Newbie Questions: 1st,2nd Shift Jerkiness and clunk?

XMetal · 12-05-2012, 11:12 AM

All I can say is that this car is an absolute blast to drive, but not very pleasant to be a passenger

Even when I do a smooth shift, I still see my passenger's head bob

RichardTS · 12-10-2012, 12:55 PM

Quote:

Originally Posted by MFGJR

Yep, has the !@#$ing CDV.

Step 1 - remove CDV

Step 2 - bleed slave cylinder thoroughly

Step 3 - install a clutch stop to take up any excess travel in the pedal

Step4 - install firmer transmission mounts

Still, you'll need to be a bit patient with the 1-2 shift

Well, I am going to be the spoiler here. I have been driving manuals for almost 40 years and bought my M new after driving British sports cars for 35 years.

1. I have NEVER had a problem with the CDV.
2. Clutch stops are absolute BS. You need to press the clutch all the way to the floor EVERY time you shift. If you don't hear a thump when the pedal hits the floor you're not getting there.
3. If you practice you do not need firmer mounts. You only need those with serious racing efforts.

Food for thought - our clutches are hydraulic and the master cylinder and slave cylinder work together to provide the mechanical leverage that makes driving the car reasonably easy. This translates to the fact that a LOT of pedal movement results very little pressure palte movement. In fact the pressure plate is only lifted form the disc enough to let it spin free.

Installing a clutch stop causes the lever to be shorter. And what does this do? It causes the pressure plate to not lift as far off the clutch disc. So far this sounds like a good thing but it is a bad thing if reduced to so short that the clutch disc is still slightly touching the pressure plate. A great illustration of this is a car with a weak hydraulic system with a clutch that does not fully disengage. And what are the symptoms of a weak hydraulic system? A crunch everytime you shift...

And yes, the M is a bit tricky but you CAN learn how..

strokeoluck · 12-10-2012, 02:03 PM

Quote:

Originally Posted by RichardTS

Well, I am going to be the spoiler here.

Well...now I'm second guessing whether I should install the clutch stop doo-hickey.

I will say, working this clutch - particularly in the city - is great exercise for the left leg calf muscle!

johanness · 12-10-2012, 02:22 PM

Quote:

Originally Posted by MFGJR

Yep, has the !@#$ing CDV.

Step 1 - remove CDV

Step 2 - bleed slave cylinder thoroughly

Step 3 - install a clutch stop to take up any excess travel in the pedal

Step4 - install firmer transmission mounts

Still, you'll need to be a bit patient with the 1-2 shift

Do this. You'll find things improve significantly.

As far as the above comments re: clutch stop... It takes up the excess travel - so yes, it does work very well in conjunction with everything said here. Generally, people who say otherwise haven't taken the steps discussed. In our specific cars CDV delete, tranny mounts, clutch stop, & ZHP (weighted) knob should almost be mandatory.

silverfishZ4M · 12-10-2012, 02:41 PM

whew, I didn't want to be the first one to say it but I have no problem with 1st-2nd gear shifts either.

Finnegan · 12-10-2012, 03:08 PM

RichardTS--Good points.

Those who don't have issues may actually be driving a car with a CDV delete or a modified Zeckhausen CDV. Unless your the original owner, there's no way to tell w/o looking--the only telltale sign would be a missing CDV. (The idea with the Zeckhausen CDV was to make it "look stock" during the warranty period to avoid any potential hassles--not that I know of anyone who had those mind you.)

If the clutch stop is too aggressive, yes, it can cause (clutch and synchro wear). If it's used sensibly to take up what seems like an inordinate amount of room past any part of engagement (plus allowing a tiny bit of "slack" on top of that), there should be no issues. Once installed in that manner, then yes, you've got to go all the way to the stop of you risk the issues mentioned.

The problem with the CDV is that is restricts hydraulic flow and the speed that the clutch engages. That results in a somewhat variable engagement point from engagement "feel" perspective. If you move more quickly and have a non-linear engagement path with your foot (e.g. faster, then slower at engagement point), the CDV is going to intervene and limit the rate throwing off the driver's inputs. Assuming the driver has some skill, it just gets in the way and actually causes extra wear (not to mention a horrible loss of control/feel). Yes, you can learn to live with it, but why do that, along with added wear, if there's a way to get better feel/control?

