4x4Review Off Road Magazine
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Our FJ40’s 11 year life span as a product test mule has officially ended. We celebrated its life with a few cold libations, said a few words and then threw some dirt on it memorializing its past existence. Its days of having hundreds of goodies bolted and welded to it have finally come to an end. Just moments after our eulogy, it was reborn as a would-be hard-core, dedicated trail rig,
 ready to be stretched to a new wheel base with a 4-link suspension.  We needed something that would hold up to our 400+ HP fuelie motor that was recently transplanted, give us awesome articulation, better stability and a better departure angle. Sure, we could have done the math and built our own 4-link, but frankly I don’t have time or the cash and besides, Project In Too Deep (the little, green CJ5) is currently being converted to a custom home-grown 4-link so this will make for a great compare-and-contrast when it’s all said and done. While our FJ-40 will never be truly finished, we are fairly confident that the rear suspension will live out the rest of its years in its new configuration.The four-link suspension is arguably the best of all worlds whether it is for hot rods, drag racers and certainly 4×4’s. For the 4-wheel drive enthusiast, it offers unparalleled suspension articulation, little to no axle wrap, if done correctly and needed adjustability as it relates to axle alignment and caster too. What’s more, it can be configured with several types of springs – air bags, coil-over shocks, air springs, and in our case coil springs with shock absorbers. So what’s better than a 4-link suspension you might ask? A kit-form 4-link that you can install yourself – here’s why; 1) You don’t have to do all of the math and risk setting up the geometry all wrong – wasting time and money, getting flex-steer, incorrect anti-squat When I made the decision to convert from leaf springs to a 4-link, I knew there was only one company I could trust to provide the best 4-link do-it-yourself kit, and that’s Proffitt’s Cruisers in Austin, Colorado. Jeremiah Proffitt and his crew are Land Cruiser geniuses and the undisputed champions when it comes to building custom Land Cruisers and making top shelf products. Moreover, their products are well engineered and affordable – a combination that we are all looking for.
Proffitt’s 4-Link Coil Spring Conversion KitProffitt’s Cruisers has two 4-link kits available for your FJ40; a bracket-only kit, and a full 4-link kit. The bracket-only kit comes with all of the necessary brackets for the frame and axle, plus an axle truss, heim joints, bushing rod-ends, threaded inserts, and full instructions. You provide the DOM tubing for the links, but you can also add lower coil over shock mounts or their complete spring bucket system for coil springs for an extra few bucks. Proffitt’s offers custom quarter elliptic spring capture tubes as well. We chose the full 4-link kit for our project as we have a custom-built Ford 9” rear axle, and we wanted to stretch our wheelbase further than most, pushing the back of the rear tire to be nearly even with the back of the body. With the full Proffitt’s Cruisers 4-link kit, you get all of the items mentioned above, plus all 4 links are pre-made for your specified wheel base.
InstallationAs with any project, take stock of the parts you have and the parts you need. Our Proffitt’s kit came with all of the weld-on / bolt-on parts that we needed, including bushings, heim joints, tabs, spring buckets, nuts, bolts and more. This is a VERY good 4-link kit and the craftsmanship is top-shelf.
Next, we needed to remove the rear suspension (leaf springs, spring hangers, etc.). Our FJ’s rear suspension (aside from the lift) is in stock form – meaning that the spring is under the axle. Secure the axle with jackstands (use three of them – two under the axle tubes and one under the pinion). Be sure your vehicle is secure! You will be wrenching on it and laying underneath it quite a bit. Now, begin disconnecting the driveshaft, emergency brake cable and brake lines. Lastly, remove the U-Bolts that hold the leaf spring to the axle. |
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Note: This is a time-consuming job and is not recommended for the novice. Experienced welding skills are needed.
