Question about struts

[frenaud]

I'm currently rebuilding/cleaning my suspension and have removed all 4 struts and separated them from the coil springs. From what I can see the struts are OEM. I can press the "shiny" part of the strut back into it's housing on 3 of the struts. The 4th one, I can push back in with my force, but it keeps coming back out again by itself over the course of a few seconds.

What is the "normal" behavior of the struts once removed? Should I bother to open them up and replace the oil? The 2 front ones had slightly torn shock boots which I will be replacing and a bit of red-ish liquid in them if that matters.

[Hardway]

The shiny part of the strut is the strut piston. If 3 struts have failed the 4th won't be too far behind. More than likely they have been replaced at some point with after market strut cartridges so swapping them should be straight forward. Getting them apart can be the hardest part of the swap. You will need a large wrench or pipe wrench to get the gland nut off and another wrench to hold the tube. The reddish liquid is probably ATF as most people put some in the tubes to keep the strut cool if they are using them in high performance applications. Normal behavior should be what you are seeing with the 4th strut. Keep us posted and let us know if you have anymore questions.

[frenaud]

Well, bugger! So I should just replace all 4 while I'm at it? The springs are some Eibachs (black) that were already there when I bought the car. They "seem@ good, but I don't really have any way of checking them.

From what I just researched there are some KYB, Tokico HP and Tokico Illumina. The Illumina will be out of my price range. Are the HPs really worth the price difference? The 280z's a semi-daily driver during the summer and I'm currently replacing all the bushings with poly. I really love a tight handling car, but not to the point of investing in a full coilover setup

[beermanpete]

It is not too likely that any of your struts are actually original. The only way to know for sure is to remove them and look. The strut that extends itself is gas charged. That is the normal behavior for a gas charged strut/shock. The originals are not gas charged so the one that self-extends certainly is not original. The other 3 are likely the same but the gas has leaked out. Any sign of an oil leak at the seal means you need new struts.

[jfa.series1]

KYB's are reported to be a softer ride. HP's are definitely a firm ride - I've got them on my car. Be sure to keep your front and rear springs marked so you don't accidently mix or swap them. Check out the strut bearings installed on the front insulators - lube or replace as required. The rear insulators do not have bearings but do have a rubber insert that is frequently overlooked - replacements are available from Nissan.

Here is the link to the online catalog where you can get the Nissan P/N's:

Datsun 240Z/260Z/280Z Parts Manual