Revolution Gear & Axle Ford 9in 3.50 Ratio Ring & Pinion Set
Revolution Gear & Axle F9-350 is a 3.50 ring and pinion for the Ford 9-inch, the drop-out rear end found under 1957-1987 F-100 and F-150 pickups, 1966-1986 Broncos, 1965-1973 Mustangs and 1967-1979 Cougars, and in more street rods, pro-touring builds and swap projects than any other axle. Buyers usually land here with a 9-inch that whines on the highway after decades of use, or with a project car whose 2.75, 2.80 or 3.00 gears feel soft with a modern engine and an overdrive transmission. A 3.50 gives a noticeable kick off the line while keeping freeway rpm sane.
In a 9-inch the ring and pinion, carrier and bearings live in a removable third member that bolts into the front of the housing, so the whole gear set can be built and checked on a bench. The pinion is held by two tapered bearings in a separate pinion support plus a straddle bearing behind the gear head, which keeps the pinion from deflecting under load. This set uses a 9.0 inch ring gear fastened with ten 7/16 inch bolts and a 28 spline pinion, cut from 8620 steel in standard rotation. Revolution notes there is no carrier break across 9-inch street ratios, so the carrier you have will accept 3.50 gears whether it ran 3.00 or 3.89 before. At 3.50 the driveshaft turns three and a half times for every turn of the wheels.
Make sure the car really has a 9-inch; the 8-inch and 8.8 look similar from underneath, and our 8.8 vs 9-inch comparison shows the quick tells, chiefly the removable third member and the lack of a rear cover. Pinion support bearing wear is the classic 9-inch noise and is often blamed on the gears; the Ford 9-inch problems and rebuild cost guide covers how to tell them apart, and the accel vs decel whine diagnosis narrows it down from the driver's seat.
Revolution lists F9-350 for 1966-1986 Ford Bronco, 1957-1983 F-100, 1975-1987 F-150, 1965-1973 Mustang and 1967-1979 Mercury Cougar, and it fits any Ford 9-inch third member that takes a 28 spline pinion, including aftermarket housings. Factory axle options varied a lot in those years and many of those vehicles left the plant with an 8-inch or another axle, so check what is actually under yours, or send us the year, model and VIN. The 28 spline pinion needs a matching yoke and pinion support. Carrier bearing size is the other variable: 9-inch carriers use different bearings, which is why overhaul kits are sold by bearing number, such as the USA Standard ZK F9-B for LM501310 carriers and the Koyo kit for 2.891 in. carrier bearings. Pull a bearing and read its number before ordering.
Set the gears on the bench with new bearings. The Allstar installation kit with a solid spacer suits 3.062 in. carrier bearings and removes the crush sleeve guesswork. Revolution's Ford 9-inch starting numbers are a 0.022 in. pinion depth shim, 13-15 in-lb pinion bearing preload, 0.006-0.010 in. backlash and 60 ft-lb on both the ring gear bolts and the bearing caps; adjust depth until the drive and coast patterns center on the tooth, as shown in our backlash and pinion depth setup guide. Use 75W-90 gear oil for street use, or 85W-140 for heavy towing and hot climates, with friction modifier for a clutch-type limited slip. Keep the first drives short and easy so the gears heat-cycle, then change the oil, as laid out in the break-in procedure. If traction is next on your list, the Grizzly locker for 31 spline 9-inch axles drops into the same third member.
| Brand | Revolution Gear & Axle |
| Part number | F9-350 |
| Fits | Revolution Gear & Axle Ford 9in 3.50 Ratio Ring & Pinion Set |
| Type | Ring & Pinions |
| 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. Revolution lists no carrier break for this Ford 9-inch set, so a standard 9-inch carrier that ran other street ratios accepts it. Check the carrier bearing size so you buy the right bearing kit.
It has a 28 spline pinion with a 9.0 inch ring gear and ten 7/16 inch ring gear bolts. Your yoke and pinion support must match a 28 spline pinion.
It depends on the carrier bearings in your third member. Common 9-inch carriers use 2.891 in. or 3.062 in. bearings, and kits are labeled by bearing number such as LM102910 or LM501310. Remove a bearing and read the number before ordering.
75W-90 is fine for most street cars and trucks; 85W-140 suits heavy towing or hot climates. Add friction modifier if the axle has a clutch-type limited slip.
Yes. With an AOD, 4R70W or a five-speed manual, 3.50 gives quicker launch than a 2.75 or 3.00 while overdrive keeps highway rpm comfortable.
A growl or rumble that stays fairly constant with road speed usually points to bearings, while gear wear tends to whine and change between throttle and coast. Inspect both when the third member is out.
