I posted something similar when I first joined the forum, but maybe someone has researched this further since then. I am trying to determine certain perameters in the suspension systems of the sedan and coupe. As we all know, the coupe is lower than the sedan, but I believe there are more differences than that between the two systems. I have the service manuals for the two vehicles, and have noticed this: The coupe seems to have more bracing for the front and rear suspension members. The front has the most noticeable difference; it has a tubular brace that seems to tie the suspension member and the chasis together, thus reinforcing it. The sedan does not have this (according to the manual). This could prove to be a major advantage (as far as deflection goes) between the two.
I am also trying to determine where the roll centers are for the front and rear. I believe that the suspensions are essentially the same (bolt-on sub systems). Unfortunately, the manuals do not provide part numbers for the larger parts, so I can not compare. If this is true, however, then we can assume that lowering the sedan to coupe specs will not harm overall handling due to roll migration from lowering the roll center too far. If this is not true, then I question how far we can lower the sedan before we run into issues with body roll, as well as bump steer, excessive understeer, etc. (Anyone who has experienced bump-steer due to lowering the vehicle please let us know). I just want to know how much room there is in the factory tolerances. I am also curious as to which roll center is at a higher plane, the front or the rear? This would help determine how far to lower the vehicle for optimum handling. If anyone knows any information that may be helpful, please let me know. My goal is to come up with the optimum suspension setup for this vehicle. Thanks for any help.



'03.5 Brilliant Silver AT Sedan, Premium, Aero Kit/Package, Sport, Winter, Stillen Air Box, Z pipe, Clear Corners, Alum. Pedals, Polk Tweeters, Clifford RSX 3.5, Gram Light 57F Pro's (on the way!)

 

I don't think I qualify to answer your questions but one way to accomplish what your looking for is to get some coilover setup like the JIC-FLTA2. Height adjustable from stock height all the way to like 2+" drop. Rebound adjustable, damper adjustable, camber adjustable, etc. etc. It has so many fine tuned adjustments that a qualified suspension tech could dial it in for you depending on what your goals are. Also you might want to consider custom springs and spring rates instead of the ones that come stock. Good luck.

04' G35S 6MT Ivory Pearl, Willow, Premium

 

I understand what you are saying, and I appreciate the post. I know that kits like that are available, but they don't allow me to figure out the specs of the suspension. I need measurments, etc. I do all of my own work, so I would be dialing it in myself. I am interested in what the specific geometry of the vehicle is, so I can fine tune a suspension like you mentioned. In order to do that, I need info on the differences between the coupe, sedan, and the 350z. This will give me a general idea of how much room there is in our suspension to lower and adjust. If I see what nissan did to the other vehicles, I will be able to assume some of the optimum perameters. I will be taking measurements as soon as it gets warm up here, so I can determine some of what I am looking for.

'03.5 Brilliant Silver AT Sedan, Premium, Aero Kit/Package, Sport, Winter, Stillen Air Box, Z pipe, Clear Corners, Alum. Pedals, Polk Tweeters, Clifford RSX 3.5, Gram Light 57F Pro's (on the way!)

 

like they do in racing, just do it! Set it try it, it didn't work, set it different, try it again, it works, see if you can make it better and so on and so on.

That is my R&D technical plan

Better Life thru Chemistry
Black on Black 03.5 Sedan 6MT - Custom Catback, Custom Intake Tube, HyperGround Kit