EarlyCJ5.com Technical Library

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Early/Intermediate CJ-5 to Wrangler(YJ) Spring Conversion

Story and Photos by John Stone, AKA hudsonhawk

Edited by Adam Sparks

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So you've decided to take the plunge in the search for a smoother ride and better stability and wondering where exactly you start. Well the first place is a parts list. At the time this was written there was no "Kit" available with all the parts. Also, it is not a simple bolt-on procedure. Here is a good idea of what it will take.

Parts list:

Wrangler (YJ) springs (2 front, 2 rear)
New bushings for the spring (24 in total)
'76 and up Main Spring Eye Hanger (4)
Main Spring Eye bolts (4 - greasable if you can get them)
'76 and up CJ rear or YJ Shackle hanger (4 - CJ fronts are only 2 inches wide)
76 and up CJ rear or YJ Shackle (4 - again greasable bolts if you can get them)
YJ Spring plate (4)
U-bolts to fit your axles ( 8 total - always replace the u-bolts when you take them off)
2.5" wide spring pad for the axle (2 for rear and I would not change the front).
Various nuts and bolts (I was on a first name basis with most of the people at the hardware store when this was done)

All of these parts are available off-the-shelf at most 4x4 parts stores and websites.

Also, since you are cutting off the old suspension anyway, now is a good time to consider any other modifications you may want to make: i.e. spring over, shackle reversal, lift springs, longer wheel base, etc.

Tools:

eye protection
gloves
cutting tool (plasma, angle grinder, cut-off tool, air hammer, hacksaw..... whatever you have lying around)
hand-held grinder to clean up frame and axle tubes
hand drill and good metal bits
ratchet set (air impact makes it so much easier)
hand wrenches
Welder (pay someone to do it if you don't have one)
small C-clamps
floor jack (not necessary but very helpful)

Getting started.

Difference between original and new springs

This pic shows you the difference between the 2.5" Wrangler springs and the original 1.75" hardware. The new springs in this picture are actually 4.5" lift springs from Rubicon Express. The stock Wrangler springs will not drop nearly that much.

You need to find a place on the frame that is symmetrical on each side as a reference point. A good place is the bolt holes for the tranny cross member. This reference will be used to locate all the spring mounts so your Jeep does not crab walk when you are finished.

We will start with dismantling the rear, but the technique is the same for all the springs. There is no need to disconnect the brake lines or steering linkage to do this modification.

Put the vehicle up on jack-stands and remove the tires.
Remove the u-bolts and old spring plate. This may require using your cutting tool of choice on the u-bolts if the nuts are rusted badly.
Lift the axle and support it with whatever is handy. I used some old pieces of scrap 2x4 to build blocks to set the axle on. Small jack stands work too, if you have an extra pair.
Mark the center of the axle spring pads on the axle so you know where the new ones need to be mounted. Then cut them off and clean up the axle tube in preparation for the new pads.
Remove the shackle and main spring eye bolt. Throw everything you just removed into a pile (including springs) for later sale or scrapping.
Cut off the Shackle Hanger. On my 72, the shackle hangers were riveted to the frame as well as being welded. I cut off one ear of the hanger and the caps off the rivets. I drilled the rivet out and then I ground the welds off to remove the hanger.
Cut off the Main Spring Eye Hanger using the same technique as on the Shackle Hanger.

At this point in time it is a really good idea to thoroughly inspect your frame for damage and repair any that you find. You will also want to grind the welds down and generally clean up the areas around where the old hangers were.

Okay, once everything is clean and ready to start construction:

Use the front hole in the frame where the old main spring hanger was and the front hole on the new main spring hanger to mount it. I had to drill out the hole just slightly to make sure I had a snug fit with the bolts I used.
Install the bolt to hold the hanger in place.
Using the hanger as a guide, drill the second hole. Install and tighten the bolt.
Mount the Wrangler spring to the Main Eye Hanger.
Use your floor jack to hold the spring in its approximate full droop position.
Put the new shackle on the spring and into the shackle hanger.
Now slowly raise/lower the spring until you get the hanger into the position you like. It may or may not line up with the existing holes from the rivets. A floor jack makes this much easier. *
Use a small C-clamp to hold the hanger in position.
Mark and drill the holes for the hanger.
Bolt it on.
Install the shackle into the hanger and the spring.

