Have any of you done the CDV delete?

[M3TA5IN]

Just curious if anyone has, or do you guys recommend it?

If you have, do you actually notice a difference in shifts?



The reason I am asking is, I was thinking about doing it, but I over think everything lol. I see a lot of e46/e9x guys do it, but then I think why the hell would BMW make it that way if it wasn't for a reason?

I wasn't actually going to completely remove mine either, i was just going to hollow it out for better flow.

Just curious what the mafia thinks.

[ryankokesh]

I'm still having issues getting the 1-2 shift smooth, so I was thinking of doing it. Good timing on creating the thread, I just looked into it today!

[Rovert]

I took mine out but never really noticed a difference. Maybe I'm not as quick as you guys when upshifting. But a majority swear by it. Wish I could. LOL.

[kayger12]

I did it- and I could've kicked myself in the ass for waiting so long to do it.

Night and day on faster shifts. When you get it out and see how damn small that restrictor is (little pin hole) you'll be amazed you could shift smoothly at all.

And from what I've read, the only reason BMW uses them is to reduce the warranty claims for drive train damage from people who don't know how to drive manual properly.

Droid X. Tapatalk. Use it.

[elric]

Took mine out last November. Shifts SO MUCH better now.

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[danewilson77]

I did it- and I could've kicked myself in the ass for waiting so long to do it.

Night and day on faster shifts. When you get it out and see how damn small that restrictor is (little pin hole) you'll be amazed you could shift smoothly at all.

And from what I've read, the only reason BMW uses them is to reduce the warranty claims for drive train damage from people who don't know how to drive manual properly.

Droid X. Tapatalk. Use it.

+1

[nike001]

I'm still having issues getting the 1-2 shift smooth, so I was thinking of doing it. Good timing on creating the thread, I just looked into it today!

The trick is to shift early. I shift at about 2k into 2nd.

[M3TA5IN]

Ok you have convinced me. I don't know how the e46 CDV is but I know on my car I can basically take it out and take a punch and pop out the restrictive part of it. So I think I'm just going to do that and put it back in.

Now the only problem is I gotta find where it is lol, none of the write ups have pictures I can find. Remember guys I'm new to BMWs, go easy on me :p

I have a really stupid question I'm going to ask one of these days that's going to make you laugh :rofl

[danewilson77]

No need to punch out internals. Just squeeze lines, pull it out, and re-connect lines together. Plus... If you don't like or need to re-install, you would be destroying it.

HTC Thunderbolt+TT

[ryankokesh]

No need to punch out internals. Just squeeze lines, pull it out, and re-connect lines together. Plus... If you don't like or need to re-install, you would be destroying it.

HTC Thunderbolt+TT

Do you need to bleed afterward?


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[danewilson77]

Do you need to bleed afterward?


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I did not. Depends on how smoothly it goes, and how much air you introduce into system.

HTC Thunderbolt+TT

[bimmeryota]

I never did this mod but heard that it made the biggest primary difference in paralell parking where precise modulation is key. Is this true for those that have done it?

[danewilson77]

http://www.zhpmafia.com/forums/showthread.php?4493-Clutch-Delay-Valve-Removal&p=97325

HTC Thunderbolt+TT

[brettbimmer]

Good mod. DO IT! Like Keith said, makes shifting so much better. I actually bought the hollowed-out part from Bavauto, but there is enough play in the lines that it wasn't actually needed. Valve is a check-valve of sorts that was installed as a CYA move by BMW so that people dumping the clutch on a repeated basis wouldn't damage the clutch & drivetrain.

On the e46, it is located on the driver's side of the transmission tunnel where it meets flat underbody of the car near the transmission. I would assume somewhere close on e90 also. Might be worth checking on realoem.com to be 100% sure.

It would def. make for better clutch modulation at low speeds, so it would help you with parallel parking.

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[kayger12]

I bled mine. Easy enough to do and then you know she's good to go before you get her down.

[nike001]

Is mine deleted? Idk what to look for..

http://img.tapatalk.com/4b6199dc-2613-2230.jpg


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[danewilson77]

Just asking... Did you look at diy above?

HTC Thunderbolt+TT

[nike001]

I did. I'm just hoping that someone who knows can make out if there is a CDV there or not. I'm having a hard time making out what's in the picture.

[kayger12]

Tough to make out on the phone, but yeah- it looks like yours is still there.

Droid X. Tapatalk. Use it.

[nike001]

That's weird. Because I drove a 6MT ZHP a few weeks ago and the clutch was WAY different than mine.. so I figured that theirs(hers) was still there and mine wasnt because of the differences.

I also need new Throw Out Bearings since mine rattle when starting out/reversing sometimes. My buddy works at the local Steve Shannon garage so maybe him and I can bang this out real quick soon.

[kayger12]

Always a chance someone stuck an after market one on there that's hollowed out.

Droid X. Tapatalk. Use it.

[danewilson77]

I couldn't tell from the pic you posted Nike...

[danewilson77]

Look for this Homie....

http://www.zeckhausenracing.com/

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/E46_CDV.jpg

[LivesNearCostco]

Avus Autosport in Glendale, CA, deleted it from my car... two owners ago. So I don't know what it's like to drive with a CDV. But I felt compelled to do something to the clutch system, so I bled it once I got a Motive power brake bleeder. And then I put in a UUC stainless steel clutch line. There was nothing wrong with the old clutch line; I just couldn't resist the urge to make these small mods and tinker with the car.

