Transmission and drivetrain
Automatics, manuals, clutch, torque converter, differentials. ← Browse sections
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Clutch judder from a standstill: what it is telling you
A shudder as you pull away means the clutch is not engaging evenly. The cause is sometimes the clutch and often something around it.
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Crunch on downshift: synchros, clutch drag or oil
A crunch going into a lower gear usually means the clutch is not fully releasing, not that the gearbox is worn out. The distinction is worth several hundred.
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Humming that rises with speed: bearing, tyre or driveline
Three causes, and a free road test that separates them. Doing that test first stops people buying tyres for a bearing problem.
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Manual gearbox will not go into gear: clutch or linkage
Whether it refuses every gear or only one narrows the cause immediately. A clutch that will not release and a stretched selector cable feel similar and cost very differently.
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Clunk when shifting into drive: mounts, backlash or gearbox
Some clunk is normal — drivetrain slack has to be taken up somewhere. Telling normal slack from a worn mount or a failing gearbox comes down to timing and repeatability.
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Automatic gearbox slipping: what to check before a rebuild quote
Revs rise, speed does not. Before accepting a four-figure quote, three checks separate a fluid problem from a worn clutch pack — and they are all cheap.
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Whining noise when accelerating: belt, pump or gearbox?
Whether the pitch follows engine speed or road speed is the entire diagnosis. One test in a car park separates a cheap belt from an expensive differential.
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The car will not move in Drive: gearbox, fluid, or limp mode
Selector in D, engine running, car stationary. The causes from fluid level to limp mode, and what to check first.
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Reverse will not engage: manual gearboxes and what goes wrong
On most manuals reverse has no synchroniser — which is exactly why it crunches. The causes and what to fix.
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The clutch pedal went to the floor: hydraulics, not the clutch
A pedal that suddenly drops almost always means hydraulics rather than the disc. The cylinders, the fluid, and what to do on the road.
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Automatic or manual: cost of ownership without the ideology
The question is decided by the specific design and your route, not by the gearbox type. The automatic types and what each costs to run.
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Shuddering at low speed: adaptations, clutch, or engine mounts
Jerkiness in traffic on a dual-clutch gearbox more often means lost adaptations than wear. The causes and the order of checks.
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Differentials and transfer cases: the units people remember after the whine
Axle and transfer case oil has a schedule that quietly gets skipped. Wear signs and why mismatched tyres destroy four-wheel drive.
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The CV boot: a cheap rubber gaiter the whole driveshaft depends on
A crack in a boot turns a cheap repair into a new driveshaft within weeks. The signs, the timescale, and why it cannot wait.
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Automatic transmission fluid: "filled for life" and the other myths
A "lifetime fill" means the life the manufacturer assumed, not yours. When to change it, how a partial change differs from a full one, and why the fear is misplaced.
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Clutch nearing the end: the signs, the checks, and the driving habits that cause it
A clutch rarely dies suddenly. The early signs, two checks that need no ramp, the difference between manual and dual-clutch units, and what diagnostics sees.
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Towing a car with an automatic: why "just a hundred metres" sometimes costs a gearbox
On a manual, towing is a question of having a rope. On an automatic it is a question of the lubrication pump, which only runs with the engine running. The limits and the safe options.
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Transmission will not shift: limp mode, fluid, and what to read before the workshop
The automatic is stuck in third, the manual will not select a gear, the dual-clutch judders. Diagnosis by transmission type, why fluid is usually to blame, and what to read before clearing anything.
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Torque Converter Diagnostics via OBD-II: P0741, TCC Slip, Live Data
How to diagnose automatic transmission torque converter through OBD-II: P0741 TCC lockup slip, P0740 solenoid, Live Data slip percentage — step-by-step without disassembly.
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ATF and the automatic: how OBD-II sees the trans, and when it's really time to change the fluid
What OBD shows about AT: codes P0700, P0741, P0742, adaptation values, ATF temperature, why "sealed for life" is a marketing myth, and how to diagnose slip.