Yukon Gear Grizzly Locker / Ford 8.8in w/ 31 Splines
The Ford 8.8 sits under F-150s, Broncos, Explorers, Expeditions, Sport Tracs, Lincoln Aviators and plenty of Mustangs, and most of them came with an open carrier or a Traction-Lok that has long since worn out. The Yukon Grizzly Locker YGLF8.8-31 is a full automatic mechanical locker for the 8.8 with 31-spline axle shafts, all ratios, built for trail, crawling and drag-strip use. If your truck lifts a tire on a ledge and stops moving, or your Traction-Lok just spins one side, this is the hard-core fix.
Instead of spider gears, the Grizzly uses a pair of driven clutch rings with face teeth. Under power the rings stay meshed and both axle shafts turn together, so 100 percent of the available torque goes to both rear tires even when one is in the air. When you turn, the outside wheel overruns, ratchets its ring out of engagement and lets the axle get around the corner, then the teeth drop back in. Yukon's patented tooth profile uses a larger radius at the base of the inner clutch teeth, which it rates at up to 350 percent stronger than back-cut designs, with 8620 steel internals, a .875 inch diameter cross pin and US assembly. It replaces the whole carrier, unlike a lunchbox locker that reuses the factory case.
Count the axle splines. Ford built the 8.8 with both 28-spline and 31-spline shafts, and this carrier only takes 31-spline shafts; a 28-spline axle needs the 28-spline unit or a shaft upgrade. Our 8.8 locker buyers guide shows how to tell them apart, and the Ford 8.8 rear axle problems guide covers pinion and axle bearing wear worth fixing in the same job. If your real problem is a chattering limited slip on a street truck, read the Traction-Lok chatter fix first, and compare selectable options in ELocker vs Grizzly Locker.
Yukon's application list for the YGLF8.8-31 includes the 8.8 rear in 1983-1996 Bronco, 1983-2008 F-150, 1997-2001 Expedition, 1991-2001 Explorer, 2001-2010 Explorer Sport Trac, 2003-2005 Lincoln Aviator, E-150 vans, 2012-2014 Mustang and the 8.8 IRS used in some 1999-2011 Mustangs. It also lists the 31-spline reverse-rotation front 8.8 in 2009-2014 F-150 and Expedition 4WD. Several older cars and Rangers on the list came with 28-spline shafts and need 31-spline axles to use it. It does not fit the 34-spline Super 8.8 in 2015-and-later F-150s. Match your spline count and axle tag or send us your year and VIN. For a street-friendly alternative, see the Dura Grip posi for 31-spline 8.8. Other carriers and axle parts are in our hard parts category.
A solid-axle 8.8 rear uses C-clip shafts (the IRS and front versions use bolted half shafts instead): drain the oil, pull the cross pin from the old carrier, push the shafts in, remove the C-clips and slide the axles out. Move the ring gear to the Grizzly case with new bolts and threadlocker, and press on new carrier bearings. A Timken master bearing kit for the 8.8 covers bearings, races and seals, and if the pinion is coming out the crush sleeve eliminator kit makes pinion preload easier to hold. Set backlash and check the pattern. Fill with 75W-90 or 75W-140 gear oil with no friction modifier, since this locker has no clutch packs. Expect some ratcheting clicks in tight turns; that is normal for an automatic locker.
| Brand | Yukon Gear & Axle |
| Part number | YGLF8.8-31 |
| Fits | Yukon Gear Grizzly Locker / Ford 8.8in w/ 31 Splines |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Not with the stock shafts. This locker only accepts 31-spline axles. A 28-spline axle needs the 28-spline version or a pair of 31-spline shafts.
No. Those trucks use the Super 8.8 with 34-spline shafts and a different carrier, which this unit does not fit.
Yukon lists it for the 31-spline reverse-rotation front 8.8 in 2009-2014 F-150 and Expedition 4WD. Keep in mind a front automatic locker makes steering heavier on pavement in 4WD.
No. The Grizzly is a mechanical locker with no clutch packs, so use a plain GL-5 gear oil in 75W-90 or 75W-140.
Yes. Automatic lockers ratchet as the outside wheel overruns in a turn. Steady clunking under straight-line power is not normal and should be checked.
A lunchbox locker reuses your factory carrier and costs less. The Grizzly replaces the whole carrier with a stronger case and is the better choice for big tires and hard use.
