CDV question

Si-M240i · 12-11-2008, 01:42 AM

What exactly does this alter ?

is it the speed at which the clutch engages or does remove any delay in the boost / timing etc on gear changes ?

Oregon · 12-11-2008, 01:52 AM

The CDV, or, Clutch Delay Valve, eliminates slowish clutch engagement designed-in by BMW engineers(now, bean-counters?:iono

, however, engine management is not affected. The clutch-response modification can transform your 1-Series into a proper German hot rod. What you do with/to your car is your decision, just remember, with every day, life presents all individuals with many choices.:wink:

Here's a DIY - http://www.1addicts.com/forums/showthread.php?t=6329

Si-M240i · 12-11-2008, 02:25 PM

What exactly does this do ?

My clutch engages fast and solid so I guess it does more than just the mechancial action of the clutch. Does it affect how quickly the boost or timing is applied or something like that ?

JohnL135I · 12-11-2008, 05:31 PM

No.

The Clutch delay valve simply replaces the factory CDV with a non restricted CDV.

Si-M240i · 12-12-2008, 02:13 AM

So I am guessing it is a mechanical action only then?
how can this help? if the clutch didn't engage fast enought it would slip and I do not experiecne that. Please can someone explain to me exactly how this works and benefits to car.....

Cheers,
Si

JohnL135I · 12-12-2008, 11:52 AM

Ok, I'll try and explain. When you drive your manual and shift into 3rd gear, then release the clutch nice and smooth... you'll still feel a slight jolt through the car upon clutch engagement. This is because as your releasing the clutch pedal the Clutch delay valve has a restrictor inside of it which is controlling the pressure to the clutch for engagement. So basicly the clutch is either engaged or disengaged and no inbetween. Without the factory CDV (with a modified CDV), there is no restriction in the pressure (fluid). This results in more of a direct control of the clutch pedal release and clutch engagement. From what I gather, a modified CDV will allow a more possitive clutch feel and control while shifting.

I think the idea of the factory CDV is to help prevent the clutch from slipping (being partially engaged), however, this leads to some jerky shifts when driving the manual.

Not really sure if anything I just typed makes sense... I have a modified CDV I'm installing on 23 Dec... I'll let you know how it works out.

Mike@N54Tuning.com · 12-12-2008, 01:33 PM

The modified valve is just a normal BMW valve which is hollowed out, which basically eliminates the valve altogether.

It makes a big difference on the feel and smoothness of your shifts. I don't think BMW should have used this on their cars.

Also, its pretty cheap so can't really go wrong with trying one out

Mike

sethchan · 12-12-2008, 01:37 PM

Quote:

Originally Posted by JohnL135I

Ok, I'll try and explain. When you drive your manual and shift into 3rd gear, then release the clutch nice and smooth... you'll still feel a slight jolt through the car upon clutch engagement. This is because as your releasing the clutch pedal the Clutch delay valve has a restrictor inside of it which is controlling the pressure to the clutch for engagement. So basicly the clutch is either engaged or disengaged and no inbetween. Without the factory CDV (with a modified CDV), there is no restriction in the pressure (fluid). This results in more of a direct control of the clutch pedal release and clutch engagement. From what I gather, a modified CDV will allow a more possitive clutch feel and control while shifting.

I think the idea of the factory CDV is to help prevent the clutch from slipping (being partially engaged), however, this leads to some jerky shifts when driving the manual.

Not really sure if anything I just typed makes sense... I have a modified CDV I'm installing on 23 Dec... I'll let you know how it works out.

Thanks for writing that. How do I get one?

WhiteOne · 12-12-2008, 01:44 PM

The stock CDV has a valve in it. This valve slows down the fluid flow when letting out the clutch. Remove the CDV. Push the valve out. It is very easy to do. Put the modified CDV back in. Less fluid restriction equals more clutch feel. Cost..a little brake fluid. JMHO

mynew135 · 12-12-2008, 04:48 PM

+1

No need to buy a "modified" CDV. I did this a few days ago. Took the old out, stuck a screw driver into the valve and tapped out the restrictor and reinstalled the CDV. Done, complete. Lost a couple drops of fluid, but did not need to bleed the lines.

Si-M240i · 12-13-2008, 03:40 AM

Thanks for the info, very helpful and I have a better idea of how this works now. What is the risk of needing to bleed the clutch, as I don't really want to get into all that type of stuff.

If I did this I would just want to swap over the valve with no risk of other stuff being affected.

