SOA or SUA?

[justinfonder]

I'm hoping this starts a constructive debate as I'm undecided which way to go and would like to hear from both sides. I'm planning an axle swap for my CJ5 , most likely waggy 44s. I'm not sure if i want to go SUA and 4.5" springs or SOA and 1.5" springs. I'll be riding on 35x12.50s, possibly 37s for off-road only. not a rock crawler, just heavy trails, sand, and mud. just want to know the pros/cons of each. this is my first jeep build, only other off road vehicle i've had is a LWB chevy that was SOA, so would like to hear how each fair on a CJ in conditions other than mud. Which is better for articulation? ride quality? overall performance?

thanks for all the input.

 

[CJ]

With that much lift - IMHO - SOA using YJ springs... A 37" tire is huge for a CJ5 .

 

[justinfonder]

will definitely be using YJ springs either way. been reading the SOA with less lift on the springs is a better ride, a flatter spring pack i guess?

 

[CJ]

Exactly, by going SOA you gain about 4.5" just by flipping the perches (give or take as I have never seen a real #)...

That is a lot of lift for a 5! How do you plan on compensating for the drive shaft angle?

 

[IOPort51]

hAVE YOU GIVEN UP ON THE IDEA OF THIS jEEP BEING AT ALL STREET DRIVABLE??

 

[CJ]

hAVE YOU GIVEN UP ON THE IDEA OF THIS jEEP BEING AT ALL STREET DRIVABLE??

Caps lock...

 

[Incommando]

You are right about the idea behind a SOA is keeping the leaves as flat as possible. Highly arched lift springs have their own set of issues. But to go SOA ( as stated = 4.5-5" of lift) plus 1.5" lift springs is quite a bit of lift for that short of wheel base. I assume you want to use this on-road by your concerns about the ride quality but the instability possibility with your lift plans might make on-road kinds dicey. A small lift and a sawzall to the rear wheel wells then covering the bigger holes with TJ flares may be a more street friendly way to run 35's or 37's.

BTW: 37's only provide 1" of height increase over 35's so for many reasons including gear ratio changes 35's may be a better choice for your application. Everyone has their opinion as to lift and axle strength. To me if you go to 37's they are at the ragged edge of Dana 44 durability unless you invest a ton of money in them. By the time you invest that ton of money it still won't equal the strength of a stock D60 front. Pass. drop king pin D60 fronts from older Chevys or Dodges aren't as expensive as the more in demand driver's drop versions. Rear 3/4 ton axles like a D60 or 1-ton rear axles can be ridiculously cheap. The Waggy's already have a different bolt pattern than a CJ so as you have to get rims anyway the lug difference on the heavier axles is moot. This might be something you want to investigate before swapping axles and then having to re-do it all if you find the Dana 44 's inadequate.

 

[justinfonder]

hAVE YOU GIVEN UP ON THE IDEA OF THIS jEEP BEING AT ALL STREET DRIVABLE??

hahaha, pretty much. after i did the 4" lift and took it off and sent it back because i realized it wasnt enough for me, i decided i'll need something else for highway trips. i still want to be able to drive the CJ to work and to wherever i'll be wheeling, but the days of 500 mile highway trips will be over. it will never be a trailer queen, thats for sure.

as far as "so much lift". i'm going to have to play with it a bit if i go SOA. Try the SOA with stock YJ springs first. i'll be cutting the rear fenders and probably tube fenders up front for clearance as well so maybe that will be enough.

the driveline issues. will definitely be going to a CV shaft in the rear as well as moving the axle back 5-6 inches to try and reduce the driveline angle and give me some more stability with the lift/tire size i want.

 

[justinfonder]

You are right about the idea behind a SOA is keeping the leaves as flat as possible. Highly arched lift springs have their own set of issues. But to go SOA ( as stated = 4.5-5" of lift) plus 1.5" lift springs is quite a bit of lift for that short of wheel base. I assume you want to use this on-road by your concerns about the ride quality but the instability possibility with your lift plans might make on-road kinds dicey. A small lift and a sawzall to the rear wheel wells then covering the bigger holes with TJ flares may be a more street friendly way to run 37's.