[mLuMaN83]

I went to do mine and found out it was already gone.:dunno

No other way to compare as the only other e46 I drove was a CSL M3 in highschool, 1st to second is rugged and I have to shift faster than I was used to with other cars. There seems to be a sweet spot in the rpm's to shift at and it's early. When it's right tho it's butter. Shifting is precise as well. Dont know if this will help but I have no CDV and thats how it feels to me. There is a definitive sweet spot right in the middle of the clutch pedal and it engages without much delay.

[UdubBadger]

its better mostly for the 1-2 and 2-3 shifts when you push the car hard. otherwise you won't feel a difference.

[zj96sc]

My CDV is gone, PO did it. First ZHP still had it. Night and day for the better. Guibo probably takes the brunt of the impact, still if you know what you're doing it is a non-issue.

Add in a clutch stop and SSK and it is a whole nother world.

1-2 and 2-3 are hardest because they are the largest jump in ratio. Low RPM makes it easy because the RPM difference is smaller. For high RPM/WOT shifts, give the engine more time to wind down to your next RPM and you'll see them start to smooth out. LTW flywheel would probably help in this regard.

1st Gear 4.35
2nd Gear 2.50
3rd Gear 1.66
4th Gear 1.23
5th Gear 1.00
6th Gear 0.85
Reverse 3.93

As an example:

Shift 1->2 at 6500RPM, your new RPM is 3700, so ~2800 RPM (give or take some for accel/deccel during shift) that she has to fall to line up smoothly.

Shift 1->2 at 2000RPM, your new RPM is 1150, so ~850 RPM that she has to fall to line up nice.

You get the picture. I've let my shifts take a little longer and it is getting better. Doesn't help if you're trying to rip gears, but that's not what I spend most of my time doing.

[RITmusic2k]

The biggest benefit you get from the CDV delete is consistency and feedback.

The thing to remember about the CDV is that it is a limiting factor, not a scaling factor. In other words, the CDV doesn't make the clutch close at some set fraction of the speed that your foot moves on the pedal - it lets the clutch close at the same speed your foot moves on the pedal up to a certain point, after which any faster motion from your foot doesn't increase the speed at which the clutch closes.

The effect from the driver's standpoint is that while at slow pedal-release speeds the clutch engagement point correlates nice and directly with clutch pedal position, but when you try to release quickly, the engagement point moves artificially (and inconsistently) higher up the pedal's travel. This throws your muscle memory out the window, and most often results in you applying throttle too soon, which translates into excessive and unnecessary clutch slippage.

For that reason,


I never did this mod but heard that it made the biggest primary difference in paralell parking where precise modulation is key. Is this true for those that have done it?

the thing you heard is exactly backwards - at low engagement speeds you will not notice a difference, but when driving aggressively and shifting quickly, there's a significant difference between cars with and without the CDV installed.

At the end of the day, rev-matching your upshifts and downshifts does much more to prolong the life of the entire driveline, and it's only possible to learn how to do this properly on a car without a CDV installed.

[Nivo]

Before removing mine, the car would grind 1-2 shift and 2-3 shift. This is while WOT shifting. without it it is gone. (high rpms, shifting fast).

[webster]

i put in the modified hollowed out unit and felt night/day in 1-2 and 2-3 shifts

[aurelius]

I realize the OP has an E90 but FYI not all manual-trans E46's came with a CDV.

Neither of mine ever had one but my E39 did and removal is highly recommended. Unlike what some have posted above, for me the biggest improvement was in low speed parking situations where you're on & off the clutch pedal in 1st gear & reverse. Should be mod #1 on any model that has it.

[kayger12]

I realize the OP has an E90 but FYI not all manual-trans E46's came with a CDV.

Neither of mine ever had one but my E39 did and removal is highly recommended. Unlike what some have posted above, for me the biggest improvement was in low speed parking situations where you're on & off the clutch pedal in 1st gear & reverse. Should be mod #1 on any model that has it.

Yeah, I think I read that they started putting them in with the e46 facelift.

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[RITmusic2k]

for me the biggest improvement was in low speed parking situations where you're on & off the clutch pedal in 1st gear & reverse. Should be mod #1 on any model that has it.

Hmm, that brings up a bit of detail that I may have left off my reply - the CDV's effects aren't based on vehicle speed, only on clutch pedal travel speed. So during parallel parking or other low vehicle speed scenarios, I can see how it could still come into play - especially if you quickly 'pulse' the clutch pedal, or really do anything at all that would exceed its restricted flow rate.

[aurelius]

Yeah, I think I read that they started putting them in with the e46 facelift.

I test drove a 330 in summer of Y2k and it def had a CDV. Didn't know what it was at the time but I never forgot that terrible clutch action.

[kayger12]

I test drove a 330 in summer of Y2k and it def had a CDV. Didn't know what it was at the time but I never forgot that terrible clutch action.

Hmm. Maybe it was when they started putting the M54 in. I remember there was a specific point that they started using them, just can't remember when.

[328ioc]

Hmm. Maybe it was when they started putting the M54 in. I remember there was a specific point that they started using them, just can't remember when.

+1 When I was driving my E36 there was a random point there that that started putting it on certain cars also.

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[Oli77]

I have not done a CDV delete for several reasons:

1. I am used to it now after driving the car for ~2 years.
2. I have a throwout bearing going bad and I would rather clutch engagement be more slow and gentle.