Also where is the CDV ?
How easy is it to get to it ?
How long does it take to do this MOD ?

Thanks again in advance

Si

Oregon · 12-13-2008, 03:55 AM

Quote:

Originally Posted by Si-135i

Thanks for the info, very helpful and I have a better idea of how this works now. What is the risk of needing to bleed the clutch, as I don't really want to get into all that type of stuff.

If I did this I would just want to swap over the valve with no risk of other stuff being affected.

Also where is the CDV ?
How easy is it to get to it ?
How long does it take to do this MOD ?

Thanks again in advance

Si

A read of the DIY will answer your ?'s.:smile:

Lester · 12-13-2008, 10:02 AM

Quote:

Originally Posted by Si-135i

What exactly does this alter ?

is it the speed at which the clutch engages or does remove any delay in the boost / timing etc on gear changes ?

CDV = Clutch Delay Valve. This device restricts the flow of fluid into the clutch cylinder, slowing the release of the clutch from the pressure plate. Think of a water flow restrictor, that you might install at home in your bathroom. It simply blocks the flow of fluid.

This device has been installed by BMW to reduce shock to the drive train, if fast shifting and high revving is the mode of operation (eg. racing). So - it is a trade off, do you want a little more clutch slippage (ie. wear) - or do you want more wear and tear on the transmission, drive shaft, rear differential, rear half shafts, etc? The clutch disk is not all that expensive compared to the other components, and it is the one piece that is designed with wear in mind.

If you are going to race the car, and you don't care about warranty or costs anyways, so you might as well remove it or modify it to gain that extra 5-10% benefit in shifting. But if you plan to keep the car for several years, past warranty - and if you plan to drive it normally (most of the time) - I would say leave it in.

audi2bmw1 · 12-13-2008, 06:11 PM

IMO you wont do any harm by replacing the stock CVD with the modified one...^^^ i highly doubt allowing a lil more fluid to flow will cause any harm to be done to either the tranny or rear DIFF...

Lester · 12-13-2008, 09:49 PM

Only if you like to chirp the tires in first second and third a lot. Under normal driving, it should make no difference at all. Has anyone ever had an official explanation from BMW as to why they put this device in line with the clutch cylinder? It is curious that it is listed as a 'Lock Valve' in the real oem parts list. Lock what?