Firmer mounts provide better shifter feel, and racing or no racing, going 3rd to 2nd even on the street can be denied from time to time in ordinary driving. As long as the replacements are neoprene and not urethane, it really doesn't add any noticeable NVH (if the bolts are over torqued however, it will). Stock mounts are exactly the same part # for the 2.5, 3.0, 3.0SI, and M. The HP/TQ of these models varies greatly. What may be find for a 2.5 isn't necessarily optimal for the 3.0 or the M.

RichardTS · 12-11-2012, 07:23 AM

Quote:

Originally Posted by Finnegan

RichardTS--Good points.

Those who don't have issues may actually be driving a car with a CDV delete or a modified Zeckhausen CDV. Unless your the original owner, there's no way to tell w/o looking--the only telltale sign would be a missing CDV. (The idea with the Zeckhausen CDV was to make it "look stock" during the warranty period to avoid any potential hassles--not that I know of anyone who had those mind you.)

If the clutch stop is too aggressive, yes, it can cause (clutch and synchro wear). If it's used sensibly to take up what seems like an inordinate amount of room past any part of engagement (plus allowing a tiny bit of "slack" on top of that), there should be no issues. Once installed in that manner, then yes, you've got to go all the way to the stop of you risk the issues mentioned.

The problem with the CDV is that is restricts hydraulic flow and the speed that the clutch engages. That results in a somewhat variable engagement point from engagement "feel" perspective. If you move more quickly and have a non-linear engagement path with your foot (e.g. faster, then slower at engagement point), the CDV is going to intervene and limit the rate throwing off the driver's inputs. Assuming the driver has some skill, it just gets in the way and actually causes extra wear (not to mention a horrible loss of control/feel). Yes, you can learn to live with it, but why do that, along with added wear, if there's a way to get better feel/control?

Firmer mounts provide better shifter feel, and racing or no racing, going 3rd to 2nd even on the street can be denied from time to time in ordinary driving. As long as the replacements are neoprene and not urethane, it really doesn't add any noticeable NVH (if the bolts are over torqued however, it will). Stock mounts are exactly the same part # for the 2.5, 3.0, 3.0SI, and M. The HP/TQ of these models varies greatly. What may be find for a 2.5 isn't necessarily optimal for the 3.0 or the M.

Good points as well.

One of the more obscure points about excessive travel is that, more than likely, the slight excessive travel is built in to accomodate wear. As we drive the clutch plate wears, the the seals in the hydraulic system leak a tiny bit around the edges and, last but not least, the bushings and clevis pins in the clutch pedal wear. All of this wear is additive. And conspires to reduce the pressure plate travel through slack.

Now, while I agree somewhat with the excessive travel, I have two points to consider:

1. How do you measure excessive travel? How do you tell the precise point which is just right? Since there is a bell housing in the way and I don't have x-ray vision I can't tell. And I don't buy any measurement on the outside as being reliable because, while you can feel the beginning of disengagement the point of true and complete disengagement is nebulous at best.
2. How do you tell when all of the excessive travel has been taken up with wear? How do you know when the clutch stop should be removed during the clutch wear cycle? Unfortunately that usually happens when you start feeling the crunch...

While I love to do anything that will make my car go faster, I also want my car to last a long time. And I want the clutch to last a long time. I suppose my cautions are born from past experience. As a long time owner of British sports cars, I can tell you that a clutch in one of those lasts 50-60K only. And most of them require the engine to be pulled to do it.

My dealer told me it takes about 6 hours to replace the clutch in an M. On top of the clutch price itself, this makes worrying about longevity a priority with me that extends all the way to putting the car in neutral and taking my foot off the clutch at red lights. Every single second counts on the way to the clutch's inevitable demise. Not a question of if - a question of when. And I want the 'when' to be a long way off.

inTgr8r · 12-11-2012, 08:04 AM

Quote:

Originally Posted by Finnegan

...
Those who don't have issues may actually be driving a car with a CDV delete or a modified Zeckhausen CDV. Unless your the original owner, there's no way to tell .....

