We Build, And Beat, A '96 Bronco 4x4
The '80-'96 Ford Twin-Traction Beam (TTB) front suspension uses a swing arm design that's become the foundation for thousands of long-travel four-wheel-drive suspensions over the years. Ford's TTB suspension benefits from a simple robust design that requires only four pivot points, as opposed to six on a typical leaf-sprung front axle, eight on an IFS GM truck, and ten on a four-link Dodge frontend.
Why It Works So Well
The Ford TTB axle beams are mounted to a massive engine crossmember and pivot on two rubber bushings near the center of the frame. A pair of radius arms locate the axle beams front-to-rear, and are tied to the frame with bayonet-style bushings that allow almost unlimited rotation. Due to the length of the TTB axle beams, it's possible to get double-digit suspension travel numbers from the Ford system - if you add the right parts.
16 Inches Of Travel
John Ehmke's Autofab is based in Santee, California, smack-dab in the heart of the off-road racing community. Autofab has been building off-road parts for more than 30 years, and when it comes to long-travel TTB suspensions its 16-inch front wheel travel kit is elegantly simple, and brutally effective.
To install the Autofab kit on our '96 Ford Bronco we began by hoisting the truck up on a friend's lift and removing the stock suspension in order to bolt on the Autofab coil buckets, radius arms, and modified axle beams. The only difficult part was removing the rivets Ford used in these frames. We did so to bolt the Autofab pieces on with Grade 8 hardware.
18-Inch Travel 2-Link
Then we took the Bronco home and mounted a set of Deaver Spring's J40 rear leaf springs. We chose the 3-inch wide J40 spring packs instead of using 2.5-inch wide F-150 springs because we were going to ditch the rear sway bar, and the extra spring width will help with sway control.
When the leaf springs were mounted we bolted Autofab's two-link traction bar system onto its reinforced frame brackets, and a friend welded the two-link mounting tabs to our rear 8.8-inch rear axle.
To finish off the new suspension we added a set of 2.5-inch diameter Sway-A-Way Race Runner shocks (10-inch travel in the front and 12-inch travel in the rear) with remote reservoirs. To play it safe we plumbed the brakes with a set of extended-length DOT-legal brake lines from Superlift.
We'd still like to add some limit straps and do some bumpstop tuning, but overall the suspension has proven to be far more forgiving over the big bumps and ruts. The 35-inch tall tires have made some minor contact with the front bumper and inner wheelwells. Which is probably why Autofab recommends 33-inch tires mounted on the factory forged wheels in order to take advantage of all 16-inches of travel. We'll keep pushing our luck with the 35s, and save our money for a set of Autofab's Ashley-style fiberglass fenders.