SOA to SUA - JeepForum.com
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post #1 of 27 Old 03-03-2020, 08:23 AM Thread Starter
thebobmannh
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SOA to SUA

Hi All,

Recently bought an '81 CJ-5. It's got a SOA lift with 35" tires, which is more than I need for my purposes (roads, some light dirt but no rock crawling). Plus, they did a s**t job with the steering after the lift (basically made zero accommodations; it's like steering a snowmobile with all the bump steer, and the drag link is bent like a pretzel in addition to being at a horrible angle).

Thinking of just going back to SUA with a small lift (BDS 2.5" kit is what I'm looking at) and some 31" tires for better road use (not to mention my wife won't need a step ladder to get in....)

I understand what is involved in going from stock to a 2.5" lift, and I understand the basics of an SOA lift, the question is what extra issues might I run into while attempting this?
  • My biggest concern that I am aware of is the driveshaft -- I have to assume they got a longer one after the lift, which will likely be too long after I lower it back down.
  • Any issue with the brackets for the SOA that are welded to the top of axles or can they just stay there?
  • Am I crazy to attempt this myself?

Some pics of the effed steering and the driveshaft attached.

Thanks!

Attached Thumbnails
driveshaft.jpg   steering2.jpg  
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post #2 of 27 Old 03-03-2020, 09:29 AM
jurgen24
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You’ve identified the main changes, it’s not too tricky to make the swap. You can leave the perches on top of the axles. I also noticed a drop pitman arm, I would suggest going back to straight arm. I would also expect to get new shocks. Don’t bother trying to straighten draglink, chuck it and get a new one.

The tricky parts are setting the front and rear pinion angles. The rear angle will depend on drive shaft type, single vs. double cardan. For front, I would initially set to be parallel with transfer case and then adjust until you end up with a negative caster of about 5 deg (Which should be OK for small lift)

After than you can do the final weld for the perches and then measure for drive shaft length.

Your brake lines might now be a bit long. Also I could not see an anti wrap bar in the back, remove if present.

BTW, what are the spring widths in the front, are they CJ or YJ springs?


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post #3 of 27 Old 03-03-2020, 09:36 AM
jurgen24
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Do you know the gear ratio on the axles? Going from 35” to 31” is a big jump. Use a gear calculator to make sure you are happy with top speed, otherwise you may need to regear. Alternatively going to 33” might be another option.


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post #4 of 27 Old 03-03-2020, 09:43 AM Thread Starter
thebobmannh
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Quote:
Originally Posted by jurgen24 View Post
BTW, what are the spring widths in the front, are they CJ or YJ springs?
Thank you so much for the input. I believe they are YJ springs, I'll measure when I go home. Will I need new shackles if that's the case? YJ is wider, correct?

Quote:
Originally Posted by jurgen24 View Post
Do you know the gear ratio on the axles? Going from 35” to 31” is a big jump. Use a gear calculator to make sure you are happy with top speed, otherwise you may need to regear. Alternatively going to 33” might be another option.
I don't. The page for the 2.5" lift suggested that 31" was the biggest I could go.
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post #5 of 27 Old 03-03-2020, 09:59 AM
Fourtrail
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Looks like the old perches are still there so should be as simple as doing a stock lift kit. You will likely need new spring plates for the front that have the shock mount on them and you will need to cut off the current front shock mount. remount the front brake flex hoses to the correct spot on the frame. as long as the 'new' spring perches on the top of the axle clear the ubolt, you don't have to worry about cutting the off.


post up a couple pictures of the rear so we can help out on that also. like said, you will likely need new drive shafts/have the current ones shortened. not crazy to attempt this, a lift kit is relatively simple in the grand scheme of jeep upgrades/maintenance and there is lots of knowledge and help to be had from this place

80 CJ-5, 74 CJ-6, 56 CJ-5
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post #6 of 27 Old 03-03-2020, 10:13 AM Thread Starter
thebobmannh
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Originally Posted by Fourtrail View Post
Looks like the old perches are still there so should be as simple as doing a stock lift kit. You will likely need new spring plates for the front that have the shock mount on them and you will need to cut off the current front shock mount. remount the front brake flex hoses to the correct spot on the frame. as long as the 'new' spring perches on the top of the axle clear the ubolt, you don't have to worry about cutting the off.
Good news, as the one thing I can't do is weld. At least I've never tried and don't have the equipment.

Quote:
Originally Posted by Fourtrail View Post
post up a couple pictures of the rear so we can help out on that also. like said, you will likely need new drive shafts/have the current ones shortened. not crazy to attempt this, a lift kit is relatively simple in the grand scheme of jeep upgrades/maintenance and there is lots of knowledge and help to be had from this place
Thanks, will post pics of the rear tonight when I get home.

