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Default How to build a three or four link suspension
by 4.3LXJ 08-21-2011, 09:56 PM



Many people have asked on forums how to build long arm front suspensions for a Jeep Cherokee. Many of these people want blue prints, but there are really none available, unless they belong to a suspension company, and they will not let them out. So I will take the reader through the steps with some measurements included. But, I need to caution everyone. If you are an inexperienced welder or have never made anything from steel before, then this is not the project for you. I will assume you know how to do things like cut steel and weld ant that you have some knowledge of fabrication. If you run out and buy yourself a cheap welder and consider yourself ready to go, then you will just ruin a good vehicle and likely build something unsafe.

The first issue is track bars. There are many on the market, but if you want a beefy one, I suggest getting one from Iron Man Andy. If you want a normal one, then there are many choices. Be sure to order one for your lift height and that is adjustable. So by now you have a lift height in mind. If you go over 4.5” of lift, the front long arm suspension is for you. Advantages include greatly improved ride and articulation. So, to get started. Do one side at a time. This will keep your front axle from flopping around while you are trying to make measurements.



First, remove the driver side wheel, support the axle and remove the lower and upper suspension links. Then cut the lower link bracket off. Once you have done this step, you past the point of no return because unless you fabricate a new bracket, you cannot put your suspension back on.

Next, support the transmission and remove the cross member. Most long arm suspensions articulate at the point on the frame where the cross member bolts. Next, cut two pieces of ΌX4” flat bar 16” long. Place it on the bottom of the frame so that the outside edge is even with the part of the frame that turns up and mark the holes for the two bolts that hold the cross member in place. Drill two 3/8” holes so that the plate can be bolted to the bottom of the frame.

Next it is time to build the bracket for the joints. At this point you need to have made a decision on what kinds of joints to use.



The picture has lower links made from three types of joints. The lower one, has stock lower link rubber bushings. This link was made from scratch, and was adequate and based on older technology. When suspensions first came out, the link was allowed to twist on a threaded bolt welded to a bushing sleeve. Keep the threads greased and it will last a long time and can be made fairly cheaply. The upper link was bought as a kit and uses a clevite bushing on one end and a spherical rod end with nylon inserts. Here is a close up of them.





There is a world of difference in the strength in the two of these joints. What you use is up to you. The sleeves and rubber bushings can be purchased at 4WD.com and the spherical rod ends and link kits can be purchased at Parts Mike. It is a matter of cost and purpose, but the goal of this build is to have a suspension that is as strong as any rock racer could want in a daily driver that has a degree of comfort in it. So the rest of the build will use the stronger stuff. However, they both fit in the same space and brackets.

Next, it is time to build the brackets for the rod ends. First start with a piece of 1/4X6X8” steel.



Measure up 1” from the bottom and 2 ½” from the left side. Mark that and then measure up 4” and to the right 4” and mark that. Then drill two 9/16” holes. Then take two 9/16” nuts and weld one on one side of the plate and one on the other side so that you can bolt two joints on either side as shown in the pictures.







Next, cut a piece of 2XX3/16” rectangular tubing from a length long enough to go from one frame member to the other. The length of this needs to be the same as the width of your joints. In this case, it was 2 ½”. Center it over the welded on nut facing the inside of the vehicle, the one that is one inch up from the edge and 2 ½” from the edge as shown in the pic.



Next you can trim up the plate to save some weight, although not necessary. Next cut another plate 8 ½X6” and place one leading even with the edge on the right. Drill a 9?16” hole that is in the same exact place as the upper right hand hole. The trailing edge should be about a half inch behind. Also cut a piece of 1/4X2” flat iron 6” long and place along the bottom so that the trailing edge of the flat iron is even with the trailing edge of the larger plate and drill two 3/8” holes through both plates 1” up from the bottom and ½” from the edge of the flat iron as shown in the pic.



You can also trim to save weight as shown. Next place the plates together and run a bolt through a joint as shown and weld the plate to the square tubing. You now have half of your bracket and three inches of cross member. As you can guess, there was a reason for welding that lower nut in place. You cannot get a wrench on it. Make sure it is secure, but don’t distort the threads from too much welding.



Now it is time to tack the bracket to the edge of the 4X16” plate. The center of the hole that is in the cross member should be lined up with a perpendicular line in the equidistant between the two holes in the plate and 1 Ύ” up the bracket from the center of the hole. The idea is that the joint
which is just over 3” in diameter, or a 11/2” radius will not bind on the frame when secured.



After mounting the plate, it is necessary to check the top joint for clearance. So install the joint and rotate it. Mine had about 1/16” clearance, which is enough.

