Ford 7.5 Differential Rebuild Kit, Timken DRK315

If your Ranger, Bronco II, Aerostar or four- or six-cylinder Mustang has started to howl on deceleration, whine at a steady cruise, or weep gear oil from the front of the pumpkin, the Ford 7.5-inch rear axle is telling you its bearings are done. The Timken DRK315 is the standard bearing and seal kit for that axle: it puts new pinion bearings, new carrier bearings, a pinion seal, a crush sleeve and a pinion nut in one box, so the center section goes back together with nothing tired left inside.

What this kit does in a Ford 7.5 axle

The 7.5 is a small integral-carrier axle with a 7.5-inch ring gear, a 28-spline pinion and a 10-bolt cover. The pinion rides on two tapered roller bearings, a large head bearing behind the gear and a smaller tail bearing near the yoke, and a collapsible crush sleeve between them sets how hard those bearings are loaded. The differential case spins on two more tapered carrier bearings. Once any of those four start to pit, the gear mesh moves under load and you hear it. The DRK315 replaces all four bearings plus every single-use part on the pinion, and Timken adds marking compound, RTV and thread locker so you can check the pattern and seal the cover in the same job.

Symptoms that point to this kit

• Whine or howl that changes between acceleration and coast, usually loudest at highway speed (worn pinion bearings)
• A low rumble or growl that stays the same on and off the throttle (carrier bearings)
• Gear oil seeping from the pinion seal and slinging onto the driveshaft or crossmember
• Clunk or slack in the driveline caused by a loose pinion nut or collapsed preload
• Noise that came back after someone replaced only the pinion seal and reused the old crush sleeve

How to confirm it is the axle before you buy

Plenty of 7.5 owners chase a rear-end whine that turns out to be a tire, wheel bearing or transmission. Drive the truck at the speed where the noise is worst, then let off the throttle: a sound that changes or goes away when load comes off the pinion is classic pinion bearing wear. Pull the fill plug and look for glitter or bearing chunks on the plug magnet. Our guide on telling a bad transmission from a bad differential by sound walks through the road test, and the Ford 7.5 rear axle problems and rebuild cost guide covers what else fails in this axle.

Fitment

This kit fits the Ford 7.5-inch rear axle with a 28-spline pinion and standard ring gear rotation. That axle sits under 1983-2011 Rangers (Rangers with the 4.0L and late SuperCab 4x4 trucks mostly got the 8.8 instead), 1984-1990 Bronco II, 1985-1997 Aerostar and many 1979-2011 Mustangs without a V8. Do not order by vehicle alone. Read the axle tag held on by a cover bolt, or the axle code on the driver door label, and confirm the ring gear is 7.5 inches. Both axles use 10 cover bolts, so bolt count alone does not separate a 7.5 from an 8.8. If you have an 8.8, use the Ford 8.8 master overhaul kit instead. Browse every gear and axle part we carry in hard parts.

What is and is not in the box

Included: pinion head and tail bearings, both carrier bearings, pinion seal, pinion nut, crush sleeve, marking compound, RTV sealer and thread locker. Not included: pinion and carrier shims, ring gear bolts, cover gasket, axle seals and axle bearings. If you are changing ratio or your shims are damaged, step up to the Motive Gear Ford 7.5 master bearing kit or the Yukon Ford 7.5 master overhaul kit, which add the shim packs.

Install notes

• Measure pinion depth before teardown and reuse the original pinion shim if you keep the same gear set.
• Always use the new crush sleeve and pinion nut. Tighten in small steps and stop when rotating torque reaches 14-19 in-lb with new bearings; overshoot means another sleeve.
• Set backlash in the 0.011-0.016 inch range, then paint the ring gear with the supplied marking compound and read the pattern.
• Torque ring gear bolts and bearing cap bolts to 70-85 ft-lb, with thread locker on the ring gear bolts.
• Fill with hypoid gear oil, SAE 75W-80 or 80W-90; a full fill is about 5 pints. Traction-Lok units need friction modifier added.
• Inspect the yoke seal surface; a grooved yoke will eat the new seal, so replace it with a Ford 7.5 truck yoke if needed.

Does the Timken DRK315 fit my Ford 8.8 axle?

No. The DRK315 is built for the 7.5-inch ring gear axle with a 28-spline pinion. The 8.8 uses larger bearings and needs its own kit. Check the axle tag or door-label axle code before ordering, because both axles have a 10-bolt cover.

Are shims included?

No. Pinion and carrier shims, ring gear bolts, the cover gasket, axle seals and axle bearings are not included. If you reuse your original gear set, reuse the original shims. If you are changing gear ratio, a master kit with a shim pack is the better buy.

Can I reuse my old crush sleeve?

No. A crush sleeve deforms once to set pinion bearing preload. Reusing it, or tightening past spec and backing the nut off, is one of the most common reasons a rebuilt 7.5 whines again, which is why a new sleeve and nut are in this kit.

What gear oil and how much does a Ford 7.5 take?

Use hypoid gear lubricant, SAE 75W-80 or 80W-90. A full fill after a rebuild is about 5 pints. Limited-slip Traction-Lok axles need friction modifier added to the oil.

Will this kit stop my rear end from whining?

If the noise comes from worn pinion or carrier bearings, yes, once the bearings are installed with correct preload and the gear pattern is set. If the ring and pinion teeth themselves are pitted or chipped, new bearings will not quiet them and the gears need replacing too.