Quantitative measure of CDV on Z4

[igeak691]

I'm not here to argue that removing a CDV is a good idea or not, we've seen plenty of times and conclude that removing the CDV is a good idea if you know how to drive stick, as it only impedes spirited driving and our skill.

My question really is how much does the CDV slow down clutch engagement? Is it on the scale of milliseconds? Surely it isn't one second long, which would be absurdly long. But has anyone quantified how much slower it causes clutch engagement?

Also on the same note, when people test these cars, wouldn't having the CDV slow down 0-60 times? So the advertised times for our cars would actually be a little less? Probably a minuscule difference there though.

 

[Adamski]

I suspect that the time lag will be around 0.2 seconds. Or that's what it feels like


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[srhutch]

I suspect that the time lag will be around 0.2 seconds. Or that's what it feels like


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It will be quicker in an ///M of course :lol:

 

[dario]

As i understand the CDV system its there to stop you giving it 7,000 revs and dumping the clutch. the CDV will progressively let the clutch out because it restrict the flow of hydraulic oil back from the clutch cylinder to the master cylinder. in this way the clutch will not fully engage like a switch it will progressively (over what time span i don't know) but it will be in the millisecond range.

BMW therefore don't get wrecked drive trains, just clutches, which are not covered under warranty LOL.

 

[Montjeu]

I dumped my CDV last week, and quite honestly cannot sense any difference whatsover (on a 2.5Si). Perhaps because I'm driving as if it is still there.

 

[dario]

When I had my e85 it was all evident in the pull away. I used to find when pulling away on a slight incline and with some lock on, the bloody thing would kangaroo.

It made me feel like I was novice driver and not driving for 25 years at that time.

 

[Adamski]

CDV removal was one of the best mods in my 3.0i

Will do the same with my current zed when the warranty goes...

 

[srhutch]

I dumped my CDV last week, and quite honestly cannot sense any difference whatsover (on a 2.5Si). Perhaps because I'm driving as if it is still there.

Was like night and day when I did mine.

It could be that it had already been removed, but they left the valve in like I did. If you have the valve see if you can push a drill bit through that is the same size as the main bore.

 

[itguy]

Interesting, I didn't really notice a difference on my 3.0i when I removed the CDV.

Maybe I'm not trying hard enough from the lights!!

 

[Montjeu]

I dumped my CDV last week, and quite honestly cannot sense any difference whatsover (on a 2.5Si). Perhaps because I'm driving as if it is still there.

Was like night and day when I did mine.

It could be that it had already been removed, but they left the valve in like I did. If you have the valve see if you can push a drill bit through that is the same size as the main bore.

Highly unlikely to have been modified already, possible but the car was completely stock on purchase. I should have a Storm gear knob to fit on Saturday so look forward to seeing how those two forum recommended mods enhance the gear changes.

 

[Montjeu]

Fitted the Storm today and together the mods seemed to have improved changing gear procedure significantly. I had a great opportunity to test the launch 'all out' in a safe manner and it was very smooth. I did have trouble selecting first gear at one point

 

[igeak691]

Today I did a clutch stop, so with the combination of the ZHP short shift knob along with the clutch stop its pretty good already. Now I can't wait to remove this CDV. Is the bleeding procedure hard? Any guides on how to do it?

 

[Montjeu]

There's a How To on this forum, which is mainly about modifying the CDV. I just decided to get rid of it. And handed this to my mechanic

http://forum.e46fanatics.com/showthread.php?t=763107

 

[mcbeee]

I could bounce the front end of my M3 like a Mexican low rider .... :thumbsdown: :thumbsdown: :thumbsdown: