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02-05-2011, 11:57 AM | #1 |
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Manual Trans CDV
Just wondering if anyone has replaced their CDV (Clutch Delay Valve) item 16 in Diagram. The E89 uses the same CDV as the E90 (21526764872). Zeckhausen racing http://zeckhausen.com/cdv.htm#CDV sells a modified unit. Basically they remove the guts (orifice) to allow a more rapid clutch engagement/disengagement. This will probably be a summer mod for me when I've got the car up on the jackstands for its 10K 296 wheel inspection.
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HerrK - 2021 X5 40i M Sport l PCD l Atlantis Blue/Ext'd Tartufo Merino l M Sport w/blue Calipers l Matt Popular l HK Sound l 740's l Exec & Drive Pro Pack Sold w/Great Memories - E89 Z4 l ED 2010 l 2011 35i l Crimson/Ext'd Coral Red w/Alum l 6 sp MT l Prem Sound l Sport Pack l 296's |
02-05-2011, 04:45 PM | #2 |
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Drives: 2009 Z4 s35i, 2007 997TT
Join Date: Jan 2011
Location: Littleton CO/Laguna Beach
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I did this exact mod on my 2006 M3, I never really could tell the difference, however alot of people swear by it. Some just removed the valve, but I did install the gutted one you described.
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02-05-2011, 04:46 PM | #3 |
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Just be careful -- it's usually there to protect the 'glass' parts of the transmission. Even minor accidental missteps of the clutch pedal could make something go bang from a dead stop if the plates hook up to abruptly. Then again, if it improved feel, maybe there would be less of a chance of killing the engine to begin with. There is definitely a lot of molasses in this car's clutch release.
BTW, I believe most valves only affect engagement. |
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02-05-2011, 04:49 PM | #4 |
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It really depends on the time constant of the valve. Most of them add just enough delay to prevent damage from a sidestep. In normal driving, most of us are probably not fast enough to notice unless we're Evil Knievel....
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02-05-2011, 05:11 PM | #5 |
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My opinion is if you have driven manual transmissions for most of your driving history then removing the valve will make a marked improvement. I have been using manual transmissions for more than 20 years. The first BMW I purchased I could not use the clutch smoothly, could not understand why until I read on E90 about the CDV. I purchased a gutted one from a vendor for my 335i, and on the Z4 I just saved a few dollars and drilled it out, not difficult really.
I did the Z4 directly after leaving the dealer, first thing. I really dislike that valve. |
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02-05-2011, 06:01 PM | #6 | |
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Quote:
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02-05-2011, 09:02 PM | #7 | |
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You will have to bleed the system after R&R. Not sure what's inside - maybe Nicolak can enlighten us. I was thinking about buying one, as their only like $8-9, just to see what it looks like for a DIY. The most important in DIY will be to get it cleaned out after rework to avoid contaminating the slave unit.
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HerrK - 2021 X5 40i M Sport l PCD l Atlantis Blue/Ext'd Tartufo Merino l M Sport w/blue Calipers l Matt Popular l HK Sound l 740's l Exec & Drive Pro Pack Sold w/Great Memories - E89 Z4 l ED 2010 l 2011 35i l Crimson/Ext'd Coral Red w/Alum l 6 sp MT l Prem Sound l Sport Pack l 296's |
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