Quote:
Originally Posted by M235ForNow
I did the CDV mod in both of my Z3's. It certainly made a positive difference. The CDV valve is just a restriction and doing the mod just means drilling the hole bigger, or replacing the valve with a length of "not restricted" tube. In my case I ordered a modified DCV (drilled) and swapped it with the original. The user control of the clutch engagement is much enhanced for fast shifting. If you're shifting slowly there's no particular effect. The purpose of the CDV to just to protect the system from someone who is shifting "too fast" and not coordinating the clutch/throttle properly by enforcing "slow" due to the restricted opening. In other words, avoiding warranty repairs from inexperienced manual transmission users by not letting them hurt the tranny at the expense of reduced control for those who DO know how to shift.
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Good feedback, thanks.
Many improvements were mentioned in the forums doing the CDV delete. I like all of them. Just wonder how many make a noticeable difference. If it is only affecting fast shifting it wouldn't be so interesting to me.
Quotes from the f30 thread:
- You can feel a difference in driving immediately, i used to hate the 1st to 2nd shift, but it transitions so smoothly now.
- Clutch pedel feels less resistance towards the end of its travel.
- Grabs harder and downshifts are more precise too.
- Understand that the CDV delays clutch engagement by limited the flow of fluid. Without it you now have complete control of the clutch.
- Thank you! For figuring this out. Made an account just to say so. The clutch was just about my only gripe with my f32. Now it is worlds better. The car will lug around in low gears and when on the highway will over take quicker. First gear takes off like a Normal car without the hesitation of the clutch delay.To those debating the outcomes. If you intended to drive the car with any type of gusto(like you should be) then do it. Don't let this pedal instill bad habits. Downshifts are now possible and she kicks out better than ever.
- Hell yea! Glad you did the mod. I love my car a lot better now. It also makes for a much easier driving experience.
- This really is different .. downshifts in particular have been amazing, every time. Can't even feel it. This is a nice gearbox all of a sudden.
- Along with a perfectly responsive clutch pedal and no more unnecessary slippage, you get a lot more feedback through the clutch pedal. I also have the clutch pedal return spring removed from my car so the pedal is very firm and I can feel everything that's going on. I think I finally understand why the CDV is there, it does improve smoothness by filtering out some of what the fluid could be telling you through your foot but I am much, much happier this way. If you like your clutch pedal to be as soft and smooth as possible, you'll probably be happier with the CDV left alone.
- For sure the best thing I've done to the car. I notice the downshifts are super quick and smooth, less noticeable change on the upshifts for me, but for sure improved.
Not positive:
- Ok, I only asked because people talked about it being a must mod on the e46 m3 and I did it on mine after about a year of driving it with the cdv in tact and noticed like no difference whatsoever.
I think sometimes with this stuff people sort of hype it up like it is something super noticeable when it really isn't and just get the ol placebo effect.