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      01-06-2011, 12:51 PM   #5
MA128
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Drives: 2013 128 Coupe 6MT
Join Date: Mar 2009
Location: Boston Suburbs

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2013 128 Coupe  [0.00]
The Clutch Delay Valve (CDV) restricts the flow of hydraulic fluid in the line that operates the clutch when you press the pedal. BMW added this to most or all of its manual transmission cars over the last five to ten years. As I understand it, the purpose is to protect the differential from abrupt power delivery such as dumping the clutch at 5,000 RPM for a drag racing start.

The problem is that the momentary delay makes it hard to feel exactly when the clutch disengages as you release the pedal. It's more of a problem at relaxed speeds / low revs when you're simply trying to drive smoothly. If you're driving more aggressively - say upshifting quickly at > 4,000 RPM - it's not noticeable.

There are many CDV threads on this site and I'm sure most of the explanations are more accurate and thorough than mine - but I hope this is helpful. It's supposed to be a very easy DIY but you need to know how to bleed the air out of a hydraulic line to complete the job properly. Because the clutch and brakes share a fluid reservoir, the tech at my shop also checked all four brakes for air after he changed the CDV.

You can simply remove the valve and reattach the lines on either end but that's a problem if you are still under warranty and don't want the dealer to know that you've modified the car.

see http://www.1addicts.com/forums/showt...&highlight=CDV

and http://store.zeckhausen.com/catalog/...dv-005&x=0&y=0
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SOLD: 2013 128 Coupe / 6MT / Premium / M-Sport / Cold / Xenon / HK Audio / CDV Delete / M3 RSFB
SOLD: 2009 128 Coupe / 6MT / Premium / Sport / Cold / Xenon / HK Audio / CDV Delete / M3 Suspension
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