Yukon Gear High Performance Gear Set For Ford 9in in a 3.50 Ratio
The Yukon YG F9-350 is a 3.50 ring and pinion for the Ford 9-inch rear end, the drop-out third member used under 1957 to 1986 Ford trucks, Broncos, Mustangs, Falcons, Fairlanes, Galaxies and a long list of Mercury and Lincoln cars, plus countless street rods and swaps. A 3.50 is the ratio people pick when a car with highway 2.75 or 3.00 gears feels lazy off the line, or when a truck or Bronco gets slightly taller tires and needs back the pull it had on stock rubber, without the freeway rpm of a 4.11.
The 9-inch puts the ring and pinion, carrier and bearings in a removable third member that bolts into the front of the housing. The pinion sits low and is supported at three points: two tapered bearings in a separate pinion support, and a straddle (pilot) bearing behind the pinion head. That design is why the 9-inch handles torque so well and why it is easy to set up on a bench. This Yukon set has a 9.00 inch ring gear held by 10 bolts and a 28 spline pinion, the common pinion for 9-inch street gearing. At 3.50, every turn of the axle takes 3.5 turns of the driveshaft, a middle ground between cruising rpm and launch.
Pull the third member and read the tooth counts stamped on the ring gear, or count driveshaft turns per wheel turn. Our Ford 9-inch problems and rebuild guide covers pinion support bearing wear, which is the most common 9-inch noise and is often mistaken for bad gears. If you are not sure whether the car has a 9-inch or an 8.8, the 8.8 vs 9-inch comparison shows the quick tells. For noise that comes and goes with throttle, use the accel vs decel whine diagnosis.
Yukon lists this set for the Ford 9-inch in 1966 to 1986 Bronco, 1957 to 1987 F-100 and F-150 with the 9-inch, 1964 to 1973 Mustang, 1960 to 1970 Falcon, 1957 to 1970 Fairlane, Galaxie and Galaxie 500, LTD, Custom, Maverick, Granada, Thunderbird, Econoline vans, Lincoln Continental and Mark III, and Mercury Comet, Cougar and Grand Marquis of the same era. Not every one of those vehicles came with a 9-inch; many got the 8-inch or another axle, so confirm the housing before ordering. The ring gear and pinion swap on the third member, but the bearings do not always match: spline count does not tell you which carrier bearing your case uses, so check the bearing numbers before buying a kit. Send us your year and VIN if you are unsure, or browse the hard parts catalog.
Yukon's setup chart for an aftermarket 9.0 inch gear set lists a 0.022 inch baseline pinion depth shim, 13 to 15 in-lb pinion bearing preload on new bearings (6 to 8 used), 0.006 to 0.011 inch backlash, and 60 ft-lb on both the ring gear bolts and the bearing caps; a Daytona pinion support takes 14 to 17 in-lb. Pinion depth is set with shims between the pinion support and the case, so have a set of Ford 9-inch pinion depth shims on hand. Replace the pinion and carrier bearings with a Yukon 9-inch LM501310 master overhaul kit if your case uses that carrier bearing, or a solid spacer installation kit for a race build. Fill with 75W-90 or 85W-140 gear oil and follow the ring and pinion break-in procedure, with an oil change at 500 miles.
| Brand | Yukon Gear & Axle |
| Part number | YG F9-350 |
| Fits | Yukon Gear High Performance Gear Set For Ford 9in in a 3.50 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.
It is a standard 9-inch set with a 28 spline pinion and 10 ring gear bolts, made to bolt to a 9-inch carrier. Confirm your carrier, its bearing size and the axle spline before ordering bearings or a locker, because those vary from case to case.
3.50 is a common street ratio for 9-inch cars and light trucks: quicker off the line than 2.75 to 3.00 gears without the highway rpm of 4.11. With an overdrive transmission or larger tires it can feel close to a stock ratio on the freeway.
Yes. The 9-inch third member unbolts from the front of the housing, so the gears are installed and set up on a bench, then the assembled third member goes back in with a new gasket.
Pinion support bearings, carrier bearings and races, the pinion seal and pilot bearing, a crush sleeve or solid spacer, and pinion depth shims. A master overhaul kit covers most of these once you know your carrier bearing size.
75W-90 or 85W-140 gear oil. Add friction modifier only for a clutch-type limited slip. Break the gears in gently and change the oil after the first 500 miles.
