Koyo master bearing kit for the first-design GM 10.5 inch 14-bolt, 4.10 and lower ratios, on 1972-1987 Chevy and GMC C20, K30 and G30 trucks and vans.
If your 1972-1987 Chevy or GMC C20, K20, C30, K30, G30 van or three-quarter-ton Suburban has a 10.5 inch 14-bolt full-float rear that growls on the highway, leaks at the pinion seal no matter how many seals you put in it, or is coming apart for new gears, this is the bearing kit that puts it back together. It is the Motive Gear R14RMKH master kit for the first-design 14-bolt with the 4.10-and-lower carrier case, built around Koyo tapered carrier and pinion bearings.
The 14-bolt pinion is held by three bearings: two tapered bearings in the front of the housing and a straight nose (pilot) bearing at the head of the pinion. The tapered bearings are loaded against each other through a crush sleeve, and that preload is what keeps the pinion from walking forward and back under the torque of a loaded truck. The carrier rides on two more tapered bearings, and the shims behind them set where the ring gear sits against the pinion. When any of those bearings wear, the pinion moves under load, the gear contact pattern shifts, and the noise you hear is the gears telling you their mesh is no longer where it was set. Because the front pinion bearing sits highest in the case, it is usually the first to run dry when the oil level drops, which is why low oil and a leaking seal so often come before the growl.
Drain the oil and look at it first. Fine metal haze is normal wear; chunks, flakes or a rough feel on the pinion when you turn it by hand mean the bearings are done. With the driveshaft off, grab the yoke and check for any in-and-out or up-and-down play. Then drive the truck at the speed the noise appears and note whether it is loudest on acceleration, on coast or both. Our whine on acceleration vs deceleration guide walks through how to tell bearing noise from gear noise, and the 14-bolt problems and rebuild cost guide covers hub bearings, which can sound the same from the cab.
This kit fits the GM 10.5 inch 14-bolt full-float rear used from 1972 through 1987 in Chevrolet and GMC three-quarter and one-ton trucks, Suburbans and G-series vans, including the C20, K30, G30 and C2500. Two things have to match. First, the year: GM made running changes to the 14-bolt pinion bearings in 1988 and again around 1998, so later axles take a different kit. Second, the ratio: the 14-bolt carrier case changes between 4.10 and 4.56, and this kit only fits the 4.10-and-lower case. Read the ratio tag on the cover bolt, check the RPO code on the glovebox sticker, or count the ring and pinion teeth. If you have a 4.56 or deeper set, or your truck is 1988 or newer, send us the year and VIN and we will match the right kit. You can also browse all differential and transmission rebuild kits. This kit replaces the Richmond 83-1063-1 and the Timken-bearing Motive R14RMKHT.
Koyo carrier bearings and races, Koyo inner and outer pinion bearings and races, a crush sleeve, pinion shims and carrier shims, a new pinion nut, RTV for the cover, marking compound and thread locking compound for the ring gear bolts.
Use a press and a bearing separator to remove the old pinion bearings, and do not hammer the new races in crooked. Start pinion depth with the original shim pack, then measure and adjust from the pattern. Tighten the pinion nut gradually and check rotating torque often with an inch-pound torque wrench; Yukon's published setup chart lists 20 to 35 inch-pounds of pinion preload with new bearings for the 14T 10.5 and a backlash window that starts around .006 inch. If you overshoot preload, install a new crush sleeve rather than backing the nut off. Our backlash and pinion depth setup guide covers reading the pattern. Fill with 75W-90 gear oil, or 75W-140 on a hard-towing truck, to the bottom of the fill hole.
While the axle is apart, it is the right time to do the hub side too. The 14-bolt axle bearing and seal kit handles the wheel bearings that the full-float design depends on, and a heavy-duty 14-bolt diff cover protects the ring gear on a truck that sees rocks or job sites. If you are adding traction at the same time, the Dura Grip posi for the 4.10-and-down 14-bolt is built for the same 4.10-and-down ratio range as this kit; confirm the carrier bearing fit with us before ordering both.
| Fits | GM 10.5 inch 14-bolt, 1st design, 4.10 and lower ratio carrier case; 1972-1987 Chevy/GMC C20, K30, G30, C2500 |
| Part number | Motive Gear R14RMKH |
| Bearings | Koyo tapered carrier and pinion bearings |
| Includes | Carrier and pinion bearings, crush sleeve, shims, pinion nut, RTV, marking compound, thread locking compound |
| Interchange | Richmond 83-1063-1, Motive R14RMKHT |
| Condition | New |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. This kit is for 1972-1987 first-design axles. GM changed the 14-bolt pinion bearings in 1988 and again around 1998, so a 1990 truck needs a different kit. Send us the year and VIN and we will match it.
No. The 14-bolt carrier case changes between 4.10 and 4.56, and this kit is for the 4.10-and-lower carrier only. A 4.56-and-up axle uses different carrier bearings.
Retailer listings for R14RMKH disagree on the seal and ring gear bolts, so plan on reusing good ring gear bolts with the included thread locker and have a pinion seal on hand. The bearings, races, crush sleeve, shims, pinion nut, RTV and marking compound are included.
You can, but it is the most common reason a fresh gear set whines. Old bearings have worn to the old gears and lose preload once disturbed. Replacing everything at once is cheaper than doing the job twice.
Use 75W-90 gear oil for normal service, or 75W-140 if the truck tows hard or runs hot. Add friction modifier only if the axle has a clutch-type limited slip.
A press and bearing separator, an inch-pound torque wrench for pinion preload, a dial indicator for backlash, a yoke holding tool and a large breaker bar to crush the sleeve. Without a press and inch-pound wrench, have a shop set it up.
