Porsche front strut inserts

Common to older cars is having blown suspension. The M30 is no different. Additionally, the cost for a whole new strut assembly is $300 each ( x 4) and that was years ago.

Part of F31club was finding other options. F31_pilot (James) did a detailed comparison between strut inserts. Mr. 25/8 (Edward) was the “guinea pig”. It worked and Edward made write up. We lost the pictures, but then GillyGil (Gil) recently got in contact with me and send me a scanned copy of his print out!

Original post:


First off, I would like to thank F31_Pilot for giving me all the information I needed to complete the installation. SUCCESS!!!!!

After 2 days of hard work, I got the KYB GR-2 front strut inserts from a 1988 Porsche 944 non-turbo to fit in the strut housing from the M30. It was a lot of hard work (for me at least) but it was worth it. 8)

You can check out this link for more specific info on the parts needed to do this install and for ordering the inserts.




If you would like to be the “guinea pig,” I have some measurements of a strut insert you could try. My measurements show that the strut insert would work, but you would lose the adjusting sonar option. Let me know if you are brave and would like to try. I’ll get back to you about the the exact part numbers for the strut insert.



I would like to try.



Cool, thanks for taking up the offer Mr. 25/8.

90-92 Infiniti M30

Front strut insert/cartridege measurements:

Strut insert body length: 14.375″
Extended length: 22.500″

85.5-88 Porsche 944 (non-turbo)

Front strut insert/cartridge measurements:

Strut insert body length: 13.750″
Extended length: 22.125″

14.375 (M30 front strut insert body length)

13.750 (994 Porsche front insert strut body length)


* If you use the 1985.5-1988 Porsche 944 front strut insert/cartridge, the body of the 944 Porsche strut insert/cartridge is shorter by .625 of an inch. So this means that you would need to use some washers or a strut spacer under the 85.5-88 Porsche strut insert/cartridge.

13.750 (944 Porsche front strut insert body length)
.625 (one or more washers or a strut spacer)


* You will need to use the Infiniti M30 front strut gland nut to secure the 944 Porsche strut insert/cartridge into the M30 strut casing/tube.

22.500 (M30 front strut extended piston shaft length)

22.125 (944 Porsche front strut extended piston shaft length)


* The 944 Porsche extended strut piston shaft length is .375 an inch” shorter before you use and or add the .625 of washers/strut spacer under the 944 Porsche strut insert.

22.125 (944 Porsche front strut extended piston shaft length)
.625 (washers or strut spacer)


22.750 (944 Porsche front strut insert + .625 washers or strut
– spacer)
22.500 (M30 front strut extended piston shaft length)


* When using the 944 Porsche front strut insert/cartridge + .625 of an inch of washers or a strut spacer you will get a total extended piston shaft length of 22.750. It will be .250 of an inch longer. This means that you should have enough extended piston shaft length to compressed the M30 springs back on properly.

I hope my simple math above and explaining of what exactly you need to do in order to use the 944 Porsche front strut insert/cartridge helps.

P.S. These strut insert/cartridge measurements aren’t BS numbers that I made up. I actually got these strut measurements off of Gabriel shocks/struts website a little while back.



85.5-88 944 Porsche

Front strut insert/cartridge part number and brands:


Part # 50356
Price: $45.79 each (www.rockauto.com)


Part # 115153
Price: $97.79 each (www.rockauto.com)


Part # P30-0104-H0 (heavy duty)
Price: $176.99 each (www.rockauto.com)


Part # 73948
Price: $41.79 (www.rockauto.com)


Part # KY363014
Price: $42.95 (www.pitstopautoparts.com)

If indeed using the 944 Porsche front strut insert does work. It opens up a whole new selection of a bunch of different brand strut inserts/cartridge we can use.

Now it was not a direct fit,

as I had to modify the strut mount. As you can see here I had to drill the center of the mount a little bit bigger so it would accept the new insert.

Drilled center to be bigger


This was my tool.


After I took the old, rusty, leaky, oily, smelly, cheap ass inserts out of the strut casing, I had to drop in 5 washers (approx. 1/3 of an inch or .33″ thick when stacked together) that were 1-1/2″ (one and a half) outer diameter into the strut casing. Then I put the new insert in, secured it with the gland nut, put the compressed spring back on and then put the modified strut mount back on top. (Note that the shaft was spinning as I tried to tighten the nut onto the strut mount. I did not tighten it all the way as I was going to have to take it back off. You will see why below)


After I put the complete strut back in the car with everything tightened, I had to take off the strut mount bolt back off to drop in 4 “modified” washers (they were the same washers as above but I drilled the center of them a lil wider so the shaft could fit in it) so there would be no space between the strut mount and the bolt (just an fyi the bolt is provided with the new inserts). As you would have guessed, there was not as much thread on the new shaft as on the old shaft. That’s why I had to use the 4 washers to secure the bolt on tightly. Here’s a pic.


Whew! I am not too good at explaining so bear with me here. Here is a picture of the old ass struts I was talking about.


Now my M30 is sitting on all KYB GR-2 Suspension!!  It drives really smooth now and the handling is great! I was so happy that I had to go fill her up! You don’t see this every day.


Credit: F31_Pilot (James), Mr. 25/8 (Edward) and GillyGil (Gil)


3 thoughts on “Porsche front strut inserts”

  1. Hey roger, I’m looking for the parts list on this … I haven’t been able to log into the forum yet.

  2. I’m in the middle of the cartridge swap… fairly easy process so far… first question is, how do you separate the strut assembly from the swing arm?

    • I think that info is available in the maint manual, that small thick book that comes with M30s. IIRC, it is some nuts and bolts.

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