Regears a Ford 8.8-inch rear axle to 3.73:1 for stronger launch and towing. 30-spline, 10-bolt, 8620-steel gear set for F-150, Mustang, Ranger and Explorer.
If your F-150 got a set of 33s and now drops out of overdrive on every hill, your Mustang still has the economy 2.73 or 3.08 gears it left the factory with, or the 8.8 under your Explorer or Ranger has started to howl, a 3.73 gear set is usually where the conversation ends up. This is the Motive Gear F8.8-373A, a new 3.73:1 ring and pinion for the standard-rotation Ford 8.8 inch rear axle. It is the A-line version of Motive's 8.8 gear, priced for a daily driver or work truck regear rather than a race build.
The 8.8 is a ten-bolt, C-clip rear axle. The driveshaft turns the pinion, the pinion drives the ring gear bolted to the carrier, and the carrier turns the axle shafts. A 3.73 set cuts 41 teeth on the ring gear against 11 on the pinion, so the driveshaft turns 3.73 times for each turn of the tires. Compared with a 3.31 or 3.55, the engine sits a little higher in its rpm range at every road speed, which means a quicker launch, less downshifting under a trailer and better throttle response on a taller tire. This set has a 30-spline pinion and an 8.8 inch ring gear cut from heat-treated 8620 alloy steel, and it is made to run in the factory-style Ford 8.8 carrier.
Make sure the noise is really gears. Pinion bearing wear and axle bearing noise are both common on high-mile 8.8 axles and cost far less to fix; our whine on acceleration vs deceleration guide shows how each one sounds. Then confirm the axle and ratio from the door sticker axle code or the tag on the cover, using our axle code and gear ratio guide. The 7.5 inch Ford rear looks similar and also uses ten cover bolts, so measure the ring gear or read the tag before you order. Common 8.8 problems are covered in our Ford 8.8 rear axle guide.
The listing covers the standard-rotation Ford 8.8 rear in Ford, Lincoln, Mazda and Mercury vehicles from 1980 to 2020, naming the F-150, Mustang, Ranger, Explorer, Crown Victoria, E-150, F-250 and Thunderbird. That range is broad, so be careful at the edges. Published F-150 fitment for this part number is 1997-2014; the 2015-up F-150 and Mustang 8.8 uses a different gear, and for that axle we stock the 2015-up F-150 8.8 3.73 set. The 8.8 independent front axle on 4x4 F-150s and Explorers is reverse rotation and does not take this set. Match the 30-spline pinion, ten-bolt ring gear and tooth count to your old gears, or send us your year and VIN and we will check it. If you want a less aggressive change, compare the Ford 8.8 3.55 set; for bigger tires look at the 8.8 4.11 set. More Ford axle parts are on our hard parts page.
This is the gear set only. Plan on new carrier and pinion bearings and races, a pinion seal, a crush sleeve or solid spacer, shims and ring gear bolts; the Timken Ford 8.8 master bearing kit covers the bearings, and the 8.8 carrier installation kit handles the carrier side. Pull the pinion shaft lock bolt and cross shaft, push the axles in and remove the C-clips before the carrier comes out. Revolution's setup chart for the 8.8 lists 0.026 in as a starting pinion shim, 14-19 in-lb pinion bearing preload, 0.006-0.010 in backlash and 60 ft-lb on both the ring gear bolts and bearing caps. Use the old pinion shim as the starting point, adjust to the pinion head marking, and confirm drive and coast patterns with marking compound. Fill with 75W-140 or 75W-85 gear oil (add friction modifier for Traction-Lok), take it easy with no towing for the first few hundred miles, then change the oil and update the tire size and axle ratio in the PCM so the speedometer and shifts are right.
| Type | Ring and pinion gear set (gears only) |
| Axle | Ford 8.8 inch, 10-bolt |
| Ratio | 3.73:1 |
| Pinion | 30-spline |
| Material | 8620 alloy steel, heat treated |
| Part number | F8.8-373A |
| Fits | Ford, Lincoln, Mazda, Mercury 1980-2020 (F-150, Mustang, Ranger, Explorer, Crown Victoria, E-150, F-250, Thunderbird) |
| Cross reference | Richmond 49-0104-1, EXCEL F88373, Motive Gear F8.8-373 |
| Does not include | Install kit (bearings, crush sleeve, shims, pinion seal, ring gear bolts) |
| Weight | 11.84 lb |
| Brand | Motive Gear |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. The 2015-up F-150 and Mustang 8.8 takes a different gear set. This F8.8-373A is for the earlier standard-rotation 8.8; the F-150 fitment listed for it is 1997-2014. We carry a separate 3.73 set for 2015-up trucks.
No. The independent front 8.8 is reverse rotation and needs reverse-cut gears. This set is for the standard-rotation rear 8.8 only.
Not normally. This set uses the factory-style Ford 8.8 carrier, so most owners reuse their open or Traction-Lok carrier. A 30-spline pinion and 10 ring gear bolts are standard for this set.
Only the ring and pinion. You will need bearings, races, a crush sleeve or solid spacer, shims, a pinion seal and ring gear bolts, which a master bearing kit or install kit supplies.
Use 75W-140 or 75W-85 gear oil, and add friction modifier if the axle has a Traction-Lok limited slip. Change it after the first few hundred miles of break-in.
On many half-ton F-150s 3.73 brings back usable performance on 33s, especially with an overdrive automatic. Heavy towing or 35s usually call for 4.10 or deeper. Check your tire height and transmission before choosing.
