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Old 02-03-2015, 04:29 PM   #21 (permalink)
sandersd
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Join Date: May 2014
Location: Houston, TX, USA
Posts: 280
Drives: 2014 370z Nismo
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Quote:
Originally Posted by Robert Yuras View Post
All springs should have preload. If they don't, they will bounce during sudden transitions and make a clunk. You should be able to keep your ride height, but adjust your preload if the coil over has a threaded shock body.
The fronts had preload set as shipped. The rear had preload set at 5mm during installation. What I'm going to do is jack up the car, remove the wheel, and measure the preload with the suspension weight unloading the spring, then bump up the preload to 10mm per my discussion with BC tech support.

I believe as you said above that, due to the amount of play in the shock mount, the preload is moving between 5mm and <0mm as the suspension moves through its travel, allowing the spring to strike the lower/upper perch with a clunk. This time I will be sure to recheck after I release the jack supporting the lower spring seat and apply pressure in each direction to verify it remains at 10mm preload.

I don't expect the top nut to be loose - I'd be surprised if it was. I did notice the width of the lower mount was wider than the OEM mounting point and this might account for the rattle, but not the clunk. If it seems significant enough I'll add a washer/spacer to achieve a snug fit.

Some have also complained that the locking rings have loosened over time and their solution was to add blue Loctite to keep it from backing off.

There are only so many joints in the rear (or front) suspension system. It's just a matter of eliminating them one by one till the culprit is found.
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2014 370Z NISMO -- HKS Hi-Power Exhaust -- Swift Springs -- BC ER Coilovers -- SPL Suspension Components -- Nismo R-Tune Intake -- Seibon BD CF Hood
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