Then cut a 1/4X3” flatiron 3 ½” long, just long enough to fit between the bolts on the 16” flat iron and not interfere. Drill a 9/16” hole 1 Ύ” from the top and 1 Ύ” from each edge and tack with a joint in place as shown. Next you can take it all down and tack in a 1/4X2 1/2X3” gusset in the rear behind the joint, making sure you don’t have any interference from the joint. Then weld it all together and paint the hard to get places. It should look like this when done.







When installed, it should look like this.





Now it is time to weld the long plate to the frame.

Next is the links. The first thing is that whatever link you build, it will need to be adjustable. XJs aren’t entirely square, they can be a little out of adjustment. That is why they shim the lower links, to adjust the track. The classic question everyone asks is: How do I know long to make the links. The answer is that the bracket has to be in place first. They all you have to do is measure. You measure from the center of the eye on the lower link to the center of the bump stop, then subtract the distance from the center of the bump stop to the center of the eye on the lower link mount on the axel tube. That distance will have the lower spring mount centered when stuffed on to the bump stop as it was designed to be. The distance on mine is 32 Ό” So no to make the links. I bought a link kit from Parts Mike. Mike has really done his homework and come up with a line of products made for wheelers, since he is an old wheeler himself. Here is a finished link and the pieces next to it.



Make sure you leave about ½” of threads left so you can shorten it a little if you need to. When you get your first link done, mount it.

Next, you need to make your top link. It needs to be made a little different than the bottom. This link needs to have right and left hand threads so you can easily adjust your castor angle. If you have a custom axel in the front, you can just weld a couple of tabs on for another bushing or rod end. But if you have a standard D30 front end, it is a little more complicated. You have to come up with a good bushing for the standard hole. I have had trouble finding them. The rubber ones are not tough enough for a three link. So I made mine. I had a sleeve turned down from left over rod link tubing to fit the stock hole on the pumpkin. I then used a bushing from a Chevy K series front spring which just happens to fit the inside diameter of the DOM tubing. You can cut the bushings down with a hack saw to fit a standard 2” wide top link end, which I cannibalized from my last suspension. Otherwise you can build one from 1/4X2” flat bar.





After you have made the end, the link needs to be welded up. It has a spherical rod end on it with a left hand thread. The left hand is important, because the other end needs to be made with some 1 1/4X12 all thread. I guarantee you that you will not find any left hand thread in that size laying around. I got mine at a machine shop. It is a common farm thread. My finished length ended up at about 30 ½” after adjustment for castor angle.





When you have finished your top link, mount it, Remove your passenger side top link.
and adjust your castor angle. In an XJ it should be in the neighborhood of 5°





I used my Droid phone, which has an app for a level. I just put it on the top of the upper ball joint and adjusted the axle to 6°


Now it is time to move to the passenger side of the vehicle. You already have a plate 16” long drilled for the cross member bolts. Now you need to make a decision. If you want a 4 link front, then you need to repeat the steps already mentioned and make a mirror image of the bracket on the driver side. If instead you are satisfied with as three link, as I am then you just need to cut two pieces of steel, one 1/4X6X2.5” for the inner part of the bottom link bracket and one the same size as the outer part of the lower link bracket and drill the same holes in the same places and weld these brackets in the same places as the other side. I elected to reuse the brackets I made with these relative dimensions that I used for my Y link that was on before.

Now it is time for the cross member. In the previous part of this build, it was neglected for a reason. I elected to have a removable cross member that can be removed without dismantling my suspension and future skid plates that I can remove also for service and repair without affecting my suspension. So the cross member will bolt in between the two brackets that have been welded in place. Remember the little piece of 1/4X26” flat bar that was drilled to fit the driver side bracket? We haven’t used it yet, but now is the time. It is welded to one end of the cross member that needs to be drilled for the transmission mount in the same position as the stock cross member. If you have a three link as I do, then you need to make another flat plate the same size or out of 1/4X2 1/2X6” flat bar for the other end. The difference is that this one has to have a hole large enough to clear the nut for the bolt for the passenger side lower link.



If you have any clearance issues for things like exhaust pipes, such as my 3” exhaust, now is the time to account for that in the new cross member. Welded up, it looks like this.







Installed, it turned out like this.







That completes the three link suspension. I did not address the track bar. I fabbed my own with the same rod ends used for the suspension build. One of the nice things about this type of situation with a double shear track bar is that you can tune your suspension by changing springs in about 20 minutes if you have air tools. Also, the three link puts less strain on the links, bushings and frame than a four link.
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On board air
Warn 9.5ti on custom bumper
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