We started our project by disconnecting the battery and lifting the vehicle on jack stands, securely on the frame rails.  Now you can begin removing the leaf springs. We prefer to remove them from the shackle-side first. Have a friend hold the axle on the jack stands to keep it from rotating and carefully remove the shackle bolt on one leaf spring. Slowly rotate the leaf spring towards the ground and repeat on the other side. Next, remove the leaf springs from the vehicle by removing the bolts on the spring hangers. Discard or sell – you won’t need these anymore. |
 At this point, you can either remove the axle from the jack stands to get it out of the way, or you can cover it up. |
| With the axle and leaf springs out of the way, you can begin removing the spring hangers and shackle hangers from the frame. This can be an all-day chore, even with plasma cutters, grinders and such. Take your time and do it right. Spray some paint on the freshly ground steel to prevent rusting. |
| Our next step will be different than most. We have a custom-built Ford 9” rear axle and we decided to build a custom box-style truss to mount our upper links to. Here are a few pictures of the fully bulk-headed truss that we built. At this point, you will also want to cut / grind off all of the original spring perches (the flat parts that the leaf springs bolt to) |
 Once your axle is prepared, it is time to put the axle back under your vehicle and secure it with three jack stands again. We found that by putting a little grease on the pad of the jack stand that it is easier to move the axle around a bit. Here’s where you will need a LOT of patience and a second set of hands; You will need to get your axle centered perfectly left-to-right and completely square to the vehicle. You can adjust this a little bit with the 4-link kit, but you are far better off getting your axle completely square to begin with. At this point you also need to set your new pinion angle – again, it can be adjusted a small amount, but get it right the first time. If you are using a CV style drive shaft (like we have), then the pinion must point directly at your T-case output and be within 1-2 degrees of this imaginary line. |
   Once you have your axle centered, square and you have the pinion angle set appropriately, you can now begin to set and tack-weld the 4-link brackets in place on both the frame and the axle. Begin by balancing the aft section of the upper link-ends on top of the axle truss, then placing the forward link-end bracket on the frame and tack welding it into place. I did this part by myself, but it was a complete nightmare even with copious use of clamps – a second set of hands will be greatly appreciated and well worth the extra 6-pack that you’ll have to buy. |
We started by tack welding the upper links on the frame side into place first. Then we tacked the rear upper link end tabs onto the axle truss. Be sure that the bolts on the axle-side of the 4-link (the rear) point inward. Otherwise, you’ll never get them out again as there won’t be enough room in between the heim joints. You will probably end up busting the tack welds loose a few times to realign things, so have your right-angle grinder and welder handy at all times.
 With the upper 4-links tacked into place (heavy tack welds) and everything aligned and in appropriate locations you can now move onto the lower links. We started by tack-welding the axle-side lower link brackets to the axle, with the heim joint, spacers and bolts all in place (this assures better alignment). |
 Next, you can swing the lower link arms and link-end bracket up to the frame for tack welding. You will need to cut a hole into the side of your outer frame rail for the brackets to fit onto your frame. Here a plasma cutter will save hours of work, so if you don’t have one, borrow one or rent one. A grinder could be used, but you will be blowing black boogers out of your nose for a month. |
 Prior to welding the lower-link brackets to the frame, grind away all paint and rust to ensure a good weld. Then place a few well-positioned (but easily ground off) heavy tack welds into place. |
    Before you do anything else, measure, measure, measure, measure, measure! Then re-measure 4 or 5 more times. Once you think you’re all set, measure it one more time to be absolutely sure. Make sure your axle’s pinion angle is correct, it is square to the frame (assuming your frame is straight), and is located exactly where and how you want it. Once you lay in all of your welds, there is almost no going back. In case you didn’t get our point… double and triple check all of your measurements before final welding. Here are a few pictures of what your upper and lower links will look like with the Proffitts Cruiser’s 4-Link suspension kit. |