......

^happened with my coupe

bosstones · 12-11-2012, 08:12 AM

I don't have a clutch stop and also still have my CDV and stock mounts in. I don't have the complaints others have. I get an occasional un-smooth shift, but it's no where near "MT newbie" rough.

The clunk/chatter is normal. Higher revs is where the car wants to be...shifting 1-2 is a lot smoother there. Obviously, that can be a problem in rush hour. When slower acceleration is in order, the timing of clutching in/out, throttle, and shifting is a little different...slightly slower/delayed is as best I can describe it without hopping in the car and paying attention to it. The timing is just a little different. Also, remember that our cars have a 'notchy' shifter. Weak handing it won't work too well.

XMetal · 12-11-2012, 12:36 PM

Does anyone noticed that this car also wants you to pull the lever very quickly from 1st into 2nd? If I'm lazy on that action from 1st to 2nd, I would sometimes get a "crunch" feel at 2nd.

johanness · 12-11-2012, 03:27 PM

RichardTS... You're going to wear your clutch more by keeping your stock CDV than you ever will worrying about the last 1/2 inch of free-play on your clutch pedal (i.e. clutch stop)

EenyBear · 12-11-2012, 04:49 PM

Quote:

Originally Posted by RichardTS

Well, I am going to be the spoiler here.

I am intrigued. Is it possible you have a 2008 owned since new? Perhaps there is a difference there (any definitive comments from a BMW insider?). If you have a used Z4M, perhaps you have mods to your CDV you are not aware of (mine looks stock but is a spoof part from Zeckhausen). Or perhaps you have a rare example that works perfectly out of the gate. I do not think, however, that years of experience with manual clutches (which we share, by the way) can explain away the need for many car owners to seek relief from Z4M shifting quirks.

Of all the things I have tried to smooth out the shifting, the clutch stop is the most effective ... and the least expensive ... and the easiest to experiment with.

In my case, when I press the pedal to disengage the clutch, there is sufficient free play remaining so I am confident that there is no internal rubbing - no creeping forward or even an RPM drop that would signal partial engagement. There is so much excess free play that it bears consideration to remove most of it with a stop adjustment. As a backup, I also trust that the car will not start until the clutch is disengaged and that appears to be the case (I have not monkeyed with the magnet switch).

Every car is different, I understand this and admit it freely, but a significant number on this board have tried and succeeded with a clutch stop.

As for the CDV, I know that I was risking premature clutch failure with that nanny-device still in place (not to mention soft tissue neck injury and near-fatal embarrassment for failing to drive in a controlled manner).

Even BMW mechanics have quietly confirmed the wisdom of the CDV removal although they will not do it themselves (of course). My independent mechanic took one look at my spoof Zeckhausen "CDV" and said "... that's the first thing to go..." and was delighted to hear it was already gone.

As for tranny mounts and Royal Purple fluid... meh. I can't say if it made a tangible difference but it certainly did no harm and I'm happier having done it.

I want my car to shift and re-engage when I want it to do so. This has been accomplished with the above mentioned modifications. That's good enough for me. On the other hand, I am pleased to hear that you are satisfied in not having to spend the money and time to do the same.

Thank you for your insights.

RichardTS · 12-12-2012, 07:17 AM

Quote:

Originally Posted by EenyBear

I am intrigued. Is it possible you have a 2008 owned since new? Perhaps there is a difference there (any definitive comments from a BMW insider?). If you have a used Z4M, perhaps you have mods to your CDV you are not aware of (mine looks stock but is a spoof part from Zeckhausen). Or perhaps you have a rare example that works perfectly out of the gate. I do not think, however, that years of experience with manual clutches (which we share, by the way) can explain away the need for many car owners to seek relief from Z4M shifting quirks.

Of all the things I have tried to smooth out the shifting, the clutch stop is the most effective ... and the least expensive ... and the easiest to experiment with.

