Then simply, a whole lot of factor's were wrong, but it brings out much more serious issues that have to be addressed before anyone should put money down on the product, especially where brand name is on everyone's mind.

1. I get to ask why, point blank why did D2's tech not answer me when directly asked about the rear springs, not answering that part of my question which dealt with rear spring diameter was critical, add in the picture I have plainly showing 5" OD rear springs and D2's own web site pic of the Z33 application is also plainly NOT of a Z33 coilover either http://www.d2racingsport.com/absorbe...350Z%20J33.htm ,.....you get the idea.

2. Another issue, D2's email to me states that the recommended spring rates differ from what you list, they said they are 15Kg/13Kg and the optional rate is 13Kg/10Kg.
d2-racing@umail.hinet.net Ok, the 10Kg optional rear rate doesn't make sense since D2 does not do their rates in even numbers (15, 13, 11, 9 ect). Yet, if we work the math and take into account actual spring rates due to the new rear spring location, D2's stated rates DO NOT ADD UP! Here's what I mean.

D2 recommended spring rate (15Kg/13Kg)
Front:840 to 664 +168% stiffer then oem
Rear: 728 to 429 +250% stiffer then oem ( rear spring location is factored in)
Transfers 118% roll stiffness to the rear!!!

This means that if the 15Kg/11Kg rates are truely correct, things are a whole lot better. So in this case I hope D2 did not have their facts straight.
D2 coilover, if 15Kg/11Kg
Front:840 +168% stiffer then oem
Rear: 616 + 195%
Still a +33% transfer of roll stiffness to the rear, but a lot better then a +118% transfer to the rear.

Ok, compair the above to a few other systems in the same light. All use the oem rear spring location of course.

Tein Flex
Front:672
Rear:672
Transfers +16% to front

Jic Flta-2 350Z fitment
Front:560
Rear:672
Transfers +20% roll stiffness to rear

Tein Basic
Front:504
Rear:504
Transfers +18% to front


3. This of course does nothing concerning the issue of leveraging forces to a area of the body structure that was never designed for it and any long term effects. Though I really WANT to think it's ok, it's still something to ponder.

Some additional things to know.
oem front motion rate is .79
oem rear motion rate is .36
rear motion rate when springs are run in the same location as the shocks mount is .59

 

We test fitted a set (the ones in the pictures) on our Z six month ago and they sucks!!! The ride was WAY TOO harsh...... this is why we did not carry D2 coil-over at this point, but I heard they may have new design for the rear where the spring and strut are separated just like the OEM ones.....

 

Yeah 15Kg is pretty much for the track only. Thank you for your honesty. As painfull as walking away from the product may have been, you did the right thing.

 

Just to make a clarification, the D2 that you see sponsor cars in the DTM, DOES NOT MAKE SUSPENSION, they are a cellphone service provider in Germany. They have sponsored the Mercedes factory DTM cars for a number of years. I dont ever remember them being involved as a sponsor in F1.

I have been involved in racing for over 10years and have never heard of this D2 suspension company. They do not make shocks for DTM or F1 cars (the Mercedes DTM cars have used special SACHS or Bilstein race shocks for a number of years) and most F1 teams either make their own shocks or us special shocks made by SACHS, Ohlins, or Penske. Obviously someone is using the D2 name and logo to try and legitimize themselves....falsely I may add!