- Take-off shudder from 0 to 30 mph is the classic carrier bearing symptom.
- The rubber cushion usually fails before the bearing itself.
- Mark both halves before separating them, because reassembling out of phase causes vibration.
- Some two-piece shafts can be converted to a single large-diameter aluminum shaft.
What a center support bearing does
Long-wheelbase vehicles (crew-cab and long-bed pickups, vans, some SUVs and cars) use a two-piece driveshaft, because one long shaft would hit its critical speed and whip. The center support bearing, also called a carrier or hanger bearing, holds up the middle of the shaft. It's a sealed ball bearing in a rubber cushion, bolted to a crossmember.
Symptoms of a bad center support bearing
- Shudder pulling away from a stop that smooths out around 25 to 35 mph. This is the most common sign.
- Clunk when accelerating, letting off the gas, or shifting into gear.
- Squeal, chirp or rumble from under the middle of the vehicle that rises with speed.
- Vibration at certain speeds felt through the floor.
- Visible damage: cracked, torn or oil-soaked rubber, or a shaft that sags or moves when you push it.
What causes it to fail
- Rubber cushion aging, cracking or softening from heat (exhaust runs close by)
- Oil or fluid contamination softening the rubber
- Driveline angles changed by a lift, lowering or sagging springs
- Bearing wear or a failed seal letting water and grit in
- Towing and heavy loads
How to inspect it
- Safely support the vehicle and chock the wheels.
- Look at the rubber cushion for cracks, tears or separation from the bearing.
- Grab the shaft next to the bearing and push up, down and side to side. A little rubber give is normal, but slop or a clunk isn't.
- Spin the shaft by hand (in neutral, wheels chocked) and listen for roughness.
- Check the u-joints on both shaft sections while you're there.
Replacing it the right way
- Mark everything. Paint-mark the two shaft halves and the yokes so they go back together in the same phase. Out of phase means vibration.
- Remove the driveshaft, unbolt the bearing bracket, and separate the halves.
- Press the old bearing off and the new one on with a press or puller. Don't hammer it.
- Reassemble on your marks, reinstall, and torque the bracket and flange bolts.
- If the vehicle has been lifted or lowered, the bracket may need shims to set the angle.
- Replace worn u-joints at the same time, and have the shaft balanced if there's any doubt.
Converting to a one-piece driveshaft
On some trucks, a two-piece shaft can be replaced with a single large-diameter aluminum shaft. Aluminum raises the critical speed enough to run one long piece, which removes the center bearing for good and cuts weight. Whether it works depends on length and driveshaft speed. See steel vs aluminum vs chromoly.
Frequently asked questions
What does a bad carrier bearing sound like?
Often a squeal, chirp or rumble from under the middle of the vehicle that rises with speed, plus a clunk when accelerating or shifting.
Can a bad center support bearing cause vibration?
Yes. It typically causes a shudder pulling away from a stop that fades at higher speeds, and can cause vibration at certain speeds.
Can I drive with a bad center support bearing?
Briefly, with caution. If it fails completely the shaft can drop or damage the u-joints and transmission, so have it replaced soon.
Do I need to balance the driveshaft after replacing the carrier bearing?
If the shaft was reassembled on your marks and nothing else changed, often not. If u-joints were replaced, the shaft was disturbed, or vibration remains, balance it.
Who replaces center support bearings near Edmond?
Drivetrain Industries in Edmond, OK builds custom two-piece and one-piece conversion driveshafts. Call (572) 568-1838.