Clutch Delay Valve (CDV)
12-11-2008, 04:32 PM
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Hi Guys,
I did my searching, but aside from opinions and advertisments of what the valve should do, I found no useful information.
My original problem is here http://forums.e60.net/index.php?showtopic=66862
I don't know if this problem originated from the CDV or from the self adjusting of the clutch.
The whole "ultimate driving experience" that BMW promises has become "ultimate frustration" for me.
My clutch feels like its about to fail. Before I could downshift (and heel-toe) with unbelievable precision and poise. Clutch feel was amazing. Now its more like just trying not to jerk the car. When downshifting and matching revs, the clutch cannot keep up, it grabs the gear long after I passed the release point and then jerks the car.
For those who have replaced the CDV, what kind of clutch behaviour have you noticed before and after replacement. Is it worth it? Is it hard to replace or the dealer has to do it?
TIA,
~Andy
I did my searching, but aside from opinions and advertisments of what the valve should do, I found no useful information.
My original problem is here http://forums.e60.net/index.php?showtopic=66862
I don't know if this problem originated from the CDV or from the self adjusting of the clutch.
The whole "ultimate driving experience" that BMW promises has become "ultimate frustration" for me.
My clutch feels like its about to fail. Before I could downshift (and heel-toe) with unbelievable precision and poise. Clutch feel was amazing. Now its more like just trying not to jerk the car. When downshifting and matching revs, the clutch cannot keep up, it grabs the gear long after I passed the release point and then jerks the car.
For those who have replaced the CDV, what kind of clutch behaviour have you noticed before and after replacement. Is it worth it? Is it hard to replace or the dealer has to do it?
TIA,
~Andy
12-11-2008, 04:43 PM
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Andy, Dave Zeckhausen at ZeckhausenRacing.com is a great guy and sells Modified CDV's. I did not see one for the 535 on his website but it would be worth sending him an email in regards to the 535. He has always been prompt and helpful anytime I have had questions and have purchased from him in the past.
From his Zeckhausenracing.com:
Problems shifting your BMW E60 5-Series?
Many models of BMWs with 5-speed or 6-speed manual transmissions have a Clutch Delay Valve (CDV) installed by the factory. This valve is the culprit behind the jerky shifting that makes your BMW hard to drive, even if you have been driving a standard transmission all your life. When replaced with the Zeckhausen Racing modified CDV, your clutch is suddenly transformed into the smooth, easy to modulate clutch that should have been delivered from the factory as standard. Extend the life of your clutch and increase the enjoyment of your BMW driving experience today!
Theory of Operation - What is a CDV?
The Clutch Delay Valve (CDV) is a one-way restrictor installed by the factory between the clutch slave cylinder and clutch master cylinder, as shown in Figure 1. It "delays" the engagement of the clutch, much like old record players used a damped tone-arm to gently lower the needle onto the surface of a record.
Because of this valve, no matter how quickly you lift your foot off the clutch pedal, the clutch engages the flywheel at a constant (slow) rate. In theory, it can save the driveline from shock, were an inexperienced (or immature) driver to dump the clutch at high RPM. But in practice, all it does is prematurely wear out the clutch and turn experienced drivers into people who, despite 20 years of practice, cannot shift gears smoothly. During parallel parking maneuvers, the delay can be infuriating, causing constant clutch slippage. And during hard acceleration, the large amount of clutch slippage can greatly shorten the life of your clutch. During normal, sedate driving, the shift from first into second gear is often jerky, leading passengers to question your skill. As the driver, you can see your passengers' heads bobbing back and forth during every shift! Yes, in their minds, they are laughing at you.
Interestingly, BMW did not install a CDV on the E39 M5. The terrible shifting behavior would be unacceptable to these high performance customers. For some reason, BMW does not seem to think the rest of their 3-Series & M3, 5-Series, 6-Series, X3, X5, Z3, Z4 and Z8 customers who shift their own gears will notice. They were very wrong!
Since BMW models have different clutches, they have different CDVs with different valve openings and springs. In order to reduce the odds of a factory worker installing the wrong part on the assembly line, each CDV has a different number of ribs and may even have a different barrel shape. (See Figures 3 & 4 below) The effect on all of these cars is the same. The driving experience is degraded.
From his Zeckhausenracing.com:
Problems shifting your BMW E60 5-Series?
Many models of BMWs with 5-speed or 6-speed manual transmissions have a Clutch Delay Valve (CDV) installed by the factory. This valve is the culprit behind the jerky shifting that makes your BMW hard to drive, even if you have been driving a standard transmission all your life. When replaced with the Zeckhausen Racing modified CDV, your clutch is suddenly transformed into the smooth, easy to modulate clutch that should have been delivered from the factory as standard. Extend the life of your clutch and increase the enjoyment of your BMW driving experience today!
