Pro Comp’s Long-Travel Suspension For TTB Ford Broncos And F-150sPosted in How To: Suspension Brakes on December 13, 2016
It’s always fun to read about lift kits being installed on brand-new 4x4s. But there’s a large number of readers who are starting out with rigs destined for weekend four-wheeling that are far less pristine and way less expensive than iron that’s just rolled off the showroom floor. We’re talking decades-old 4x4s with odometers that are on their third lap and stock suspensions that haven’t seen a mechanic’s wrench or grease gun in a quarter century. Rigs like these, which can be purchased for a couple thousand dollars, make excellent trail projects. Mid-’80s through mid-’90s Ford F-150s and Broncos are perfect examples of such finds.
The fullsize Broncos, which share the F-150’s platform and Twin-Traction Beam (TTB) suspension, are becoming especially popular because they are roomy and abundant, making them a very good candidate for anyone who wants to build a decent family trail rig on a limited budget.
Fit For The TrailOne of the key factors for making TTB Fords more adept at moderate levels of off-road driving is improving ground clearance. That’s done by stepping up tire size. The stock suspension can accommodate 32-inch tires, usually without fender-clearance issues, but the tire will rub on the radius arms. When 33s are run there’s minor fender issues under extreme suspension flex. That’s where upgrading the suspension comes into play.
A 4-inch suspension lift is ideal for TTB-era Fords that are going to be used primarily as a daily driver and weekend four-wheeler tackling light to medium off-road exploring of the desert, mountains, or backcountry. Such a lift allows the use of 33s without any clearance or rubbing issues—and one could run 35s with minor fender trimming.
Long-Travel BenefitsSome TTB suspension kits use drop brackets to lower the radius arms and the axle beams, while retaining the factory radius arms. A better solution for both ride comfort and trail performance is replacing the factory radius arms with longer and stronger versions.
The benefits of a long-travel TTB suspension is the longer radius arms increase suspension flex and increase ground clearance while improving the TTB’s strength and durability. Although such kits cost more than those that retain the factory radius arms, the improvement in overall suspension performance is worth the cost. That’s why we opted to slip Pro Comp Suspension’s Stage II (PN K4054B) suspension under our ’91 Bronco instead of a less expensive kit. The kit’s racing-influenced technology and engineering show in the tubular radius arms that are nearly 15 inches longer than the OE versions. Pro Comp’s radius arms are considerably stouter, too, so they could take the stress of extreme flexing during off-road excursions.
The kit comes with Pro Comp’s ES3000 shocks and an add-a-leaf or lift block for the rear suspension. For this truck, we didn’t want to use lift blocks and our old Bronco’s rear leafs have more than 200,000 miles on them so add-a-leafs aren’t going to give us the full 4 inches of lift. Our solution: replace the old springs with Pro Comp’s 4-inch leaf springs (PN 23211).
On The LiftDoing a TTB suspension upgrade can be done in your driveway, but it’s definitely not recommended. You really need a hoist to do the work. Better yet, have a shop that has a lift, air tools, and expertise handle the install, which is about a 12-14 hour job. We turned to Dunks Performance in Eugene, Oregon, to handle our installation.
The rear suspension is a piece of cake. The front, however, requires a lot of grinding and drilling to remove the factory TTB brackets in order to replace them with the new drop-down bracketry. The longer radius arms require relocating the rear hangers on the framerails. Pro Comp’s instructions are excellent, and the kit has all the hardware to do the job without interruption.
Our Eddie Bauer–model Bronco came with factory optional dual shocks in the front, which required ordering a second pair of ES3000 shocks. Installing the longer front coils and new shocks is pretty straightforward. Be forewarned that some of the nuts and bolts on a suspension this old are going to be buggers to get loose. Have plenty of penetrating lubricant and muscle handy!
Nonetheless, it’s all worth the effort when it’s done. The highway ride and handling of our Bronco is night and day better than it was before we started. The off-pavement performance is also remarkably better; the suspension flex gives our old Ford nearly 15 inches of front wheel travel, which is considerably more than the old girl had in stock form.
Now we are able to run 33-inch Pro Comp A/T Sport tires without fear of body clearance problems or rubbing on the radius arms when we need lock-to-lock turning ability. The taller tires have also given us another 2 inches of ground clearance. That’s a good combination to have for our mild- to moderate four-wheeling needs.
Should we want more lift down the road, the Pro Comp brackets are already set up to easily change to a 6-inch lift. All we need to do is drop the beam’s center ends to the lower bracket hole and swap in longer springs and shocks.
Trail Report: Pro Comp A/T Sport
The Pro Comp A/T Sport, which is the tire we chose to run on our Bronco, has a tread compound that is engineered to work across a wide spectrum of driving conditions. The grooves and siping are ideal for expelling water so the rubber stays in contact with wet road surfaces, while the more aggressive, staggered side lugs improve traction over rocks and softer terrain. The A/T Sport also uses alternating tread block sizes to help reduce tire-generated noise.
We have only put a few hundred miles on our LT305/70R16s as of this writing. Our initial impression is they are one of the quieter A/Ts on the market, and the grip on pavement and over rocky, sandy terrain is impressive. The highway ride is a little firm as one would expect from a load range E. But drop the air down for medium-type summer trail running and they seem to do well against chipping and cuts. The 60,000-mile treadwear warranty gives us confidence they will remain for a number of years to come. We’ll have a full review of the Pro Comp A/T Sport soon.