[wsmeyer]

I'm going to throw my 2 cents in:

I had it in the back of my mind for a while after reading about it in several different forums. A few months back I bought a UUC short shifter so I was under the car anyway and finally got around to removing it. It's simple enough to do, just remove it and put the line back and bleed it. I'm an old school bleeder kind of guy, I've tried the power bleeders but I don't believe they do as good of a job as the old fashioned two person approach. So I get in the car and push the pedal to the floor, my buddy opens up the valve to let all the pressure out, and closes the valve. When I lifted my foot off the pedal and watched it come back up ever... so... slowly... I realized it was all a waste of time. Our cars don't use a return spring to bring the pedal back up, when you release the clutch it is the force of the pressure plate pushing the hydraulic fluid back up into the master cylinder that pushes the pedal back up. If the valve is restricting this flow, then it would also be limiting the speed at which the pedal comes back up. Other than intentionally side stepping the clutch, I personally have never, in any car, released the clutch so fast that my foot came off the pedal before it reached the upper travel stop. Which means that for me, the speed at which the clutch disengages is being limited by my foot speed, NOT the speed of the fluid traveling through the CDV.

So why do people swear it makes a difference? In my opinion, the only explanation is that the difference they are feeling is due to bleeding the line and not the removal of the valve.

The next time I'm under my car I will probably put mine back in. I do on occasion get into my car after stepping in water or snow, so while it has happened yet, there certainly is a possibility of my foot slipping off the clutch, and if that happens just as the synchro's are meshing, the CDV could be the difference between a stalled engine and a completely destroyed transmission.

I know this goes against what everyone else is saying but it was my experience and only my opinion, I certainly don't have any scientific testing to back it up and "your mileage may vary".

It would be interesting though if someone that hasn't done it would try just bleeding their line first, get used to that, and then remove the valve and see what they experience.

William.

[zj96sc]

So....if that is the case, why is the CDV there at all?

[zhp43867]

I'm going to throw my 2 cents in:


Very interesting post but I can't say I agree. I did not bleed the line when I installed the CDV, and it made a huge difference. I actually just bought another ZHP with a CDV and the difference is readily apparent. Situations where I notice it the most:

- Low speed 1-2 shift is easier to make jittery with the CDV
- Take off is more often jittery in 1st with the CDV
- Clutch reengagement is rarely ever seamless with the CDV especially at lower speeds, reengaging say, 2nd gear at 35mph.
- Hard WOT 1-2 shifts are noticeably jerkier.

I think all the above scenarios are when I am using the clutch pedal the "quickest". For example when I reengage 2nd, I may be behind someone slowing down and turning and I'll push the clutch pedal in, once they are out of the way I will rapidly blip the throttle to the appropriate RPM and let the clutch out quickly as well. Here the CDV seems to make the car jitter way more than when it is not present.

Oli77: Throw out bearings go bad more often due to improperly leaving your foot on the clutch pedal- while in gear or in neutral- or from not releasing the clutch all the way. Are you sure that isn't what killed your clutch?

The CDV was originally there to prevent people who are inexperienced or just bad at driving a stick from destroying a clutch in 40k miles. It lessens the wear on the clutch if you dump it or- for a new driver- rev too high and burn the clutch.

[zj96sc]

The CDV was originally there to prevent people who are inexperienced or just bad at driving a stick from destroying a clutch in 40k miles. It lessens the wear on the clutch if you dump it or- for a new driver- rev too high and burn the clutch.

I was asking it as a theoretical question to wsmeyer.

I think you've actually got that backwards - in both of those cases the CDV would actually increase wear due to longer clamp up time therefore longer slip time, heat, etc. The CDV intent I believe is largely NVH - just another "buffer" to soften up the drivetrain feedback to the cabin.

[zhp43867]

I was asking it as a theoretical question to wsmeyer.

I think you've actually got that backwards - in both of those cases the CDV would actually increase wear due to longer clamp up time therefore longer slip time, heat, etc. The CDV intent I believe is largely NVH - just another "buffer" to soften up the drivetrain feedback to the cabin.

I just worded it wrong, here's what zeckhausen says:


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 use 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.

I didn't realize your question was directed towards wsmeyer so... carry on.

[wsmeyer]

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.

No doubt that is it's purpose and why it is there, but I believe that it will allow a high enough flow rate that under normal operation of the clutch pedal it won't come into play.

William.

[nike001]

I don't think that a CDV delete is a deciding factor in having a destroyed engine or just a stalled one if your foot slips off the clutch on accident.

That being said, I just deleted mine and 1-2 shifts are awesome


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[UdubBadger]

^ agreed no chance


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[wsmeyer]

Very interesting post but I can't say I agree. I did not bleed the line when I installed the CDV, and it made a huge difference.


But if you didn't bleed the line then you've essentially done two things: removed the CDV, and introduced air into the system that is acting as a pneumatic spring. It isn't any different than a brake line where even a tiny amount of air can make a huge difference in pedal feel.

The only way to accurately compare with and without the CDV would be to bleed the line, get use to that, then remove the CDV and bleed the line again. Thus only changing one thing.

If I had known what I know now that's what I would have done. As it is I changed two things at once and while I feel a difference, it cannot be explained by the removal of the CDV valve because of the mechanics as I described above.

William.

[RITmusic2k]

These last few posts raise a lot of interesting questions.

