Nico-derm

Sounds like we are using the same inter-web navigator because I can't find OE rates either.... don't feel bad.

The chart doesn't make sense to me ^^^ I was looking at it after Ape posted the links.

1) Sedan and coupe have the same wheelbase length (diffenent overhang)
2) Sedan is lighter (weight distribution obviously different)
3) Dimensions differ slightly effecting center of gravity/Aero
4) Coupe has wider track (larger turning radius)

I obviously don't know anything about how these differences effects spring rate and damper valving but all in all I don't see anything that attributes to the drastic variance other then "Implied" sedan driving style...

Ape Factory

iTrader: (3)

Well if the actual linkage with the spring perch on the sedan is inboard of where it is on the coupe, that would affect the needed spring rate. The way the G37 suspension sits now, the OEM spring location makes the setup progressive in the rear. Move it inboard and it's far, far more linear. Plus you can eliminate what I assume is a fairly heavy lower control arm/spring perch, aka unsprung weight. These are two reasons why I won't be upset if my coil-overs show up as a true type in the rear. I've not gotten a response yet from KTS on which type it is.

I think they also may consider intent. How the car is going to be used. Maybe they just lean towards a more conservative setup with the sedan. Maybe the narrower track makes it a bit more tail-happy.

I do notice that despite the spring rates being higher in the front, the rear "seems" more firmly sprung. I feel it more in the rear over rough patches than I do in the front. Traveling at lower speeds, say under 50mph, you can feel the rear skip "over' the bumps whereas the front seems to follow the road better. Whether that's down to spring rate, damper valving or suspension geometry, I do not know as haven't swapped out any hard parts yet.

I guess this is why we experiment!

slartibartfast

iTrader: (7)

I hadn't considered the coupe rear rate on a true-type. The rate will be rather lower than OE.

As for the rear feeling stiffer, it's not spring rate so much as wheel frequency. I really noticed this when I changed the stock Sentra springs from 132/90 to 300/200 on aftermarket struts. The front felt sublime while the rear kicked hard.
I'll bet Infiniti was shooting for "flat ride". Rear frequency has to be higher.

Ape Factory

iTrader: (3)

Yep, with a true type, spring rate goes down.

As far as the wheel frequency in the rear, you may be right. If you picture the rear tire going over a bump, you can feel the wheel track up the bump, over the crest and then skip the downslope. I notice this in the slow stuff only, not while at speed.

slartibartfast

iTrader: (7)

What you're describing sounds more like too much low-speed rebound. The damper isn't allowing the spring to push the wheel down the back side of the bump.

Ape Factory

iTrader: (3)

Well yeah. The wheel frequency isn't high enough to track the bump. It's being reduced by the rebound damping.

slartibartfast

iTrader: (7)

Technically, wheel frequency is separate from damping but you drive with dampers so I can see the connection. It'll be interesting to see if the Aragostas behave similarly.

Waste86

I am very excited to hear how the Aragostas turn out for you. I am sure you will write a very thorough review!

Ape Factory

iTrader: (3)

Definitely. The wait is killing me! It'll most likely be a month before they arrive.

MaQG37

iTrader: (4)

You going to any of the events for NismoFiesta? I will be there, just not sure which days.

Ape Factory

iTrader: (3)

I actually didn't know about it. Have a link?

MaQG37

iTrader: (4)

Nismo Fiesta 2016 | San Antonio

It's getting bigger and bigger every year. Send me a PM if you want to meet up one of the days. I will for sure go to the garage meet at Drury Inn on 1604/I-10.

Ape Factory

iTrader: (3)

Haven't looked at schedule yet but will try to make it! Need to work Saturday if it's this weekend but I live just south of there so I should be able to make it even if just for a bit.

I'll shoot you a PM. Maybe I can have a few peeps over for the install after they arrive as I'm doing it myself.

Ape Factory

iTrader: (3)

Ok looked at the schedule. Going to be tough for me to make anything except the car show. I may be able to make it Saturday night but I most likely wouldn't be there til 9:30. And if there's breaking news or late assignments that day, won't be able to make it at all.

slartibartfast

iTrader: (7)

I took a look at AST coil-overs. They're rather proud of their product, especially the lower end single-adjustables. I can understand pricing for the two- and three-way adjustables with remote reservoirs. I'd definitely want a shock dyno before coughing up $2,500 USD for the single-adjustables.

Did you happen upon JRZ fitments for the 370Z in your search? There's a fellow running a 350Z in Time Attack Canada that was recently sponsored by a shop that GAVE him a set which the Z owner claimed to be worth about $4k.