Wednesday, December 4, 2013

Lotus Clutch Delay Valve

Have you noticed a slight delay when quickly shifting your Lotus S240/S260?  A clutch delay valve is installed, by the factory, on the ‘08+ S240 & S260 models.  This little one-way restrictor is plumbed in before the clutch slave cylinder; it’s job is to limit the amount of fluid that passes through it when you release the clutch pedal.  It ‘delays’ the engagement of the flywheel and clutch to a pre-defined rate – this is not a pleasant ‘feature’ when you are driving the car aggressively!   Keeping this in a car that is track driven can increase clutch wear by constantly slipping the clutch at every shift.

You can find this delay valve with the undertray removed.  It is located on the firewall side of the engine, down low.  See it in place above.

Luckily, there is a fix – straight from Lotus.  Clutch Pipe C120Q0003F is the same shape clutch line without the delay valve built in! A great time to install this bit is to do it while you are flushing the brake fluid – the clutch and brakes share the same reservoir.  Bolt it on, bleed the clutch, and enjoy some positive clutch engagement!

Recognize that there is a trade-off...Why did Lotus fit such a device to these models?  Our guess is to protect the transmission.  This delay valve will limit the shock transmitted to the transmission by these more powerful engines.  The stock transmission durability is severely compromised as power starts to exceed 270hp.  Lotus have to deliver cars with warranties and replacing transmissions gets very costly.  Other OEs, like BMW, also employ the same trick.  If you remove your stock delay valve and run on track with slicks, expect more frequent trans rebuilds - especially if you have also added more power!