Ol Grumpy Dilemma - Soa And Yj Conversion Or Just Yj Spring Under?

I figure you'd be more active at retirement, I would. More reason to build something that is 100% top to bottom. Definitely don't sell what you have. More the better.

 

Neither SOA nor SUA is better than the other. It all comes down to what you want out of your rig, preference and perhaps driving style. Each suspension system can be set up to rival the other for hard 4 wheeling. Each has benefits and drawbacks. SOA became popular in the mid 90's, but folks gravitated back to the SPU set-ups in the early to mid-2000's. Its worth considering the pros & cons of each.

The advantage of YJ springs, especially with BIG tires... say 35" or bigger is that they are wider providing stability, and longer (44.5"ish) providing for better flex. The YJ spring also has a large selection of off the shelf options for whatever you want out of a custom set-up.

I would suggest doing frame work and letting that nice suspension do the flexing. Stock CJ fames are old, weak and subject to breakage. I suffered a major frame break on my big-tired SOA ECJ5 on the Rubicon in mid-Oct, many years ago (1995) and was nearly stranded. I only saw one other small Jeep group that weekend and by chance they had a welder (not many folks had OBW back then). It took some work but we fixed it. So I got lucky...lesson learned. OR....Consider a Throttle Down Customs Frame as a starting point.

In a CJ, SOA definitely requires steering solutions and it will likely create rear axle wrap also requiring a correction with additional fabrication work. SOA is great for articulation with lift because it uses a softer spring with less free arch to obtain height, while simultaneously changing the leverage point. It will require creative drive line work because of lift. SOA provides for better clearance at the axle tubes. It changes the dynamics of a short-wheel base rig and has to be well thought-out. SOA is a lot more work. I liked being able to just drive over stuff by having 6.5" of lift with amazing flexibility. A HP rear-end (High 9 or Dana 60) is useful to correct the steep pinion angle and to keep that driveline tucked up tight.

SUA in a CJ is obviously more common. If you want lift, then you need to use a spring with more free arch and by virtue of that, they will be stiffer. But today, there are many high quality 4.5" lift springs that will articulate very well. It is probably easier to set up a custom suspension SUA. Steering is easier to set-up. Some folks feel safer, or that the rig is more stable with SUA. Low profile tie-plate skids can be made. The low center of gravity style of build utilizes SUA and just 2.5"ish springs. Member Tymbom here, who has an amazingly capable rig comes to mind on this concept. Check out his build thread.

So finally, after all that banter, Here are some walk-around videos of old leaf sprung Jeeps on 35's for your viewing pleasure and for ideas on how they set them up. Some of these have been posted before. Some are flat fenders, but the same engineering applies. If you don't know WFO, it's a custom 4x4 shop based in Auburn CA, not far from your old Rough and Ready stomping grounds...there's lots of SOA around that shop and they also love those LS swaps.

48 Willys

46 Willys

1960 CJ5

Late Model CJ5

 

Thank you for all that useful info!!! WFO I have seen on YouTube with their LS1 swaps. When I was in the club Capital Jeepers was where we all went. Also went on Gary's steak runs up on the Rubicon for many years! This is all a lot to consider and myself and the other 1/2 will be mulling it all over!

 

That’s awesome! I was in high school in the late 80s - early 90’s. I grew up near Folsom Lake / Orangevale-Rocklin. It’s was kind of the sticks back then…how things have changed. Gary was always good about helping out us kids with our Jeeps. I loved that shop. I remember seeing truck transmissions just laying around in the front room. Reference books on the counter. A real jeep shop.

 

I was sad to see Gary had passed. We our last names were similar, Bergman and Borgman, so we always had a running joke about it! RIP Gary.

https://www.legacy.com/us/obituaries/sacbee/name/gary-borgman-obituary?id=38705467

 

That’s unfortunate… I’m sorry to hear that. Thanks for sharing. It’s been a long time since I’ve been in that area. Many people have fond memories of him. Yes, RIP Gary.