Eaton Detroit Locker Diff 31 Spline 1.32in Shaft Dia 4.56/4.88/5.13 Ratio Front/Reverse Rear 8.8in
If your F-150, Mustang, Explorer, Expedition or Bronco with a Ford 8.8 axle leaves one tire spinning in mud, snow or at the drag strip while the other sits still, the differential is doing exactly what an open or worn Traction-Lok unit does: sending power to the wheel with the least grip. The Eaton Detroit Locker, part number 187C145A, replaces that carrier with a fully automatic locker built for Ford 8.8 axles with 31-spline, 1.32 in diameter axle shafts. It is a complete differential case, so your ring gear bolts to it in place of the factory carrier.
A standard 8.8 carrier uses spider gears that let each axle shaft turn at a different speed, and a Traction-Lok adds clutch packs that only resist that difference until they wear. The Detroit Locker works the other way around. It is normally locked, so in straight-line driving it sends equal torque to both rear wheels even if one is in the air. When the vehicle turns, internal components let the outside wheel overrun and unlock automatically, then re-engage when the wheels return to the same speed. There are no air lines, switches or wiring to add, and Eaton describes the unit as maintenance free. The tradeoff is a different feel on pavement: because the axle is locked whenever power is applied in a straight line, it can push in tight, low-speed turns, and you may hear the mechanism engage and release.
Confirm the axle is a Ford 8.8 and count the axle shaft splines. This unit is for 31-spline axles; earlier and lighter-duty 8.8 axles with 28-spline shafts need a different locker. If the noise you hear is a whine that changes from drive to coast rather than a chatter in turns, the pinion bearings or ring and pinion are the problem, not the carrier; a Ford 8.8 master bearing kit is the right fix there. If you only want to cure Traction-Lok chatter on a street truck and keep the factory feel, the 8.8 Traction-Lok spider gear and clutch pack kit is the cheaper route.
Revolution Gear & Axle lists 187C145A as the Ford 8.8 rear Detroit Locker for 31-spline axles with no carrier break, meaning one case covers every ring gear ratio. Retailer application lists include 1987-2014 F-150, 1986-2014 Mustang, 1983-1996 Bronco, 1991-2015 Explorer, 1997-2015 Expedition, 2001-2010 Explorer Sport Trac, 2003-2005 Aviator and Panther-platform cars, but those lists vary between catalogs and not every vehicle in a range has the 31-spline axle. Eaton's catalog name also mentions reverse units; reverse-rotation 8.8 axles take their own gears, such as the reverse-rotation 4.88 gear set. Send us your year, VIN and spline count and we will confirm, or browse more axle parts in hard parts.
The 8.8 is a C-clip axle, so the axle shafts must be pushed in and the clips removed before the old carrier comes out, and refitted with the locker in place. Follow the instruction sheet supplied with the locker for the clip and cross-shaft steps. With 4.56 and numerically higher ratios, the ring gear tooth crowns need relief grinding for clearance, which is why the listing names 4.56, 4.88 and 5.13. Revolution's setup chart lists 60 ft-lb for 8.8 ring gear bolts and 60 ft-lb for the bearing caps, with .006-.010 in backlash. New carrier bearings from a master kit are cheap insurance while it is apart, and pairing the locker with a re-gear such as the Yukon 8.8 4.11 gear set saves a second teardown.
Fill with a quality petroleum GL5 gear oil; synthetic can be used if the axle maker allows it.
| Brand | Eaton |
| Part number | 187C145A |
| Fits | Eaton Detroit Locker Diff 31 Spline 1.32in Shaft Dia 4.56/4.88/5.13 Ratio Front/Reverse Rear 8.8in |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. 187C145A is for 31-spline axles with a 1.32 in shaft diameter. A 28-spline 8.8 needs a different locker or an axle shaft upgrade to 31 splines.
No. There is no carrier break, so this case works with all 8.8 ring gear ratios. For 4.56 and numerically higher gears, the ring gear tooth crowns need relief grinding to clear the case.
It is locked in a straight line and unlocks automatically in turns. Expect it to push in tight turns and to make some noise as it engages and releases. Many street and tow trucks run one, but it feels different from a limited slip.
A quality petroleum GL5 gear oil is recommended, and synthetic can be used where the axle manufacturer allows. Check your axle's capacity and fill to the bottom of the fill hole.
Yes, the existing ring gear bolts to the locker case if it is in good shape. Check backlash and contact pattern after install, and replace worn carrier bearings while the axle is apart.
