What are the different types of automatic gearbox?
Torque converter, dual clutch, CVT and automated manual — how each one behaves, what tends to go wrong with each, and what to look for on a test drive.
- Difficulty
- beginner
- Time
- 18 min
- Read
- 5 min
Short answer
Four different mechanisms all get called automatic. A torque converter box is the smooth traditional type, most tolerant of abuse. A dual clutch box is quick and efficient but is two computer-operated manual gearboxes, so it dislikes crawling traffic and hill holds. A CVT has no fixed gears and makes the engine drone under acceleration. An automated manual is a manual with a robot on the clutch, and it lurches. Which one a car has explains most of how it drives.
Anyone shopping for a used car now meets all four types under the same word, and the differences matter far more than the badge suggests. They differ in how they feel, in what they cost to maintain, and above all in how they fail. A torque converter box is a large, heavy, robust thing that most people never touch. A dual clutch box has clutches that wear like a manual's, plus a mechatronic control unit that is a known expense on some models. A CVT relies on a steel belt or chain under enormous pressure and is very sensitive to fluid condition. None of this is a reason to avoid any of them, but it is a reason to find out which one you are buying.
Step by step
- Find out what your car actually has.The handbook says, and manufacturers' badges hint: DSG, S tronic, PDK, DCT, Powershift and EDC are dual clutch; CVT, Multidrive, Lineartronic and e-CVT are continuously variable; ZF 8HP, Tiptronic and most torque converter boxes are simply called automatic. Automated manuals were often badged with names like ASG, Easytronic or Selespeed.
- Recognise a torque converter box by how it creeps and shifts.It creeps forward smoothly at idle, changes gear with a soft blur rather than a click, and slurs when you accelerate hard. Modern eight and nine speed versions are extremely good. They are the most tolerant of stop-start traffic and towing, and the most common on larger cars.
- Recognise a dual clutch by its speed and its low-speed manners.Shifts are almost instant because the next gear is already selected on the second clutch. The trade-off is at walking pace: many are slightly jerky pulling away, can hesitate in a slow-moving queue, and dislike being held on a hill with the accelerator instead of the brake.
- Recognise a CVT by the absence of gearchanges.Accelerate hard and the engine rises to a fixed speed and stays there while the car catches up — the effect people call rubber-banding or droning. Many now simulate steps to feel more familiar. They are efficient and very smooth in town.
- Recognise an automated manual by the pause.A distinct interruption in drive at every gearchange, with the car nodding. Mostly found on older small cars and some vans. Cheap to make, and they feel it. Not a reason to reject a car outright, but do drive it in traffic before buying.
- Learn what tends to fail on each.Torque converter boxes: the converter lock-up clutch and the valve body, usually gradually. Dual clutch: the clutch packs as a wear item and the mechatronic unit. CVT: belt or chain wear and fluid degradation. Automated manual: the clutch and its actuator. In every case, fluid condition is the biggest single lever the owner has.
- Test drive deliberately for the type.For a dual clutch, spend real time in slow traffic and on a hill start, not just on an open road. For a CVT, accelerate hard from about thirty and listen for whine or shudder. For a torque converter, feel for shudder at light throttle around fifty, which is the lock-up clutch. For any of them, a warning light or a delay before drive engages is a walk-away.
- Ask about the transmission fluid history.This is the single most useful question about any automatic gearbox on a used car, and the one most sellers cannot answer. "Sealed for life" is a manufacturer's warranty position, not a mechanical fact, and independent specialists are near-unanimous that changing the fluid on schedule extends these boxes considerably.
Common mistakes
- Holding a dual clutch car on a hill with the accelerator — It slips a real clutch to do that, exactly as riding the clutch does in a manual, but with an expensive automated clutch pack. Use the brake or the hill hold function.
- Assuming any automatic is the same to own — The maintenance needs and failure costs differ by a large factor across the four types. A dual clutch on a hard-worked car in city traffic is a different ownership proposition from a torque converter box on a motorway commuter.
If it doesn't work
Dual clutch hesitates or lurches in slow traffic
Cause: Normal characteristic, or clutch wear if it is getting worse — Fix: A degree of it is inherent. Increasing jerkiness, a shudder when pulling away, or a burning smell after heavy traffic means the clutch packs are wearing and need assessing.
Shudder at light throttle around fifty in a torque converter box
Cause: Torque converter lock-up clutch judder, often from degraded fluid — Fix: A fluid and filter change resolves a proportion of these if caught early. Left long enough, the debris damages the valve body.
CVT whines or shudders under acceleration
Cause: Belt or chain wear, or fluid past its life — Fix: Get the fluid checked immediately — CVT fluid is specific and its condition matters more than in any other box. A whine that is getting worse is not something to defer.
Delay of a second or two before drive engages
Cause: Low fluid, internal wear or a valve body problem — Fix: Have it diagnosed promptly. This is one of the classic early symptoms and it does not improve on its own.
Gearbox warning light and the car locked in one gear
Cause: The box has gone into a protection mode — Fix: This is limp mode for the transmission. Get somewhere safe, restart once, and have the codes read. Often a sensor or overheating rather than the gearbox itself.
Questions people ask
Which type is the most reliable?
A well-maintained torque converter box, generally — it is the oldest and most developed design and is used where durability matters, including in tow cars. That said, reliability varies far more by specific model and by fluid history than by type, so research the exact gearbox in the exact car.
Can I put a dual clutch in neutral at traffic lights?
Most manufacturers say it is unnecessary and to leave it in drive with the brake on. Repeatedly selecting neutral and drive adds wear to the actuators for no benefit. On a long wait, applying the parking brake and selecting neutral is reasonable.
Do automatics really use more fuel?
Not any more. Modern eight and nine speed torque converter boxes and dual clutch boxes frequently match or beat the equivalent manual on official figures, because they keep the engine in a better place than most drivers do.