In my case, when I press the pedal to disengage the clutch, there is sufficient free play remaining so I am confident that there is no internal rubbing - no creeping forward or even an RPM drop that would signal partial engagement. There is so much excess free play that it bears consideration to remove most of it with a stop adjustment. As a backup, I also trust that the car will not start until the clutch is disengaged and that appears to be the case (I have not monkeyed with the magnet switch).

Every car is different, I understand this and admit it freely, but a significant number on this board have tried and succeeded with a clutch stop.

As for the CDV, I know that I was risking premature clutch failure with that nanny-device still in place (not to mention soft tissue neck injury and near-fatal embarrassment for failing to drive in a controlled manner).

Even BMW mechanics have quietly confirmed the wisdom of the CDV removal although they will not do it themselves (of course). My independent mechanic took one look at my spoof Zeckhausen "CDV" and said "... that's the first thing to go..." and was delighted to hear it was already gone.

As for tranny mounts and Royal Purple fluid... meh. I can't say if it made a tangible difference but it certainly did no harm and I'm happier having done it.

I want my car to shift and re-engage when I want it to do so. This has been accomplished with the above mentioned modifications. That's good enough for me. On the other hand, I am pleased to hear that you are satisfied in not having to spend the money and time to do the same.

Thank you for your insights.

Mine is a 2006 and I bought it new off the dealer lot in Nov. 2007 for a steal. It currently has 55K on the clock.

You may or may not have seen earlier posts a couple years ago about this same subject. When I bought this car new and after I drove it for about a year I was surprised to see that it actually takes about 10K miles to truly break it in. This includes the gearbox. It took mine the full 10K to ease up on the crunch and it still does it from time to time.

But I need a true (not anectdotal) explanation from everyone here how keeping the CDV in wears out the clutch. This thing is only an orifice that reduces the flow velocity. The only thing that can happen when reducing the flow velocity is delayed engagement and clutch slip while under power, neither of which have I ever experienced. No matter how fast I shift, the clutch engages as sharply as I shift.

Without slip there can be no wear...

And yes, as much as everyone else here, I too get the 'bunny hop' as my wife calls it when shifting from 1st to 2nd.

EenyBear · 12-12-2012, 01:33 PM

From one enthusiast to another, I fully appreciate your hesitation and reluctance to accept anecdotal evidence. It may be appropriate to contact Zeckhausen and ask them to defend their claims expressed here:
http://zeckhausen.com/cdv.htm

You may find that a CDV delete virtually eliminates the occasional bunny hop as it has for many here. You can always reverse it if it does not suit your driving style. According to some experts here, BMW did not place the optimum transmission in the Z4M and the CDV is a factory work-around. At the very least, this is plausible.
http://store.zeckhausen.com/catalog/...roducts_id=276

I freely admit, based on advice I received in the forum and then matching my experience to the claims on the website above... I took the claims at face value. Notwithstanding this, I am satisfied with the results.

At the risk of beating a dead horse on the related point, the clutch stop experiment would cost $10 and may provide you with a surprise experience as well.
http://www.ebay.com/itm/BMW-Clutch-S...item35bdfa39ca

Kindest regards,
Ian

Finnegan · 12-12-2012, 01:40 PM

^WHS. Great post.

beta · 12-12-2012, 02:35 PM

Quote:

Originally Posted by EenyBear

You may find that a CDV delete virtually eliminates the occasional bunny hop as it has for many here.

I have to chime in, I've learnt to deal with it and do not get any hopping, on both regular and hard starts. The technique involves pulling out the clutch quickly and then pausing it at the right spot, then letting out slowly the last little bit. It's tricky to describe, but can be learned.

My biggest concern, and the reason I haven't removed mine, is what is the possibility of long-term damage? If I'm injured or sick, and my girlfriend has to drive me to the hospital, will she cause damage by removing this part?

No one is arguing that it isn't better and no one is ever going to put it back on because it feels better. What we don't know (and probably will never know unless we get an insider) is why BMW keeps installing these. It could be just to prevent bad driving/dropping clutches/etc., it could be some other metric of long-term usage. But they keep installing these even in current models.

