i bought a set of these Z1 upper arms as well with the solid joints when they came out, did the install myself. rode them for a while and as others stated noticed a creeking in the suspension on certain bumps and pops every now and then. Then i got the letter about the bolt issue and had nissan do the replacement when it got in. Update it doesn't pop anymore but i do get an occasional creek. I will be replacing these out with the SPL arms as well. I'm big on paying for what you get. But the drivabilty of the Z1 arms always has me worried on the back burner so I'll make the switch soon.

Good idea, mine always were loud then the ball joint snapped off. Since going with SPL very quiet and more responsive. I should have gone with SPL in the first place!
I have learned going cheaper can be more expensive in the long run.

I just got a call from Z1 stating that the set of UCA I ordered in Feb has a manufacturing defect in one of the joints for one of the batches they made. They're shipping a set of replacements to me... Someone had a failure and sounds like they may be contacting some other owners out there to prevent anything else going wrong. I appreciate Z1 being upfront about this and doing the right thing!

hope the ones they are supposed to ship out to me (when they feel like it) are defect free

Idk be prepared I have them. I would hook em up to a grease gun pre install and pump em up until its oozing out like a good creampie. And make sure the ball joint is aligned perfectly east to west on both arms. So it doesn't look crooked. You"ll see what i mean when they are installed, that fixed my squeaking issue...for now...


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I got a call too and Z1 is doing the right thing, they are paying return shipping (I had not installed mine yet) and that is fine with me. My experience with Z1 has been awesome and would not hesitate to purchase from them.

I found a SPC deal on the forum and got those with less than 10K miles on them. I'm still debating on doing any suspension mods at this point.

Z1 caster front upper arms
 

Nice man. Howre your arms going on the 370z. Can i ask how much more the side of the control arm closer to the rear of the car is dialed in vs the other side to achieve the positive 8 degree caster?
Thanks man appeciate it. Seems to be a difficult question to get answer to :)

For those who are still experiencing creaking I found a solution a few months back. I didn't realize other people were having issues with the z1 arms creaking and thought I'd gotten a bad set of bushings or something but here's what was happening and how I fixed the problem.

Going over bumps created a TON of squeaking so I added energy suspension lube via the little ball valve on the bottom of the bushing housing. This didn't fix it so I added more, which also didn't fix it. On a third attempt I squeezed the pump handle as hard as I could to see if maybe the grease just needed to get into some crevice before it stopped squeaking. This actually made the problem worse so I pulled the whole arm off to inspect. I pulled the urethane bushing apart and noticed that after a certain amount of grease the bushing actually is pushed out of the housing slightly. Essentially I was displacing the bushings from sitting correctly. This caused the urethane contacting the chassis to exert pressure and squeak.

Solution for me...
Disassembled the bushings and actually removed the energy suspension lube with my fingers and a few rags. I left a very thin bead of lube surrounding all parts of the bushing and reinstalled. I also used a little lube on the part of the bushing that contacts the chassis. I noticed that the arms installed more easily than they came out because the bushings weren't being pushed out of their housings and the squeaking has completely stopped. Hope this helps someone!