The Dynatrac Free-Spin hub conversion kit, SKU FO60-3X1104-I, replaces the factory unit bearings on 1999-2004 Ford F-250 and F-350 Super Duty 4x4 trucks with a fixed-spindle setup. It combines heat-treated chromoly spindles, serviceable Timken bearings and seals, and 35-spline, 1.50-inch outer axle shafts with DynaLoc locking hubs. Installation is bolt-on, with no machining or welding, and Dynatrac states the kits are made in the USA.
Why convert away from unit bearings
A factory unit bearing is a sealed assembly. Dynatrac describes it as non-serviceable, impossible to inspect, and prone to failure, so when it goes bad the entire unit is replaced. The Free-Spin conversion changes the front end to a conventional spindle with separate inner and outer tapered roller bearings, races, and a hub seal, so you can pull the hub, inspect the bearings, repack them, and replace only what is worn. Dynatrac lists a smoother ride, better fuel economy, and longer axle life as benefits of the design. Those are manufacturer claims, and results depend on the truck, tires, and driving.
What is in the kit
- Heat-treated chromoly spindles
- Cast nodular wheel hubs (8-on-170mm)
- Serviceable Timken bearings, races, and seals
- 35-spline, 1.50-inch outer axle shafts
- DynaLoc manual locking hubs
- Wheel studs and mounting hardware
- ABS tone rings and sensor mount
DynaLoc locking hubs
This kit uses Dynatrac's own DynaLoc manual locking hubs in place of the Warn Premium hub. Dynatrac says DynaLoc offers improved locking function, more strength, and a shorter profile, and that its short, custom-machined bezel gives the shortest hub stickout in the Free-Spin line, so the hub sits further inside the wheel and tire package and is less likely to be hit on the trail. Like any manual hub, you set it to lock for four-wheel drive and to free for the street.
Fitment for 1999-2004 Ford Super Duty
This version is for 1999-2004 Super Duty trucks running coarse wheel studs (14mm x 2.0 coarse-thread). Check your truck's studs before ordering, because Dynatrac sells a separate kit for each thread. The other thread is DT FO60-3X1104-H (fine studs, DynaLoc hubs).
The 8-on-170mm hubs reuse your existing brake rotor, and ABS tone rings and a sensor mount keep the factory ABS sensors in service. Dual rear wheel trucks in this year range need a separate dually wheel adapter from Arrowcraft (248-280-0210), which is made to work with Dynatrac's Free-Spin kit.
Service parts are easy to find
Dynatrac says every Free-Spin kit uses K30 bearings and seals, so replacements come from ordinary bearing suppliers. The common wear items are the Timken 387A inner bearing with 382A race, the Timken LM104949 outer bearing with LM104911 race, and the Timken 475960 hub seal. The spindle hardware is a Spicer 33732 six-point nut and 33733 washer, and the axle-end parts are the Spicer 700014 spindle needle bearing, 44506 thrust washer and seal combo, and 50381 boot seal.
Before you order
- Confirm the truck is a 1999-2004 Ford F-250 or F-350 Super Duty 4x4 and that your model year falls inside that range.
- While the knuckles are apart, it is a sensible time to replace the axle u-joints and ball joints. One owner-written install by two people, ball joints included, took just under nine hours.
- Dynatrac backs the kit with a one-year, unlimited-mileage written warranty.
- If anything about your truck's year, axle, or wheels is unclear, contact Skinny Pedal Racing with your model year and cab and chassis type before ordering.
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