A clutch delay valve is an automotive component added to the

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

system of an automobile to standardize clutch engagement speed. Its purpose is to engage the

drive train A drivetrain (also frequently spelled as drive train or sometimes drive-train) is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering, the drivetrain is the components o ...

of an automobile without introducing shock to the drive train components by engaging too quickly. By preventing drive train shock, CDVs also prevent an automobile's balance from being upset, which aids in handling characteristics. Clutch delay valves operate on the principle that engagement only needs to occur at a certain rate to be efficient and that engaging at a quicker rate can damage the drive train components of an automobile. Engaging the drive train to the engine too quickly can damage

parts, including the

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...

, differential,

half shaft An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearin ...

axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...

s, and

CV joints Constant-velocity joints (also known as homokinetic or CV joints) are mechanical joints which allow a drive shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. They ...

. Engaging the drive train too slowly can damage the clutch friction disc and cause clutch slippage. Clutch delay valves operate as one-way restrictor valves that limit the volume of fluid that can move through the lines in a given time. This ensures a steady quick and firm engagement without being too fast for the drive train to handle since clutches can quickly disengage but re-engagement is damped. The clutch delay valve slows clutch engagement and was intended to reduce drivetrain shock in the event that an inexperienced driver quickly engaged the clutch at higher revs. BMW have used clutch delay valves on the E39 and E46 models, and others, from 1997. These valves have been unpopular with some drivers and they are sometimes removed to leave a conventional clutch action. The BMW valve is a separate pipe fitting and easily removed.

Honda is a Japanese public multinational conglomerate manufacturer of automobiles, motorcycles, and power equipment, headquartered in Minato, Tokyo, Japan. Honda has been the world's largest motorcycle manufacturer since 1959, reaching a product ...

have also used such valves on some

Civic Civic is something related to a city or municipality. It also can refer to multiple other things: General *Civics, the science of comparative government *Civic engagement, the connection one feels with their larger community *Civic center, a comm ...

models, but these are integral to the clutch slave cylinder and must be dismantled ''in situ''.

References

{{Reflist, refs= {{Cite web , title=Clutch Delay Valve (CDV) Modification , author=Dave Zeckhausen , website=Zeckhausen Racing , url=https://www.zeckhausen.com/catalog/index.php?cPath=6562 {{Cite web , title=Clutch Delay valve Removal , year=2013 , website=Honda Civic 9th Generation , url=http://9thcivic.com/forum/threads/clutch-delay-valve-removal.8624/ Valves