The drivetrain carries torque from the transmission to the wheels through the transfer case, driveshafts, joints and axle shafts. Here you will find parts for rear-wheel and four-wheel drive.
In this guide: 4WD actuators, Axle shafts, Clutch and transmission parts, CV joints, U-joints and drive axles, Driveshaft couplers, Driveshafts, Drivetrain seals, Transfer cases, Wheel seals.
4WD actuators
What it is: An actuator is a vacuum or electric unit that engages the front axle or hubs when 4WD is selected.
Where it is fitted: On the front axle, at the wheel hubs or on the transfer case.
Signs of wear: 4WD does not engage, the 4WD light flashes or there is grinding when engaging it.
Did you know: With vacuum actuators the culprit is often a cracked vacuum line rather than the actuator itself, so check the lines first.
Axle shafts
What it is: An axle shaft is a steel shaft that carries drive from the differential to the wheel in a solid axle.
Where it is fitted: Inside the drive axle housing, from the differential to the wheel hub.
Signs of wear: A whining axle bearing, gear oil leaking from the axle onto the brakes, or wheel play.
Did you know: Oil at the wheel often points to a worn axle seal, and oil on the brake linings can noticeably weaken braking.
Clutch and transmission parts
What it is: This group covers clutch and transmission parts, which connect the engine to the rest of the driveline and change gear ratios.
Where it is fitted: Between the engine and the driveshaft, in the bellhousing and transmission case.
Signs of wear: Clutch slip, judder, hard or delayed shifts and transmission fluid leaks.
Did you know: Chrysler automatic transmissions require fluid meeting the ATF+4 specification; the wrong fluid can harm shifting.
Shop — Clutch and transmission parts
CV joints, U-joints and drive axles
What it is: U-joints and CV joints transmit drive at changing angles as the suspension moves or the wheels steer. CV drive axles power the wheels on vehicles with independent suspension.
Where it is fitted: At the ends of the driveshafts (U-joints) and between the differential and the wheel hub (CV joints).
Signs of wear: A clunk when pulling away or selecting a gear, vibration at speed, a squeaking U-joint or a clicking CV joint when turning.
Did you know: A U-joint with a grease fitting can be greased periodically; sealed versions without a fitting are lubricated for life.
Shop — CV joints, U-joints and drive axles
Driveshaft couplers
What it is: The driveshaft coupler, often a flexible joint, connects the shaft to the transmission or axle flange and dampens vibration and driveline shock.
Where it is fitted: Where the driveshaft meets the transmission, transfer case or axle.
Signs of wear: Vibration, a clunk when pulling away or shifting, and cracks in the rubber of the coupler.
Did you know: When inspecting, look for small cracks in the rubber around the bolts; that is where couplers usually start to break apart.
Driveshafts
What it is: The driveshaft carries torque from the transmission or transfer case to the drive axle. It has U-joints at the ends and often a sliding splined section.
Where it is fitted: Under the vehicle, between the transmission or transfer case and the front or rear axle.
Signs of wear: Vibration that grows with speed, clunks when pulling away, play in the U-joints or slip joint.
Did you know: Mark the shaft's position relative to the flanges before removal; reinstalling it in a different position can cause vibration.
Drivetrain seals
What it is: Seals keep oil inside the axles, transfer case and transmission where rotating shafts exit.
Where it is fitted: At the axle pinion, the transfer case and transmission outputs, and at the axle shafts.
Signs of wear: Oil drips or stains under the car, oily driveshafts and a falling oil level in the axle or transfer case.
Did you know: When replacing a pinion seal on an axle with a crush sleeve, mark the nut position; overtightening changes the bearing preload.
Transfer cases
What it is: The transfer case splits drive between the front and rear axles, and in many off-road vehicles it also provides 4L low range.
Where it is fitted: Behind the transmission, with output shafts leading to the front and rear axles.
Signs of wear: Trouble engaging 4WD, clunks, whining, a skipping chain or oil leaks.
Did you know: The chain-driven NP231 is a very common transfer case in Jeeps; a stretched chain shows up as clunks and noise when load changes.
Wheel seals
What it is: A wheel seal keeps grease or oil inside the hub or axle end and protects the bearing from water and dirt.
Where it is fitted: In the wheel hub or at the end of the axle housing, next to the wheel bearing.
Signs of wear: Grease or oil leaking on the inside of the wheel, contaminated brakes and bearing noise.
Did you know: Seals are not reused after removal; always fit a new one when replacing a wheel bearing.
Where to next
- Catalogue: drivetrain — choose your make, model and generation.
- Parts by VIN — we will check the fit for your car.
- Parts guide — other systems.
We sell aftermarket replacement parts, not genuine parts from vehicle manufacturers. Descriptions are general — check the fit for your vehicle by OEM number or VIN.