280z spring rates and sway bar combinations

[nick-james]

I built my car many years ago not knowing about suspension. I bought/pillaged a person's adjustable coilovers from their s30 project they failed to complete. I know nothing of the stats on the coilovers I bought other than it rides like a medieval ox cart lol. I'm assuming they went for some extreme track setup and its absolutely punishing on the street. Very bouncy and it seems (my guess) that the super stiff spring rates are overwhelming the damping of the strut. I've actually hit my head on the roof going over a train track. I'm wondering when my strut tower mounts are going to start cracking from metal fatigue lol. I'd like to change the entire setup out with different struts/coils/sway bars. 

 

My car is what I call a weekend warrior, daily driver street machine. I want a compliant ride with decent handling still. I'd like to hear some combinations and experiences that people have liked on their cars. I know that many people have had good luck with going with softer springs and increase thickness of the sway bars but I'm willing to hear thoughts on every setup. I do like the thought of adjustable dampers too.

 

If this topic is an existing sticky, i missed it  

 

Stats on car:

 

76 280z

LS1+T56

2550 lbs ( don't know the load distribution but probably close to the original car)

 

Thanks in advance guys and gals!

 

 

[jhm]

There's actually quite a few discussions along these lines; but you may have to search for them using Google search....the website search engine isn't the best.  Just be sure to include "HybridZ" in your search string.

 

First thing you need to do is figure out what you have currently.  If there are no markings on the springs, use an online spring rate calculator to estimate the spring rate.  Open up the struts and see what kind of shocks you have.  What sway bars, if any, do you currently have?  What condition are the bushings in?  What size wheels and tires do you have (and what brand/model tire)?  Do your current coilovers incorporate camber plates, or have they retained the stock strut isolators?  (The stock isolators actually do a very good job damping out road noise and vibration.  And I'd recommend you corner-scale the car, to determine your corner weights (primarily to determine your F-R distribution, since there's typically not a large variation in L-R distro.)  Are you planning to keep the car for a long time?  If so, it's worth spending some $ on quality parts that will last a long time.  Finally, decide what your budget goals and constraints are, if any.

 

Next....if street use and compliant ride really is your #1 priority, start compiling list of what changes you'll want to achieve that goal.  For a compliant ride, I'd go no stiffer than 200-250 lb/in spring rate.  (Even softer if your local roads are in rough shape.)  A longer spring of the same rate will typically be more compliant than a shorter spring of the same rate.  Are you planning to lower the car?  If so, realize that doing so often compromises streetability and the fact that you may need to section the struts in order to retain good bump and droop suspension travel.

 

Shock damping rates play as big a role in ride comfort as spring rate does, so don't ignore shock selection when considering your spring selection.  Adjustable shocks are nice; dual adjustable (compression & rebound) are really nice, but often not necessary.  Keep in mind that each shock manufacturer has a different design for their shock adjustability.  (e.g. Koni single adjustable shocks function differently than Tokico single-adjustable, etc, etc.)  Shocks are an area where one can spend a fortune, so factor that into your budget decision process. 

 

Tire selection is also extremely important, from both a performance and ride comfort factor, so plan to spend some time (and money) deciding which tire brand/model/size best meets your performance and comfort goals.

 

You'll have to decide for yourself how stiff a sway bar front and rear you'll want.  For many street-driven cars, the stock sway bars are fine, especially if you freshen up the bushings with some good PU pieces.  BUT, PU can also transmit more road noise and vibration vs rubber....so you may decide to go with a mix of PU and new rubber bushings.

 

I'm sure I'm missing several other items here to consider; just trying to highlight some of the major decision points.  You may want to peruse some of the member's builds to find those with similar setups and goals as yours to see what's worked well (and maybe not so well).  Good luck with it.