[MartinHattingh]

Hi all,

I have always noticed a bit of shudder/judder when releasing the clutch on take-off when driving normally, in parking areas, pulling away from stop streets etc. Up to now I have just fobbed it off as nothing to worry about, but on a long trip of +-1200km this weekend, it felt as if it got much worse later in the drive. My co-driver (we swopped halfway) also commented on this as feeling strange.

Has anyone else experienced clutch release from standstill inducing a shudder before it bites properly? I haven't felt it this badly in any previous manual car I've owned.

[Bob UK]

Likely the normal operation as the car has a dual mass flywheel, don't worry as if it does fail you will certainly know about it.

[donaldt]

I believe its the CDV, common first mod to stick BMW owners, get a bypass and you will get a much better response on the clutch
search online about it to see if this is what you are experiencing

[rickk]

In my experience, it's pretty common on BMWs if the clutch gets hot.. Both my E30 and E46 do it when I overheat the clutch, but I didn't notice it on my F21 yet.

I've made it standard practice to put the gearbox in neutral when stopped for more than a few seconds, this seems to avoid the issue 99% of the time.

[Bob UK]

Originally Posted by donaldt

I believe its the CDV, common first mod to stick BMW owners, get a bypass and you will get a much better response on the clutch
search online about it to see if this is what you are experiencing

But you feel the CDV pulsing as you put your foot on the pedal, not so much at the bite point. I have even reached down on the move and felt the pedal with my hand - it pulses with the slightest pressure. The CDV was a bad idea on the part of BMW imo.

[donaldt]

Originally Posted by Bob UK

But you feel the CDV pulsing as you put your foot on the pedal, not so much at the bite point. I have even reached down on the move and felt the pedal with my hand - it pulses with the slightest pressure. The CDV was a bad idea on the part of BMW imo.

CDV is the worse thing ever
the thing about it is that it delays everything including the biting
thats why I believe the abnormal behavior at the biting point is perhaps from the CDV
and you should still get rid of it no matter what

[Bob UK]

Originally Posted by donaldt

CDV is the worse thing ever
the thing about it is that it delays everything including the biting
thats why I believe the abnormal behavior at the biting point is perhaps from the CDV
and you should still get rid of it no matter what

I don't think BMW will like that with the car under warranty though.

[donaldt]

Originally Posted by Bob UK

I don't think BMW will like that with the car under warranty though.

there is a bypass valve that looks exactly the same

[Bob UK]

Originally Posted by donaldt

there is a bypass valve that looks exactly the same

Yeah but you just know the service would feel a "Normal" clutch operation and realise what had been done.

If I still have it outside of warranty it's something I'll do straight away.

[ovekvam]

I first drove a car with clutch delay valve a few years ago. It was an E46 Compact, and the delay was very annoying. I have however not noticed it at all on our F20. Either the delay must have been made less since then, or they forgot to install the device on our car.

[mowflow]

The CDV bypass valve is just a normal CDV valve with the internals knocked out. They only cost a few £s but you could just modify your own by removing it and knocking the internals out. I doubt very much that any tech would ever remove it and take a look.

[BenN]

Hi,

After reading your post I wondered if this could explain what feels like a jerky clutch on my 120d. I've never had any problems with other diesels before, both my old Golf 6 and our other car, seat Leon both had the same tdi cr 140 engines in and clutch operation was a breeze.

I just find the bite point abit unpredictable in the F20. It's hard to describe, but sometimes when you pull the clutch up the bite ends up being at a different point, which can cause a jerky gear change. I find its mainly at slower speeds in low gears or at low revs after a change. Coincidentally it appears to happen more in Eco pro mode than sport, so I'm pretty sure it's down to the throttle mapping. The low rev changes also seem to be those where gear im changing upto only ticks over at say just over 1k rpm (so little to no throttle being applied on the way up). The jerk rocks the car back and forth similarly to that when you engage the hand brake and release the foot brake. Has anyone else experienced this, or is this normal BMW behaviour? (First time owner here)

If I don't have too thick soled shoes on I can feel the bite point perfectly and there's no problem, it just becomes abit tiresome having to carefully pull the clutch up and feel for what appears to be a feel-less clutch pedal. My cars got 7.5k miles on now of that helps.

I'm fine in any other car I drive, the drivetrain doesn't feel faulty in this car either, so I'm hoping this is just one of those things!

Any tips on living with this (if its normal) would be greatly appreciated also? When on my own I tend to drive her a lot harder than when I have passengers. It's when I drive less aggressively that my passengers seem to have a harsher ride

Thanks,
Ben

[Bob UK]

It's all down to the Clutch Delay Valve (CDV) designed to limit stress placed on the drivetrain by popping the clutch with high revs. It's something you will gradually get used to but the vibrating pedal feel will always be there unless you fit a modified valve. Not sure if it's also there for the hill start assist which is quite useful in itself.

[ant234]

Its not just you Ben, but I too have been struggling at times with my 125i. Its been over 6 months and I still have a shocking gear change once in a while...

[rs-6]

maybe it is all between the ears, but sometimes I have the feeling that in sport-mode my throttle input is altered when downshifting. As a result I sometimes fail to rev-match perfectly. Anyone else noticed something similar? Or might it just be an effect of the CDV as well?

[ovekvam]

Originally Posted by rs-6

maybe it is all between the ears, but sometimes I have the feeling that in sport-mode my throttle input is altered when downshifting. As a result I sometimes fail to rev-match perfectly. Anyone else noticed something similar? Or might it just be an effect of the CDV as well?

On the 116i, the throttle response seems quicker (maybe only the pedal mapping) in Sport Mode than Comfort Mode, so the rev matching is not the same when downshifting. You need to push the throttle pedal further down, or keep it down longer in Comfort Mode. Even worse in Eco Pro. Makes it difficult to do heel-toe downshifts while braking.

I haven't noticed the CDV myself. If it is there, it is far less annoying than it was on E46.

[Bob UK]

As the name suggests when it's operating it is limiting the friction and so the torque put through the drivetrain at the bite point. The resultant feel is almost like the bite point varies making smooth 1st to 2nd shifts awkward, I'm starting to get the hang of it after 2 months but the chance of a less than stellar shift will always be there.

Just the price to pay for the other advances in these cars until something better is designed but you can always avoid it by getting an auto.

[westphone]

I have experienced some clutch "vibe" when accelerating really hard. Heard something like not well lubed spring from time to time, but everytime I drive to the dealer it stops

[BenN]

Originally Posted by rs-6

maybe it is all between the ears, but sometimes I have the feeling that in sport-mode my throttle input is altered when downshifting. As a result I sometimes fail to rev-match perfectly. Anyone else noticed something similar? Or might it just be an effect of the CDV as well?

The throttle response definitely changes between sport and Eco, if you sit the car still and blip the throttle you should instantly see the difference.

So does anyone have any tips for mastering a smooth yet fast shift with the CDV installed? I did some research on the CDV and I suppose it explains why there's a jerky shift every once in a while, since the clutch is still engaging after uve applied the throttle. You would have thought the system could have been engineered electronically, so that it plays with the throttle aswell. I'm sure that delaying the clutch can't be good for the car if its being driven hard and the driver applies throttle thinking the clutch has been released.

Does anyone know if it delays the clutch both engaging and disengaging?

Thanks,
Ben

[ovekvam]

The clutch delay valve is just a piece of clutch line with a smaller diameter. It can not delay the action when you push the pedal in, but it can delay the action when you let the pedal back out, depending on how stiff the spring plate is.