Yukon Gear High Performance Gear Set For Ford 8.8in in a 4.56 Ratio
A 4.56 ratio is what Ford 8.8 owners reach for when the tires get big: an Explorer or Ranger on 33s or 35s, a Bronco built for the trail, or a Fox-body Mustang that needs to launch hard at the drag strip. The Yukon Gear & Axle YG F8.8-456 is a new 4.56 ring and pinion for the standard-rotation Ford 8.8 rear used from the late 1970s through 2014. It also replaces noisy, worn factory gears in a high-mile axle.
The 8.8 is a hypoid, semi-floating rear: the pinion turns on two tapered bearings held by a crush sleeve, and drives an 8.80 in. ring gear bolted to the carrier with 10 bolts. At 4.56, the driveshaft turns 4.56 times for each turn of the wheels, which multiplies torque hard and brings back the low-end response that large, heavy tires take away. The trade-off is higher engine speed on the highway, so this ratio suits off-road builds, tow rigs on big tires and drag cars more than a stock-tire commuter. Yukon specifies this set with a 30-spline pinion.
Check the ratio code on the door sticker or the axle tag, or count turns: mark the driveshaft and a tire, turn the tire once and count driveshaft revolutions. Compare that to the tire size you run now and the gearing in your transmission; our 4R70W gear ratios guide shows the first-gear and overdrive numbers for many F-150, Expedition and Crown Victoria builds that share this axle. For a noise complaint, pull the cover and inspect the teeth and the magnet before deciding whether you need gears or just bearings.
This set fits the standard-rotation Ford 8.8 rear. Applications listed for it include 1983-2014 F-150, 1979-2014 Mustang, 1990-2011 Ranger, 1991-2010 Explorer, 1997-2014 Expedition, 1983-1996 Bronco, Crown Victoria, Grand Marquis, Town Car and E-150 vans, in both solid-axle and IRS versions. It does not fit the 2015-and-later Super 8.8 with the 12-bolt cover, and it does not fit front IFS 8.8 axles, which are reverse rotation; for those we carry the reverse-rotation 4.56 set. Ford used different inner pinion bearing sizes and 28 or 31-spline axles over the years, so match the install kit to your housing, or send us your year and VIN.
One detail is specific to this deep ratio: the pinion head sits closer to the cross pin, and the fitment notes call for a notched cross pin shaft with this set. Check your carrier before assembly; for 1985-and-older carriers we stock a notched 3/4 in. cross pin shaft. Use a full bearing kit such as the USA Standard ZK F8.8 master overhaul kit or the Yukon kit for 2009-and-earlier 8.8 axles. Yukon's chart gives the 8.8 a starting pinion shim of 0.026 in., 14-19 in-lb of new pinion bearing preload and 60 ft-lb on both the ring gear bolts and the bearing caps. Confirm the pattern with marking compound, refill with 75W-140 or the grade in your manual plus friction modifier for Traction-Lok, and break the gears in gently with an oil change after the first 500 miles.
| Brand | Yukon Gear & Axle |
| Part number | YG F8.8-456 |
| Fits | Yukon Gear High Performance Gear Set For Ford 8.8in in a 4.56 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 are the redesigned 8.8 with a 12-bolt cover and a different pinion. This set is for 2014-and-earlier standard-rotation 8.8 axles.
Yes, the fitment notes for this set call for a notched cross pin shaft because the larger pinion head comes close to the pin. Check yours before final assembly; many aftermarket carriers already have one.
It is usually chosen for roughly 33 to 35 in. tires on trucks and SUVs, or for drag cars that want maximum launch. With stock-size tires, a 4.56 will spin the engine high on the highway.
It is not recommended. Setting up new gears changes pinion depth and preload, and old bearings and the crush sleeve rarely hold the new settings. Order a master overhaul kit with the gears.
Use the grade in your owner's manual, commonly 75W-140 synthetic for the 8.8. Traction-Lok limited slip axles need friction modifier. Change the oil after the first 500 miles to flush break-in wear.
