Hi all, A few questions to go along with along with a couple of screen shots of #'s I've come up with, for the front and rear suspension, using the spring calculator found on the Brunton Performance Products web sight http://coilovershock.com/suspension_worksheet.htm
I appreciate it is a matter of personal preference, just interested in knowing if what I have here is reasonable.
A bit of back ground.
My build is Miata based so A arms front and rear.
I plan on using narrow body Gaz shocks purchased from Jack @ Kinetic.
I need a min of 2 inches bump and droop to be street legal.
Car is intended for street with the occasional trip to an autocross.
For D2, The worksheet uses pivot to tire center line. Another spring calculator posted in the Spring Rates sticky gives different end points depending on the type of suspension used http://f-o-a.com/calculator.html
. For A arms it suggests either end of pivot arm. Based on this I used end of the arm in the Brunton calculator as well (Ball joint center). I plugged the #s into both calculators and got the same # with in 2 lbs.
Screen shots from the Brunton calculator, of front 1st and rear 2nd.
File comment: Front
front snapshot.png [ 143.8 KiB | Viewed 837 times ]
File comment: Rear
rearsnap shot.png [ 145.67 KiB | Viewed 837 times ]
From these #'s-
angle is 10', so 182lbs (180lb spring) with 6.0' travel shock (4.9' travel + 1' for the bump stop)
angle is 45', so 367lbs (375lb spring) with 4.5' travel shock (3.4' + 1' for the bump stop)
1st- Is there anything grossly amiss with the #s I have imputed.
2nd - Is the calculator itself reasonable?
3rd- Regarding a couple of the 'tips' included in the worksheet.
3rd.1- It suggests using 33.33% droop. What practical effect will there be if I deviate form this (as I have to affect frequency,and droop in a given travel)
3rd.2- From the worksheet- "Important- The front frequency should be less than the rear...theories vary, but 10-15% seems to be popular
(I have tried to do this, again by changing droop % and travel front to rear). Is this important (why). I don't recall this being discussed in any other topics.
4th- What is the maximum shock angle one can have (using Jacks arms and I'm struggling to get 45' with the narrow upper arms and keeping my lower mount as far out as possible)
5th- What is the approximate OD of the Gaz springs (ID is 1.9’) so I can check for clearance on the upper arm (may help with ‘4th’).
6th- Better to round up or down for the springs (rear I've round down, front I've round up, base on what closest- calculated to available).
7th- Are springs for these shocks avalible in North America (much as I don't want to think about puchasing the next set before I've ordered the 1st set, switching springs down the line seems like a common practice so the question must be asked).
Thanks in advance for taking the time to read this and answering any questions.