint to the wedge pin type. This was a major safety improvement and influenced my decision.

Best,
Grady

[Oldporsche]

Grady is correct about this midification.

I have a lathe. I have done this modification several times. You can fit almost any kind of insert into these tubes. You can do Bilstein, Koni, Spax, Gabriel, Monroe, Boge, Mulhollon,,etc. The Koni conversion on my 911E was done with Plastic pipe used as bushings. I used aluminum for bushing material in the rest of the conversions.

The cost of doing this commercially would probably be in the range of a set of struts. Since these are custom approaches, you wouldn't have any standard replacement parts. (except for the insert)

Send me a pm and I'll tell you how to do it. It's a little long and slightly boring for this forum.

David Duffield

[tobluforu]

Pretty much junk. Some of the old bmw 633 csi's had them as well and one of the first things people did was change them out .