Originally Posted by RobRoss

The reason I asked for corner weights (or axle) was to make comparisons between G, B and F code springs. All spring charts that I have seen are for 1 spring (hence the orginal corner weight ?). Although B or Modded B seems to be the most common, I felt like I needed more confidence on the subject. See the link for my spreadsheet, there is more to it than what is shown but I think what is shown is all that is needed if you subscribe to it. I started with the corner weight provided earlier in this thread (Thank you Tom!) but shortly after found the G code spring drawing (curb was shown as ~1300 lbs). Since I was lucky enough to find these spring charts (G, B, F and a few others that I couldn't identify with codes) I picked deflections off at the same load for comparison sake. From there I calcuated the natural frequency based on STATIC deflection to see if the spring is happy at that particular deflection. I also compared the same load to our original springs. A natural frequency (NF in my chart) of 1.5 or less is "supposed" to give a good ride. Above 1.5 and the ride can be percieved as harsh. The G code springs certainly appear to be more harsh in terms of NF and ride quality as a lot of folks who have upgraded their springs have confrimed. After I finished this I actually found real weight data for our trucks from the factory (full weight and unsprung). That info appears in the last 5 columns.

Here is the link to my spread sheet. Ford Truck Enthusiasts Forums - RobRoss's Album: Spring Comparison - Picture

Of course once you "mod" a spring and if that mod affects rate, it will alter the NF.

What does all this mean? Maybe not much but it was fun to do and I confirmed for myself to go with the B codes but I will mod mine. I don't see the bottom G code leafs affecting rate too much and I'm guessing the thicker spring spacers will slightly lower the rate. Have fun looking at the info!

Originally Posted by RobRoss

I forgot to mention the other reason I did this was to see how close I might be to the auxilary spring. Meaning if the secondary rate engages it will make the ride harsh. My findings show the B has the most travel before the secondary.

Originally Posted by WE3ZS

Good stuff Rob, You are investing a lot more thought and research into this spring swap than anyone I've seen yet! My brain started to hurt going over your spreadsheet. I think that you will be very happy with the mod Bs, I know I am.




This comment caught my attention, are you talking about the B code top overload leaf? If so, you have to remove that leaf before mounting the Bs on an EX. The top overload leaf can hit the rear AC lines on an EX and the EXs don't have the frame mounted landing pads for the top overloads like the SuperDuties do. Maybe you are already aware of this and were referring to the bottom spring plate on the Bs, but that plate's contribution is a lot more linear than the how the top comes into play on the trucks. If you were talking about the top leaf, then you don't need to concern yourself with the secondary rate making the ride harsh, because it won't be there to start with!