280z Rear Suspension clunk

[Jaymanbikes]

I rebuilt my entire suspension about 8 months ago, I used the prothane bushings throughout.  At the same time I replaced my struts with KYB's and installed lowering springs.  The car has a slight clunk in the rear when I hit small sharpe bumps, a good example would be small traffic markers.  I have double checked every nut and bolt and they are torqued to spec. 

The lowering springs do not seat into the perch's until the car is loaded and I am wondering if that might be the source of the clunk.  I did zip tie the springs to the lower perchs but that didn't help.   

The cars suspension was original and had a lot of noises to start with so I'm not certain if this was there to begin with or not.  

Thanks to all!

Jay

[siteunseen]

Did you replace the differential mount?  Those cause a lot of the thunks on Zs.

[Jaymanbikes]

Yep, I replaced that as well.  It sounds sort of like what you would think a loose strut would sound like.  

[Zed Head]

Is the gland nut pressing on the KYB shock body, or is it bottomed out on the external strut housing?  Sometimes a washer on top of the shock is necessary to get proper clamping.

[Jaymanbikes]

Thanks, will double check that next time I have it on the lift


Sent from my iPhone using Classic Zcar Club mobile

[jbond]

After I rebuilt the rear suspension on my 280 I also had a clunk when I hit small bumps.  Solved by greasing the 2 blocks holding the rear sway bar to the body. I think they were binding until they let go over a bump and then CLUNK. Maybe an easy fix?

 

 

 

 

 

[Jaymanbikes]

After I rebuilt the rear suspension on my 280 I also had a clunk when I hit small bumps.  Solved by greasing the 2 blocks holding the rear sway bar to the body. I think they were binding until they let go over a bump and then CLUNK. Maybe an easy fix?
 
 
 
 
 

That's an easy try! Thanks!



Sent from my iPhone using Classic Zcar Club mobile

[Jaymanbikes]

On ‎5‎/‎29‎/‎2017 at 1:23 PM, Zed Head said:

Is the gland nut pressing on the KYB shock body, or is it bottomed out on the external strut housing?  Sometimes a washer on top of the shock is necessary to get proper clamping.

So I finally got around to disassembling one of my rear struts.  The gland nut hits the top of the strut cartridge and thus does not allow the gland nut to bottom out.  Also, inside the gland nut is a sleeve that is removable and pictured.  This is the gland nut that came with the KYB struts, the instructions that came with the struts was very generic and zero help.  Thanks for any suggestions.  I am hoping that this might be the root cause of my suspension noise when going over sharp bumps. 

[Zed Head]

1 hour ago, Jaymanbikes said:

The gland nut hits the top of the strut cartridge and thus does not allow the gland nut to bottom out.  Also, inside the gland nut is a sleeve that is removable and pictured.

All of that is correct.  The nut is supposed to clamp the insert in to the strut tube.  The sleeve keeps the insert centered.

Your gland nut does look a little bit deep though.  When you tighten it down are you sure that it is actually clamping the top of the insert?  It might be bottoming out on the internal threads.  Tighten it down with the shock/insert inside then grab the shaft of the shock and see if it can be moved side to side or up and down.  You can put a washer on top to get more clamping if it's bottoming out on the internal threads.

[Jaymanbikes]

3 hours ago, Zed Head said:

All of that is correct.  The nut is supposed to clamp the insert in to the strut tube.  The sleeve keeps the insert centered.

Your gland nut does look a little bit deep though.  When you tighten it down are you sure that it is actually clamping the top of the insert?  It might be bottoming out on the internal threads.  Tighten it down with the shock/insert inside then grab the shaft of the shock and see if it can be moved side to side or up and down.  You can put a washer on top to get more clamping if it's bottoming out on the internal threads.

OK, looks like I had everything correct on the struts.   I reassembled everything, I also installed a set of the Whiteline Mustache Bar bushings which are supposed to be a lower durometer than the standard Poly bushings.  Well, I must say the bushings made a huge difference, reduced road noise and gear whine significantly.  I wasn't really expecting that big a difference, they feel just slightly softer to the touch. 

[Zed Head]

Did the clunk go away?

The bag looks nice but are the bushings black?  Are they shiny or dull?  How do they feel on your face?  Soft and smooth?  I digress...

Good info on the results, you had the hard polyurethane before?  Do you know the brand?

[Jaymanbikes]

5 hours ago, Zed Head said:

Did the clunk go away?

The bag looks nice but are the bushings black?  Are they shiny or dull?  How do they feel on your face?  Soft and smooth?  I digress...

Good info on the results, you had the hard polyurethane before?  Do you know the brand?

The clunk is gone...The new bushings are black and shiny, also notice the taper on the end of the bushing.  See the first pic.  The green stuff is a marine grease I used to keep the washer in place as I installed the bar.  The bushings were extremely tight, I had to shave a small amount of material to get them pressed into the bar. 

  The old ones are Prothane, see second pic.  I purchased them in a kit from Zcardepot.  they are dullish and and have no taper.