Help with spring mount locations

All right, you guys did so well with the windshield problem, I thought I'd give you something a little tougher to work on. I need help locating the spring mounts on the frame. I am building a custom frame based on the JP magazine design. However, my length is custom. It's stretched about 35". \

The basics:
BDS wrangler 2" lift SUA and Currie shackles. The drivetrain will probably be Gen III V8 with automatic. Exact motor and transmission yet to be determined.

The rear:
I'm guessing I center the axle in the wheel well. But with the pinion angle should I set it to stock or try and align it with the driveshaft? Since I don't have the drivetrain, it's hard to know exactly the length and thus the angle. Also, can anyone tell me the eye spacing, both in height difference between the front and rear and the distance from eye to eye? Remember these are YJ springs. I've seen 22"-11/16" from the center to the eye and heard 45" eye to eye.

The front:
Since I'm planning the V8 swap I'm probably going to switch to a later model front end. My understanding is that this is about 3" longer. I also know the wheelbase is a little longer on these. Should I be moving the axle forward for this front end? If so, how much? Also, since I don't have the front end yet but need to place the mounts, does anyone have spring mount locations in relation to the firewall? Again, this is for the YJ springs. Finally, I'm under the impression that you set the front spring mounts based on the caster angle. What I don't know is what the angle should be and if (when) I swap to a Dana 30 or 44 if the angle is the same as the 27 in relation to the spring perch.

I'm planning all this without really considering doing a shackle reversal. I've read mixxed opinions on whether to do this and a couple people I talked to last weekend with shackle reversals on their YJs regretted it based on the front mounts being too low and hanging up on things. I know that's a ton of questions but I appreciate the help.

 

Each vehicle is unique. There is no "magic number". You need the full vehicle weight on the suspension and the drivetrain installed before even thinking about setting pinion angles.


Sent from my iPhone

 

:iagree:

 

You need all your axles and springs, wheels and tires all ready when you're doing this kind of custom work. It eliminates guess work and mistakes. Once you build your frame and get the body mounted, then you can positiin the axles and stuff where they need to be. Leave the spring pads un-welded, then with the full weight on the springs you'll be able to set the pinion angle. Do a lot of research and don't be afraid to ask questions. Good Luck. Take pictures of everything

Sent from my SCH-I500 using Tapatalk 2

 

Besides pinion angle and caster, you really can't set up your shackle angle without the entire weight of the Jeep on the suspension. Caster can only be separated from the pinion angle if you are willing to cut and re-position the outer "C"s on the front axle. Otherwise your caster will dictate your front pinion angle. Unless you are doing a big lift your pinion angle is relatively unimportant. Caster is very important to your steering geometry.