Yukon Gear Master Overhaul Kit For Dana 70-U Diff

The Dana 70-U is the single-rear-wheel version of the Dana 70 full-float rear axle, and it hides under a lot of hard-working trucks: Ford, GM and Dodge all used it from the 1980s on, and second-generation Dodge Ram 2500s with the Cummins diesel or the V10 and an automatic carry it almost without exception. When one of these rear ends develops a rising howl on the highway, a rumble under load while towing, or a wet pinion seal, the fix that lasts is new bearings, races and seals set up correctly. The Yukon Gear & Axle YK D70-U master overhaul kit is the parts set for that job on the 70-U specifically.

What this kit does in a Dana 70-U

The 70-U is not just a Dana 70 with a different tag. It uses a smaller pinion bearing than the heavier 70HD, which is exactly why a generic Dana 70 bearing kit can leave you holding the wrong pinion bearing on assembly day. The 10.5 in. ring gear and pinion are held in mesh by two tapered pinion bearings and two carrier side bearings, and their preload and the shim stack behind them decide pinion depth and backlash. Yukon packs this kit with Timken carrier and pinion bearings and races, the pinion seal, a complete shim kit, ring gear bolts, a new pinion nut, oil baffles and slingers, thread locker, gear marking compound with a brush, and a cover gasket. There is no crush sleeve in the parts list, so pinion preload on this axle is set with shims rather than by crushing a collapsible spacer.

Symptoms that point to a 70-U overhaul

• A whine or howl that changes pitch between acceleration and coast, usually a sign of worn pinion bearings letting the gear pattern move
• A low growl or rumble that stays steady with speed, more typical of a pitted carrier bearing
• Clunk on take-off or excess play when you rock the yoke by hand
• Gear oil weeping from the pinion seal or the cover, often after the seal lip has worn a groove in the yoke
• Metal paste on the drain plug magnet or a glittery look to the drained oil

How to confirm it before you buy

Pull the cover and look at the ring gear teeth and the oil. Bearing noise with clean, unchipped gear teeth is the ideal case for this kit, because the original gears can go back in. If teeth are chipped or scored, plan a new ring and pinion at the same time. On a full-float axle, also spin each hub with the shaft out: a rough wheel bearing can sound like a differential problem and is a separate repair. Since the 70-U often lives behind a diesel automatic, rule out transmission and driveline noise by checking whether the sound follows road speed rather than engine speed.

Fitment

This kit fits the Dana Spicer 70-U rear differential. Dana 70 axles share a similar 10-bolt cover with the Dana 60, so identify the axle from the tag on the tube or the numbers cast into the housing before you order. A 70-U is a single-rear-wheel axle with a 7,500 lb gross axle rating and usually 32-spline shafts; if your housing is a 70HD, a Dana 80 or a Super 70, it takes a different kit. If you are unsure, send us your year and VIN and we will check it. Compare other heavy-duty axle kits in our rebuild kits collection, including the Dana 60 and 61 rear overhaul kit if the tag turns out to read 60.

Install notes

• Use a housing spreader to remove and install the carrier, and never spread the housing more than needed to clear the bearings
• Press bearings and races with proper drivers; a bearing race and seal driver set saves the new races from hammer marks
• Start with the original pinion shim as a baseline, then confirm depth and backlash with the marking compound in the kit
• Torque the pinion nut to spec and check rotating preload with an inch-pound wrench before installing the carrier
• Inspect the yoke sealing surface; a grooved yoke will chew up the new seal, so replace it with a Dana 70 companion flange if needed
• If the factory Powr-Lok limited slip chatters, rebuild it while the carrier is out with the Power Lok clutch set
• Refill with the gear oil grade your owner's manual specifies, adding friction modifier if the axle has a clutch-type limited slip

Will this kit fit the rear axle in my 1998 Ram 2500 diesel?

Second-generation Ram 2500s with the Cummins or V10 and an automatic used the Dana 70-U, so it is the expected axle. Confirm it from the tag on the axle tube or send us your VIN before ordering, because other configurations of the same trucks can carry a different Dana axle.

What is the difference between a Dana 70-U and a Dana 70HD?

The 70-U uses a smaller pinion bearing and is a single-rear-wheel axle rated at 7,500 lb. The 70HD has a larger pinion bearing, so the bearing kits are not interchangeable.

Does this kit include a crush sleeve?

No. The kit contains Timken carrier and pinion bearings and races, a complete shim kit, pinion seal, pinion nut, ring gear bolts, oil baffles and slingers, thread locker, marking compound and a gasket. Pinion preload is set with shims.

Can I reuse my original ring and pinion?

Yes, if the teeth show no chips, pitting or scoring. Keep the original pinion shim as your starting point and check the pattern before final assembly.

Are axle shaft bearings and seals included?

No. The 70-U is a full-float axle, so the wheel bearings ride in the hubs and are serviced separately from this differential kit.