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Completed 4/28/2004

Replace stock Clutch Delay Valve with modified Zeckhausen unit.


11mm Flair Wrench
15mm Wrench
Clear Rubber Bleeder Hose and Bottle
Brake Fluid

Most modern manual transmission BMWs come with a Clutch Delay or Lock Valve (CDV). The purpose of this valve, according to BMW, is to smooth out shifts and extend the life of driveline parts. It functions by only allowing hydraulic fluid to pass through it at a certain rate. Since it is inline on the clutch system, it effectively removes the ability to control your clutch use manually. It was designed to make the car nicer to drive for the average person. If you are reading this, you are not that average person! The CDV "dumbs" down the clutch pedal feel, and under hard driving, will actually cause the clutch disc to wear out *faster* due to slower engagement at high speed.

Thanks to the great people over at Zeckhausen Racing, they will provide BMW owners with a modified CDV for a small price, or modify one you send them, or provide you one for *free* if you send them two (2) stock original CDVs. Zeckhausen safely removes the internals of the CDV (without drilling) allowing it to go back into factory OEM location but now without interfering with clutch operation. These are modified factory parts and look, feel, and fit the same as your existing stock valve.

1. Park the car on a level surface and set the parking brake.

2. Jack up the front of the car and support it with jackstands.

3. Right forward of the clutch slave cylinder is a mounting point for the hydraulic line. The clutch delay valve can be see here both in and out of the car (Photos A & B).

4. I used a small plastic pair of locking pliers to crimp the rubber supply line about 3" away from this mount. This will keep excess fluid from draining out when you remove the CDV.

5. Using a 11mm Flair Wrench, disconnect the metal piping from CDV and pull the CDV from the bracket. A Flair Wrench grabs a nut/bolt on all six sides and is specifically designed to remove brake line and other hose nuts (Photo C). Be sure to use the correct tool for the job!

6. The CDV can then be removed from the supply line with a 15mm Wrench.

7. Replace with the modifed CDV and reconnect the lines. Hydraulic lines are flaired and need to be snug, but not overly tight.

8. Remove the hose clamp and prepare to bleed the clutch slave cylinder.

9. Open the hood and check that you have plenty of brake fluid in the master cylinder. The master cylinder feeds both the brakes and clutch system (Photo D).

10. Remove the rubber nipple on the slave cylinder bleeder screw (Photo E). Attach a length of rubber tubing and run that tubing into a small clear container filled partly with fresh brake fluid. You want to keep the end of this hose submerged at all times to keep air from creeping back into the system.

11. Attach a 8mm wrench to the bleeder valve and have a friend pump the clutch pedal a few times and then hold it down.

12. Open the bleeder for just a second. You will see the bubbles and fluid shoot down your rubber hose. Close the bleeder.

13. Have your friend pump the clutch pedal again and hold it. Again, crack the bleeder for a short period and close it.

14. I only needed to do this 3 times and I no longer saw bubbles. The system was now bled. If you have to do it more times than this, be sure to check on the master cylinder level periodically to make sure you have plenty of brake fluid and top off as needed.

15. Replace the bleeder nipple, check your connections for leaks, and go take it for a drive, you will notice the difference immediately!


Photo A

Photo B

Photo C

Photo D

Photo E


What a incredible change! If you were like I was and couldn't nail a smooth 1-2 shift very often, your evil CDV is to blame! Now the clutch responds quickly and exact. No more moving clutch points or burning of the clutch during speed shifts. For someone who has driven manual since day one, from street to track, this is the way every other clutch is already and the way BMW should always have been. No more CDVs!

If you think you currently have one, you won't regret taking it out. Not once.

  © MarvelPhx