*This the tricky bit, as there is no hard and fast rule of thumb on how much angle you want on the shackle. You want enough angle so that the shackle will not invert when the spring is at full droop. But you do not want enough to cause it to bottom out against the frame before the spring is fully flat. With stock springs this is not really an issue. But if you move up to 4.5" lift springs (like I did), this becomes a real problem. These 2 pics show how I set mine up.

You want to make sure that the shackle and spring do not line up straight at full droop. If they do the shackle can possibly invert and bend the spring. You want the angle on top (the side the axle is on in this picture) to be less then 180* to stop that from happening.

This is the finished product with the full weight of the jeep on the new springs. As you can see, there is plenty of room for the spring to flex without the shackle hitting on the frame.

Now you have one spring on and it should look like the picture at the beginning of the article. Repeat this procedure for the other side. Use your reference points to make sure the main hangers are mounted at the same points on the frame to keep your axle square. To do this simply measure from the reference you marked earlier to the hanger on each side. If the distance is the same then you are good to go. If not, you need to move the hangers and drill new mounting holes to make these measurements the same. You need to do the same for the shackle hangers. This procedure works even if you decide to move the axles in order to increase the wheel base.

Once you are happy take it all apart and paint the holes in the frame to help combat rust.
When the paint is dry, reassemble the springs and hangers.

And now, onto mounting the axle.

If you are using lift springs while doing this conversion, this is where you actually get an advantage. By replacing the spring pads now, you can rotate the axle up so that the pinion points directly at the transfer case output. This, in conjunction with a CV style driveshaft, will help eliminate problems associated with lifting the very short CJ-5s. This is what mine looked like when it was done.

Put the new spring pad on the top of the spring.
Place the axle on the spring pads.
Adjust the pinion so that is it parallel with the ground. Also make sure the center of each pad lines up with the mark you made before you cut the old pads off.
Mount the new spring plate and tighten the U-bolts down enough to hold the axle/spring assembly together.
BUT DO NOT TORQUE THE U_BOLTS. You will just remove them after you tack weld the spring pads on.
Put the tires on and then lower the jeep so that all its weight is on the springs.
Now place the floor jack under the pinion.
Slowly adjust it until the pinion is pointing at the rear output of the t-case. It may help to have a piece of dowel rod to help you visualize the link as you make adjustments. If you want to use the old driveshaft then just leave the pinion parallel to the ground.

If you don't have a welder now is the time to make arrangements with your buddy who does to come over and start making everything permanent.

Tack weld the hangers in place once you are satisfied with the pinion angle.
Put the jeep back up on jack stands and remove the u-bolts/spring plates. You may have to remove the tires if your jack stands are not tall enough (I know I had to).
Weld the axle spring pads in place.
Weld the main spring eye hangers to the frame.
I did not weld the shackle hangers. I wanted them set up so that I could move them if necessary to adjust my rear ride height and shackle angles. (Don't laugh, I have already had to do it as I added the cage and a lot of other weight to the Jeep after I did the suspension.)
Now paint all the bare metal to keep it from rusting out and put it all back together.
Make sure to torque the U-bolts to spec and then check them after about 50~100 miles.

The front procedure is the same as the back and you don't even have to disconnect the steering linkages. I did not replace the spring pads in the front because the passenger side spring pad on the Dana 30 is cast into the pumpkin. Although, you will have to grind a little on the top of the pumpkin so the U-bolt will sit correctly. After 700 miles of on- and off-road driving I have not had any problems with using the stock spring pads. Here is an example of the articulation my CJ has with this spring conversion. And, on the highway it will do 60mph with a nice smooth ride. Well, smooth for a short wheel-base CJ anyway.

Once you have finished this process you need to check your shock and drive shaft lengths. They should be fine but if you moved the axles forward or back or added lift they will probably need to be replaced or modified.

Good Luck and Happy Modding.

John Stone AKA HudsonHawk

Elsewhere on the web

Jp Magazine's Article