William, I disagree with your conclusions as well, for a couple reasons.... I'm not, however, equipped to fully defend each of them. But if you'll pardon my doing so, I want to put a couple thoughts on the table:

First, the assertion that the difference reported is due more to the effect of bleeding the clutch system ignores all the reports of increases in clutch pedal responsiveness from people who removed their CDVs without bleeding - I count myself among these people. I accept that this is not a rigorous test because we changed two variables at once, but I'll also suggest that you can safely ignore it as a biasing factor. If anything, the introduction of air into the hydraulics will have a damping effect of its own and would only serve to reduce the effective increase in responsiveness that we're reporting. If air got in my lines during the CDV removal and I still experienced a significant improvement, then I can confidently expect there to be an even greater improvement by bleeding the lines.


The point you seem to be sticking to is the idea that the clutch pedal position is directly linked to the pressure plate position, and if it were, then your argument would stand, but I suspect -- and this is the part where I'm not fully capable of backing my argument -- that this is not exactly the case. We know that the clutch pedal position is not directly tied to the pressure plate, because if it were then the clutch pedal would stop immediately at the friction point. But the pedal keeps moving past this point as the diaphragm spring continues to release and pressure is increased on the clutch plate. This entire top half of the clutch pedal's travel influences the clamping force exerted on the clutch, but the clutch and pressure plate have already stopped moving in relation to each other by this point.

So with that in mind, I'm suggesting that a manual transmission without a CDV will behave more or less like you describe, where the clutch pedal position, pressure plate position up to the friction point, and the friction point itself are all directly related and 'fixed', so to speak. Adding a CDV, however, serves to uncouple the pedal position from the remaining parts of the system. I think, because of the huge mechanical ratio between the master and slave cylinders, installing the CDV can dramatically change the operation on the pressure plate while imperceptibly changing the way the pedal moves. Ergo, even though the pedal comes up off the ground just as fast as it did before removing the CDV doesn't mean that the behavior on the other end of the line isn't different enough to produce the change in responsiveness we're all experiencing.

[Johnmadd]

Great friendly debate guys, stick to your guns.:guns2:dueling

[nike001]

Just going to throw this in here:

The CDV delete for me was one of the best mods I've done yet.

[Rovert]

The CDV delete was the one mod that I didn't feel anything...LOL. Unless maybe that's just how I shift and I've got used to it. I'm not a power-slammer into gears. I try to keep my shifts as smooth to the drivetrain and ride as possible so I get no neck jerkers! Don't be rough if mom is in the car drinking something...it ends up very bad from my experience. LOL

[Oli77]

Oli77: Throw out bearings go bad more often due to improperly leaving your foot on the clutch pedal- while in gear or in neutral- or from not releasing the clutch all the way. Are you sure that isn't what killed your clutch?

I bought the car 2 years ago with a bad throw out bearing. I have not changed it. So I suppose the PO may have had issues with driving a stick. My clutch is fine though, and I am waiting for the throw out bearing to go before fixing it.

I like my CDV and I'm keeping it.

[nike001]

I bought the car 2 years ago with a bad throw out bearing. I have not changed it. So I suppose the PO may have had issues with driving a stick. My clutch is fine though, and I am waiting for the throw out bearing to go before fixing it.

I like my CDV and I'm keeping it.

I suggest you drive a car without it. I know I can feel a difference.

As for the throwout bearing... mine is bad and rattles to high hell sometimes. IF you ever decide to change it, I highly recommend just changing out your clutch anyways while you're in there. It's a costly job and a pain in the ass as well.

[Oli77]

Totally agree.

Yes the warmer, the greater the TO bearing noise. But I can tell you this, and this is a CDV delete argument, if its hot outside and the car is warmed up and I am at a stop sign, stopped, I let go of the clutch fats and it never fails, the TO rattles. Same situation 5 seconds latter and I let go of the clutch slowly, bingo, you can't hear that sucker.

The thing is, my CDV is in. This means (to me) that, eventhough I have the CDV, I can still control the speed of the engagement, perhaps arguing against the CDV being such a bad "I-don't-have-control-of-what-I-do" player.

[kayger12]

The thing is, my CDV is in. This means (to me) that, eventhough I have the CDV, I can still control the speed of the engagement, perhaps arguing against the CDV being such a bad "I-don't-have-control-of-what-I-do" player.

You only lose control of clutch engagement if you release it faster than the fluid can flow through the restricting hole.

If you're a slow shifter, the cdv won't make a difference.

If you go for a fast shift, it is impossible to control the clutch accurately with the cdv installed.

[nike001]

I've noticed rev-matching in lower gears is easier.

I REALLY love it because when creeping up to a light and it turns green, you're in between gears 1 & 2. 2 will bog it down and 1 will jerk. Now I can just slide it in to 1st with no jerking.

[kayger12]

I've noticed rev-matching in lower gears is easier.



100% agreed. When you need to get off the clutch faster than the cdv restriction allows, it is impossible to shift as smoothly or match as effectively as without it.

[Oli77]

You only lose control of clutch engagement if you release it faster than the fluid can flow through the restricting hole.

If you're a slow shifter, the cdv won't make a difference.

If you go for a fast shift, it is impossible to control the clutch accurately with the cdv installed.

Totally agree. And i guess that would be the third point as to why I don't want or need to do a CDV delete, I drive 95% in the city rarely needing faster shifts or engagements.

On faster or more rapid accelerations, the slipping clutch is annoying a bit.