  Next, assuming all of your measurements are good and your axle is set correctly, you can now determine where your upper and lower spring buckets will be placed. The Proffitt’s kit is designed to be mounted to a cross member on the frame. We chose to re-use the stock cross-member that held the original shock absorbers. To do this, we ground off and blasted out those dreaded FJ40 rivets. You can then reposition the cross member directly over the centerline of your axle and tack weld into place. |
  With the cross-member in place, you can now position and tack weld your lower spring buckets onto the axle (assuming you are going to use coil springs). |
  The upper spring buckets will require a bit of work and re-work. You will need to trim the length of the bump-stop tube to the appropriate length. To do this, you will need to articulate the suspension (or be very good with a tape measure – we chose the former to be safe) and see how much clearance you need before your tire hits the body (or binds the drive shaft). |
| With this measurement, you then need to cut and notch the bump stop tube, slide the upper spring bucket over it, and then tack weld it to the frame and cross member. |
| Next, lower your axle enough to place your coil springs into place. NOTE: you will need to source a set of coil springs on your own. There are too many variations of weight between FJ’s and Proffitt’s does not supply them. We found that a set of Ford Winstar minivan coil springs seemed to have the right compression rates for our FJ, and we cut them to the appropriate height. |
| At this point, check again for alignment of the axle and make sure that everything looks in order – do not skimp here; check and recheck all of your work 4 or 5 times over. If all is well, remove the coil springs and lay in some small stitch welds on all of your brackets for your 4-links, upper coil buckets and lower coil buckets. Double-check all of your work again. |
| Next, using a heavy-duty ratchet strap, secure your axle in its center-line and sling it under the cross–member. With this, you will be able to articulate your suspension quite effectively and check for binding and/or any problems that you might need to address. |
| If all is well and you’ve double and triple checked all of your measurements, you can now weld all of your brackets and tabs into place. Be sure you lay in REALLY good welds, as each of these brackets and tabs must support your axle and all of the horsepower that you send downstream from your engine. If you are not sure of your welding abilities, you can always tack weld everything and then have someone else burn in the final welds. |
 Once the axle is completely set in place, you can install your coil springs once again and secure them with the round plates supplied by Proffitt’s. We welded some tabs into place on these plates to act as spring-keepers. |
  Mount your shocks how you see fit. We found that we could use the repositioned cross member for our shocks once again, thus making this part of the installation pretty darned easy. |
| With your axle, springs and shocks in place you can now bolt your wheels back on the vehicle. Carefully jack the vehicle and remove all jack stands, then carefully lower it to the ground. You can now rock your rig back and forth vigorously like a wild-man if you’d like (we found this to be a rather proud moment, and I had to suppress walking like a Yeti after such barbaric movements). |
    If you’ve relocated your axle like we did (we stretched the wheelbase by nearly a foot), you will need to get a new rear drive-shaft made. We placed a call to our friends at Tom Wood’s and had them lengthen our existing driveshaft as well as replace the u-joints. Tom Wood’s makes the very best driveshafts, but they don’t cost an arm and a leg – they also ship very quickly too. |
| BEFORE you head off-road, you will need to cycle your suspension using an RTI ramp or fork lift. You will need to find out how far your axle can droop before your drive-shaft gets into a bind, and then subtract an inch or two from this. You WILL have to order a set of limiting straps and install them; otherwise you face a lot of trail-side wrenching as you will certainly blow out your drivehaft. |
| For us, the last remaining items are to double-check to make sure all bolts are tight, install some limiting straps, clean up our grinding and torching areas and apply a bit of pain to protect the surface. Then its off to the RTI ramp to see what this will do. |
| At this point your 4-link is now complete. Step back, admire your handiwork and get ready for the trails. |
The Verdict
The Proffitt’s FJ40 4-Link kit is exceptionally well engineered and crafted. They use high quality steel and all of the brackets are made to exacting standards. The components are also of very high quality, such as their Teflon-inserted Heim joints and poly bushings. The provided instructions are fairly detailed, considering that many FJ40’s aren’t exactly in OE form anymore, and any that are, won’t likely be installing a 4-link. That said, you will need to have a fair amount of fabrication experience to install a 4-link kit in your Cruiser.
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