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Ford Bronco TTB Axle Gears - Gearing Up For Adventure

Posted in How To: Transmission Drivetrain on September 1, 2009
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The venerable Ford Bronco, a true icon in the American wheeling landscape, has been out of production for--get this--13 years. It seems like yesterday that you could walk down to the local Ford dealership and pick up a fullsize Bronco, in white for those more daring trips. From 1980 to 1996, the Bronco came standard with the notorious, yet rugged Twin-Traction Beam TTB front suspension.

Ford's TTB suspension was a mainstay of 1/2-ton Ford four-wheel drive system for years, and underpins the front of countless vehicles. TTB trucks are plentiful, robust, and are still the choice of enthusiasts who require the unique qualities of TTB suspension. Roll that into the fact that Broncos are as affordable as shares in GM, and as plentiful as excess vehicle inventory on your local dealer lot, and we are seeing them reemerge on the scene again, repurposed in the hands of enthusiasts.

1. We decided to go with the Eaton Truetrac for the front differential to compliment the Eaton Detroit Locker that was already in the rear diff. The Truetrac is an excellent, helical-style limited slip that won't wear out over its service life and requires no maintenance. It is fully automatic and offers smooth operation. Keep in mind there is a case split for the diff, with two different part numbers for this application.

Despite either a 5.0L or 5.8L V-8 powering these vehicles, any increase in tire size will necessitate a gear swap to get the most from the power available. The owner of this Bronco originally had 31-inch tires on 15x8-inch wheels with 3.55:1 gears. We decided that Superior 4.56:1 gears would be perfect for what he was trying to achieve with this Bronco and would be a good match for the 35-inch BFGoodrich All-Terrain T/A tires mounted on 16x8 ProComp Series 1028 polished wheels.

This particular vehicle already had an Eaton Detroit Locker in the rear, and the owner was looking forward to some high-speed driving through the desert with the occasional technical crawl. For this type of driving, we are big fans of being set up with a rear locker matched with a limited-slip front. Eaton's Truetrac helical gear differential fit the bill for our needs. The Truetrac, which provides predictable steering control at high speed without the quirky handling characteristics of a front locker, also provides enough traction to easily get over all but the hardest obstacles.

To lube up our new components, Amsoil offered up its Severe Gear Extreme Pressure synthetic gear lubricant. Severe Gear is engineered for severe duty applications, such as extreme wheeling and towing in harsh conditions and is said to inhibit corrosion, extend seal life, and offer improved efficiency, all while reducing operating temperatures.

Check out the overview of our installation on this special long-travel Bronco below.

PhotosView Slideshow


Van Nuys, CA 91402
Superior, WI 54880
Jeff's Bronco Graveyard
Brighton, MI 48116
Pro Comp
Compton, CA 90220
Off Road Evolution
Fullerton, CA 92833
Superior Axle and Gear
4 Wheel Parts Wholesalers
Eaton Performance / Detroit Locker

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