As for the clutch stop: best mod ever. I don't worry about the safety of it, because we know how conservative bmw is (case in point the cdv). So as long as you're past the relay switch that allows you to start the car, bmw determined that the clutch, at that point of engagement, is safe. As long you depress the clutch fully before shifting your'e golden.

I might end up removing the CDV, but I want to see 100k miles without it before I do

Conservative? yes, I fully admit it.

EenyBear · 12-12-2012, 03:12 PM

Quote:

Originally Posted by beta

If I'm injured or sick, and my girlfriend has to drive me to the hospital, will she cause damage by removing this part?

My wife, an expert sports car driver, was over the moon with joy as soon as I pulled the CDV. The clutch engagement was, as she put it, so much more predictable. Happy wife, happy life.

Quote:

Originally Posted by beta

But they keep installing these even in current models.

I am reminded of the god-awful hum that continues to be part of the single-coil Fender Stratocaster guitar experience. This is easily remedied without any loss of the tone-mystique of that particular Fender guitar. Why do they continue? Because Leo did it that way.

In fairness, more recent models include shielding and other pickup modifications that I (and others) have been suggesting for years.

Here's a little hobby of mine...
http://www.stocklogic.com/nohum/

Quote:

Originally Posted by beta

As for the clutch stop: best mod ever. I don't worry about the safety of it, because we know how conservative bmw is (case in point the cdv). So as long as you're past the relay switch that allows you to start the car, bmw determined that the clutch, at that point of engagement, is safe.

Preaching to the choir, brother.

Finnegan · 12-12-2012, 04:01 PM

BMW has stopped installing these on the E92 M3 forward. At least with the M3, EAS and Zeckhausen confirmed it.

Zeck doesn't make one for the 1M, E9x M3, etc. They just don't have the product for the newer MYs.

My conclusion: either it's not necessary, or BMW got tired of us enthusiasts yanking the little ***tards out anyway and just decided to omit them.

