Chrysler 7.25 Differential Master Overhaul Kit Yukon YK C7.25

The Chrysler 7.25 in. rear end sits under a long list of Mopar cars, from 1960s Darts, Valiants and Belvederes through Dusters, Chargers and Coronets, the late-model M-body Diplomat and Fifth Avenue, and the 1987-1998 Dodge Dakota. When one of these axles starts to whine at highway speed, growls louder as the car picks up speed, or leaves gear oil dripping off the pinion yoke, the bearings are worn out. The Yukon Gear and Axle YK C7.25 master overhaul kit replaces every bearing and race in the center section with Timken parts, so the axle can be rebuilt or re-geared in one pass.

What the master overhaul kit does in a Chrysler 7.25

The 7.25 is an integral-carrier axle serviced through a rear cover. The pinion rides on an inner and an outer tapered roller bearing, with preload set by a collapsible crush sleeve and depth set by a shim under the inner bearing. The carrier rides on two tapered side bearings held by caps, and like the larger Chrysler 8.25 and 9.25, it uses threaded side adjusters to set backlash and carrier preload instead of a stack of side shims. That makes the bearings the parts that decide whether the gears mesh quietly. Once they wear, the pinion moves under load and the contact pattern wanders.

Yukon lists these contents for the YK C7.25:

• Timken carrier bearings and races
• Timken inner and outer pinion bearings and races
• Pinion seal, pinion nut and a new crush sleeve
• Complete shim kit and ring gear bolts
• Thread locker, gear marking compound with brush, and silicone for the cover

Symptoms of worn 7.25 bearings

• A whine that changes pitch between throttle and coast, usually pinion bearings
• A steady rumble that rises with road speed and stays the same in turns, typical of carrier bearings
• Clunk when getting on and off the gas from a pinion that has lost preload
• Oil weeping from the pinion seal or wetting the front of the housing
• Bronze or steel glitter in the old oil when the cover comes off

How to confirm before ordering

Jack the rear up, put the transmission in neutral and rock the pinion yoke up, down, in and out. Any free play means the pinion bearings and crush sleeve are done. Spin a wheel and listen at the housing; a rough, gritty feel points to carrier bearings, while a noise that changes when the car swerves is more often an axle bearing at the wheel end, which this kit does not cover. Pull the cover and check the ring gear for chipped or pitted teeth before you commit, since damaged gears should be replaced along with the bearings. Our whine diagnosis guide and pinion bearing noise guide walk through the road test.

Fitment

Yukon's fitment chart for this kit covers the 7.25 rear in 1963-1971 Belvedere, 1965-1976 Coronet, 1966-1978 Charger and Fury, 1965-1978 Monaco, 1970-1974 Challenger, 1970-1976 Duster, the Dart across most of 1966-1976, 1977-1989 Diplomat, 1977-1982 New Yorker, 1981-1983 Imperial and 1983-1989 Fifth Avenue. It also lists the 1987-1998 Dakota 7.25 rear and the 1987-1996 Dakota 4WD 7.25 front. Plenty of these cars left the factory with an 8.25 or 8.75 instead, and many have had axles swapped since, so confirm the ring gear size before ordering. If yours turns out to be an 8.25, the Yukon 1976-2004 Chrysler 8.25 overhaul kit is the match. Send us the year, model and VIN, or the numbers off the old bearings, and we will check it for you. More kits are in our rebuild kits collection.

Install notes

• Mark the bearing caps and count the adjuster turns on teardown so you have a starting point.
• Press the carrier bearings off with a bearing separator and puller set; prying them off risks the journals.
• Yukon's setup chart for the Chrysler 7-1/4 in. lists 12-14 in-lb of pinion preload with new bearings (6-7 in-lb reusing old ones), 0.006-0.010 in. backlash, 55 ft-lb on the ring gear bolts and 50 ft-lb on the caps.
• Tighten the pinion nut in small steps and check turning torque with an inch-pound torque wrench. If you overshoot, fit a new crush sleeve rather than backing the nut off.
• Read backlash with a dial indicator and magnetic base, then confirm the pattern with the marking compound in the kit.
• Seal the cover with the supplied silicone and fill with GL-5 hypoid gear oil; add friction modifier if the axle has a clutch-type Sure-Grip.

Will this kit fit my Dodge Dakota?

Yukon lists it for the 7.25 in. rear on 1987-1998 Dakotas and the 7.25 in. front on 1987-1996 Dakota 4WD. Some Dakotas came with an 8.25 rear instead, so check the ring gear size or send us your VIN before ordering.

Does the YK C7.25 come with a cover gasket?

Yukon lists silicone for sealing the cover rather than a formed gasket, along with the bearings, races, pinion seal, crush sleeve, pinion nut, shims, ring gear bolts, thread locker and marking compound.

Can I reuse my old gears with this kit?

Yes, if the teeth are not chipped, pitted or blued. Run a pattern before teardown, keep the original pinion shim as a starting point, and reset backlash to the old setting. Worn or noisy gears should be replaced at the same time.

How do I tell a 7.25 from an 8.25?

Measure the ring gear or look up the axle by VIN. Many classic Mopars were built with more than one axle option, and swaps are common, so the car model alone does not prove which one you have.

Does this kit fix noise from the wheel ends?

No. It covers the center section only. A noise that changes when you swerve or load one side is usually an axle shaft bearing, which is a separate part.

What gear oil goes in after the rebuild?

A GL-5 hypoid gear oil in the weight your service manual lists, plus friction modifier if you have a clutch-type limited slip. Change it after the first few hundred miles to flush out break-in wear.