[aurelius]

I would argue the more stop & go city driving you do, the more you'd appreciate CDV removal.

To the multiple variables argument earlier in the thread, I can report that in 2008, my E39 530i brake lines were flushed and the CDV was removed at a later date.

Did not have a place to do that kind of thing myself at the time. Therefore, all was done by my very thorough indie BMW shop.

Huge positive difference. I only wish I had 4 hands, so that I could rate CDV removal 4 thumbs up.

[wsmeyer]

I'm still mulling this around in my head trying to make sense of it. Please don't take any of it personally as even though it sounds like I am, I'm not implying that any of you are wrong in your observations. Just that there has to be some reason being overlooked that accounts for the difference in your experience vs mine.

I started drawing out diagrams and was even going to cut my CDV in half to show how it worked but I've already come across one potential culprit. I've read many forum threads about the CDV and heard it described as having a disc and spring inside, I've even seen a picture of one and you couldn't see through it as the disc was solid.

Here's mine:
3491

Not only does it have a hole in the center of the disc, there is no spring. The disc freely slides back and forth about 4mm. In you push the clutch pedal down, the disc slides into the 'on' position and the fluid flows around the disc and through the hole in the center and when I blow through it there is very little resistance. When the fluid is flowing the other direction, the disc slides into the 'closed' position and fluid can only flow through the hole in the center and there is a noticeable amount of resistance.

My car is a 2006MY so while I still believe the valve is there to protect the drivetrain from forces greater than what would be encountered during even spirited driving, it's quite possible the design of the CDV was changed over time to address the adverse effects that some people experienced.

William.

[wsmeyer]

To the multiple variables argument earlier in the thread, I can report that in 2008, my E39 530i brake lines were flushed and the CDV was removed at a later date.

The brake lines and the clutch line share a common reservoir fill point but the actual reservoir and the hydraulic system for each are completely separate and bleeding one won't ave any effect on the other.


William.

[wsmeyer]

I don't think that a CDV delete is a deciding factor in having a destroyed engine or just a stalled one if your foot slips off the clutch on accident.

That being said, I just deleted mine and 1-2 shifts are awesome

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I've never actually seen the inside of an E46 transmission but my opinion is based on the observations of various other brands of transmissions and quite a number of years drag racing cars when I was younger.

In my observations watching the movement inside manual transmissions, the first 10% of lever travel is dead space, the next 30% is the synchros meshing, and the final 60% the engagement of the actual gears.

That combined with the fact that I have never seen a transmission fail at any any time other than during a shift leads me to the conclusion that if your clutch suddenly engages during the part of the travel that the synchros are meshing, either by a missed throttle on shift, or your foot slipping, your transmission is toast.

William.

[terraphantm]

Bumping an old thread...


So I get in the car and push the pedal to the floor, my buddy opens up the valve to let all the pressure out, and closes the valve. When I lifted my foot off the pedal and watched it come back up ever... so... slowly... I realized it was all a waste of time.


I'm surprised no one mentioned anything about this.. I think something is wrong with your car. Even before deleting the CDV in mine, the pedal came back up plenty quick - it would snap back hard if I were to just lift my foot off.

That said, when I deleted the CDV on my old ZHP, I can't say it was a night and day difference. It definitely did feel more precise, but it did not feel like I was missing something. Perhaps because I was still new to driving stick at the time. I did not bleed the clutch line at all - I didn't lose a single drop of fluid from my line (I clamped it really freaking tight), so I wasn't particularly worried. I did eventually rebleed it when I did my brakes at a later date. I felt no difference in the clutch.

Edit: Our clutches *do* have a return spring. Part # 8: http://realoem.com/bmw/showparts.do?model=BW53&mospid=47707&btnr=35_0186&hg=35&fg=05

[wsmeyer]

Bumping an old thread...




I'm surprised no one mentioned anything about this.. I think something is wrong with your car. Even before deleting the CDV in mine, the pedal came back up plenty quick - it would snap back hard if I were to just lift my foot off.

That said, when I deleted the CDV on my old ZHP, I can't say it was a night and day difference. It definitely did feel more precise, but it did not feel like I was missing something. Perhaps because I was still new to driving stick at the time. I did not bleed the clutch line at all - I didn't lose a single drop of fluid from my line (I clamped it really freaking tight), so I wasn't particularly worried. I did eventually rebleed it when I did my brakes at a later date. I felt no difference in the clutch.

I was explaining what happens to the clutch pedal while bleeding the line and after the valve had been opened and pressure in the line had been released. On the E46, there is no clutch pedal return spring. With or without the CDV what is pushing the pedal back up is the pressure plate pushing the fluid back through the line.

What I highlighted above in your quote is pretty much my whole point. I don't think under normal use it is possible to release the clutch fast enough for your foot to come off the pedal, which is what would happen if the CDV were restricting the fluid and delaying the clutch engagement.

William.

[terraphantm]

I was explaining what happens to the clutch pedal while bleeding the line and after the valve had been opened and pressure in the line had been released. On the E46, there is no clutch pedal return spring. With or without the CDV what is pushing the pedal back up is the pressure plate pushing the fluid back through the line.

What I highlighted above in your quote is pretty much my whole point. I don't think under normal use it is possible to release the clutch fast enough for your foot to come off the pedal, which is what would happen if the CDV were restricting the fluid and delaying the clutch engagement.

William.

Look at the link in my edit. There is a return spring.