12-05-2012, 11:12 AM	#23
XMetal Colonel 1130 Rep 2,864 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	All I can say is that this car is an absolute blast to drive, but not very pleasant to be a passenger Even when I do a smooth shift, I still see my passenger's head bob
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12-10-2012, 02:41 PM	#27
silverfishZ4M Second Lieutenant 6 Rep 247 Posts Drives: 2007 Z4M Coupe Join Date: Sep 2012 Location: US iTrader: (0)	whew, I didn't want to be the first one to say it but I have no problem with 1st-2nd gear shifts either.
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12-10-2012, 03:08 PM	#28
Finnegan Dog Listener 701 Rep 7,850 Posts Drives: Z4M/. Z3M, E36/46 M3 Join Date: Oct 2008 Location: Teaching the dog to slalom iTrader: (22)	RichardTS--Good points. Those who don't have issues may actually be driving a car with a CDV delete or a modified Zeckhausen CDV. Unless your the original owner, there's no way to tell w/o looking--the only telltale sign would be a missing CDV. (The idea with the Zeckhausen CDV was to make it "look stock" during the warranty period to avoid any potential hassles--not that I know of anyone who had those mind you.) If the clutch stop is too aggressive, yes, it can cause (clutch and synchro wear). If it's used sensibly to take up what seems like an inordinate amount of room past any part of engagement (plus allowing a tiny bit of "slack" on top of that), there should be no issues. Once installed in that manner, then yes, you've got to go all the way to the stop of you risk the issues mentioned. The problem with the CDV is that is restricts hydraulic flow and the speed that the clutch engages. That results in a somewhat variable engagement point from engagement "feel" perspective. If you move more quickly and have a non-linear engagement path with your foot (e.g. faster, then slower at engagement point), the CDV is going to intervene and limit the rate throwing off the driver's inputs. Assuming the driver has some skill, it just gets in the way and actually causes extra wear (not to mention a horrible loss of control/feel). Yes, you can learn to live with it, but why do that, along with added wear, if there's a way to get better feel/control? Firmer mounts provide better shifter feel, and racing or no racing, going 3rd to 2nd even on the street can be denied from time to time in ordinary driving. As long as the replacements are neoprene and not urethane, it really doesn't add any noticeable NVH (if the bolts are over torqued however, it will). Stock mounts are exactly the same part # for the 2.5, 3.0, 3.0SI, and M. The HP/TQ of these models varies greatly. What may be find for a 2.5 isn't necessarily optimal for the 3.0 or the M.
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12-11-2012, 08:12 AM	#31
bosstones Lieutenant Colonel 1154 Rep 1,543 Posts Drives: o_0 Join Date: Mar 2008 Location: Suburbia iTrader: (0)	I don't have a clutch stop and also still have my CDV and stock mounts in. I don't have the complaints others have. I get an occasional un-smooth shift, but it's no where near "MT newbie" rough. The clunk/chatter is normal. Higher revs is where the car wants to be...shifting 1-2 is a lot smoother there. Obviously, that can be a problem in rush hour. When slower acceleration is in order, the timing of clutching in/out, throttle, and shifting is a little different...slightly slower/delayed is as best I can describe it without hopping in the car and paying attention to it. The timing is just a little different. Also, remember that our cars have a 'notchy' shifter. Weak handing it won't work too well. __________________ - Jeff bosstones' flickr Last edited by bosstones; 12-11-2012 at 08:17 AM..
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12-11-2012, 12:36 PM	#32
XMetal Colonel 1130 Rep 2,864 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Does anyone noticed that this car also wants you to pull the lever very quickly from 1st into 2nd? If I'm lazy on that action from 1st to 2nd, I would sometimes get a "crunch" feel at 2nd.
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12-11-2012, 03:27 PM	#33
johanness Banned 56 Rep 1,739 Posts Drives: 2008 Z4MC Join Date: Aug 2010 Location: Seattle, Vancouver iTrader: (3) Garage List 2008 BMW Z4M COUPE [7.00] 2012 BMW X1 xDrive 28i [9.00]	RichardTS... You're going to wear your clutch more by keeping your stock CDV than you ever will worrying about the last 1/2 inch of free-play on your clutch pedal (i.e. clutch stop)
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12-12-2012, 01:33 PM	#36
EenyBear Accidentally in BMW 15 Rep 221 Posts Drives: Z4MC & R1200S Join Date: Mar 2011 Location: Canada iTrader: (0)	From one enthusiast to another, I fully appreciate your hesitation and reluctance to accept anecdotal evidence. It may be appropriate to contact Zeckhausen and ask them to defend their claims expressed here: http://zeckhausen.com/cdv.htm You may find that a CDV delete virtually eliminates the occasional bunny hop as it has for many here. You can always reverse it if it does not suit your driving style. According to some experts here, BMW did not place the optimum transmission in the Z4M and the CDV is a factory work-around. At the very least, this is plausible. http://store.zeckhausen.com/catalog/...roducts_id=276 I freely admit, based on advice I received in the forum and then matching my experience to the claims on the website above... I took the claims at face value. Notwithstanding this, I am satisfied with the results. At the risk of beating a dead horse on the related point, the clutch stop experiment would cost $10 and may provide you with a surprise experience as well. http://www.ebay.com/itm/BMW-Clutch-S...item35bdfa39ca Kindest regards, Ian
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12-12-2012, 01:40 PM	#37
Finnegan Dog Listener 701 Rep 7,850 Posts Drives: Z4M/. Z3M, E36/46 M3 Join Date: Oct 2008 Location: Teaching the dog to slalom iTrader: (22)	^WHS. Great post.
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12-12-2012, 04:01 PM	#40
Finnegan Dog Listener 701 Rep 7,850 Posts Drives: Z4M/. Z3M, E36/46 M3 Join Date: Oct 2008 Location: Teaching the dog to slalom iTrader: (22)	BMW has stopped installing these on the E92 M3 forward. At least with the M3, EAS and Zeckhausen confirmed it. Zeck doesn't make one for the 1M, E9x M3, etc. They just don't have the product for the newer MYs. My conclusion: either it's not necessary, or BMW got tired of us enthusiasts yanking the little ***tards out anyway and just decided to omit them.
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