Last edited by thebobmannh; 03-03-2020 at 11:16 AM.
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post #7 of 27 Old 03-03-2020, 02:24 PM Thread Starter
thebobmannh
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Hmm so looks like the original perches are NOT on the rear axle, which isn't great news. I am not in a position to crawl around underneath at the moment -- I was hoping to see if I could get some markings from the rear diff to figure out what is there from a gear ratio perspective.

Anyway, here's what I'm working with on the rear.
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jeeprear2.jpg   jeeprear.jpg  

Last edited by thebobmannh; 03-03-2020 at 02:28 PM. Reason: added photo
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post #8 of 27 Old 03-03-2020, 02:48 PM
MetalMountainGoat
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I did exactly what you are trying to do. YJ springs and all. Check out my build thread (link below). The castor angle is the most important thing that you need to get right. The PO of my jeep cut off the front spring perches when he went SOA, so I had to figure all that out again to weld on the new ones.

https://www.jeepforum.com/forum/f8/m...build-4347225/
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post #9 of 27 Old 03-03-2020, 04:37 PM
BrutusBlue
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Only sure fire way to check gear ratio is to spin the pinion with both wheels turning at the same rate or pull the diff pan and look at the stamped number on the ring gear.
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post #10 of 27 Old 03-03-2020, 09:42 PM
CSP
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Quote:
Originally Posted by MetalMountainGoat View Post
The PO of my jeep cut off the front spring perches when he went SOA, so I had to figure all that out again to weld on the new ones.
Lucky for the OP, the stock perches are still there, so with stock length shackles (or close to it), caster should be good to go.
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post #11 of 27 Old 03-03-2020, 11:05 PM
MetalMountainGoat
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Quote:
Originally Posted by CSP View Post
Lucky for the OP, the stock perches are still there, so with stock length shackles (or close to it), caster should be good to go.
He should be close, but I would measure it all anyways. The slightest bit off and the steering will be all over the place.
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post #12 of 27 Old 03-04-2020, 09:11 AM Thread Starter
thebobmannh
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Well, based on the fact that I'd need to do welding and there's a bit more involved here than I had thought, I'm probably going to hold off, see if I can fix the steering as is for now and deal with the lift at a later date, either by learning how to weld or finding someone who's able to do it. Thanks everyone for all the help and advice, it will not go to waste
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post #13 of 27 Old 03-04-2020, 11:09 AM
NormWild
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Quote:
Originally Posted by thebobmannh View Post
Well, based on the fact that I'd need to do welding and there's a bit more involved here than I had thought, I'm probably going to hold off, see if I can fix the steering as is for now and deal with the lift at a later date, either by learning how to weld or finding someone who's able to do it. Thanks everyone for all the help and advice, it will not go to waste

Post a pic of the full Jeep so we can see how high it is. It looks like the springs are pretty flat, so you might be able to just drop down to 33s. It might be easier to just fix the SOA for the short term. Correct the steering linkage, check castor angle, replace shocks, go with a CV rear DS, and put in a single link for the rear axle.

1985 CJ7- 4.5" BDS/Fiberglass Tub/33s/Many Mods
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post #14 of 27 Old 03-04-2020, 11:21 AM Thread Starter
thebobmannh
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Originally Posted by NormWild View Post
Post a pic of the full Jeep so we can see how high it is. It looks like the springs are pretty flat, so you might be able to just drop down to 33s. It might be easier to just fix the SOA for the short term. Correct the steering linkage, check castor angle, replace shocks, go with a CV rear DS, and put in a single link for the rear axle.
Here's a full pic of the Jeep as it currently stands (on 35's). Also a pic of the driveshaft.

(I know a lot of people are probably thinking "doesn't he even know what he has" and hte answer is mostly no, I just got this thing for pretty short money, and have driven it all of twice, and it's winter in NH and I don't have a garage so I haven't been able to spend much time exploring, so I'm just trying to do as much research as I can now before spring. So I appreciate everyon'es patience and input with my basic questions)
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Last edited by thebobmannh; 03-04-2020 at 11:54 AM. Reason: edit
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post #15 of 27 Old 03-04-2020, 03:11 PM
MetalMountainGoat
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I can almost guarantee you that the castor angle isn't right in the front, and no matter what you do to that steering, it will be dangerous to drive this thing at any sort of speed. If the castor angle is incorrect, then there is no way around doing to some welding because the perches will have to be adjusted, so while you are at it, you may as well pull everything out from under it and swap it back to SUA.

It really isn't that hard to weld the perches on. I know you said you had no welding experience, but someone with only little could pull it off with a cheapo harbor freight welder (I did). If anything, pull axles, take it to local muffler/fab shop and have them weld on the new perches with the correct castor angle in the front. After that, throw the axles back under there in SUA configuration.
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