Porsche 944 strut comparison
Or, how to waste a perfectly good afternoon not rebuilding your Porsche's struts.Home | Back to Projects | Email (web form - pops) | Email (your client)
So I own a 1988 Porsche 944... This car has the standard suspension, no M030 or M474 options. Unfortunately the stock struts for this car (Porsche part nos. 944 343 031 17 and 944 343 032 17) are unitized, theoretically non-serviceable assemblies. The earlier (up to '86) struts (Porsche part nos. 944 343 031 12 and 944 343 032 12) look like the struts used on the VWs that I know and love, and have threaded caps that can be screwed off to replace the strut cartridge inside. Unfortunately, the only available struts for the 87-88 seem to be the stock Sachs/Boge replacements, and I'm not a big fan of Sachs/Boge after a set of "Turbo Gas" struts lost all damping within about 9 months on my old GTI. Another option is a retrofit from Koni where you cut the tops off of your late style strut tubes and bolt a cartridge in from the bottom of the strut. Those, unfortunately seem to be the *only* options available for these cars. If anyone knows of anything better, by all means please let me know, but it would appear that Koni, Bilstein, etc. have all dropped replacement struts for this application from their catalog.
So on to my idea. My thought process was this - if I had a set of early struts, and a set of late struts, are they similar enough to simply thread the top of the tube of the late struts, and use the early insert (which is readily available from a number of manufacturers) in the late housing? Or could the early housing be modified to fit a late car?
They do look awfully similar, don't they? (yes, the shaft of the cartridge is bent; that isn't an optical illusion. This is just proof of concept, remember?)
You can't see very well in this pic, but what I'm trying to show here is that the opening in the mounting bracket of the early strut (on the left in the picture) is actually wider than the opening in the later strut.
As you can see here, the mounting holes are in different locations as well. Far enough off that you couldn't simply file the hole bigger, it looks like it would be too close to the edge of the bracket for comfort, at least to me. So you can't use an early strut on a late car, at least without backdating some of the rest of the front suspension.
Here I'm measuring from the bottom of the "cup" that holds the spring. This is obviously the old strut.
Here's the new strut with the crimped on cap removed. I sliced it up with a cutoff tool, but it came off so easily that I suspect that it's really not crimped at all, just a press fit cap that is hammered or lightly pressed into place. As you can see here, the top of the tube itself where it is crimped over is really what holds the strut cartridge into the housing. You can also see here that the tube is taller than the early strut, which isn't a deal killer. You can always make something shorter; it's the making it taller that is the problem.
And here's the top of the new style strut, again with the cap removed. Unfortunately, this is where this project came to a screeching halt. I didn't take pics of the measurements, but the new style strut is a good 1/8" larger in diameter than the old style strut, meaning my original idea of having a machinist cut threads in the tube just isn't going to work - the cap from the old style struts won't fit on the new ones, no way, no how. I don't know why Porsche changed just about every dimension of the new struts from the old ones, but they did. Such is life...
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