Thread: CDV DIY Compilation
12-14-2010, 06:47 PM #1
CDV DIY Compilation
I thought since the modification and/or removeal of the stock CDV (Clutch Delay Valve) was a pretty common topic I'd combine some of the information floating around and put it up. So here we go:
What is the CDV and why should I get rid of it?
The Clutch Delay Valve (CDV) is a one-way restrictor installed by the factory between the clutch slave cylinder and clutch master cylinder. It "delays" the engagement of the clutch, much like old record players use a damped tone-arm to gently lower the needle onto the surface of a record.
Because of this valve, no matter how quickly you lift your foot off the clutch pedal, the clutch engages the flywheel at a constant (slow) rate. In theory, it can save the driveline from shock, were an inexperienced (or immature) driver to dump the clutch. But in practice, all it does is prematurely wear out the clutch and turn experienced drivers into people who, despite years of practice, cannot shift smoothly. During parallel parking maneuvers, the delay can be infuriating, causing constant clutch slippage. And during hard acceleration, the slippage can greatly shorten the life of your clutch. During normal, sedate driving, the shift from first into second gear is often jerky, leading passengers to question your skill. As the driver, you can see your passengers' heads bobbing back and forth during every shift! Yes, in their minds, they are laughing at you. (taken from here
Let Me See this So Called Restriction
Modified CDV vs. Removal
If you remove the CDV entirely you will have removed all restriction in the clutch engagement chain and your clutch will move exactly the way you (via the pedal) tell it to. The downside is you have just modified your driveline in a way that is easily found via a visual inspection. The effect this has on your warranty service is arguable however what is not is that you've just given them something to argue with you about if you have a claim.
If you use a modified CDV (DIY or purchased here, here, or here) you will get the majority of the benefit of removing the CDV entirely while still maintaining a stock appearance. This is the option the majority of users choose.
The DIY (Do It Yourself)
Required Time: 15 to 45 minutes depending on tools, experience, and loss of brake fluid
Required Tools: Jack/Ramps (with required safety devices), 8mm socked wrench, small slotted screwdriver, C-Clamp or Vise Grips, catch pan for brake fluid
Suggested Tools: Brake Fluid, Brake Bleeder Kit, small allen key, hammer
1. Get under the front of the car via your preferred method (ramps, jack, lift). Use appropriate safety measures such as jack stands, chock blocks, etc.
Do this at your own risk
2. Remove approximately seven 8mm screws that hold the center underpanel in place. Rotate the panel to remove it from the retaining clip. This should be the one under the transmission, with the air vent in it.
the panel removed
3. Locate the CDV. It will be right beside the transmission. Depending on year, xi/i, etc it may look different but should be very similar to this.
with CDV already removed
4. Clamp the Hose side of the CDV. Suggested options are a C Clamp or Vise Grips with some type of padding. It will take some force to stop the brake fluid from leaking out, however you need to be careful not to cut or otherwise damage the line. Err on the side of too little pressure as you can (and will probably need to) add more brake fluid.
5. Release the clips from the CDV inlet, and the CDV outlet. Do this by rotating the CDV so you can access the clips with your screwdriver.
Location of clips
Closeup of how to remove the clips
6. Now that the CDV is released you can remove it. One you disconnect the CDV brake fluid is going to drain from both connections. It will stop after a moment if your clamp is tight enough, but either way moving quickly is best. If you are going to remove the CDV just connect the hose where the CDV just was and you're done. If you purchased a modified CDV, put it right were the stock one was using the clips.
-To modify your stock CDV just put the larger side of the CDV down on a workbench, put a small allen key into the top (small end), and tap until a little metal ring drops out. You will feel it release. In my case I did not need the hammer as it just fell free when I pushed down.
7. Check your clutch pedal for operation. If it falls to the floor or feels 'spongy' you need to bleed your line. The simplest method is to go to the engine bay and add some brake fluid (DOT 4) to the reservoir and pump the clutch. Keep in mind the reservoir is divided and even if it looks 'full' you need to make sure it is fully topped off so your clutch will get the fluid, as I learned this the hard way. Repeat adding and pumping as necessary. If you are still having clutch pedal problems you need to use a brake bleeder. Reply here or google that if required.
Location of reservoir
8. Replace the aerodynamic underpanel.
All credit for the pictures goes to Bill's Webspace as I apparently lost all of mine. The guide I originally used is by EvanL
12-14-2010, 11:25 PM #2
Thread stuck, this is very useful. Thanks for putting this compilation up.Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale: http://www.boostaddict.com/showthrea...r-kit-for-sale
02-10-2013, 06:25 PM #3
I didn't modify mine, I simply removed it. If for some strange reason I wanted to go back to stock, you could then add it back in, but the CDV sucks, and I threw it away.
03-12-2014, 03:41 AM #4Member
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