Have any of you done the CDV delete?

[aurelius]

I realize the OP has an E90 but FYI not all manual-trans E46's came with a CDV.

Neither of mine ever had one but my E39 did and removal is highly recommended. Unlike what some have posted above, for me the biggest improvement was in low speed parking situations where you're on & off the clutch pedal in 1st gear & reverse. Should be mod #1 on any model that has it.

[kayger12]

I realize the OP has an E90 but FYI not all manual-trans E46's came with a CDV.

Neither of mine ever had one but my E39 did and removal is highly recommended. Unlike what some have posted above, for me the biggest improvement was in low speed parking situations where you're on & off the clutch pedal in 1st gear & reverse. Should be mod #1 on any model that has it.

Yeah, I think I read that they started putting them in with the e46 facelift.

Droid X. Tapatalk. Use it.

[RITmusic2k]

for me the biggest improvement was in low speed parking situations where you're on & off the clutch pedal in 1st gear & reverse. Should be mod #1 on any model that has it.

Hmm, that brings up a bit of detail that I may have left off my reply - the CDV's effects aren't based on vehicle speed, only on clutch pedal travel speed. So during parallel parking or other low vehicle speed scenarios, I can see how it could still come into play - especially if you quickly 'pulse' the clutch pedal, or really do anything at all that would exceed its restricted flow rate.

[aurelius]

Yeah, I think I read that they started putting them in with the e46 facelift.

I test drove a 330 in summer of Y2k and it def had a CDV. Didn't know what it was at the time but I never forgot that terrible clutch action.

[kayger12]

I test drove a 330 in summer of Y2k and it def had a CDV. Didn't know what it was at the time but I never forgot that terrible clutch action.

Hmm. Maybe it was when they started putting the M54 in. I remember there was a specific point that they started using them, just can't remember when.

[328ioc]

Hmm. Maybe it was when they started putting the M54 in. I remember there was a specific point that they started using them, just can't remember when.

+1 When I was driving my E36 there was a random point there that that started putting it on certain cars also.

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[Oli77]

I have not done a CDV delete for several reasons:

1. I am used to it now after driving the car for ~2 years.
2. I have a throwout bearing going bad and I would rather clutch engagement be more slow and gentle.

[wsmeyer]

I'm going to throw my 2 cents in:

I had it in the back of my mind for a while after reading about it in several different forums. A few months back I bought a UUC short shifter so I was under the car anyway and finally got around to removing it. It's simple enough to do, just remove it and put the line back and bleed it. I'm an old school bleeder kind of guy, I've tried the power bleeders but I don't believe they do as good of a job as the old fashioned two person approach. So I get in the car and push the pedal to the floor, my buddy opens up the valve to let all the pressure out, and closes the valve. When I lifted my foot off the pedal and watched it come back up ever... so... slowly... I realized it was all a waste of time. Our cars don't use a return spring to bring the pedal back up, when you release the clutch it is the force of the pressure plate pushing the hydraulic fluid back up into the master cylinder that pushes the pedal back up. If the valve is restricting this flow, then it would also be limiting the speed at which the pedal comes back up. Other than intentionally side stepping the clutch, I personally have never, in any car, released the clutch so fast that my foot came off the pedal before it reached the upper travel stop. Which means that for me, the speed at which the clutch disengages is being limited by my foot speed, NOT the speed of the fluid traveling through the CDV.

So why do people swear it makes a difference? In my opinion, the only explanation is that the difference they are feeling is due to bleeding the line and not the removal of the valve.

The next time I'm under my car I will probably put mine back in. I do on occasion get into my car after stepping in water or snow, so while it has happened yet, there certainly is a possibility of my foot slipping off the clutch, and if that happens just as the synchro's are meshing, the CDV could be the difference between a stalled engine and a completely destroyed transmission.

I know this goes against what everyone else is saying but it was my experience and only my opinion, I certainly don't have any scientific testing to back it up and "your mileage may vary".

It would be interesting though if someone that hasn't done it would try just bleeding their line first, get used to that, and then remove the valve and see what they experience.

William.

[zj96sc]

So....if that is the case, why is the CDV there at all?

[zhp43867]

I'm going to throw my 2 cents in:

Very interesting post but I can't say I agree. I did not bleed the line when I installed the CDV, and it made a huge difference. I actually just bought another ZHP with a CDV and the difference is readily apparent. Situations where I notice it the most:

- Low speed 1-2 shift is easier to make jittery with the CDV
- Take off is more often jittery in 1st with the CDV
- Clutch reengagement is rarely ever seamless with the CDV especially at lower speeds, reengaging say, 2nd gear at 35mph.
- Hard WOT 1-2 shifts are noticeably jerkier.

I think all the above scenarios are when I am using the clutch pedal the "quickest". For example when I reengage 2nd, I may be behind someone slowing down and turning and I'll push the clutch pedal in, once they are out of the way I will rapidly blip the throttle to the appropriate RPM and let the clutch out quickly as well. Here the CDV seems to make the car jitter way more than when it is not present.

Oli77: Throw out bearings go bad more often due to improperly leaving your foot on the clutch pedal- while in gear or in neutral- or from not releasing the clutch all the way. Are you sure that isn't what killed your clutch?

The CDV was originally there to prevent people who are inexperienced or just bad at driving a stick from destroying a clutch in 40k miles. It lessens the wear on the clutch if you dump it or- for a new driver- rev too high and burn the clutch.