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280ZX rear struts

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    So I ordered new shock struts, all 4. They are KYB Gas A Just.

    Long story short, the rear end sits about 2 inches too high, the ride is very harsh.

    So I contacted KYB and ask them to research the part number with them telling me I had the correct part.

    I went back and forth with them saying that something is not right, but there was nothing else they could offer me to help solve the problem. I drover the car around for a few months thinking they may settle, but nothing changed.

    Has anyone had a similar issue?

     

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    What are the part numbers and what is the car?  The 280ZX does not have struts in the back.  It has what's called a trailing arm suspension design.

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    2 hours ago, Zed Head said:

    What are the part numbers and what is the car?  The 280ZX does not have struts in the back.  It has what's called a trailing arm suspension design.

    82' NA.

    • KYB KG9113 Gas-A-Just

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    Just trying to help.  Sorry, didn't really have a good picture of the ZX rear suspension.  I guess it is a strut, by strict definition.  Rockauto says that's the correct part.

    I could ask a bunch more questions but I don't have a ZX anyway.  Who installed them, did you mess with the springs, did it ride correctly before, do the new ones look like the old ones, etc.  The basics would be to check that the shocks aren't bottomed out.  The springs hold the car up, the shocks might only add 1/4" from the internal gas pressure.

     

    Good luck.

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    18 minutes ago, Zed Head said:

    Just trying to help.  Sorry, didn't really have a good picture of the ZX rear suspension.  I guess it is a strut, by strict definition.  Rockauto says that's the correct part.

    I could ask a bunch more questions but I don't have a ZX anyway.  Who installed them, did you mess with the springs, did it ride correctly before, do the new ones look like the old ones, etc.  The basics would be to check that the shocks aren't bottomed out.  The springs hold the car up, the shocks might only add 1/4" from the internal gas pressure.

     

    Good luck.

    I did all the work, everything is correct. It doesn't make sense that just changing out the shock makes the car sit higher in the rear. Looks like Starsky and Hutch Torino.

    So I installed an old set of worn out struts I had, and it sits back normal.

    Something ain't right.

     

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    Did you examine the two parts, side-by-side?  Check the spring perch, push the rod in to the shock body, all the way down?  You can do it by hand or by putting your body weight on it.  It's actually good exercise.  

    You have the KYB's right there, right?  Give it a stroke.  Measure the distance to the spring perch.

     

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    6 hours ago, Zed Head said:

    Did you examine the two parts, side-by-side?  Check the spring perch, push the rod in to the shock body, all the way down?  You can do it by hand or by putting your body weight on it.  It's actually good exercise.  

    You have the KYB's right there, right?  Give it a stroke.  Measure the distance to the spring perch.

     

    All even, nothing out of place.

    Nothing to see. Just sits too high, and ride is very harsh.

    20180605_182247 (2).jpg

    20180605_182334.jpg

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    Why are the springs mounted?  They should be on the old set of shocks that you reinstalled.

    It's looking like you just got some higher rate springs on your new KYB's.  It's not the shocks it's the springs.

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    15 minutes ago, Zed Head said:

    Why are the springs mounted?  They should be on the old set of shocks that you reinstalled.

    It's looking like you just got some higher rate springs on your new KYB's.  It's not the shocks it's the springs.

    I had an old set lying around, put them on just to see if the car would lower.

    Dont have the spring compressor handy. You think those are higher rate? It seemed they were the same as the old ones. I'll recheck.

    Thanks.

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    21 minutes ago, Zed Head said:

    Why are the springs mounted?  They should be on the old set of shocks that you reinstalled.

    It's looking like you just got some higher rate springs on your new KYB's.  It's not the shocks it's the springs.

    Here's the ones I just put on, factory strut, dropped the rear of the car 2+ inches, rides normal.

    Dimensions are the same as the KYB sitting side by side.

    20180604_143651 - Copy.jpg

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    If you didn't use the same springs then you can't really say it's the shocks.

    If you like the ride height of the car is it is now, with the old shocks, then the odds are in your favor if you take those same springs and put them on the KYB's.  You might get an extra 1/4 to 1/2" inch.  I'm sure that they're the same internal pressure as the KYB's we use on the 280Z's.  We get a little pop from the gas struts too.  Not 2" though. 

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    4 minutes ago, Zed Head said:

    If you didn't use the same springs then you can't really say it's the shocks.

    If you like the ride height of the car is it is now, with the old shocks, then the odds are in your favor if you take those same springs and put them on the KYB's.  You might get an extra 1/4 to 1/2" inch.  I'm sure that they're the same internal pressure as the KYB's we use on the 280Z's.  We get a little pop from the gas struts too.  Not 2" though. 

    Yes, Ill swap them over when I get a chance.

    The Starsky an Hutch look on a ZX isnt becoming.

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    On 6/6/2018 at 12:41 AM, Zed Head said:

    If you didn't use the same springs then you can't really say it's the shocks.

    If you like the ride height of the car is it is now, with the old shocks, then the odds are in your favor if you take those same springs and put them on the KYB's.  You might get an extra 1/4 to 1/2" inch.  I'm sure that they're the same internal pressure as the KYB's we use on the 280Z's.  We get a little pop from the gas struts too.  Not 2" though. 

    Installed the new KYB shocks with the older springs, and its now sits normal.

    So the springs that came with the car have a different rate, but they look identical. Micrometer at my other shop, so once again, I'll check that at a later date.

    Only explanation I can come up with, is that a long time ago this car had been wrecked in the rear, evidence of a new rear panel and a lot of body work in the rear of the car, which was done flawlesly. I can only speculate that they installed new strut asseblies and they were not factory.

    Attached is the comparison before the swap.

    struts.jpg

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    Spring rate can also depend on the heat history and type of steel.  There's a bunch out there about it but here's a couple of links.  Plus the coil on the right looks like it's wound on a wider diameter so not the same manufacturer, probably. 

    https://www.meadmetals.com/blog/types-of-metal-compared-infographic

    https://www.precisionsteel.com/spring-steel

    https://www.mw-ind.com/faq-items/what-is-the-difference-between-cold-winding-and-hot-winding-and-when-is-one-chosen-over-the-other/

     

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