Yukon Gear Pinion Flange For 11-15 Ford F250/ F350/F450 10.5in Pinion Flange w/ Balancer 37 Spline
On a 2011-2015 Ford F-250, F-350 or F-450 Super Duty with the 10.5 inch rear, the driveshaft bolts to a round pinion flange instead of a U-joint yoke. If that flange has a grooved seal track that keeps eating pinion seals, worn splines that clunk on takeoff, or a damaged bolt face after a driveshaft failure, the Yukon Gear and Axle YY F100609 is the new replacement. It is a 37-spline pinion flange with a balancer, made for the 2011-2015 Ford 10.5.
The flange slides onto the splined end of the pinion gear and is clamped by the pinion nut, which also loads the pinion bearings through the crush sleeve. The driveshaft's companion flange bolts to its face, so every bit of torque from the transmission to the ring gear passes through these splines. The smooth neck behind the face is the surface the pinion seal lip rides on, which is why a scored or rusted flange will make even a brand new seal leak. The balancer on this part matters on a heavy Super Duty driveline turning highway speeds; it keeps the flange from adding its own vibration to the driveshaft. Ford changed the pinion for 2011: according to Denny's Driveshafts, the 10.5 used a 31-spline pinion from 1999 to 2010 and a 37-spline pinion from 2011 to 2015, and the 2011 axle is not to be confused with a 37-spline Dana 80.
Mark the driveshaft and flange so they go back in the same position, unbolt the shaft and tie it up. Rock the flange to feel for spline slop or pinion bearing play, and spin it to check for roughness. Clean the neck and inspect the seal track under good light. If the pinion bearings are rough or the oil shows metal, the flange alone will not fix it; our pinion seal leak guide and Ford Sterling 10.5 problems guide walk through the checks, and the Yukon YK F10.5-D master overhaul kit covers a full bearing job on the same axle.
The YY F100609 is listed for the 2011-2015 Ford F-250, F-350 and F-450 Super Duty with the 10.5 inch rear axle and a 37-spline pinion. The 10.5 has a 12-bolt rear cover, while the Dana 60, 70 and 80 use 10 bolts, so count before you order. A 1999-2010 truck uses a 31-spline pinion and takes the YY F100606 long spline flange instead. If your truck is outside 2011-2015, has been re-geared or has an axle swap, count the pinion splines or send us the year and VIN. More parts are in hard parts.
| Brand | Yukon Gear & Axle |
| Part number | YY F100609 |
| Fits | Yukon Gear Pinion Flange For 11-15 Ford F250/ F350/F450 10.5in Pinion Flange w/ Balancer 37 Spline |
| Vehicle fitment | Ford F250/ F350/F450 (2011-2015) |
| Type | Pinion Flanges |
| 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. 1999-2010 Ford 10.5 axles use a 31-spline pinion. This YY F100609 is 37-spline for 2011-2015 trucks. The 31-spline long spline flange is YY F100606.
Yes. Install a new pinion seal whenever the flange comes off, and especially when the old flange had a worn seal track.
Measure rotating torque and mark the nut before removal, then tighten back to the original reading. Overtightening crushes the sleeve and requires a new one.
It keeps the flange balanced at driveshaft speed so the part does not add vibration to the driveline.
It is listed for the Ford 10.5 with a 37-spline pinion. A Dana 80 also has 37 splines but is a different axle with a 10-bolt cover. Count the cover bolts and check the axle tag first.
A pinion flange holding tool, a breaker bar for the nut, an inch-pound torque wrench to check preload, and a seal driver for the new pinion seal.
