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Bronco Bolt-On Suspension

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Craig Perronne
| Brand Manager, Dirt Sports & Off Road
Posted July 1, 2000

James Duff Goes Long Travel

Step By Step

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  • Here is the stock front suspension before surgery. The main travel-limiting factors are the puny shocks, old-school coils, and short radius arms. The Duff kit changes all this.

  • The original factory piece is used to attach the head unit to the axle. We also opted to replace all of our wasted bushings with new polyurethane units from James Duff.

  • The rears of the radius arms attach to the frame using a beefy mount and massive rod end that allows for even more flex. We chose to weld the mounts to save time, but they can be bolted to the frame.

  • We were so excited about the new radius arms that we had to put them on first. They are 11 inches longer than the stock arms and are ultra-stout with a 3/8-inch-thick wall. The aft end has a solid rod that has been machined to accept a giant rod end. Ours were prototypes (as was the rest of the kit) that were cut and welded to make the bend for tire clearance. Future arms will be bent with a heavy-duty bender, eliminating the cut and weld process.

  • The new radius arms are actually a two-piece design with the arms sliding into a head unit that attaches to the axle with C-bushings. By using two bushings at the front of the radius arms, the two-piece design helps to eliminate some of the binding of the stock radius arms during articulation, thus giving extra flex.

  • Our original 3-inch lift coils were replaced with new ones from James Duff. The new coils supply 3-1/2 inches of lift, but are also taller than the originals because they are softer and flexier.

  • To make room for the James Duff Stage II shock hoops, the old factory shock mounts have to come off. We found the best technique was to use a torch, but a grinder can be used.

  • We were even able to coax ORU assistant manager Steve Deitsch out of his air-conditioned office to give us a hand putting shocks on, and he was more than happy to help. The front uses two super-long, 15-inch-travel James Duff 70/30 Auto Adjust shocks per corner to give a massive increase in articulation.

  • A track bar drop bracket is a necessity. The James Duff bracket bolts onto the original bracket so it is a good idea to check the condition of the original. Ours needed a few welds and we then added a small bead to the sides and top of the new bracket for safety.

  • Once we finished the front, we shifted our attention to the rear of the Bronco. Short shocks and a bad traction bar design seriously limited articulation out back.

  • The first pieces to go on the back were the new upper shock mounts. Our Bronco already had a 2-inch body lift so only slight trimming of the body seam was necessary. Once again we welded the piece, but it can bolt on.

  • To finish off the rear, we used 11-leaf, 3-1/2-inch lift springs from James Duff, which are made to give lots of articulation and handle some extra weight. In this finished shot, you can also see how the 12-inch-travel 70/30 Auto Adjust shocks are positioned. The only pieces that actually need to be welded on are the lower shock mounts.

  • On our first testdrive of the Bronco we experienced some bumpsteer. A dropped Pitman arm solved this problem. James Duff doesn’t include them in the kits because of so many variations (power steering conversions, tie-rod over conversions, and so on), but an easy way to tell if you need one is if your track bar isn’t parallel with your drag link.

  • The last step was to install a set of new James Duff Urethane fender flares. Our original ones were hard fiberglass units that were destroyed from trail usage. The urethane units are flexible and will take more of a beating. We suspect with this much backspacing and articulation that we might have to trim the rear fenders all the way up to body line.

If you are an Early Bronco fan then you know one thing—in stock form, your suspension sucks. Short shocks and radius arms seriously hamper efforts to get articulation. Older coil designs give a tank-like ride and zero flex. To make things even worse, no one has yet to offer a complete system that gives loads of articulation. This had made those folks who actually use their Broncos go through the headache-ridden process of custom suspension building that often resulted in ill-working suspensions.

Many Bronco owners have dreamed of a suspension that is easy to install and gives massive gains in articulation. That dream has become reality with the introduction of the James Duff Long Travel System for ’66-’77 Broncos. The new system combines the company’s Stage II Ultimate Suspension System with its new Stage III radius arms, and replaces every old suspension component on your pony with new ones that have been designed with maximum articulation and performance in mind.

We were lucky enough to get our hands on a prototype kit to give you an early sneak peek at what the system (which should be available by the time you read this) is capable of. The folks at James Duff informed us that the kit will be very similar in its final form to what you see here. We took the new parts and our old Bronco down to Off Road Unlimited (ORU) to install the system. We found the installation time-consuming, but not technically difficult.

With a deadline looming, we only had time for a quick trail run, but the increase in articulation and suspension performance was amazing. Of course, this newfound suspension flex also transformed our Bronco into an extremely capable trail rig. It walked through sections that were previously impassable.

The Bronco was very stable when crossed up, which we attribute to its equal amounts of articulation front and rear. A quick run up a 23-degree RTI ramp also confirmed the extra flexiness of the suspension. In stock form, the Bronco managed only a pathetic 380, but with the new James Duff system it ramped a very respectable 900 with the same wheels and tires. We suspect the Bronco will easily do 1,100 as our original tire and wheel package rubbed the new shock hoops because of wheels with 4 inches of backspacing.

Equally as impressive was on-road handling, where the Bronco could be driven with confidence and ease. This is in stark contrast to other high-travel trail rigs we have driven on-road, which usually have loads of body roll and spooky steering habits. If you are looking for an easy-to-install suspension for your Bronco—one that gives loads of articulation and can still easily be driven on the highway—then this is it!


James Duff Enterprises
Knoxville, TN 37921
Off Road Unlimited
4 Wheel Parts Wholesalers