Yukon Gear High Performance Gear Set For Ford 8.8in in a 3.73 Ratio
3.73 is the ratio Ford 8.8 owners reach for when the truck or car needs real punch back. It is the go-to swap for a Fox-body or SN95 Mustang leaving a 2.73 or 3.08 behind, the fix for an F-150, Explorer or Ranger that went up a tire size or two and now feels lazy, and the ratio Ford itself used in many towing packages. The Yukon Gear & Axle YG F8.8-373 is a new 3.73 ring and pinion for the standard-rotation 8.8 rear used from the late 1970s through 2014.
Yukon specifies this set with an 8.80 in. ring gear, a 30-spline pinion and 10 ring gear bolts. The pinion turns 3.73 times for every turn of the axle shafts, about 21 percent more torque at the tires than a 3.08 and 37 percent more than a 2.73. On a Mustang that turns a soft launch into a strong one; on a truck it gives back the leverage lost to a taller tire, roughly enough to offset the jump from a stock tire to a 33 in. tire on many half-tons. Engine rpm at cruise climbs by the same percentage, which is why 3.73 is a balance point: deep enough to wake the vehicle up, tall enough to stay livable on the highway, especially with an overdrive automatic like the 4R70W or 6R80.
Check the axle code on the door tag or the metal tag on a cover bolt, or mark the driveshaft and count its turns for one tire revolution, as shown in our axle ratio and code guide. Our 4R70W gear ratios guide lists the transmission gearing behind many 8.8 axles, so you can work out the overall ratio for your tire size. If the complaint is noise, the Ford 8.8 rear axle problems guide covers what usually fails and what a rebuild involves.
Yukon's table covers the standard-rotation 8.8 rear in the 1983-2014 F-150, 1979-2014 Mustang, 1990-2011 Ranger, 1991-2010 Explorer, 1997-2014 Expedition, 1983-1996 Bronco, 1986-1997 Aerostar, 1983-2014 E-150 and 1983-1998 E-250 vans, 1992-2011 Crown Victoria, Grand Marquis and Town Car, Lincoln Navigator, Aviator and Mark LT, Mercury Mountaineer and Marauder, and Mazda B3000, B4000 and Navajo, in both solid-axle and IRS versions. It does not fit the 2015-and-later Super 8.8 with the 12-bolt cover; for that axle use the Yukon 3.73 set for 2015-up F-150. It also does not fit the reverse-rotation 8.8 used as an IFS front axle. Ford built the 8.8 with 28 and 31-spline axles, and 2010-2014 Mustangs and some late straight axles use a larger 3.250 in. pinion bearing; those differences change the bearing kit, not the gears, so match your axle or send us your year and VIN. Other ratios include the Yukon 8.8 4.11 set.
Order bearings with the gears. The Yukon master overhaul kit for 2009-and-earlier 8.8 axles covers pinion and carrier bearings, races, shims and seal, and the Yukon 8.8 carrier installation kit handles the carrier side if the pinion bearings are covered elsewhere. Yukon's chart lists a 0.026 in. starting pinion shim, 14-19 in-lb of new pinion bearing preload and 60 ft-lb for the ring gear bolts and bearing caps. Remove the cross-pin bolt and C-clips before pulling the axles, set depth, preload and backlash, then confirm the pattern with marking compound. Fill with 75W-140 or 75W-85 gear oil as your manual specifies, plus friction modifier on Traction-Lok axles. Drive lightly for the first 15 to 20 miles and let it cool, skip hard launches for 100 miles, wait 500 miles before towing, and change the oil after break-in.
| Brand | Yukon Gear & Axle |
| Part number | YG F8.8-373 |
| Fits | Yukon Gear High Performance Gear Set For Ford 8.8in in a 3.73 Ratio |
| Type | Final Drive Gears |
| 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.
No. 2015-and-later F-150 and Mustang rears use the Super 8.8 with a 12-bolt cover. We carry a separate Yukon 3.73 set for that axle. This YG F8.8-373 is for 2014-and-earlier 8.8 rears.
Not for the gears. Axle spline count is set by the carrier. You keep or swap the carrier to match your shafts and use this same ring and pinion.
It is a common choice for 33 in. tires on half-ton trucks with an overdrive automatic. Heavy towing or 35 in. tires usually push owners to 4.11.
We do not recommend it. Pinion depth and preload change with new gears, and used bearings and crush sleeves rarely hold the new settings. Install a master overhaul kit with the gears.
Yes. Changing the axle ratio changes the speedometer reading. Most late trucks and Mustangs need the tire size and axle ratio reprogrammed with a tuner; older vehicles use a speedometer gear change.
