- Engine
- Clutch or torque converter
- Transmission
- Transfer case (4WD/AWD)
- Driveshaft or CV axles
- Differential
- Wheels
Transmission and clutch
An automatic transmission shifts on its own using hydraulic pressure and electronic control. A continuously variable transmission uses belts or chains and pulleys instead of fixed gears. A manual transmission uses a clutch that the driver works with a pedal, through a hydraulic or cable system.
Common parts
- TD·1Complete transmissions, new or remanufactured
- TD·2Transmission filters, pans, and gaskets
- TD·3Solenoids, valve bodies, and transmission control modules
- TD·4Torque converters
- TD·5Clutch kits with disc, pressure plate, and release bearing
- TD·6Flywheels and dual-mass flywheels
- TD·7Clutch master and slave cylinders
- TD·8Shifter cables, bushings, and transmission mounts
Signs of trouble
Slipping, flaring between gears, harsh or late shifts, or a delay when you put it in gear can point to low fluid, a solenoid, or internal wear. Check the fluid level and condition first, if the transmission has a way to check it. On a manual, a clutch that engages high in the pedal travel, a burning smell, or engine speed rising without the car speeding up are signs of a worn clutch. A soft or sinking pedal points at the hydraulic side.
Finding the right fit
Transmissions are matched by model code, which is often on a tag on the case or tied to the VIN. The same model can use different transmissions by engine, drive type, and year. Clutch kits differ by engine and sometimes by flywheel type.
Axles, driveshafts, and differentials
Front-wheel drive vehicles use constant-velocity axles to the front wheels. Rear-wheel drive and four-wheel drive vehicles use a driveshaft to a differential, and four-wheel drive vehicles add a transfer case that splits power to the front axle.
Common parts
- 1CV axles, CV joints, and CV boots
- 2Driveshafts, U-joints, and center support bearings
- 3Differential covers, gears, bearings, and seals
- 4Axle shafts and axle bearings
- 5Transfer cases and transfer case motors
- 6Hub locking parts on some four-wheel drive vehicles
Finding the right fit
Axles differ by side, drive type, transmission, and sometimes by whether the vehicle has ABS. Differentials are matched by axle model and gear ratio, which may be on a tag on the cover or in the build data tied to the VIN.
Symptom to part
| What you notice | Usually points at | Check first |
|---|---|---|
| Click when turning sharply | Outer CV joint | Look for a torn boot and grease on the wheel |
| Vibration that rises with road speed | Driveshaft, U-joints, or wheel balance | Check U-joints for play |
| Whine that changes on and off the throttle | Differential gears or bearings | Check the fluid level and look at the drained fluid |
| Engine revs rise, car does not speed up | Slipping clutch or transmission | Check fluid level and condition first |
Before you order
Start with the year, make, model, and engine, then narrow it down with the trim, drive type, and any option the part depends on. The VIN is the most reliable way to do that, because many parts catalogs and dealer counters decode it to the exact build. If the old part is in hand, its original-equipment number is the best cross-reference. Aftermarket brands publish their own numbers and usually list the original number they replace. Two listings that both say they fit can still differ, so compare the photos, connectors, mounting points, and the notes in the listing. The find the right part guide covers this step, and the all makes reference lists each maker’s official parts catalog.
Once you know the part number, compare the same number across stores. Look past the first price at the core charge, shipping, the return window, and what the warranty covers and who honors it. A remanufactured part, a new aftermarket part, and an original-equipment part can each be the right choice, but they are not the same purchase. The compare prices and warranties guide walks through what to read. Prices on PartIndex carry the date they were recorded, so confirm the current price and fitment with the retailer before you buy.
Support the vehicle on stands, chock the wheels, and never rely on the parking pawl alone when working under a vehicle. Transmissions and transfer cases are heavy and need a proper jack to remove.