CDV ... do it...

[Black///Mamba]

Originally Posted by nickpapa

not trying to start a fight or anything, just clarifying that i was one of the "not much of a difference" guys and i completely removed the CDV. I didnt replace it with a modified one.

and yes def bleed the line. i clamped my line and a few drips came out but when i bled it i definitely got some bubbles coming out.

what kind of issues can arise if you do not bleed the clutch line?

[nickpapa]

Originally Posted by Black///Mamba

what kind of issues can arise if you do not bleed the clutch line?

its not so much like something bad will actually happen, its more of just not moving the fluid correctly.

its kinda like drinking soda out of a straw that has a hole on it at the very top. when you suck up you get air/soda coming in rather than straight soda. a little confusing analogy but thats the best i can think of lol

basically (and this goes for brakes as well), the pedal feel will not be as responsive compared to a line that was correctly bled. I never had an issue with air in a clutch line so im not sure how different that would feel, but with air in brake lines it is a night and day difference.

[chris719]

I just had it done earlier today on my M roadster and I can say that it is a very worthwhile modification. It was immediately noticeable and would be noticeable in a blind test also. Mostly, the difference is that there is no more "lag" in engagement, so you can properly feel where you are. Biggest differences are in low speed stuff (parking / reverse and the 1-2 shift). My clutch pedal also seems very slightly lighter, but this might be a mental thing. Overall, everything feels like it works the way it should have from the factory, much smoother.

[thekurgan]

Great observations, I too, have notice that in the cold weather, there is absolutely no more horse-bucking action, even while shifting slowly and clutch engagement is much better modulated as well as lighter. So far, my best mod.

[Mikewarlover]

I had my cdv modified few days ago and the effect was very big and dramatic much more than wat i was expecting. Do it

[jmillet]

Just finished circumcising the clutch line on a 2008 Sepang Bronze Metallic (color looks much better in person than in pictures) Z4MC with 7000 miles on the clock.
One trick to not losing much brake fluid and minimizing air in the line is seal the reservior cap with Saran Wrap. A wooden golf tee also works well to plug the slave cylinder side of the line while removing the CDV. After reconnecting the clutch hose sans CDV I pressure bled the system at the slave cylinder using a Motive Power Bleeder. Pumped up the clutch pedal several times during the bleeding process and when complete we had a firm clutch pedal and no clutch delay.
Total cost: one hour of my sorry a$$ retired time and some brake fluid.

[MMMazing07]

Originally Posted by jmillet

Just finished circumcising the clutch line on a 2008 Sepang Bronze Metallic (color looks much better in person than in pictures) Z4MC with 7000 miles on the clock.
One trick to not losing much brake fluid and minimizing air in the line is seal the reservior cap with Saran Wrap. A wooden golf tee also works well to plug the slave cylinder side of the line while removing the CDV. After reconnecting the clutch hose sans CDV I pressure bled the system at the slave cylinder using a Motive Power Bleeder. Pumped up the clutch pedal several times during the bleeding process and when complete we had a firm clutch pedal and no clutch delay.
Total cost: one hour of my sorry a$$ retired time and some brake fluid.

[ChiefRes]

Does anyone else find it absolutely ridiculous that BMW puts the CDV on cars at all? I love my Z4M Coupe, but I find the shift action (particularly the 1-2 shift) appalling.

I did the 2 day Porsche Sport Driving School in Birmingham in October, and all I kept thinking on the track was how much better the Porsches shifted.

[Mikewarlover]

Yea its amazing why they put CDV on the M it totally ruins car. With the CDV modified the car now shift much more smoothly.