BTW: Everyone has their opinion as to lift and axle strength. To me 37's are at the ragged edge of Dana 44 durability unless you invest a ton of money in them. By the time you invest that ton of money it still won't equal the strength of a stock D60 front. Pass. drop king pin D60 fronts from older Chevys or Dodges aren't as expensive as the more in demand driver's drop versions. Rear 3/4 ton axles like a D60 or 1-ton rear axles can be ridiculously cheap. The Waggy's already have a different bolt pattern than a CJ so you have to get rims anyway so the lug difference on the heavier axles is moot. This might be something you want to investigate before swapping axles and then having to re-do it all if you find the Dana 44 's inadequate.

i guess i was thinking the SOA -vs- SUA was only a 3" difference (the height of the axle tube) but i guess once you factor in perches, it is more than i had thought, i think stock springs on SOA would clear 35s nicely. i want dana 60s but was going to use the waggy 44s as they dont need to be cut down. all the D60 axles i've found are like 65"+ wms to wms.

 

[Incommando]

i guess i was thinking the SOA -vs- SUA was only a 3" difference (the height of the axle tube) but i guess once you factor in perches, it is more than i had thought, i think stock springs on SOA would clear 35s nicely. i want dana 60s but was going to use the waggy 44s as they dont need to be cut down. all the D60 axles i've found are like 65"+ wms to wms.

Sticking to 35's would make those 44's happier...

 

[CJ]

Sticking to 35's would make those 44's happier...

Truer words...

 

[Az84cj7]

I just went through this with my CJ. I debated a long time which way to go. Finally I decided to go for the SOA after having numerous Jeeps that were spring under. My best advise is, if your gonna go SOA dont have A#* it. Take every measure to make it drivable and safe.
I personally love mine. It has crazy articulation and rides like a stock jeep. I drive mine almost everyday.
Just somthing to think about is with as much flex as mine has I would rub alot if I had went to 37's. 35's are perfect. Unless you want to trim alot. plus thats a big tire for Dana 44

 

[justinfonder]

I just went through this with my CJ. I debated a long time which way to go. Finally I decided to go for the SOA after having numerous Jeeps that were spring under. My best advise is, if your gonna go SOA dont have A#* it. Take every measure to make it drivable and safe.
I personally love mine. It has crazy articulation and rides like a stock jeep. I drive mine almost everyday.
Just somthing to think about is with as much flex as mine has I would rub alot if I had went to 37's. 35's are perfect. Unless you want to trim alot. plus thats a big tire for Dana 44

what springs did you use? any other aspects of your axle swap/lift that you would recommend to someone else?

 

[Petescj]

Heres a Yj Im buying that was rolled. It has about 7.5 in of lift total with some lift springs and a bolt on s.o.a. conversion. The P.O. knew that it wasnt the optimum set up for anything off camber but ran into that situation on the trail. Heres the end result:

 

[Incommando]

I missed it earlier but you are really doing some mods if you are moving the axle back that far. You will probably need to replace your gas tank with a bed mounted fuel cell. An RCI 2191 fits perfectly behind the seats of a 7 but I don't know about a 5. A common leaf for a SOA is stock height YJ springs. But if your are relocating the rear axle you might look for a leaf spring that is longer on one side of the center pin of the spring set than the other instead of centered like a CJ/YJ. This can help you move the axle back without shackle hangers sticking way out back. Also if you are moving the axle you are probably planning on some sort of "comp cut" to the rear body which as mentioned earlier in the thread will allow you to run less lift.

 

[justinfonder]

I missed it earlier but you are really doing some mods if you are moving the axle back that far. You will probably need to replace your gas tank with a bed mounted fuel cell. An RCI 2191 fits perfectly behind the seats of a 7 but I don't know about a 5. A common leaf for a SOA is stock height YJ springs. But if your are relocating the rear axle you might look for a leaf spring that is longer on one side of the center pin of the spring set than the other instead of centered like a CJ/YJ. This can help you move the axle back without shackle hangers sticking way out back. Also if you are moving the axle you are probably planning on some sort of "comp cut" to the rear body which as mentioned earlier in the thread will allow you to run less lift.

will be moving the tank, dont have the room behind the seat like in a 7, but i think i can move it up underneath the back seat enough to get it out of the way of the axle. Will probably use a fuel cell to accomplish this.

the YJ springs are actually shorter spring eye to center pin than the XJ springs that alot of people use when stretching the rear. It's the extra length on the long end of the XJ spring that is needed to keep the spring hanger in its close to stock location. I'll just be moving the spring and shackle hanger equal distance. about 3 inches to the rear, which should not put the spring hanger in the arch of the frame, so i should be ok with the YJ springs. Also going to try ruff stuffs spring perch kit that moves the axle back 2-3".

i do not want to comp cut the rear and dont think i'll have to with SOA and 35s. i will do alot of cutting, but not the full comp cut, want to keep some arch in the rear fender.

 

[Az84cj7]

I used the stock YJ springs. They bolt up real nice. Plus I didnt want any more lift from a spring with more arch in it.