To put all the answers in one place:
1) Durability
In THEORY, yes, a true coilover setup will put "more" stress on the strut towers; however, in reality this has not actually shown to be a significant enough difference to worry about. People track their cars with true coilover setups, which is a far harsher condition than bumming around down, without experiencing failure.
More to the point, if you were to run stiff enough suspension with stressful enough conditions to actually need to worry about it . . . you'd be a racing car with no DD duties and you'd have custom fabbed reinforcements in that area.
Bottom line, unless you're shooting for competitive laptimes, don't its not a problem
2) Spring Rate
Changing from a divorced to true style DOES change the geometry of the rear suspension and you should not run the same rates in a true style as in a divorced style.
Refer to this thread:
Aero and Suspension Tuning With True Type Coilovers
Specifically
Quote:
Originally Posted by Brendan
With a true type rear suspension, it makes the motion ratio very close to 1 to 1. If you ran a 750lb/13k rear with the divorced set-up, that would put you at a natural frequency of about 2.00 hertz. If you were to then run that same spring with a true type rear, that bumps things up to over 3.00 hertz. Based on my calculator, you would need to go back down to 7-5k or 400lb to 300lb spring range if you wanted the rear to feel the same as when you were running the divorced set-up with 13k/750lb springs. I don't know how aero effects this as I have been focused on autocross, but I imagine you need to run on the stiffer end of the range since you have a force pushing down on the car.
I would love to see what he comes up with. Have my math checked so to speak.
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Summary: if you chose a "true" type setup, you will need to run a LOWER spring rate than a divorced setup
3) Alignment adjustment
There are THREE arms you need for the rear for full adjustment:
- a camber arm. SPL makes two versions, the "billet" style is just a newer design
https://www.splparts.com/products/re...-370z-g37.html
or
https://www.splparts.com/products/re...t-version.html
- a traction arm
https://www.splparts.com/products/re...-370z-g37.html
- a midlink OR toe arm
If you have a divorced setup, get this:
https://www.splparts.com/products/re...-370z-g37.html
***
NOTE: The SPL midlink requires a 65mm diameter spring. Check with your coilover provider to see what diameter their rear springs are. Most good places offer Swift springs as an upgrade; Swift makes a spring with the correct 65 diameter that fits perfectly. The STOCK spring bucket is like 4.5 inches and way, WAY wider - it will not fit on the SPL bucket.***
if you have a true setup, get EITHER:
https://www.splparts.com/products/re...-370z-g37.html
or
https://www.splparts.com/products/re...t-version.html
Again, the billet version is just a newer design
NOTE:
You will also need to get an Eccentric Lockout kit:
https://www.splparts.com/products/ec...-370z-g37.html
the STOCK adjustment points in the rear are eccentric bolts that may slip over time. These remove that movement, so adjustment is made purely on the arms themselves, which are more stable
Optional
Tie Rod Ends with bumpster adjustment.
https://www.splparts.com/products/bu...5-z34-q50.html
Also, they make swaybar end links which you don't NEED either