Our coilovers will typically use a Dual Rate spring setup. We use a Main Spring and a Tender Spring.
The Main Spring is the bottom spring that covers the shaft of the shock. The Main Spring should have the same or higher spring rate and a longer length than the Tender Spring. The rate of the Main Spring will be the Secondary Rate.
The Tender Spring is the top spring that covers the body of the shock. The Tender Spring should have the same or lower spring rate and will most likely be shorter than the Main Spring.
A Dual Rate spring configuration will have a Primary Rate that is a combination of the Main Spring and Tender Spring. When the Tender Spring coil binds or hits the stopper, the Secondary rate will take effect.
To figure spring rate, we must know the vehicles WHEEL TRAVEL, SPRUNG WEIGHT, and DROOP PERCENTAGE. We need to know the suspension configuration as well. (A-Arm, I-Beam, Four Link rear, etc.) See Figures 1-3
You will need to measure the distance from the suspension pivot, to the lower shock mount, and the distance from the suspension pivot to the end of the arm, or tire centerline. If your shock will be mounted at an angle, you will need to measure that angle as well. For our calculator, 0 degrees is straight up and down. The further away from vertical, the higher the angle number..10 degrees, 15 degrees, etc.
The SPRUNG WEIGHT is the weight that each shock is supporting (i.e., the corner weight less unsprung weight). Unsprung weight is the tire and wheel, hub, upright, brakes, and about half the weight of the shock and A-Arm or I-Beam. For the rear suspension of a truck, the unsprung weight is the tires and wheels, the entire rearend and half the weight of the shock and trailing arm.
The DROOP PERCENTAGE is the desired ride height as a percentage of total wheel travel. (i.e if you have 10" of wheel travel, and you want the vehicle to sit right in the middle of the wheel travel at ride height, that would be 50% droop. If you wanted it to sit lower..say 7" into the wheel travel, that would be 70% droop.) Most desert cars get around 40% droop, with rockcrawlers getting up to 70% droop.
Figure 1


Figure 2


Figure 3




Below is the information needed to properly calculate Spring Rates.
________________ inches 1. Wheel travel
________________ pounds 2. Sprung weight of each applicable vehicle corner
________________ inches 3. Pivot to lower shock mount distance (D1, D3, or D5)
________________ inches 4. Pivot to end of suspension arm or tire centerline (D2, D4, or D6)
________________ percent 5. Desired droop travel
________________ degrees 6. Shock angle from vertical (in degrees)

Enter the above info into our calculator to get your recommended spring rates.

 

much more understanding, now. Thank you.
it still seems that an over axle mount would greatly simplify things if I want to change something with the suspension in the future.

 

okay, you guys got me doing figures. brain hurts....thanks

question: what is the downside to doing a parallel (or near parallel) 4 link and running the panhard, essentially a 5 link?

 

less flex

 

so triangulated 4 link = most flex and stability?
it is looking crowded up front..... any pics of a front linked? 3link only?
sorry, front is where I was looking at parallel set up

 

Well, you don't really have any room to work with under there. I'm putting the normal 3/4 link in there. An a-arm design that most go with, kind of like the one in the Discovery I in the rear.


For the 3-link front you'll have to reroute the passenger side exhaust down pipe for the 3rd link. I want to do a 3-link but don't want to reroute the exhaust closer to my oil pan, but at the same time its further away from the driveshaft, which wont cook the grease in it faster.


If you want easy, and more flex then stock. Do custom castors upfront. You can get a castor to flex a lot. The only real math you need is your preferred wheel base (link length), and pinion angle.


I'll post a pic of castors up front and show you the articulation that come along. Incoming non land rover pictures.

 

yeah I think ^ that is the best route. no steering issues, etc.
but I did find this

 

That looks great, but I don't see a driveshaft or exhaust on it...

 

that pic was yanked from koombie metal fab....custom land rover isle is tucked between the fence and staircase isle.....?. I sent an email and asked about exhaust route. From pic, I think shaft works, but I'm thinking they went catless or routed to 1?

 

Yeah Jordan Blase...makes some cool ****. Used to run Rovertym, and had a collection of badass Rovers. He's building a KOH truck right now, his instagram account is landrovers