[Vas]

I am looking forward to removing mine. And I thought i might as well replace the factory clutch line since its fairly cheap and bleed the system.

[ryankokesh]

This is pretty embarrassing, but I'm not even sure if mine's in there still! :ducking


Sent from my iPhone using Tapatalk

[Rovert]

LOL

[2004_blue_zhp]

For a CDV delete for a non-mechanically-inclined owner, what do you guys suggest? Would your average independent show know what you were talking about if you waltzed in and said "please remove my CDV"? If you took your car into a BMW dealer and asked them to do it, would they (my car is fully out of warranty)?

I know this is about as easy as a mod gets. But I don't have the tools or the space to do it myself.

[danewilson77]

For a CDV delete for a non-mechanically-inclined owner, what do you guys suggest? Would your average independent show know what you were talking about if you waltzed in and said "please remove my CDV"? If you took your car into a BMW dealer and asked them to do it, would they (my car is fully out of warranty)?

I know this is about as easy as a mod gets. But I don't have the tools or the space to do it myself.

I don't know if they would know what you are talking about and even then, I'm not sure they would know to not introduce air with a possible bleed afterwards.

Sent from Williamsburg, VA USA

[JupiterBMW]

Tough to say in terms of the dealer... I honestly doubt they would do it. My dealer wouldn't even help me bleed my ABS unit because I had "aftermarket" brakes on the car (drilled rotors and SS brake lines)...

As for an independent shop, yes, that's possible. I assume you know that the CDV is the clutch delay valve. They might not know the acronym at first guess... Your other option is to find some local members of the Mafia and see about trading some help for a few beers?? Where are you located? If you were in South Florida, I'd do it for you.

[kayger12]

I can't imagine the dealer would do it.

Your best option would be to either find an indy or member nearby who's willing to do it.

[2004_blue_zhp]

Fair to say that this is like 20 minutes worth of work if you've got the right tools/lift/jack?

[kayger12]

Fair to say that this is like 20 minutes worth of work if you've got the right tools/lift/jack?

Yep. It's quick and straight forward.

Biggest pita for me was getting a wrench on the bleed screw for the clutch.

Sent from my kick-A Galaxy S3

[cakM3]

I can't imagine the dealer would do it.

Your best option would be to either find an indy or member nearby who's willing to do it.

Keith, I got my dealer to remove my CDV on my ///M... wasn't an issue since the car was no longer under factory warranty. I'm sure since these cars are no longer under factory warranty, this shouldn't be a problem. The next time I take my ZHP in for a checkup, I will be having this done when I change out my factory clutch line with a ss line...;)

[kayger12]

Keith, I got my dealer to remove my CDV on my ///M... wasn't an issue since the car was no longer under factory warranty. I'm sure since these cars are no longer under factory warranty, this shouldn't be a problem. The next time I take my ZHP in for a checkup, I will be having this done when I change out my factory clutch line with a ss line...;)

That makes sense, Charlie. Good info.

[Dave_B]

So... I wish I would have seen this when I was under the car last weekend changing oil.

You guys still recommend doing this? I've got all the tools and skill to do it. If it's truly just that simple, I'll do it this weekend.

Thoughts after all this debate?

[BavarianZHP]

It's a consensus to do the CDV delete. I've gotten kind of used to it though. Like someone said earlier, if you shift from 1->2 right at 2k it's smooth as buttah. I'm still having trouble going from 2->3 though, so I may just get rid of it myself as well.

[Vas]

I just did the CDV on my zhp. Very easy to do and worth it and clutch feels great.

[Torxuvin]

You should do a clutch stop too while you are at it. :)

[wsmeyer]

I still have yet to hear a reason for removing it that is mechanically sound.

[Vas]

never got the point of that clutch stop. Any good driver should know where the engagement point is.

[Dave_B]

It's a consensus to do the CDV delete. I've gotten kind of used to it though. Like someone said earlier, if you shift from 1->2 right at 2k it's smooth as buttah. I'm still having trouble going from 2->3 though, so I may just get rid of it myself as well.

I guess I'm one of those that can't shift that low. LOL Brainwashed previous honda driver here...



You should do a clutch stop too while you are at it. :)

Details/Link?

[Torxuvin]

I guess I'm one of those that can't shift that low. LOL Brainwashed previous honda driver here...




Details/Link?
DIY method
http://forum.e46fanatics.com/showthread.php?t=206363
UUC
http://www.turnermotorsport.com/p-3807-uuc-clutch-stop.aspx
I have a strange one in my car that I don't recognize. Like a large metal plate with a rubber pad. Works though. :)

[kayger12]

So... I wish I would have seen this when I was under the car last weekend changing oil.

You guys still recommend doing this? I've got all the tools and skill to do it. If it's truly just that simple, I'll do it this weekend.

Thoughts after all this debate?

Absolutely worth doing.


You should do a clutch stop too while you are at it. :)

And this.

[derbo]

I still have yet to hear a reason for removing it that is mechanically sound.

If you suck at engagement, the clutch wear will increase?

If you shift too hard, the shock to the diff bushings will wear out prematurely?

Thats all I the BS i can think of :)

[Dave_B]

DIY method
http://forum.e46fanatics.com/showthread.php?t=206363
UUC
http://www.turnermotorsport.com/p-3807-uuc-clutch-stop.aspx
I have a strange one in my car that I don't recognize. Like a large metal plate with a rubber pad. Works though. :)


So the point is to only shorten the travel of the clutch pedal?