12-11-2008, 01:42 AM	#1
Si-M240i Major 137 Rep 1,450 Posts Drives: M240i LCI Join Date: Aug 2008 Location: England iTrader: (0)	CDV question What exactly does this alter ? is it the speed at which the clutch engages or does remove any delay in the boost / timing etc on gear changes ?
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12-11-2008, 01:52 AM	#2
Oregon NRA Life Member, BMW CCA 30 year member 179 Rep 2,614 Posts Drives: 04' M3 Join Date: Aug 2007 Location: Oregon iTrader: (1) Garage List 1971 2002 [0.00] 2004 M3 [0.00] 2008 135i [0.00]	The CDV, or, Clutch Delay Valve, eliminates slowish clutch engagement designed-in by BMW engineers(now, bean-counters?:iono, however, engine management is not affected. The clutch-response modification can transform your 1-Series into a proper German hot rod. What you do with/to your car is your decision, just remember, with every day, life presents all individuals with many choices.:wink: Here's a DIY - http://www.1addicts.com/forums/showthread.php?t=6329 __________________ Resigned 1ADDICTS Moderator “To disarm the people is the best and most effective way to enslave them.” – George Mason
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12-11-2008, 02:25 PM	#3
Si-M240i Major 137 Rep 1,450 Posts Drives: M240i LCI Join Date: Aug 2008 Location: England iTrader: (0)	CDV question What exactly does this do ? My clutch engages fast and solid so I guess it does more than just the mechancial action of the clutch. Does it affect how quickly the boost or timing is applied or something like that ?
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12-11-2008, 05:31 PM	#4
JohnL135I Donkey Kong King 89 Rep 1,129 Posts Drives: 2012 Boss 302 Join Date: Dec 2007 Location: Sahuarita, AZ iTrader: (3)	No. The Clutch delay valve simply replaces the factory CDV with a non restricted CDV. __________________ [SIGPIC][/SIGPIC]
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12-12-2008, 02:13 AM	#5
Si-M240i Major 137 Rep 1,450 Posts Drives: M240i LCI Join Date: Aug 2008 Location: England iTrader: (0)	So I am guessing it is a mechanical action only then? how can this help? if the clutch didn't engage fast enought it would slip and I do not experiecne that. Please can someone explain to me exactly how this works and benefits to car..... Cheers, Si
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12-12-2008, 11:52 AM	#6
JohnL135I Donkey Kong King 89 Rep 1,129 Posts Drives: 2012 Boss 302 Join Date: Dec 2007 Location: Sahuarita, AZ iTrader: (3)	Ok, I'll try and explain. When you drive your manual and shift into 3rd gear, then release the clutch nice and smooth... you'll still feel a slight jolt through the car upon clutch engagement. This is because as your releasing the clutch pedal the Clutch delay valve has a restrictor inside of it which is controlling the pressure to the clutch for engagement. So basicly the clutch is either engaged or disengaged and no inbetween. Without the factory CDV (with a modified CDV), there is no restriction in the pressure (fluid). This results in more of a direct control of the clutch pedal release and clutch engagement. From what I gather, a modified CDV will allow a more possitive clutch feel and control while shifting. I think the idea of the factory CDV is to help prevent the clutch from slipping (being partially engaged), however, this leads to some jerky shifts when driving the manual. Not really sure if anything I just typed makes sense... I have a modified CDV I'm installing on 23 Dec... I'll let you know how it works out. __________________ [SIGPIC][/SIGPIC]
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12-12-2008, 01:33 PM	#7
Mike@N54Tuning.com Joint Chiefs of Staff 4907 Rep 115,980 Posts Drives: 2007 335i, 2015 M3 Join Date: Dec 2008 Location: N54tuning.com iTrader: (89)	The modified valve is just a normal BMW valve which is hollowed out, which basically eliminates the valve altogether. It makes a big difference on the feel and smoothness of your shifts. I don't think BMW should have used this on their cars. Also, its pretty cheap so can't really go wrong with trying one out Mike
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12-12-2008, 01:44 PM	#9
WhiteOne Major 28 Rep 1,000 Posts Drives: 2008 AW 135i Join Date: Dec 2007 Location: Alabama iTrader: (0)	The stock CDV has a valve in it. This valve slows down the fluid flow when letting out the clutch. Remove the CDV. Push the valve out. It is very easy to do. Put the modified CDV back in. Less fluid restriction equals more clutch feel. Cost..a little brake fluid. JMHO
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12-12-2008, 04:48 PM	#10
mynew135 assistant to the regional manager 5 Rep 242 Posts Drives: 135i Join Date: Nov 2008 Location: Virginia Beach, VA iTrader: (0) Garage List 2009 135i [0.00]	+1 No need to buy a "modified" CDV. I did this a few days ago. Took the old out, stuck a screw driver into the valve and tapped out the restrictor and reinstalled the CDV. Done, complete. Lost a couple drops of fluid, but did not need to bleed the lines.
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12-13-2008, 03:40 AM	#11
Si-M240i Major 137 Rep 1,450 Posts Drives: M240i LCI Join Date: Aug 2008 Location: England iTrader: (0)	Thanks for the info, very helpful and I have a better idea of how this works now. What is the risk of needing to bleed the clutch, as I don't really want to get into all that type of stuff. If I did this I would just want to swap over the valve with no risk of other stuff being affected. Also where is the CDV ? How easy is it to get to it ? How long does it take to do this MOD ? Thanks again in advance Si
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12-13-2008, 06:11 PM	#14
audi2bmw1 Lieutenant 21 Rep 513 Posts Drives: 09 montego 135i/acura vigor Join Date: Sep 2008 Location: IN iTrader: (0)	IMO you wont do any harm by replacing the stock CVD with the modified one...^^^ i highly doubt allowing a lil more fluid to flow will cause any harm to be done to either the tranny or rear DIFF... __________________ 09 135i montego blue 6speed..RR catch can,CDV,DCI intakes,stett charge pipe and tial bov, the above mods are not installed on my car, i just want to seem cool Devils own water/meth dealer-PM me for info former car/ 2001 audi TT ~290bhp :w00t:
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12-13-2008, 09:49 PM	#15
Lester Brigadier General 295 Rep 3,350 Posts Drives: Join Date: Oct 2007 iTrader: (0)	Only if you like to chirp the tires in first second and third a lot. Under normal driving, it should make no difference at all. Has anyone ever had an official explanation from BMW as to why they put this device in line with the clutch cylinder? It is curious that it is listed as a 'Lock Valve' in the real oem parts list. Lock what?
	Appreciate 0 Quote