Torque converter lockup shudder

A vibration felt while the torque converter's lockup clutch is engaging.

Also called: TCC shudder · lockup shudder · converter shudder

What it means

Definition

A torque converter couples engine to transmission through fluid, which is what lets the engine idle in gear. Inside it sits a lockup clutch that clamps at certain speeds to remove that slip — LuK describes lock-up clutches with dampers as used to bypass the torque converter and minimize the losses due to slip. Shudder is a vibration felt while that clutch is partly engaged rather than fully in or out.

Why a buyer cares

What it changes

It shows up at steady light throttle rather than under hard acceleration, which is exactly the part of a test drive people skip. Manufacturers have published bulletins on it for named models: Toyota's covers some 2012–2014 Camry vehicles with a U760 transmission exhibiting a brief shudder under light loads.

In practice

Where you meet it

Felt at cruise on a test drive, and written on estimates as TCC or converter shudder.

Two things that look alike

Not the same as

An engine misfire and worn mounts produce a similar vibration at similar speeds.

Where this comes from

Sources

The Toyota bulletin bounds one model, transmission and year range. It says nothing about how common the condition is elsewhere.