My concern here is that you'd not be fully engaging and disengaging the clutch disk. Or does it go a lot farther than I'm thinking in my mind?

[Mtnman]

So the point is to only shorten the travel of the clutch pedal?

My concern here is that you'd not be fully engaging and disengaging the clutch disk. Or does it go a lot farther than I'm thinking in my mind?

Yes. It does. A lot further.

[Vas]

You shorten the travel so it only goes to the engagement point and not any further. By doing this you can shift faster like the fast and furious guys.

IMO its a handicap for people

[derbo]

So the point is to only shorten the travel of the clutch pedal?

My concern here is that you'd not be fully engaging and disengaging the clutch disk. Or does it go a lot farther than I'm thinking in my mind?


To me a clutch stop sounds like the equivalent of training wheels on a bicycle...It sounds like a clutch stop's purpose is to prevent your leg to go beyond the engagement point when shifting. I don't put my leg beyond the engagement much anymore after getting used to where it is.

Maybe I'm not getting it the purpose right...Can Anyone enlighten me on the benefits?

[Vas]

That is the point of the clutch stop.

[Torxuvin]

There is a bunch of dead space between the floor and the clutch being engaged. The clutch stop just removes some of the dead space.

[kayger12]

never got the point of that clutch stop. Any good driver should know where the engagement point is.

Has nothing to do with knowing where the engagement point is for me.

It has to do with having the exact same distance of travel from disengagement to engagement every time with a minimal amount of travel.

Without it there is a ridiculous amount of travel from the floor to the engagement point (in my car anyway).

I would never want to go back to not having one in this car.

Sent from my kick-A Galaxy S3

[Torxuvin]

Has nothing to do with knowing where the engagement point is for me.

It has to do with having the exact same distance of travel from disengagement to engagement every time with a minimal amount of travel.

Without it there is a ridiculous amount of travel from the floor to the engagement point (in my car anyway).

I would never want to go back to not having one in this car.

Sent from my kick-A Galaxy S3

+1 Not to mention it gives both of my 6 speeds a very similar engagement point. Makes life easy.

[kpro]

I've done mine and 2 others, never had to bleed anything. put a pair of vice grips on the soft line before you take it off and then just put the hard line and soft line together without taking too much time and there shouldn't be a need to bleed it.

[Vas]

I can see both sides to the clutch stop however I know exactly where that point is so I don't need a stopper there.

BTW my engagement point is different then.

[derbo]

Has nothing to do with knowing where the engagement point is for me.

It has to do with having the exact same distance of travel from disengagement to engagement every time with a minimal amount of travel.

Without it there is a ridiculous amount of travel from the floor to the engagement point (in my car anyway).

I would never want to go back to not having one in this car.

Sent from my kick-A Galaxy S3

It sounds like you hit the bottom of the clutch stop everytime you shift in order to say the clutch stop is beneficial for a perfect engagement everytime?


So in order to benefit from the clutchstop, you need to hit the clutch stop everytime to make sure you reach the perfect engagement?


Currrently, I just push in the clutch enough to disengage the clutch and then shift. I never seem to go beyond the engagement point where I felt a clutch stop would be beneficial?

I still don't see the need for it. :( I guess it takes the thinking out of figuring out where the engagement point is?

[Vas]

^ +1

[wsmeyer]

I can explain the clutch stop with a few quick graphs:

7039

Reducing pedal travel is the over simplified answer.

Without a clutch stop you can either slow down and stop in mid air (A), or push the pedal down as fast as possible till it hits the floor (B).

The best of both is a clutch stop adjusted to just past the engagement point because you are reducing travel distance but still able to hit the stop at full speed.

[derbo]

Wsmeyer,

Thank for the graphs. It seems this will only benefit if you are slamming your foot to the floor (clutch stop) to shift.

[wsmeyer]

Wsmeyer,

Thank for the graphs. It seems this will only benefit if you are slamming your foot to the floor (clutch stop) to shift.

Correct, but if you compare A&B your choice is higher velocity and long travel, or shorter travel but having to slow down and stop in mid air. If you wanted to figure out which was faster you'd have to know how much extra travel in B.

If you adjusted the clutch stop to the same stop point as in A then with the clutch stop will always be faster as you don't have to slow down in mid air. You'll be pushing the pedal down as fast as possible and hitting the stop at maximum velocity.

The other benefit is that this movement is much easier to do repetitively without being effected by sudden elevation changes, bumps, or even fatigue.

[derbo]

Thanks for the insight.

I see where a clutch stop would see to improvement engagement. I can see myself overshooting my leg and feel like my leg is hitting a bricked wall when I hit the clutch stop..LOL..

[wsmeyer]

I see where a clutch stop would see to improvement engagement. I can see myself overshooting my leg and feel like my leg is hitting a bricked wall when I hit the clutch stop..LOL..

I hear ya. I've never perfected the heel-and-toe so when I do it with the ball of my foot the shock is absorbed by ankle movement. Doing it with your heel in a real racecar with no padding on the seat might be a different story but then again, it's just going to be one of many things beating you up lap after lap.

[derbo]

I hear ya. I've never perfected the heel-and-toe so when I do it with the ball of my foot the shock is absorbed by ankle movement. Doing it with your heel in a real racecar with no padding on the seat might be a different story but then again, it's just going to be one of many things beating you up lap after lap.


