As the title suggests, would I need a front end alignment going from 2003 to 2005 springs? I'm assuming this will cure the bouncing on certain freeways. Thanks.

 

Hold on, your in for a very big let down unless you do something totally different. Your oem unrevised 03/04 shocks are really going to hate the 04.5/05 higher rear spring rates. And their's not going to be any love for the front springs either. In order to do what your after, you need to source revised shocks. NEVER ever blame springs for poor ride quality, it is the job of the shocks to conrol them. Honestly, their's no reason why you can't keep your current springs on the car and just do the revised oem shock upgrade, not unless you have specific reason to want the 24% higher rear spring rates that the 04.5/05 springs have.

Since you went with oem springs, it makes me believe that you do not wish to lower, otherwise I'd tell you to go with hotchkis springs, which were specifically designed to quell much of the 03/04 bounce problems caused by the shocks.

 

You probably need an alignment after 2 years of driving anyway, changing springs or not!!

 

For that just buy aftermarket suspension. I HIGHLY doubt there are changes on the 03-05 setups anyways.

 

any time you change the shock/strut/spring, you need to get an alignment.

 

I can't say that I've ever seen someone with your post count that isn't aware that Nissan revised the oem 350Z suspension. You can stop doubting, it is fact.

Mid way into 2004 production (10/31/03) Nissan did a running change on 350Z coupes. (All roadsteer production has the revision). This running change on the coupes consisted of revised shocks (unique part numbers that can be traced) and stiffer rear springs. The rear springs can be traced via a dial caliper, measure .57" and your holding a 04.5 rear springs, measure less and it's a 03/04 rear spring. Front springs did not change no matter what the parts department says, no change in OD, wire diameter or active coils. Also, the front sway bar is reported to have thicker wall's inside it's hollow construction, a stiffer front bar makes perfect sense given the 24% increase in rear spring rate.

oem 350Z 2003/2004 spring rates 314/342
oem 350Z 2004.5/2005 revised suspension spring rate 314/427
oem 350Z roadsteer spring rates 314/427