Clutch
Flex Plate
A flex plate connects the crankshaft to the torque converter on vehicles with an automatic transmission and carries the ring gear the starter turns. We carry 36 flex plates from $23 to $455 for 1963-2023 vehicles, from ATP, Pioneer Cables and B&M, with fits for the Chevrolet Impala, S10 and Silverado 2500 HD, Ram 2500 and Nissan Altima.
Shop flex plate by vehicle
Signs of a cracked flex plate
A cracked flex plate often makes a knocking or clunking sound from the area between the engine and transmission, which changes with rpm and can sound like a rod knock. Other signs are a grinding or whirring noise when starting from damaged ring gear teeth, a starter that spins without turning the engine, and vibration. Loose torque converter bolts can cause similar noises, so check them while you are inspecting the flex plate.
Choosing the right plate
Flex plates are engine specific. Check the balance type: internally balanced engines use a neutral plate, while externally balanced engines need a plate with weight added. Some plates are made for engines with a one-piece rear crank seal and others for a two-piece seal. Tooth counts such as 153 and 168 must match your starter, and dual pattern plates fit more than one converter bolt pattern. SFI approved plates are certified for racing use where required.
Installation notes
Choose your year, make and model and check the fitment table for engine and transmission. The transmission must come out or be moved back, so support the vehicle securely on stands and support the transmission with a suitable jack. Use the correct crank bolts with thread locker if specified, and torque them in a crisscross pattern. Make sure the converter is fully seated in the pump before bolting it to the plate, then torque the converter bolts.
Flex Plate questions
What is the difference between a flex plate and a flywheel?
A flex plate is a thin plate used with automatic transmissions to connect the crank to the torque converter. A flywheel is a heavy disc used with manual transmissions that also serves as the clutch friction surface.
Can a cracked flex plate sound like a rod knock?
Yes. A cracked flex plate or loose converter bolts can knock in time with engine speed, which is easy to confuse with a rod knock. Inspect the plate through the inspection cover before assuming engine damage.
How do I know if my engine needs a balanced flex plate?
Check the fitment table and the engine's specifications. Externally balanced engines need a plate with a counterweight, while internally balanced engines use a neutral plate. Using the wrong one causes vibration.