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Eliminating the dreaded Clutch-Delay Valve

Discussion in 'E85/E86 Z4 M roadster/coupe (2006-2008)' started by Satch, Oct 30, 2010.

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    Satch SoSoCalifortified

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    Okay: I am finally a member of the Hydraulic Fluid In The Armpits Club. That is, I finally got around to yanking out the CDV and replacing it with a bored-out version from Zeckhausen.

    In the Z4 M roadster, it's a ridiculously simple procedure. Click here to read a discussion of the advantages and procedures on other models; you can read Zeckhausen's analysis of the situation here.

    I noticed the difference within a block of La Jolla Independent, where Carl Nelson kindly allowed me enough lift time to perform this minor surgery. I no longer feel like a fourteen-year-old trying to master his first manual transmission! Best of all, the "ka-chunk" engagement of second gear---which I believe will eat the synchros sooner than later---seems to be significantly diminished.

    Michael Bird is currently writing up the CDV procedure for Roundel, as he is another passionate advocate of this procedure. I could have written such a story myself, but my hands were all slippery and I couldn't work a camera.
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    az3579

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    Jeez Satch, it took you THIS LONG to yank the darned thing out? I had my car not 2 months before I got mine removed!


    Such a great feeling though...
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    steven s

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    From http://www.zeckhausen.com/CDV.htm

    Let's see, I have +240,000 miles on my clutch.
    So if I remove replace this thing I won't wear out my clutch prematurely? That's good to know.

    I feel my shifts are fine. The only times they haven't been have been related to worn a detent spring in my shift lever and worn motor or tranny mounts. And that is only at the end of a straight, braking at 110 and going from 5-> 4-> 3.

    BTW- My waterpump also lasted +235,000 miles. ;)
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    MGarrison

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    congrats on the long-lived components, but..... none of yours listed (E36, E30, Mini) have a cdv......?? Or you're referring to a different vehicle?
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    steven s

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    My E36. It doesn't have a CDV?
    I guess that would explain the longevity. :)
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    granthr

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    I am pretty sure most E36s came with a CDV, but I am not sure about all of them.
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    MGarrison

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    I was figuring that if his car had one, Zeckhausen's list of models covered would be comprehensive - maybe not.

    Via the realoem "clutch control" diagrams, it appears BMW calls the CDV a 'lock valve'; so, if for one's vehicle and month of manufacture, if the clutch control diagram lists a 'lock valve', then, presumably, there is one.

    I checked E36 318ti with 12/96 mfg. date, and it didn't list a lock valve. But, a 328i coupe of the same month, does. If Steven's transplant used the original 'ti slave cylinder and slave lines, then it probably doesn't have a cdv (lock valve). If it had to use a different tranny & slave cyl. w/ the transplant motor, it's possible the cdv came with it.

    The cdv apparently appeared sometime after E36 production began; from some bimmerforum posts, apparently certain models (M Z3's, and possibly others) used a restrictive flexible line to the slave cylinder instead of a cdv.

    I'm going to guess Steven's 'ti doesn't have a lock valve, having attained that kind of clutch lifespan.
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    az3579

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    That's a very impressive clutch lifespan even for a car without a CDV. A lot of cars are very lucky to see beyond 100k or so...
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    steven s

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    The ti used the tranny from a 328. I'm guessing it's an early 96 build since I don't have ASC. I believe everything would have come from the same donor car.
    I bought the car in 2000,
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    MGarrison

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    The next time you're under tbe car, take a look!
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    Wretched

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    I hate the CDV! I test drove a '09 M3 that had that blasted thing! I couldn't for the life of me figure why I couldn't shift the darn thing! It drove me nuts! It really forces you to shift very slowly. It wasn't until some time later I learned of the CDV... Now no one believes me I can shift properly! :mad:

    boostm3 guest

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    It has it.. I had a '99 E36 M3, and had mine removed after a few months.

    On my brand new 135i, though, I havent found any problem with the shifting despite the presence of the seemingly omnipresent (on bmws) CDV... At this time I have no plans on removing it.. Id like to get 200K plus on my clutch too!! ;)
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    alvocado

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    The alternative line information is a huge help. I planned to have the modified CDV installed two years ago and was told by my BMW shop that one didn't exist on my car (they confirmed while doing fluid service.) This was puzzling but it's clear now that my April 2002 build 330c has the restricted hose.

    Does anyone know of a broadly available SS line option that meets the specs noted in the article? I was looking for something from Russell Performance (division of Edlebrock) but haven't been able to find anything for sale online. The link in the article to where the line was sourced didn't pull up a website.

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