Theory of Operation - What is a CDV?
The Clutch Delay Valve (CDV) is a one-way restrictor installed by the factory between the clutch slave cylinder and clutch master cylinder, as shown in Figure 1. It "delays" the engagement of the clutch, much like old record players used a damped tone-arm to gently lower the needle onto the surface of a record.
Because of this valve, no matter how quickly you lift your foot off the clutch pedal, the clutch engages the flywheel at a constant (slow) rate. In theory, it can save the driveline from shock, were an inexperienced (or immature) driver to dump the clutch at high RPM. But in practice, all it does is prematurely wear out the clutch and turn experienced drivers into people who, despite 20 years of practice, cannot shift gears smoothly. During parallel parking maneuvers, the delay can be infuriating, causing constant clutch slippage. And during hard acceleration, the large amount of clutch slippage can greatly shorten the life of your clutch. During normal, sedate driving, the shift from first into second gear is often jerky, leading passengers to question your skill. As the driver, you can see your passengers' heads bobbing back and forth during every shift! Yes, in their minds, they are laughing at you.
Interestingly, BMW did not install a CDV on the E39 M5. The terrible shifting behavior would be unacceptable to these high performance customers. For some reason, BMW does not seem to think the rest of their 3-Series & M3, 5-Series, 6-Series, X3, X5, Z3, Z4 and Z8 customers who shift their own gears will notice. They were very wrong!
Since BMW models have different clutches, they have different CDVs with different valve openings and springs. In order to reduce the odds of a factory worker installing the wrong part on the assembly line, each CDV has a different number of ribs and may even have a different barrel shape. (See Figures 3 & 4 below) The effect on all of these cars is the same. The driving experience is degraded.
12-11-2008, 04:47 PM
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Thanks for the reply, I know about Zeckhausenracing, I tried calling them today, but was too late. Also, I checked with BMW the part number for "lock valve" as BMW calls it (its really CDV) is the same as E60 530i "21-52-1-165-271".
12-11-2008, 04:51 PM
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Originally Posted by andy535xi' post='743418' date='Dec 11 2008, 07:47 PM
Thanks for the reply, I know about Zeckhausenracing, I tried calling them today, but was too late. Also, I checked with BMW the part number for "lock valve" as BMW calls it (its really CDV) is the same as E60 530i "21-52-1-165-271".
12-11-2008, 06:29 PM
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Originally Posted by DRANGED' post='743420' date='Dec 11 2008, 07:51 PM
Andy, shoot Zeckhausen an email with your symptoms. I'm sure he will get back to you tonight or early tomorrow.
I had a Zeckhausen "modified" CDV in my 03 540 as well as a Rogue short shift kit. The combination totally changed the driving experience. I pre-ordered the same two items when I ordered my 06 550i. They were with me when I picked up the car and I installed them at a friend's garage (lift is required) with 3 miles on the odometer.
BTW, I believe that the mechanic was wrong as to which cars have the CDV. It is my understanding that the M5 does not have the CDV and that all other manual shift 5'ers have the CDV.
04-14-2009, 02:32 PM
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Originally Posted by tiangco.a' post='847334' date='Apr 14 2009, 05:19 PM
cant you just remove the cdv and re-attatch the line?
On the 3-series its much easier because it has a rubber hose.
Also, if your car is CPO the dealer will notice thats its missing
and might give you a hard time.
The Zeckhausen modified CDV looks exactly the same from the
outside.
04-14-2009, 02:36 PM
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very interested in learning more about this.
Sorry for a quick thread jack, but would getting one of these be better or worse for an inexperienced driver. I pretty much can always get the car in gear and rarely stall. I just have fairly jerky shifts between 1st and 2nd (sometimes 2nd to 3rd) during harder accelerations. I know smoothness comes with time, but I just want to make sure I am doing everything I can to help make a smoooooth transition from auto to manual. Thanks and sorry for jacking your thread. I hope you get your clutch issues worked out.
Sorry for a quick thread jack, but would getting one of these be better or worse for an inexperienced driver. I pretty much can always get the car in gear and rarely stall. I just have fairly jerky shifts between 1st and 2nd (sometimes 2nd to 3rd) during harder accelerations. I know smoothness comes with time, but I just want to make sure I am doing everything I can to help make a smoooooth transition from auto to manual. Thanks and sorry for jacking your thread. I hope you get your clutch issues worked out.
04-22-2009, 02:22 PM
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04-22-2009, 04:02 PM
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The CDV valve paired with the Rogue SSK will make a night and day difference to the way your car will shift. Don't think your problem is due to the CDV though. Install is pretty straight forward. Having a lift would make install much easier but can be done without if you are not too big. 