Yukon Gear 8.8in Ford 3.31 Rear Ring & Pinion Install Kit 2.25in OD Axle Bearings and Seals

A Ford 8.8 rear that howls at 55 mph, groans when you lift off the gas, or has chewed up its ring gear teeth is usually past the point where a seal and fresh gear oil will help. The Yukon Gear & Axle YGK2216 is a complete center-section and wheel-end package for the conventional 10-bolt-cover 8.8 found under Mustangs, F-150s, Rangers, Explorers and the Crown Victoria family. In one box you get a new 3.31 ring and pinion, a Yukon master install kit with Timken bearings, and a pair of 2.25 in. outside-diameter axle bearings with seals, so the whole axle gets done in a single teardown.

What this kit does in a Ford 8.8

The 8.8 is an integral-carrier axle: the ring and pinion live in the housing behind a bolt-on cover, the pinion rides on two tapered bearings held in preload by a crush sleeve, and the carrier rides on two side bearings that are positioned with shims. The ring and pinion fix the final drive ratio. At 3.31 the driveshaft turns 3.31 times per tire revolution, which is a highway-leaning ratio. It makes sense when you are replacing a worn set of the same ratio, or when the car or truck spends most of its life at cruise on stock-size tires. If you have gone up in tire size or tow heavy, a deeper set such as the Yukon 8.8 3.55 gear set or the 3.73 set is the better match.

Yukon specifies this 3.31 set for applications with a 10-bolt rear cover and a 10-bolt ring gear, and the inner pinion bearing in the kit has a 3.250 in. outside diameter. Because the C-clip axles have to come out to remove the carrier anyway, the kit also replaces the outer axle bearings and seals while you are there.

Symptoms that call for new gears and bearings

• Whine that rises and falls as you go on and off the throttle at a steady speed
• Howl only on deceleration, a sign the pinion bearings have loosened
• Low rumble that follows road speed, not engine speed, from worn carrier or axle bearings
• Chipped, pitted or scored ring gear teeth, or glitter and metal paste on the cover magnet
• Gear oil seeping at the axle ends onto the brake backing plates

How to confirm before you buy

Rule out the transmission first. A trans whine follows engine rpm and changes with each shift, while an axle whine follows road speed and changes between drive and coast. Our 4R70W noise diagnosis guide walks through separating the two on F-150 and Crown Victoria platforms. Then pull the cover, drain the oil, look at the teeth and check pinion play by rocking the yoke. Finally confirm your current ratio from the axle tag or by counting the ring and pinion teeth.

Fitment

This kit is for the standard 8.8 in. Ford rear axle with a 10-bolt cover. It is not for the 2015-and-later 12-bolt Super 8.8, and it is not for the reverse-rotation 8.8 used as an independent front differential. Two measurements decide whether it fits your housing:

• Axle bearing size: this kit uses 2.25 in. OD axle bearings. Ford Performance lists the 2.256 in. OD bearing for 1986-2004 Mustang solid 8.8 axles, while 2005-2014 Mustang GT and GT500 axles take a larger 2.53 in. OD bearing.
• Inner pinion bearing: the kit carries the 3.250 in. OD inner pinion bearing. Some later 8.8 axles, including certain 2006-up IRS cars and SUVs, are listed with a 3.544 in. OD bearing and need a different kit.

If you are unsure, measure the old axle bearing bore, read the axle code off the door tag, or send us your year and VIN before ordering. Browse more Ford 8.8 parts in differential rebuild kits.

Install notes

Setting up a ring and pinion takes a dial indicator, a pinion depth reference and patience. Set pinion depth with the shims, crush the sleeve slowly until rotating preload is in spec, then shim the carrier for backlash and side bearing preload and read the contact pattern with the marking compound. Use thread locker on the ring gear bolts. If your axle is a Traction-Lok limited slip, this is the time to refresh it with a Ford 8.8 Traction-Lok clutch kit and add friction modifier with the gear oil. Fill with the gear oil Ford specifies for your axle, drive gently for the first few hundred miles without towing, and change the oil early to flush out break-in wear. If you want to stop fighting the crush sleeve, a crush sleeve eliminator kit sets pinion preload with shims instead.

Will this kit fit my 2015 or newer F-150 or Mustang?

No. Those use the 12-bolt Super 8.8 with larger bearings. YGK2216 is for the earlier 10-bolt-cover 8.8 with a 10-bolt ring gear.

How do I know if my axle uses 2.25 in. OD axle bearings?

Measure the old bearing or the bore at the housing end. Ford Performance lists 2.256 in. OD for 1986-2004 Mustang solid 8.8 axles and a larger 2.53 in. OD bearing for 2005-2014 Mustang GT. If yours is the larger size, this kit is not the right one.

Is a 3.31 ratio good for bigger tires?

Not usually. 3.31 is a highway ratio for stock-size tires or replacing worn gears of the same ratio. Taller tires and towing generally call for 3.55, 3.73 or deeper.

Does the kit include a carrier or limited slip parts?

No. It is the ring and pinion, the master install kit with Timken bearings and small parts, and the axle bearings and seals. Reuse your carrier, and rebuild a Traction-Lok with a clutch kit if it chatters or no longer locks.

What gear oil should I use after the install?

Use the gear oil Ford specifies for your axle, and add friction modifier if it is a Traction-Lok. Change it early after the break-in miles to remove wear metal from the new gears.