All i know is, during HPDE, fatigue isn't a major deal yet since most sessions are 20-25minutes long. I think when I start trying out longer endurance races I can see the clutch stop being beneficial but I seem to be doing just fine without it right now :)


BUT BACK ON TOPIC,

CDV delete is a MUST.

[wsmeyer]

BUT BACK ON TOPIC,

CDV delete is a MUST.

Lol. Until someone can give me an explanation that doesn't break the definition of a hydraulic system, rely on something that a restrictor valve is incapable of, or the laws of physics my opinion stands:

If you're not side stepping your clutch or releasing it so fast that your foot is coming off the pedal, removing the CDV is a complete waste of time.

[Avetiso]

I'm just fine with mine in. Once I got used to it, I just drop it when shifting. If you wait til the right moment, you can drop the clutch as fast as you want and it'll be smooth. At least that is what I do.

Sent from my SPH-L710 using Tapatalk 2

[derbo]

Lol. Until someone can give me an explanation that doesn't break the definition of a hydraulic system, rely on something that a restrictor valve is incapable of, or the laws of physics my opinion stands:

If you're not side stepping your clutch or releasing it so fast that your foot is coming off the pedal, removing the CDV is a complete waste of time.

LOL.

Please enlighten me on your opinion on why the CDV should stay in the car as I'm very curious.

Personally, I like the way the clutch engages without the CDV. It feels more direct and almost feels like there is more driver control over the way the clutch engages.

[Hornung418]

My car came from the factory with out a CDV. It's just another nanny devised by BMW so the average owner can drive it with out having to be precise or technical in their clutch releases.

From a GS3, this was sent.

[aurelius]

As others have reported, neither of the manual E46 330's I've owned had a CDV. But there was one on my manual E39 (M54 motor) and I can vouch for its removal as the single best bang for the buck in terms of drive train improvement. Specifically in terms of eliminating the annoyance factor where low speed, first gear driving is concerned. Especially on any kind of incline.

I suspect those with such strong opinions about leaving a CDV in place may in fact not even have one at all.

[Dave_B]

As easy as it sounds, I may jack up the car this weekend and just remove it. If I don't like it, I lose what? 20 minutes of my time reinstalling it?

As for the CDV delete and clutch stop... I'd like to hear from those who track their cars and specifically those who heel - toe. I find myself doing this on the street, purely out of habit after years of doing so on track. Fortunately for me, the BMW facility is about 10 minutes from my house and the local CCA chapter gets to use their short course frequently so I see myself doing that for a bit before fully going out for a weekend at CMP.

I guess I can see both sides of the CDV delete here. If you force yourself to get used to it and it's the norm then no worries. For me, coming from a different manufacturer the clutch to me feels "odd" and my 1-2 shifts are no where near perfect and I've been driving a manual trans for quite some time. I'm sure it's a new car thing too there, but I'll end up doing it since it's simple enough and almost no cost to it and I'll report back after this weekend.

[danewilson77]

No risk of not liking it brutha.

[derbo]

As easy as it sounds, I may jack up the car this weekend and just remove it. If I don't like it, I lose what? 20 minutes of my time reinstalling it?

As for the CDV delete and clutch stop... I'd like to hear from those who track their cars and specifically those who heel - toe. I find myself doing this on the street, purely out of habit after years of doing so on track. Fortunately for me, the BMW facility is about 10 minutes from my house and the local CCA chapter gets to use their short course frequently so I see myself doing that for a bit before fully going out for a weekend at CMP.

I guess I can see both sides of the CDV delete here. If you force yourself to get used to it and it's the norm then no worries. For me, coming from a different manufacturer the clutch to me feels "odd" and my 1-2 shifts are no where near perfect and I've been driving a manual trans for quite some time. I'm sure it's a new car thing too there, but I'll end up doing it since it's simple enough and almost no cost to it and I'll report back after this weekend.



Dave,

When I heel toe without the CDV, I noticed I don't have to leave my foot near the engagement point as long as if it was still in. I can lift my foot off the clutch pedal a lot faster during downshifts at the track. The major difference I feel is that I used to leave my foot around the engagement point while downshifting to make sure the clutch engaged before lifting my foot off while with the CDV removed I feel like I can remove my foot faster. This could be just a preference thing coming from the old Hondas I used to drive. I love it without the CDV.

[Stewbie]

The previous owner removed the CDV from my car, so I have no basis of comparison. However, my buddy has a 320i and complained about the CDV in his car long before I bought my ZHP. After I got my ZHP, I let him drive it and he loved the clutch. Within a month or two he had taken his 320i to the independent shop and got them to remove the CDV from his car. He loves his clutch now. His problem with the CDV was in low speed maneuvering, like backing uphill into a parking spot where throttle alone is not enough to control your speed, not with normal driving.

[Dave_B]

Dave,

When I heel toe without the CDV, I noticed I don't have to leave my foot near the engagement point as long as if it was still in. I can lift my foot off the clutch pedal a lot faster during downshifts at the track. The major difference I feel is that I used to leave my foot around the engagement point while downshifting to make sure the clutch engaged before lifting my foot off while with the CDV removed I feel like I can remove my foot faster. This could be just a preference thing coming from the old Hondas I used to drive. I love it without the CDV.

That right there is what I needed to know. :)

[kayger12]

I moved wsmeyer's posts to a new thread here. (http://www.zhpmafia.com/forums/showthread.php?8918-CDV-Hydraulics-Explained)