I am thinking about getting the Eiback lowering springs. What if any performace would I gain? I know Dennis said that it only helps like 1% or somehting. Would the ride quality outweigh the performance, how harsh does the ride get? I mean a set of good tires and a brand new suspension would the springs make a great deal of difference?

Another thing do springs wear out? Do they have a recommemded life or replacement intervel. With 144k are the springs shot? Since I replaced everyhting else should Have I also replaced the springs?

Guess thats the thing do I stay stock or lower the car and ride stiffer?

Don't forget you'll need new struts to to handle the spring rate increase and the drop. I've enjoyed my harsher ride. I believe it was a 20% increase in stiffness and I love everybit of it. Are you still on stock wheels? If so the ride might not be that bad, but it's really all a matter of opinion.

I'm sure 75% of spring kits are sold for looks only... maybe 95%. They're for people who are obessed with "wheel gap."

:chicken

Don't forget shocks will now only last 2/3rds as long and alignment problems will necessitate shimming or adjustable links.

Your performance in cruise on the highway will not increase, except for emergency maneuvers and high G turns.

Thats it? Doesnt seem really worth it

Now for the other Question:

Do springs wear out? is there a replacement intervel?

I've been very satisfied with my suspension mods, which include the Eibach springs. My perception of the handling is great improvement with some degradation in ride. Adjustable upper control arms were required, but I think they should be part of the Q anyway. I made many changes at the same time(springs, shocks, wheels, tires, brakes and rear sway bar) so I can't parse out the exact change in ride and handling due to the springs. I'd never heard that the springs lower the life of shocks, seems like firmer springs would reduce the motion that the shocks have to control, thereby increasing their longevity. I know leaf springs wear out, due to the friction wear, but I've never heard of coil springs fading.

Shocks are friction devices they convert the spring motion energy into heat. The heat boils the fluid [hopefully not] and raises the pressure allowing the Nitrogen to go into solution and thus escape.If a 166 pound spring compresses 4" you have just done 664 pound/in or 55 lb/feet of work do this 10 times and you have done 1 HP worth of work, one HP/hour is 12,000 BTU of heat [roughly the same as a small electric space heater].

A 1" bump pushes the spring up one inch since the tire side wall stiffness is 7-10 times the springs but the body may only be exterting 1000 pounds atop the spring.....you have a 1500 lb/in tire in series with a 166 lb/in spring supporting 1000 pounds in parrallel is the shock and sidewall friction respectively......the other problem is the sway bar which may be as stiff as the spring but has no shock to dampen its movement. Everything is fine if the road is smooth!

Measure the shock temperature after 10 minutes on a rough road it can be close to 300F! Race cars have shocks with external large fluid tank and fins to help lower the temperature and avoid fade.Rebound changes the most with temperature! So this is what you notice first the whopping undilating up of the rear.

And tracks are much smother than highways city streets heat them up the most!

http://www.penskeshocks.com/

Plus they use shock warmers to get the shock up to the 140-200F temp before the start of race.http://www.traxxion.com/produc...shtml

The more they are used cycles per minute /second the weaker they get as the temperature rises [stiffer in winter than summer].

SPRINGS:Springs can take a set after sitting in one position [50% compressed for 10 years with low mileage [less exercise more sitting than driving] and sagg -- not common as Nissan uses high quality steel. More common in very cold /very hot climates [Alaska/ Saudi etc].

Always good to take measurements brand new for future reference and to compare with the data provided in service manual.http://www.babcox.com/editorial/ic/ic109980.htm